# A quick note on why car audio sucks.



## ErinH (Feb 14, 2007)

The little environment sucks for balanced response. This is nothing new. We already know this. But, since I had the RTA out, I figured I'd try a few things and in the process, capture my results with some words to go with it. 

So, to start with, my setup has been tuned very little over the past year and a half. A new baby, busy work/travel schedule, and life in general hasn't given me much free time. 

The low end has always given me fits, just like everyone else. It had a good sound to it on the low end but it wasn't perfect. I set out to correct a few things today and try a few other things (random placement of pillows, etc) to see what would happen.

What you see in the picture below is how my system was at the beginning.
*Note the thin lines[/B]. The black is the left side only. The red is the right side only. See the HUGE difference? Notice the major suckout around 71hz? Phase related distance issues combined with the crap in the car.










To make a long story short, let's skip all my experimenting and finding and get to the purpose of this thread....
Let's say you thought, "hey, no problem, I can EQ all that out". So, you go ahead and start boosting 63/80hz on the left side with your graphic EQ and you start cutting a few other things on the right side to match the response. You wind up getting something that looks pretty close to perfect (note the bold lines and how blue and red lines now match up):










Hey, it's GOT to sound good now, right? I mean, the two sides' response is nearly the exact same below 200hz. And, to think... all you had to do was boost the crap out of a few bands and cut a couple other ones. 
Jump in and listen. 
Well, holy crap... it sounds..... LIKE CRAP! :mean: 
The left side pulled hard to the left. The midbass was strong but much too boomy. No amount of overall balance could fix it, nor could time alignment. The problem was simply trying to correct an acoustical issue electrically. It just isn't reliable. More often than not, you're boosting the signal so much that you're overtaxing your drivers and you bring more problems in to the mix. Sure, it looks pretty, but it doesn't sound good.

The lesson for today is pretty simple: the car environment is horrible.
The secondary lesson is a bit more complex: You can't fix everything with an EQ.
The third and continuous lessons get more complex: In the bass frequencies, the room is ALWAYS the overriding factor. Moreso in car audio. Phase is MUCH more important than levels (not to say level matching isn't important, either). Not a simple 0/180 phase difference, either. I'm talking crossover slopes and locations. Getting this right is crucial to getting the most out of your system. 
But, overall, what you have to realize is that without some experimentation in placement of your subwoofers and midbass drivers, and just cramming them in a cookie cutter location, you're severely debilitating any chance you have at getting great sound.

And this, my friends, is why I'll be doing some further location analysis and changing up my sub stage to combat a few things. 

I realize this isn't quite a revelation but I hope the newcomers realize just how important this data is and what is shows you. We don't preach "install, install, install" for no reason. Furthermore, as much of a lover for data, you have to understand how to use it. Don't take an RTA on face value. Learn what it's telling you. If you see a hole in your response, don't just try to connect dots with an EQ and assume it's going to fix the problem.


Done for now.

- Erin*


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## link2009 (Dec 16, 2010)

Great post.

This got me thinking, if electronic adjustment isn't reliable, why are the JBL MS-8, Audison Bit.One, Rockford Sixty, etc... said to improve SQ so much? They just have a lot of precision when equalizing.


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## trumpet (Nov 14, 2010)

bikinpunk said:


> I realize this isn't quite a revelation but I hope the newcomers realize just how important this data is and what is shows you. We don't preach "install, install, install" for no reason. Furthermore, as much of a lover for data, you have to understand how to use it. Don't take an RTA on face value. Learn what it's telling you. If you see a hole in your response, don't just try to connect dots with an EQ and assume it's going to fix the problem.


For anyone who needs the "TL;DR" version, before you click the back button at least read this quote.


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## ErinH (Feb 14, 2007)

link2009 said:


> Great post.
> 
> This got me thinking, if electronic adjustment isn't reliable, why are the JBL MS-8, Audison Bit.One, Rockford Sixty, etc... said to improve SQ so much? They just have a lot of precision when equalizing.


They're not _just_ equalizing. That's the point. 


The reason I posted this thread is to share just how tough low end response is to get right and how it's not as simple as plug and chug with an EQ. You may be able to fix a few things here and there but the bottom line is that you need to understand how important the install is to the low end response and how so much of it is driven by proper crossover, slopes, and phase adjustment. 
Well, realisitcally, everything about audio in any environment is about this but moreso in midbass and subbass where the room is dominant and location is critical.


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## ErinH (Feb 14, 2007)

While I was at it, I went ahead and took the time to post the results of different crossover slopes and polarity (0/180 phase). These results are in no way going to be the same for everyone and this really is only the tip of the iceberg when tuning (obviously, I'll be working more to get a better response). What you see is with my initial settings. 50hz/24dB crossover on the midbass HPF. 
I varied the sub's crossover slopes and polarity but kept the frequency constant at 50hz.

Not how varied the response is. From the looks of it, the response below 60hz is best with a 50hz/18dB reversed polarity slope. However, above 60hz, the best (using mild eq to tame the bump between 63-80hz) seems to be the same but flipped polarity. 
It's interesting to see that a polarity flip could have such drastic differences above and below a given frequency. 
The fact of the matter is that you have to look at the response as a whole. That means neither of these are the best fit, IMO; 24dB slope/reversed polarity at 50hz seems to be the best option for a more balanced response. 
Note how wild the differences in response are between all the options, though. In some cases you have dips above 10dB simply by switching polarity. You have all sorts of changes in the nulls/boosts from changing a slope 6dB. 


Again, this is more or less an analytical post. Know that every car is different because every install is different. 50hz isn't really even my crossover point; it was chosen simply for this 'test' and thread.
Note: some of these suckouts in response are due to my EQ because - as stated above - what looks good doesn't always sound good. I remove a bit between 40hz and 50hz to remove the tactile feedback from the midbasses (where others goes ape for this sort of thing, I dislike it).


Furthermore, the overall curve of the response is pretty much what it is right now. This is really all preliminary findings given to illustrate the importance of and difficulty of blending the sub to midbass in the car environment (or any smaller room, for that matter). While comb filtering isn't an issue in low frequency, room modes are. The location of the drivers and the listener always make "getting it _right_" incredibly difficult. Unfortunately, you can never have your cake and eat it, too. Choose your tradeoffs, use an RTA to guide you, and let your ears make the final decision.


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## thehatedguy (May 4, 2007)

Erin...you have a PM sort of regarding this buster.


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## ErinH (Feb 14, 2007)

I saw it last night. Still thinking of an answer. Lol.


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## highly (Jan 30, 2007)

Phase response in the midbass/sub bass is critical as you have demonstrated. This recommendation goes outside of common wisdom, but consider the phase implications of odd order:even order crossover slopes as well. I have found that in my environment, careful use of odd and even order crossovers help manage the combined phase (and therefore frequency) response through the crossover region. Another wrench into the mix is that phase response is altered with EQ, so if you are equalizing through a crossover region, you are further altering the phase response in that region and therefore manipulating the combined frequency and phase responses simultaneously. Balance that with tradeoffs that impinge on image stability at specific frequencies.

These effects can either be thorns in your side, or they can be tools. As you have documented, tuning a car is far more than wiggling the EQ until the RTA looks good. It starts back at the install, and every choice you make has overlapping implications. Getting it right ain't easy. That makes the nearly instant results of something like the MS-8 that much more technologically impressive.


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## Mirage_Man (Jun 29, 2007)

Erin, thanks for this post. I wish I had the knowledge and patience to figure stuff like this out. While I can follow along most of the time the uber technical and scientific is not my strong suit. I hope I can glean enough info from you brainiacs to make my system sound decent.


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## trumpet (Nov 14, 2010)

bikinpunk said:


> I saw it last night. Still thinking of an answer. Lol.


Are you still thinking of an answer to the pm I sent you a week ago? :laugh:


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## underdog (Jul 5, 2011)

This thread makes think of two things.
First: This is why i do not put a bunch of faith into bench testing components.
Second: This may be why many preach (Start with the basics) Many jump straight to active systems thinking they can polish a turd with magic.
They claim you must get the system correct first (The foundation) then you can go the extra mile if you wish.


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## funkalicious (Oct 8, 2007)

Subscribed


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## Hanatsu (Nov 9, 2010)

Here's my response curves, first picture over my front mids only. Left and right side measured independently. This was before I EQed and phase compensated anything. See that horrible suckout at 250Hz on the right side? 15dB down or so, I found the problem later on. It was a small leakage just a few inches from the baffle. As soon as I fixed it, response jumped 8-9dB. Tried to EQ it first but as bikinpunk said, it sounded horrible. As for crossover slopes, I found that 3rd order (18dB/oct) filters works incredibly bad, in both my cars. No matter what I match it together with I always seem to get phase issues. Anyone that use 18dB filters with good results? 

My tweets are in A-pillars and mids down low in doors. DLS Iridium 8i (openair) and DLS Nobelium 1 tweets measured.

Currently I use (LP/HP) SW: Pass/[email protected] - Mid: [email protected]/[email protected] - Midrange: [email protected]/[email protected] - Tweet: [email protected]/[email protected]

*Green: Left // Blue: Right // Red: Both playing. No highpass, [email protected] lowpass at the time of these measurements.*









Next over my tweets, dunno why I didn't upload my midrange's FR curves on photobucket...

*Green: Left // Blue: Right // Red: Both playing. HP 2,[email protected]/No lowpass at teh time of the measurements*


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## Wattser93 (Mar 12, 2010)

I find that pretty interesting. Thanks for the time put into this.

Subscribed.


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## kizz (Jun 22, 2009)

Your knowledge, as always, is very helpful!!!


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## MarkZ (Dec 5, 2005)

link2009 said:


> Great post.
> 
> This got me thinking, if electronic adjustment isn't reliable, why are the JBL MS-8, Audison Bit.One, Rockford Sixty, etc... said to improve SQ so much? They just have a lot of precision when equalizing.


Yeah, that's a damned good question. 

Electronic adjustment _is_ reliable. But Erin mentioned two things that explain why it sometimes falls short. 1) If you have to boost by 15dB to deal with a null, your speakers may have a difficult time dealing with such a HUUUGE increase in power. 2) Just because the level response is flat, doesn't mean the phase response is. It's pointless to plot one-half of the graph the way Erin did (which he mentioned already). Frequency response = level + phase. There should always be two plots, not one. You boost one that much with a narrow Q filter, and your phase response is probably going to look like dog ****.

That doesn't mean that electronic compensation can't completely repair acoustic issues. It can! You just have to be aware of all the variables that you need to compensate for, which is a tall order in the car.


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## BigRed (Aug 12, 2007)

That's why I think spending more time worrying about what happens to the energy before it reaches the car audio environment is not as important as experimentation of location and install. Good post Erin


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## Wesayso (Jul 20, 2010)

Good to see some plots I can relate to. Tried True RTA once and quickly found out EQ wasn't the answer I hoped it would be. My plots showed big problems like this and EQ-ing that out gave me the worst sound ever. Went back to my old routine by playing tones I had available as EQ settings with a dB meter and adjust that further with my ears. Set T/A first by ear and spend a few days playing with x-over slopes.
Yet I saw plenty of plots from users here showing near perfect RTA results. Always wondering how they did that. Or what it sounds like.

I'd like to get back in with TrueRTA, threads like this could profide a better toolbox to do that. Thanks!

Another note: I still have the auto tune from the Pioneer head set as a base and if I measure the test tones an the amplifier it boosts the hell out of my 80 Hz with a drop at 50 and 100 Hz. That should mess with my phase! Crossover is at 80 Hz. It doesn't sound that bad though (lol).


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## Mike_Dee (Mar 26, 2011)

You know what really sucks about why car audio sucks? All the countless thousands of dollars I've spent trying to make it sound like my home audio.


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## thehatedguy (May 4, 2007)

But bass and subbass in the car is EASY compared to the house. It's the midbass and midrange that is so problematic in the car.


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## ErinH (Feb 14, 2007)

Let me clear up something that I think people are saying ...

Measurements of raw drivers ABSOLUTELY still matters. If you don't know where you're came from you won't know how you got there. Understanding the limits and characteristics of a raw driver allows you to make a better purchase decision. Period.


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## ErinH (Feb 14, 2007)

thehatedguy said:


> But bass and subbass in the car is EASY compared to the house. It's the midbass and midrange that is so problematic in the car.


It's the transition that sucks. The thing home audio has is better filters in their DSP's (in general) and space to place speakers.


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## Hanatsu (Nov 9, 2010)

When I measure a system, I decide a reference point for a set of frequencies. For example, I want frequencies between 20-100Hz to have an amplitude of x dB (relative to other frequencies...). So I draw a horizontal line on the graph as centered as possible between peak and dips. After that I check how many dB +/- each side is at every adjustable EQ area. I NEVER add more than +3dB to any band and when I cut at some frequencies I tend to be a little more generous but I still try to avoid more than 4-5dB max. The important thing is to have the same response both sides, impossible to get a correct center stage without somewhat equal FR both sides. Also, I try not to cut and boost frequencies close together, in some cases it actually sounds worse. I try to stay within 5dB +/- when I adjust EQ near-placed frequencies (400-500Hz, 1000-1250Hz etc...) to not screw phase up too badly. Tend to sound better even if FR has some irregularities.

Btw... How do you measure phase response? I've seen that some programs include phase in the measurement, but it looks really wierd - Like flat to some point, then dips like straight down 180 degress then up again in a straight line. Am I missing something?


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## underdog (Jul 5, 2011)

bikinpunk said:


> Let me clear up something that I think people are saying ...
> 
> Measurements of raw drivers ABSOLUTELY still matters. If you don't know where you're came from you won't know how you got there. Understanding the limits and characteristics of a raw driver allows you to make a better purchase decision. Period.


I agree with that mostly.

But it still not tell you how the driver will react in the location you have selected and prepared.

Remember the old working mans adage.
"It looked good on paper"


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## vitvit (May 3, 2011)

Mmm... it's easy rule: newer boost EQ. Always cut it.
We can cut peak (to some extent) but boosting null will lead to null.
Even if it's not a null you are boosting - you endup with overload in this region and digital clipping. If not - your gain structure is wrong.


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## ErinH (Feb 14, 2007)

underdog said:


> I agree with that mostly.
> 
> But it still not tell you how the driver will react in the location you have selected and prepared.
> 
> ...


Same install will mean EVERY driver will be influenced the same way. It's an environmental effect. One driver doesn't behave any differently in the same environment than another in regards to reflections and boundary modes. 

So, again, if you understand what you had before the driver was put in the car, you can determine exactly what the car changed. If you take it a step further, you can then start buying drivers based on what you know not only about the driver, but how your car will affect the response. If you look in my build thread you'll see I did exactly that with my midrange and tweeters in the pillar. I measured the assembly out of the car. Then inside lthe car. Then I knew what problems to chase down in the pillar install and what to focus on regarding the car itself. 

So, yes, it will still tell you how the driver will act in the car.


But, really, that's not why you look at how a driver behaves on it's own... not really.
You look at how a driver behaves on it's own to determine it's weaknesses. At least, that's what I do. You can't fix a breakup mode with EQ and that environment isn't going to make it sound heavenly.
You can't make distortion sound better than by putting it on a dash vs kicks. It's still there.
Certain things change when put in a car but I've never known anyone to buy a driver because it measured like crap, thinking the car would fix it. Sure, in theory it sounds great... I just don't believe it's at all realistic. I'd rather start with something that performs great than start with something that already has peaks in the response, has severe cone breakup and has an ugly distortion profile on a whim, thinking the car would make it better.


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## MarkZ (Dec 5, 2005)

Hanatsu said:


> Btw... How do you measure phase response? I've seen that some programs include phase in the measurement, but it looks really wierd - Like flat to some point, then dips like straight down 180 degress then up again in a straight line. Am I missing something?


Remember, phase is a circular variable. 360 deg = 0 deg. If the software plots it stupidly, you get jumps where it transitions from 360 to 0 that look insane.



vitvit said:


> Mmm... it's easy rule: newer boost EQ. Always cut it.
> We can cut peak (to some extent) but boosting null will lead to null.
> Even if it's not a null you are boosting - you endup with overload in this region and digital clipping. If not - your gain structure is wrong.


Booooooo!  You most certainly can add boost. And you can do it without clipping, but it requires readjustment. As Erin mentioned, the problem with boost really comes down to power. Nothing more. If the boost means you'll be exceeding the amplifier's or speaker's capabilities, then you're right, it's a bad idea. But lots of times you can boost and still be within the output capabilities of the system. And yes, you're also correct that, depending on the source of the dip, boosts won't always get you where you want to go.


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## BigRed (Aug 12, 2007)

bikinpunk said:


> Let me clear up something that I think people are saying ...
> 
> Measurements of raw drivers ABSOLUTELY still matters. If you don't know where you're came from you won't know how you got there. Understanding the limits and characteristics of a raw driver allows you to make a better purchase decision. Period.


I agree they matter, but not significantly more than placement and install. they are BOTH very important. I can make the most perfect driver on paper and klippel sound like ass with a terrible location


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## ErinH (Feb 14, 2007)

I agree, Jim. 
The point still is measurements absolutely matter. Just like a bad install can make a great driver sound like crap, a crap driver can't be made to sound any better. Best to start with a good driver.


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## highly (Jan 30, 2007)

BigRed said:


> I agree they matter, but not significantly more than placement and install. they are BOTH very important. I can make the most perfect driver on paper and klippel sound like ass with a terrible location


So you are saying that install can make a good driver sound worse, but not better than it 'measures'. On top of that, a driver that measures poorly outside the car will rarely* sound better in it. I know YOU get that, but I expect that to be a profound statement to many. 


*It is certainly possible to have a driver with exceptional distortion measurements and a poor, peaked frequency response perform well once installed, but it isn't the rule. Certain things simply won't get better in the car, and most things tend to get worse without correction of some kind. Speaking of trends here, not absolutes. On that note, it's time for some Vodka.


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## Ray21 (Oct 19, 2009)

Great info!


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## thehatedguy (May 4, 2007)

Sounds like you are speaking from experience .



BigRed said:


> I agree they matter, but not significantly more than placement and install. they are BOTH very important. I can make the most perfect driver on paper and klippel sound like ass with a terrible location


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## req (Aug 4, 2007)

in for the subscription. thanks erin. ill have to finish reading this later


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## omegaslast (Nov 4, 2010)

The little environment doesnt suck for just "balanced" response.. it sucks for sensory response. In your home you can get lost in a song and simply stare off into nothing... try doing that while driving a car and you could kill yourself.


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## Hanatsu (Nov 9, 2010)

bikinpunk said:


> Same install will mean EVERY driver will be influenced the same way. It's an environmental effect. One driver doesn't behave any differently in the same environment than another in regards to reflections and boundary modes.
> 
> So, again, if you understand what you had before the driver was put in the car, you can determine exactly what the car changed. If you take it a step further, you can then start buying drivers based on what you know not only about the driver, but how your car will affect the response. If you look in my build thread you'll see I did exactly that with my midrange and tweeters in the pillar. I measured the assembly out of the car. Then inside lthe car. Then I knew what problems to chase down in the pillar install and what to focus on regarding the car itself.
> 
> ...


Seriously... haven't thought about measuring the car's transfer function until now lol. Seems like I have work to do tomorrow ^.^ I will post my findings.

I agree that it is very important to know what driver you put in the car. The argument that the car is a "terrible audio enviroment anyway" doesn't hold up. It's gonna be lots worse if you were to use crap drivers. Distortion is one parameter you can't change, it will always be there. Especially if the distortion is of the form of tall order harmonics or of intermodulated form, you will notice it. Klippel measurements are invaluable getting hold of this info. Remember once a few years back, there was something wrong about how my system sounded, couldn't place my finger on it. It was first when I saw a distortion plot on the web testing my mids I realized that my crossover settings were an absolute failure, I reset the crossovers and optimized it for my drivers and holy crap it sounded better. 

The fun part about car audio (imo) is to tame the enviroment, to get it as good as possible. To play with mounting positions, angles, EQ, T/A, phase, enclosures and crap. Not to mention all the modifications and rebuilding you'll have to do, neverending fun... and pain in the ass sometimes


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## Hanatsu (Nov 9, 2010)

MarkZ said:


> Remember, phase is a circular variable. 360 deg = 0 deg. If the software plots it stupidly, you get jumps where it transitions from 360 to 0 that look insane.


Ah^^ I'll take a look at my programs again. I currently have REW(RoomEQ), TrueRTA, HOLMimpulse and ARTA installed. ARTA would probably do the job best I presume? REW is the one that shows the messy phase graphs...


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## ErinH (Feb 14, 2007)

I did these measurements with Omnimic. For most of them, phase was pretty much textbook minimum phase through the sub/midbass crossover region. I didn't notice anything that called attention to itself. Something that had me very curious and I intend to go back and play with it further for higher frequency content. Sadly, I didn't even think to grab the plots for this thread. 

If I get a chance to test again, I'll make sure to grab the phase plots with FR. It's a simple checkmark. Another reason I like OM so much. It's stupid easy to use.


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## ErinH (Feb 14, 2007)

Hanatsu said:


> Ah^^ I'll take a look at my programs again. I currently have REW(RoomEQ), TrueRTA, HOLMimpulse and ARTA installed. ARTA would probably do the job best I presume? REW is the one that shows the *messy phase graphs*...


the sad thing is, that "messy" response is exactly what you're hearing. It's what happens when you get comb filtering. Thank your car for that.


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## MarkZ (Dec 5, 2005)

I'm surprised the phase was flat at the suckout, Erin ... if I'm reading you correctly.


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## ErinH (Feb 14, 2007)

MarkZ said:


> I'm surprised the phase was flat at the suckout, Erin ... if I'm reading you correctly.


Nope, it wasn't flat. Minimum phase meaning that it didn't have severe anomalies in the response. It was pretty much linear through the crossover region. I, too, was surprised but I think there's more to it and it's likely something I don't understand or am not aware of regarding low frequency content and phase (true measured phase).

This is an example of minimum phase:









What you're looking for is, in the land of perfect and theory, a true linear falloff without crazy bumps/dips. I actually don't quite know what to make of inversion as to how it relates to the car audio environment but I do pay attention to crazy stuff. It'll be terribly evident what I'm talking about if I have a chance to post a full FR vs. Phase response graph from 20-20khz of the car response. 
The one above is an example of a good home speaker design. Just wait until you guys see what the typical car result looks like...


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## Hanatsu (Nov 9, 2010)

Found "minimum phase" in ARTA now. It's excess phase which give me these "messy" graphs, minimum phase look much cleaner. Read a little bit about it, can't understand it quite yet. Is it mimimum phase I'm interested in when I'm looking for anomalies in phase response caused by EQ?


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## cvjoint (Mar 10, 2006)

Looks like my plots of left and right. I have talked extensively about this issue in my thread too IIRC. The left midbass performance is the weakest link in my car and my guess is that it is the same for most cars. 

The interesting part is that we are using completely different locations, drivers, and box alignments. I see that many reactions are to solve the problem by "installation." It's not clear to me that you can. At least it seems that in our tests kick vs. door doesn't seem to make much of a difference. Maybe someone can post plots of dash mounted midbass responses. Is there a location that does not suffer from this problem. What is the mechanism by which there is a cancellation on the left and not on the right? What if it's not a cancellation but rather the car "boosts" the response everywhere else but not there? In that case car audio is good!

EQ. is definitely good. EQ. here gives you the option to choose between linear distortion and nonlinear distortion. It gives you flexibility. Boost where there is a dip and get great linear performance OR don't EQ. and keep better nonlinear performance and rattles to a minimum. In fact this is what we all do when we use the gain control to back down the midbass as a whole. EQ. just gives you more flexiblity to do it by frequency. Call it spot treatment. 

Of course I think there is a way to have it all. Most of the boominess is from the left midbass getting nonlinear and raising Q or the box resonating. Either make a more solid box or step up to a larger midbass. In my Accord I was able to do this with 10" midbasses, in the S2k with 6.5 SLS not so much. 

I picked a compromise, raised the HP to 80hz, EQd a little but not to flat, and backed up the gains on the midbasses a bit.


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## Hanatsu (Nov 9, 2010)

bikinpunk said:


> I did these measurements with Omnimic. For most of them, phase was pretty much textbook minimum phase through the sub/midbass crossover region. I didn't notice anything that called attention to itself. Something that had me very curious and I intend to go back and play with it further for higher frequency content. Sadly, I didn't even think to grab the plots for this thread.
> 
> If I get a chance to test again, I'll make sure to grab the phase plots with FR. It's a simple checkmark. Another reason I like OM so much. It's stupid easy to use.


Omnimic... hm isn't that Daytons measurement kit? I have their WT3, measures T/S parameters. Pretty accurate actually, really easy to use aswell


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## Hanatsu (Nov 9, 2010)

cvjoint said:


> Looks like my plots of left and right. I have talked extensively about this issue in my thread too IIRC. The left midbass performance is the weakest link in my car and my guess is that it is the same for most cars.
> 
> The interesting part is that we are using completely different locations, drivers, and box alignments. I see that many reactions are to solve the problem by "installation." It's not clear to me that you can. At least it seems that in our tests kick vs. door doesn't seem to make much of a difference. Maybe someone can post plots of dash mounted midbass responses. Is there a location that does not suffer from this problem. What is the mechanism by which there is a cancellation on the left and not on the right? What if it's not a cancellation but rather the car "boosts" the response everywhere else but not there? In that case car audio is good!
> 
> ...


My doors are so damn damped so they feel like concrete walls. 3 layers of vibration dampener 35mm/~1,5inch absorb OC on both side inside door, 1inch closed cell on the front and clay around baffle. Still got rattles, low frequency response is insane from my 8's though. Response between 200-300Hz and 500-800Hz are bad in my doors no matter how much I've dampened, probably cancelation of some kind. Had dips of 30dB or so in very narrow frequency areas, like 510-525Hz then normal again. I use 3" at dash level now, response is much better from 200Hz and up, no anomalities at all in those areas. Door mounting seem to have serious issues at many levels.


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## cvjoint (Mar 10, 2006)

Hanatsu said:


> My doors are so damn damped so they feel like concrete walls. 3 layers of vibration dampener 35mm/~1,5inch absorb OC on both side inside door, 1inch closed cell on the front and clay around baffle. Still got rattles, low frequency response is insane from my 8's though. Response between 200-300Hz and 500-800Hz are bad in my doors no matter how much I've dampened, probably cancelation of some kind. Had dips of 30dB or so in very narrow frequency areas, like 510-525Hz then normal again. I use 3" at dash level now, response is much better from 200Hz and up, no anomalities at all in those areas. Door mounting seem to have serious issues at many levels.


I feel you. I had 5 layers of extreme, deflex, foam, top mounting, and a one piece fiberglass door panel 2" to 1/4" thick (decreasing away from the speaker. The rattles were still there at times. 

The ultimate test is to play your favorite midbass tracks with all other speakers completely turned off and usual volume levels. It's insane how flimsy our cars are. 

I have a wide dip in the response for the right pillar pod. Still, not as bad as the midbass problem.


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## Hiace200 (Apr 26, 2009)

cvjoint said:


> Looks like my plots of left and right. I have talked extensively about this issue in my thread too IIRC. The left midbass performance is the weakest link in my car and my guess is that it is the same for most cars.
> 
> The interesting part is that we are using completely different locations, drivers, and box alignments. I see that many reactions are to solve the problem by "installation." It's not clear to me that you can. At least it seems that in our tests kick vs. door doesn't seem to make much of a difference. Maybe someone can post plots of dash mounted midbass responses. Is there a location that does not suffer from this problem. What is the mechanism by which there is a cancellation on the left and not on the right? .............


Is it possible that it was caused by driver's leg?


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## ErinH (Feb 14, 2007)

cvjoint said:


> Looks like my plots of left and right. I have talked extensively about this issue in my thread too IIRC. The left midbass performance is the weakest link in my car and my guess is that it is the same for most cars.


There's tons of discussion on this sprinkled throughout this site. Midbass suckout is a popular discussion since everyone has it.



cvjoint said:


> The interesting part is that we are using completely different locations, drivers, and box alignments. I see that many reactions are to solve the problem by "installation." It's not clear to me that you can. At least it seems that in our tests kick vs. door doesn't seem to make much of a difference. Maybe someone can post plots of dash mounted midbass responses. Is there a location that does not suffer from this problem. What is the mechanism by which there is a cancellation on the left and not on the right? What if it's not a cancellation but rather the car "boosts" the response everywhere else but not there? In that case car audio is good!


No, I still believe install is paramount. The difference between our cars is... difference. They are different. If you want to have a true comparison you'll need to do a true A/B test in your own car. With door mounted midbasses the suckout was more noticeable on the right side than it is now while the left side was actually down about 8hz (IIRC). What's interesting is that moving the mic to the passenger's side pretty much gives you the same result... in opposite. The near side always has the null and the far side doesn't. 
The geometry, nearby incidence points, console, seat distance, seat material, etc, etc... all of this adds up. Some things you can't do anything about to some degree but the fun part is figuring out when these absolutes are busted. I've been reading up on some stuff lately and have a few things to try but I won't discuss it here until I decide if it's worth discussing. I'm a few months out yet, anyway. Gotta wait for the new JL shallow subs to come out.

You and I have discussed cabin gain and transfer function in your testing thread. Look in to room modes; it's just one more part of the horrid puzzle. Longitudinal and lateral planes contribute different effects here. 
You certainly gets boosts and it's from the modes. You get cancellation, too. Consider the use of bass traps in home theaters or listening rooms. Look in to their use and you'll discover that we're not the only suckers stuck with the problem of bass. 

Regarding installation:
Installation doesn't always mean location; it can mean use of materials to help correct response. If you get froggy sometime and feel like experimenting with low end response methods, throw some pillows in your kicks and see what happens to the response. Move a pillow to the dash. Grab a sub and put it in the trunk, then the rear seat and then the center of the car. The response will change. Or, you can just take the mic and move it around the car (analogous to moving the actual speaker itself). Whiteledge uses helmholtz absorbers to kill modes. Some use pro-audio devices with a very narrow Q to tame these while others simply cut them to some degree that is acceptable and deal with the rest. What I've found, however, is that pink noise does not tell you the whole story. So, while you may find a peak at 70hz (for example) and you cut it via the RTA, you still have the mode/resonance rear it's ugly head when you have a stand up bass played back on your system... it's a mode you thought you fixed but you didn't. That's one of the reasons I'm excited about some of the new dsp offerings as of late that provide us with more precise treatment of these peaks. It's not a 100% solution but it's better than cutting 2 bands of Graphic EQ to address one very narrow peak. 

Below X frequency, the response is room dominated (Floyd Toole's words). Geometry is the basis. At some point you're dealing with sound pressure and the speed of sound doesn't matter anymore in regards to treatment. You'll find that sound proofing options change once you get down to a certain frequency: velocity based (wide bandwidth absorption) and pressure based (specific frequency/narrow bandwidth absorption). Researching this alone can give you very good insight in to how we can deal with it, if you can think outside the box a bit.


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## ErinH (Feb 14, 2007)

A bit OT...
anyone watching this thread and wanting to use an RTA, PLEASE read this thread first before you throw a mic in your seat:
http://www.diymobileaudio.com/forum...ance-spacial-averaging.html?highlight=spatial


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## highly (Jan 30, 2007)

And some of these responses show that sometimes the best box is no box at all. Though it isn't suitable for every installation and imposes its own set of limitations, limiting the number of boxes interacting in the system can have significant impact in the overall result. Having to place your midrange in an oddly shaped undersized box produces its own set of issues that must be overcome; those of the box behind it AND the box into which it plays. 

As far as midbass on the dash is concerned, I was doing some trials this weekend on this exact vein. Unfortunately further testing is required that will require me to cut (yet more) sheetmetal to be conclusive, but anecdotal evidence seemed to indicate that getting them out of the floor cavity did have positive net benefit with regard to 'suckout'. The same held true for a few unconventional subwoofer locations I have been toying with lately. Even approaching pressure based frequencies, selecting an optimal location within the vehicle is still based on geometry first and is generally overridden by practicality.


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## rc10mike (Mar 27, 2008)

Turning my head even slightly often changes how things sound BIGTIME. For some reason, I believe the actual difference is: how a single omnidirectional mic hears things and our 2 not-so-omnidirectional ears hear things. I think that that's the problem with measuring.


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## highly (Jan 30, 2007)

rc10mike said:


> Turning my head even slightly often changes how things sound BIGTIME. For some reason, I believe the actual difference is: how a single omnidirectional mic hears things and our 2 not-so-omnidirectional ears hear things. I think that that's the problem with measuring.


My setup is pretty tightly focused and has a narrow 'sweetest spot', but that's a question of image. The frequency response sounds extremely similar from either seat. Having a narrow frequency response spot - the car does not sound the same FR wise over a reasonable (minimally head-sized) area - that's a different kind of problem that tends to imply heavy comb filtering and/or significant nodal issues. 

Part of measuring in-car, as Erin pointed out, MUST involve averaged response. There is nothing electronic that can help a widely varied frequency response as you turn your head or shift in the seat though. That is a question of room interaction and inter-driver interaction and must be addressed mechanically.

Mind you, I cannot hear your car, and I am speaking in gross generalizations that may not apply. Generally that is the case however.

-T


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## rc10mike (Mar 27, 2008)

highly said:


> My setup is pretty tightly focused and has a narrow 'sweetest spot', but that's a question of image. The frequency response sounds extremely similar from either seat. Having a narrow frequency response spot - the car does not sound the same FR wise over a reasonable (minimally head-sized) area - that's a different kind of problem that tends to imply heavy comb filtering and/or significant nodal issues.
> 
> Part of measuring in-car, as Erin pointed out, MUST involve averaged response. There is nothing electronic that can help a widely varied frequency response as you turn your head or shift in the seat though. That is a question of room interaction and inter-driver interaction and must be addressed mechanically.
> 
> ...


But lets say you are measuring right side only. The omnidirectional mic most use will pick up reflections in response from all over the car. Where as your right ear will not pick up the same reflections. Combine that with the fact that your left ear can still pick up sounds from the right side, and you get a whole new mess of whats actually happening in the measured vs hearing world.

This is my theory on why "measuring" sucks, not car audio hobby itself.


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## highly (Jan 30, 2007)

rc10mike said:


> But lets say you are measuring right side only. The omnidirectional mic most use will pick up reflections in response from all over the car. Where as your right ear will not pick up the same reflections. Combine that with the fact that your left ear can still pick up sounds from the right side, and you get a whole new mess of whats actually happening in the measured vs hearing world.
> 
> This is my theory on why "measuring" sucks, not car audio hobby itself.


I don't disagree with your assessment. The instrument is not a pair of ears and behaves differently. I do disagree with using the RTA to measure one side then the other. I also don't finish-tune the car with that instrument. I only use it to determine the source of a problem my ears hear so that a corrective action can be effected, nothing more. I have yet to own a device better than my hears for determining 'right' or 'wrong', but sometimes they need help with _why_ it's wrong. For those gross determinations, I rely on empiricism.


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## rc10mike (Mar 27, 2008)

highly said:


> I don't disagree with your assessment. The instrument is not a pair of ears and behaves differently. I do disagree with using the RTA to measure one side then the other. I also don't finish-tune the car with that instrument. I only use it to determine the source of a problem my ears hear so that a corrective action can be effected, nothing more. I have yet to own a device better than my hears for determining 'right' or 'wrong', but sometimes they need help with _why_ it's wrong. For those gross determinations, I rely on empiricism.


Well said, but I believe the mic method could be improved upon., since we cant accurately measure our ears individual freq response.


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## ChrisB (Jul 3, 2008)

I had my mind blown this evening on another forum's chat discussing relative phase and pitch. Pitch was always an important factor in my former other hobby, DJing, but I never gave it a second thought in car audio with regards to relative speaker placement and aiming until tonight.

Just when I thought I couldn't hate car audio more, I found another reason to. :laugh:


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## cvjoint (Mar 10, 2006)

rc10mike said:


> But lets say you are measuring right side only. The omnidirectional mic most use will pick up reflections in response from all over the car. Where as your right ear will not pick up the same reflections. Combine that with the fact that your left ear can still pick up sounds from the right side, and you get a whole new mess of whats actually happening in the measured vs hearing world.
> 
> This is my theory on why "measuring" sucks, not car audio hobby itself.


There are no bounds to how far you can go to emulate your hearing. If you are that picky you can design a set of small mics and mount them each in a foam insert for your ears. There is software out there that can sum the response too. But why? You don't want that frequency plot. You want one outside of your ear. The mastering is done for reproduction in an environment not isolated in ear. Professional grade in ear headphones don't have flat FR. 

Personally I think that as long as you can average and cover regions around your head in a properly weighed fashion it does a pretty good job. The things we are talking about here are sizable dips, it seems that alleviating these jumps does sound better at low volumes but stresses the speaker at high output.

Issue no. 2 is that we're interested in relative differences between left and right. The mic does not paint different pictures based on whether it's testing left or right, it is the consistency that is important. 


I've also tested from both seats and it reversed as well. Taking live snapshots of the mic going around the head it seems the suckout is worse when the mic is near the door and then gets better towards the center. At least that's how I remember it. 

Looking forward to the testing of the dash 8"s are they?


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## rc10mike (Mar 27, 2008)

One thing I might add is this (not trying to come across as some car audio snob) I believe the whole car audio world is fundamentally flawed, because we are human, and not created equal.

There seems to be some belief somewhere that music should sound as it was made, and that all people will sense and perceive things the same way. 

Look at sense of smell or sense of sight, what some find beautiful others will find offensive. What some can sense others cant.

I feel this applies equally to our sense of hearing. There's simply too many variables to satisfy all. If there were a single pair of glasses that would make everybody see perfect, wouldnt they exist by now?

My point is nobody will ever hear and or perceive things like YOU, so start doing what sounds best to you. Not even a judge. Because what he likes might sound like crap to you.


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## rc10mike (Mar 27, 2008)

cvjoint said:


> There are no bounds to how far you can go to emulate your hearing. If you are that picky you can design a set of small mics and mount them each in a foam insert for your ears. There is software out there that can sum the response too. But why? You don't want that frequency plot. You want one outside of your ear. The mastering is done for reproduction in an environment not isolated in ear. Professional grade in ear headphones don't have flat FR.
> 
> Personally I think that as long as you can average and cover regions around your head in a properly weighed fashion it does a pretty good job. The things we are talking about here are sizable dips, it seems that alleviating these jumps does sound better at low volumes but stresses the speaker at high output.
> 
> ...


Consistency IS important, but what do you what do you do when a mic is picking up a 360* sound field when you're trying to get a right side response? Your ear isnt perfect at picking up a 360* sound field, so where is the line drawn...


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## ErinH (Feb 14, 2007)

The data is there. 
This whole flat response isn't made up or just some silly goal. 

Read Floyd Toole's "Sound Reproduction".


Taking it further, your head shadows the response and that has been documented as well. Head related transfer function.


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## highly (Jan 30, 2007)

rc10mike said:


> One thing I might add is this (not trying to come across as some car audio snob) I believe the whole car audio world is fundamentally flawed, because we are human, and not created equal.
> 
> There seems to be some belief somewhere that music should sound as it was made, and that all people will sense and perceive things the same way.
> 
> ...


Though I will avoid going into a philosophical discussion on if we all see the same color as green (and there is significant medical backing to say that, given healthy eyes and brain, we do) I suspect that the vast majority of people would agree to what does and does not sound realistic. Certainly there will be differences and subtleties, but we all know what our mother sounds like. Failing to accurately reproduce that in a way that evokes an emotional response would generally be considered a failure by most of the people reading this thread. It certainly isn't easy, but if we were looking for an easy hobby we should have stopped back at our first pair of headphones. Car audio isn't that. 

I agree that judges like different things, but competition isn't the end-all be-all of car audio. For me, self satisfaction is. And so far... and this isn't easy for me to say... the judges haven't exactly been wrong. Overall, they seem to have a pretty good grasp on what reality sounds like and how my car differs from it. It's my 'job' as a competitor to close that gap. Learning how is as much work as doing it, too.

-T


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## rc10mike (Mar 27, 2008)

bikinpunk said:


> The data is there.
> This whole flat response isn't made up or just some silly goal.
> 
> Read Floyd Toole's "Sound Reproduction".
> ...


Not saying a flat response isnt a good thing, but you did say that it sounded like crap with an "even" measured LR response. So how do you explain that?

Or is that the purpose of this thread


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## cvjoint (Mar 10, 2006)

rc10mike said:


> Consistency IS important, but what do you what do you do when a mic is picking up a 360* sound field when you're trying to get a right side response? Your ear isnt perfect at picking up a 360* sound field, so where is the line drawn...


The line is drawn when you are at the cutting edge of technology. This is how we progressed through time. You wouldn't be typing on your keyboard if somebody had not picked that road already. A computer has a stochastic trend for the amount of time it crashes but that doesn't make it useless now does it?


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## underdog (Jul 5, 2011)

rc10mike said:


> But lets say you are measuring right side only. The omnidirectional mic most use will pick up reflections in response from all over the car. Where as your right ear will not pick up the same reflections. Combine that with the fact that your left ear can still pick up sounds from the right side, and you get a whole new mess of whats actually happening in the measured vs hearing world.
> 
> This is my theory on why "measuring" sucks, not car audio hobby itself.


I was watching an auto show awhile back.
JL Audio (I think) was building one of there cutting edge, spare no expense show cars.
For the tuning part they drug out what looked like a modified crash test dummy, it had mics in each ear location. Can not remember if they had other mics in the vehicle.

I think i remember others using what is like a bust they set it up at correct height.
But that leaves out the legs arms and torso.


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## ErinH (Feb 14, 2007)

rc10mike said:


> Not saying a flat response isnt a good thing, but you did say that it sounded like crap with an "even" measured LR response. So how do you explain that?
> 
> Or is that the purpose of this thread


The method used to achieve that response was crap. You can get flat any number of ways. This thread was started to note that not all ways are created equal and that achieving any desired curve can be done various ways. Getting it right isn't easy. I highlighted one way that didn't work and it's one way people often attack a problem like the one I provided. 

Again, I really encourage you to read the book I mentioned. Not trying to shovel the conversation away. I just know you'll gain more from that than you might realize. It's pretty much the standard for any audio nut and scientist. 



Regarding measuring with a single mic, I also have a thread here discussing measuring with binaural mics. The same method the ms8 employs.


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## Sulley (Dec 8, 2008)

Hey bikinpunk, Excellent info. This is why I love coming to this site. 

Is this the correct book? If it is I'll see if I can fine a more permanent place for it. 

Sound Reproduction: Loudspeakers And Rooms - Floyd Toole


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> Nope, it wasn't flat. Minimum phase meaning that it didn't have severe anomalies in the response. It was pretty much linear through the crossover region. I, too, was surprised but I think there's more to it and it's likely something I don't understand or am not aware of regarding low frequency content and phase (true measured phase).


Yeah, that's what I meant. I'm surprised that it stayed flat (or its derivative stayed flat, or whatever). Usually anomalies like that have funky phase response, especially when the bandwidth of the dip is so narrow.



> There's tons of discussion on this sprinkled throughout this site. Midbass suckout is a popular discussion since everyone has it.


Not everyone. 



rc10mike said:


> Turning my head even slightly often changes how things sound BIGTIME. For some reason, I believe the actual difference is: how a single omnidirectional mic hears things and our 2 not-so-omnidirectional ears hear things. I think that that's the problem with measuring.


Bingo! But the reason is different, and part of it is due to HRTF as Erin mentioned. Putting your two ears at two different (relative) positions gives you an extra data point. Because of temporal integration, it allows us to triangulate the sound. Head movement is one of the BIGGEST cues we have for auditory localization. It's also one of the only ways to perform front-rear localization (think about it... ITD and ILD have ambiguous front-rear positions -- the same relative delay, for example, could correspond to a position in front or behind you. Even slight head movement destroys this ambiguity).


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## chad (Jun 30, 2005)

you will never ever get rid of a suckout that is based on distance/environment with the tools we commonly have available.

Granted there are tricks with out of band filters and FIR filters, but generally, you are hosed. an EQ boost is NEVER EVER the way to deal with it.


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## 14642 (May 19, 2008)

MarkZ said:


> Yeah, that's a damned good question.
> 
> Electronic adjustment _is_ reliable. But Erin mentioned two things that explain why it sometimes falls short. 1) If you have to boost by 15dB to deal with a null, your speakers may have a difficult time dealing with such a HUUUGE increase in power. 2) Just because the level response is flat, doesn't mean the phase response is. It's pointless to plot one-half of the graph the way Erin did (which he mentioned already). Frequency response = level + phase. There should always be two plots, not one. You boost one that much with a narrow Q filter, and your phase response is probably going to look like dog ****.
> 
> That doesn't mean that electronic compensation can't completely repair acoustic issues. It can! You just have to be aware of all the variables that you need to compensate for, which is a tall order in the car.


 
Be careful with this one. In cars and because of the reflective environment, significantly boosting a null is always a bad idea. The null can be a result of the combining of the response of two speakers or it can be the result of the combining of the response from a speaker and the reflected sound from that same speaker. Or, it can be all three. If it's only the combination of the two speakers and the environment isn't reflective, boosting won't alter the null at the measurment position. We all know that this doesn't happen in cars and when we boost a null we do change the measurement at that location--not by as much as we boost however. 

So...why is it affected? Because we don't hear (or measure) only the direct sound. We also hear and measure the reflected sound. When you boost a null by 12dB, the amp clips and the speaker is over driven because IT IS OUTPUTTING MORE AT THAT FREQUENCY. At the measured location, the condition that created the null still creates a null, but the additional output in the reflected sound provides the "fill-in". While you may be able to get a better measurement, the sound will be nasty, and that's what Erin has discovered. The difference between the pleasant result in your measurement and the unpleasant result when you listen is PROOF that reflected sound matters. 

You can affect a null with delay and phase adjustments if it's caused by the location of two drivers and their combined response. You CANNOT fix the null if it's caused by a driver and the sound of that driver's reflection--see the law of causality for more info. 

So, the objective should be to choose speakers and systems of speakers (and this means choosing crossover points and slopes) for their POWER RESPONSE, not their on-axis response. If the direct sound and the reflected sound are similar, EQ in a car is more successful. If they're similar eoungh, EQ is all you need. To say that EQ is a bad tool because it can't fix this null is like saying a garden hoe isn't useful because you can't drive it to the grocery store. 

Don't sweat comb filtering t high frequencies so much. It's pretty difficult to hear, especially if your head is mostly stationary, as it is while you drive. Use 1/12th-1/6th octave resolution to figure out what's going on below 800Hz or so and 1/6th-1/3rd above 800 Hz. 

Lastly, "minimum" phase is derived from the frequency response curve in analysis tools. It's useful if you're measuring a single driver anechoically with an ungated sweep or a steady-state signal like pink noise. It is NOT a phase plot of your car.


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## thehatedguy (May 4, 2007)

Like siding a hotdog down a hallway...not going to touch it.



chad said:


> an EQ boost is NEVER EVER the way to deal with it.


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## BigRed (Aug 12, 2007)

Great discussion here guys. To answer Todd and Erin, no I'm not suggesting that a crap driver will sound better placed in an optimal location, I am suggesting that ANY driver will perform better installed in a more favorable location. Yes testing is important and graphs of drivers in raw form are absolutely valuable. My point was that I have learned from my experience of experimentation that a good driver needs a great location and install to really get the most out of it. 

I think reading Floyd's book was a great eye opener to a reflective environment. Check out page 88 about comb filtering and how overrated it is in a car . Good call Erin


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## chad (Jun 30, 2005)

I love the phrase POWER RESPONSE


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## 14642 (May 19, 2008)

chad said:


> I love the phrase POWER RESPONSE


Why? Should I explain what i mean or is it sufficient to use standard terms?


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## MarkZ (Dec 5, 2005)

Andy Wehmeyer said:


> Be careful with this one. In cars and because of the reflective environment, significantly boosting a null is always a bad idea. The null can be a result of the combining of the response of two speakers or it can be the result of the combining of the response from a speaker and the reflected sound from that same speaker. Or, it can be all three.


Or it can be the result of attenuation, either due to the speaker's intrinsic characteristics (or the enclosure's), or sound absorption, etc. In which case, electronic compensation is fine and dandy. 

I probably made a bad choice using the word "null", which has other connotations.


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## trumpet (Nov 14, 2010)

Andy Wehmeyer said:


> Why? Should I explain what i mean or is it sufficient to use standard terms?


I would appreciate if you would explain what you mean by power response. I think I had a bit of a blank stare when I read that, but the rest of your post clicked.


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## 14642 (May 19, 2008)

MarkZ said:


> Or it can be the result of attenuation, either due to the speaker's intrinsic characteristics (or the enclosure's), or sound absorption, etc. In which case, electronic compensation is fine and dandy.
> 
> I probably made a bad choice using the word "null", which has other connotations.


Right. That's what EQ is for.


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## 14642 (May 19, 2008)

trumpet said:


> I would appreciate if you would explain what you mean by power response. I think I had a bit of a blank stare when I read that, but the rest of your post clicked.


See Sean Olive's explanation in the thread in this link:

Sound Power Response vs. Frequency Response

Basically, power response refers to the response at all listening (or measurement angles)--the combination of on-axis and off axis response.


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## highly (Jan 30, 2007)

BigRed said:


> Great discussion here guys. To answer Todd and Erin, no I'm not suggesting that a crap driver will sound better placed in an optimal location, I am suggesting that ANY driver will perform better installed in a more favorable location. Yes testing is important and graphs of drivers in raw form are absolutely valuable. My point was that I have learned from my experience of experimentation that a good driver needs a great location and install to really get the most out of it.
> 
> I think reading Floyd's book was a great eye opener to a reflective environment. Check out page 88 about comb filtering and how overrated it is in a car . Good call Erin


Jim, I think both Erin and I were agreeing with you and were tying your statement back to one of the points made earlier in the thread about measuring drivers. I think we've all found this to be true, and it is a point that is important enough to underscore. The idea that a car is such a poor environment that it overshadows the need for a respectable driver in the first place is flawed, and we all agree on that point. A sow's ear in the car will not become a silk purse through install and tuning, but a silk purse can be made a pile of crap quite easily.

-T


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## chad (Jun 30, 2005)

Andy Wehmeyer said:


> Why? Should I explain what i mean or......


No, it's because, IMHO it's the ultimate goal.


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## ErinH (Feb 14, 2007)

Andy Wehmeyer said:


> See Sean Olive's explanation in the thread in this link:
> 
> Sound Power Response vs. Frequency Response
> 
> Basically, power response refers to the response at all listening (or measurement angles)--the combination of on-axis and off axis response.


Which is why off-axis plots of a driver is so useful. Power response tells the whole story. Without this, you likely won't see when a driver (or system) is giving you problems because instances such as cone modes will show up in all the plots. Makes issues easier to spot.

Thanks for jumping in, Andy.


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## ErinH (Feb 14, 2007)

chad said:


> No, it's because, IMHO it's the ultimate goal.


Agreed.

In a car, though, it's still a bit weird to me. I notice that JBL and Helix suggest using the reference curve which seems to include HRTF. So, is it HRTF, or is it a power response curve? Are the two linked or is just coincidence that both curves exhibit a falling response above some given frequency (what is it, like 5khz or something?). Kinda makes me curious.


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## chad (Jun 30, 2005)

Another thing to remember is that if you find a narrow suck-out, especially with software that's giving you a fine resolution. 9 times out of 10 you aren't hearing it unless you are doing sweeps. You are also likely to do more harm than good by correcting it electronically if it's distance or reflection based.

I have a narrow one in my listening space, I should start playing with it and write something up providing I can get to it with something in another passband.


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## sqnut (Dec 24, 2009)

Erin,

Just some thoughts and I'd like to hear what you think.

1. Its important to balance for L/R and get the drivers in proper acoustic phase. The FR roll off on the graph is also in line with our ears sensitivity. But all that by itself is not enough to ensure that you're hearing a tight and punchy lower end. With the lower end set the way it is, maybe you need to look at the FR across all 10 octaves. Going back to the FM graphs, the ears are most sensitive in ~1-4khz range. If your ears perceive this range as louder than the range where you have lower sensitivity or if there are dips and peaks here, these are going to stand out like a sore thumb and mask out the good lower end. A case where the the more sensitive range counts for more. The flip side is loss of low end impact when you turn the volume down the less sensitive zone becomes more important here.

There's tons that can be wrong here from reflections to beaming etc. I think it's about getting the different ranges balanced for our ears sensitivity levels. I'm a big believer in that. 

2. An RTA is great for locating peaks and dips but the mic hears reflections differently from our ears. It's think the FR curve that really matters would be measured at your ear drum. A flat response at say ear level doesn't mean much cause it doesn't take into account the ears sensitivity. 

3. Most cars will have a dip ~500 hz, at least for door mounted mids. I agree that boosting the dip is counter productive. Maybe the solution lies in cutting 'everything' else so that in relative terms that 15db dip is now much less and easier to handle.


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## ErinH (Feb 14, 2007)

Are you asking or telling? I'm confused.


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## sqnut (Dec 24, 2009)

bikinpunk said:


> Are you asking or telling? I'm confused.


 I'm just throwing an alternate line of thought and wondering if you can test what I'm saying.


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## MarkZ (Dec 5, 2005)

I'm not Erin, but I have a couple comments.  



sqnut said:


> Erin,
> 
> Just some thoughts and I'd like to hear what you think.
> 
> ...


First, masking is (mostly) frequency dependent, so it's difficult for high frequencies to mask lower end. At least in the traditional sense of the word. Yes, your top end can be so ugly that it distracts from the low end, but that's really something else. 

Anyway, I don't really think we should be guided by our ear's sensitivity, necessarily. The engineers already did that when they put the album together. If you're the "listen to it the way the engineer intended" type, then you want a completely flat FR.



> 2. An RTA is great for locating peaks and dips but the mic hears reflections differently from our ears. It's think the FR curve that really matters would be measured at your ear drum. A flat response at say ear level doesn't mean much cause it doesn't take into account the ears sensitivity.


Yeah, but it's hard to mimic the reflections and occlusion that your legs (and head!) provide. I think positioning the mic at ear level is a very good approximation. I think the biggest problem is that you're overestimating some of the reflections of the side windows when you don't have a head in the way. 



> 3. Most cars will have a dip ~500 hz, at least for door mounted mids. I agree that boosting the dip is counter productive. Maybe the solution lies in cutting 'everything' else so that in relative terms that 15db dip is now much less and easier to handle.


A dip at 500Hz may be the kind of dip that you CAN correct for. If the dip comes as a direct result of the off-axis response of the driver, then I see no problem with boosting here. Or, using a shallower rolloff on the LPF (same thing...), etc.


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## 14642 (May 19, 2008)

It's sufficient to adjust the target curve for your microphone's frequency response. That includes binaural mics, microphones buried inside the ears of a crash test dummy, an array of microphones arranged in some shape, etc. It's also sufficient to use a microphone correction filter. 

All of this suggests that when we talk about this kind of stuff, we should begin to specifiy the measurement condition. Something like, "When I measure flat response with a binaural microphone on my own head, it sounds too bright" might be helpful.


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## cvjoint (Mar 10, 2006)

Andy Wehmeyer said:


> Be careful with this one. In cars and because of the reflective environment, significantly boosting a null is always a bad idea. The null can be a result of the combining of the response of two speakers or it can be the result of the combining of the response from a speaker and the reflected sound from that same speaker. Or, it can be all three. If it's only the combination of the two speakers and the environment isn't reflective, boosting won't alter the null at the measurment position. We all know that this doesn't happen in cars and when we boost a null we do change the measurement at that location--not by as much as we boost however.
> 
> So...why is it affected? Because we don't hear (or measure) only the direct sound. We also hear and measure the reflected sound. When you boost a null by 12dB, the amp clips and the speaker is over driven because IT IS OUTPUTTING MORE AT THAT FREQUENCY. At the measured location, the condition that created the null still creates a null, but the additional output in the reflected sound provides the "fill-in". While you may be able to get a better measurement, the sound will be nasty, and that's what Erin has discovered. The difference between the pleasant result in your measurement and the unpleasant result when you listen is PROOF that reflected sound matters.
> 
> ...


If I get this right the dip in my car is not about reflection because boosting it is reflected in the correction almost 100%. If I boost 5 db, the FR plot lifts about that much as well. 

What Erin posted is really correlation is it not? Just because it sounds bad it doesn't mean it's reflection driven bad and can't be corrected. Maybe a bigger speaker+amp may do the trick.

If it is reflection driven and EQ. does only a little bit I believe you still have to prove that significant delays at that frequency matter a lot. If the dip is at 70hz how much reflection driven output can you tolerate? I find that without boosting the near side is very weak and the right side almost always overpowers and drives attention. 

I understand reflection driven dips are more difficult but how do we know it's the bad type? I never boost if the dip doesn't move upon boosting. But if it does I do find that even significant boosting can balance L,R.


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## Gary S (Dec 11, 2007)

This is thread is not too bad. Judges at shows like flat in-car responses, but they do nothing for sound quality - our ears and brains hear differently than an RTA. Many in shows have had a switch to bypass the eq during listening portions of a show. Others have turned off their eq's and realized better sound quality. Eq's used to be money makers when I was in the business, but I would try to talk people out of them.

This is why installation and design quality and speaker placement are king. It's hard to package that stuff in an electronic device and sell it, so the electronics companies invented EQ's.


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## chad (Jun 30, 2005)

Gary S said:


> This is why installation and design quality and speaker placement are king. It's hard to package that stuff in an electronic device and sell it, so the electronics companies invented EQ's.





> Variable equalization in audio reproduction was first used by John Volkman working at RCA in the 1920s. That system was used to equalize a motion picture theater sound playback system.


Given that back then motion picture theaters were converted playhouses and music theaters, I doubt it was due to acoustics of the room but rather that of the lack of technology in drivers andplayback equipment... 

Before that it was used as pre-emphasis/or de-emphasis for twisted pair telephony.... A couple hundred miles of wire tends to lose some top end 


But in reality I'm giving you some ****..... we know what you mean.


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## quietfly (Mar 23, 2011)

just read through this, there's some good stuff in here. I know the inherit value of using RTAs, but Ultimately, for me its about how it sounds when i'm listening to it the most often. Unfortunately those happen to be less than optimal conditions. 

Since this thread was started by Erin in the context of competition, I can understand the frustration and the desire to want to get it right. what i wonder about is that principle of diminishing returns. where each further improvement or upgrade yield fewer and fewer benefits, while the required effort to implement them increased exponentially. 
I see this in builds like the "magic bus" and "black Bette". the work behind the creation and completion of each of those was almost unimaginable, but still there are plenty of things for the "average" DIY'er to take away from each of those builds and use to make our own builds more "ideal". 
for most people who like to "tinker" (myself included) the fun part is the challenge, and not so much the solution. which is why i love threads like these, and this board in general.


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## ErinH (Feb 14, 2007)

Gary S said:


> Judges at shows like flat in-car responses


That is not true. I've yet to talk to a single judge who has said that. 



Flat... It's simple. ANY deviation from flat is a deviation in the original signal as provided on the media given by the record label. Purity in a playback system tells you that the signal must not be altered. It's simple logic. The problem is discerning the environmental effect and learning what is wrecked by the room. Direct sound bs reflected sound is an area worth pursuing but in the car, it's moot. 

Andy brings up a good poit about the measurement system, though. Which is why a calibrated mic is so useful. But moreso, understanding what you see is crucial as well.


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## ErinH (Feb 14, 2007)

quietfly said:


> just read through this, there's some good stuff in here. I know the inherit value of using RTAs, but Ultimately, for me its about how it sounds when i'm listening to it the most often. Unfortunately those happen to be less than optimal conditions.
> 
> Since this thread was started by Erin in the context of competition, I can understand the frustration and the desire to want to get it right. what i wonder about is that principle of diminishing returns. where each further improvement or upgrade yield fewer and fewer benefits, while the required effort to implement them increased exponentially.
> I see this in builds like the "magic bus" and "black Bette". the work behind the creation and completion of each of those was almost unimaginable, but still there are plenty of things for the "average" DIY'er to take away from each of those builds and use to make our own builds more "ideal".
> for most people who like to "tinker" (myself included) the fun part is the challenge, and not so much the solution. which is why i love threads like these, and this board in general.



This thread was not started in reference to competition at all. Just want to clear that up. 

This thread is certainly targeted at te average diy'r. 
This thread was started to discuss common fixes people employ based on their lack of understanding how you hear, how to use a mic, and common convention in the car fi scene and how those fixes are sometimes the completely wrong way to set out correcting response along with fiscussion on why you should be careful what and how you try to "fix".


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## quietfly (Mar 23, 2011)

bikinpunk said:


> This thread was not started in reference to competition at all. Just want to clear that up.
> 
> This thread is certainly targeted at te average diy'r.
> This thread was started to discuss common fixes people employ based on their lack of understanding how you hear, how to use a mic, and common convention in the car fi scene and how those fixes are sometimes the completely wrong way to set out correcting response along with fiscussion on why you should be careful what and how you try to "fix".


I do think it's (this thread) targeted at the average DIY'er, I just think that the perspective you and others who do compete, have added to it, is an added value. I didn't intend to skew others of what your intentions were at starting the thread. I guess i just merged reading this thread and the posts you made on Pionkej's thread and came up with my own thoughts about your tuning in preparation for competition.


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## 14642 (May 19, 2008)

I just hate it when i read "mic's and ears hear differently". Mic's don't hear. Microphones simply convert acoustic pressure into voltage. We find that useful because that voltage can be used to convert what the microphone measures into something we can see. Hearing involves our perception of what arrives at our ears. The problem isn't that they're different. The problem is that it isn't obvious to the unpracticed user of the mic and RTA how what's on the screen is related to what we perceive withour ears. In many cases, I can look at an RTA and understand what's being represented and what conditions contribute to that representation. In some cases, that understanding requires some further investigation. The RTA gives us some clues. If you know how to use the clues, then it's a useful tool. If you don't, then it's of little use. 

Flat response on an RTA is not necessarily an indication that things are correct. In some cases it may simply mean that the problem cannot be displayed by the system and that...you guessed it...further investigation is required. What you use to continue the investigation is up to you, but the tool you choose may not be the tool someone else uses. 

What i can say, for certain, is that even if all other conditions that cannot be displayed by an RTA are correct and the response measures flat when measured with a single mic in the driver's head position, most listeners won't like it.


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## quietfly (Mar 23, 2011)

Andy Wehmeyer said:


> I just hate it when i read "mic's and ears hear differently". Mic's don't hear. Microphones simply convert acoustic pressure into voltage. .......
> 
> What i can say, for certain, is that even if all other conditions that cannot be displayed by an RTA are correct and the response measures flat when measured with a single mic in the driver's head position, most listeners won't like it.


Did you purposely say single mic because averaging between multiple mics gives different results?

Also isn't what listeners like a bit subjective anyway?


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## Wesayso (Jul 20, 2010)

Andy Wehmeyer said:


> Lastly, "minimum" phase is derived from the frequency response curve in analysis tools. It's useful if you're measuring a single driver anechoically with an ungated sweep or a steady-state signal like pink noise. It is NOT a phase plot of your car.


Are there usefull measurements/tools (other than our ear) to show the phase relation between multiple drivers?
I guess that's one of the things a tool like MS8 can do well. I'd like to confirm if I did ok whith phase response with setting my crossovers and time alignment. Frequency response alone can be misleading with all the reflections and room modes right?


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## Hanatsu (Nov 9, 2010)

Hmmmm... phase is kinda confusing. So minimal phase isn't useful to measure in car response, like total output? When we are measuring T/A we're basicly measuring the DIFFERENCE in phase between speakers right? Is there any way to get a phase vs frequency plot that looks like an "ordinary" FR curve? Shouldn't it be possible to unwrap phase measurements so it doesn't jump between 0-360 and continues to change as in a "line" instead the messy up and down pattern, that way one could see how it looks.

So where do group delay come in here? Know that it's some kind of derivative of frequency and phase, can't this be used to find both frequency and phase anomalities then? Flat GD, all good huh?


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## MarkZ (Dec 5, 2005)

I'd suggest testing your T/A apart from your power spectrum / phase response. You can use an impulse response with your LPF defeated to estimate delay between drivers. This usually works but can sometimes be noisy and/or corrupted by near reflections. I don't know offhand of software that does this -- Erin does I'm sure -- but there are some o-scope tricks to do this using triggering.

There are more sophisticated ways of doing it, but I don't know of any software packages that do those either. IIRC, back when I set my T/A I settled on subtracting (or dividing?) the autocorrelation from the cross-correlation (the autocorrelation of the impulse response provides a time-domain signature of prominent reflections). Again, I don't know if this has been incorporated into a software package. TrueRTA might allow you to do the cross-correlation part... I forget. Me and that software don't get along. 

Once you have your delay set to what you're trying to achieve, then you can better address phase. I can't think of a reason why you'd manipulate delay to correct for phase. Maybe if that's the only tool you have at your disposal?

Anyway, any _good_ software should provide phase plots along with the amplitude plots. If they allow you to plot two measurements on the same axis, you have a nice picture of relative phase.


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## 14642 (May 19, 2008)

quietfly said:


> Did you purposely say single mic because averaging between multiple mics gives different results?
> 
> Also isn't what listeners like a bit subjective anyway?


Mic arrays will provide a different measurement. microphones that you wear will also provide a different measurement. I wrote single mic because that's the most common way thet people here measure and it's how all of the competition folks measure for scoring. Flat response measured in a car using an array and flat response using a binaural mic are also not pleasant for most listeners. We all like more bass in small spaces. 

Sure, there's some subjectivity, but that doesn't mean that one listener prefers something completely different than another one. Some like a little more bass. Some like a little less treble. IASCA and MECA has taught a bunch of us to like way too much midbass. That doesn't change the fact that our hearing mechanisms are similar and the events that we all hear are similar.


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## Niebur3 (Jul 11, 2008)

Andy Wehmeyer said:


> IASCA and MECA has taught a bunch of us to like way too much midbass.


Do you think that is because midbass does cause so many problems in the car. Hard to get to sound good, so when it does...blast it...lol!


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## chad (Jun 30, 2005)

Niebur3 said:


> Do you think that is because midbass does cause so many problems in the car. Hard to get to sound good, so when it does...blast it...lol!


go look at some FOH EQ even from the industry's best FOH engineers


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## 14642 (May 19, 2008)

I think it's because as stereophiles, we have some bizarre fixation on getting our really big drivers to move alot and we convince ourselves that tubby bloat is really impact because we want a "bang" but we settle for a "blormp" because we want to reduce the midrange because we don't like what a saxophone REALLY sounds so we cut 1-3k. Then we decide that we like the sound of the toms and the conga drums so we boost 80-300 because we think that's where impact comes from. Then we feel our pant legs move and say, "DAMN! That midbass kicks ass" even though there no definition left in any percussive anything. 

Oh, and because in order to get bass in the front, you have to put in big midbass drivers and drive them with big amps and turn them way up because installing them was a lot of work.


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## chad (Jun 30, 2005)

Andy Wehmeyer said:


> Oh, and because in order to get bass in the front, you have to put in big midbass drivers and drive them with big amps and turn them way up because installing them was a lot of work.


well played


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## thehatedguy (May 4, 2007)

You mean a sax isn't supposed to sound raw, aggressive, and have a lot of bite to it...and make you blink when someone plays it loudly?

Maybe that's where I have been going wrong all of these years...

I apologize to anyone who I've judged at the shows that I've told the sax on the MECA disk was too polite and didn't have enough bite to it...and your midbass was too heavy and bloated.

And lets not forget that pianos are really precussion instruments either...


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## chad (Jun 30, 2005)

thehatedguy said:


> And lets not forget that pianos are really precussion instruments either...


harpsichords should just flippin POUND!


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## cvjoint (Mar 10, 2006)

Andy Wehmeyer said:


> I think it's because as stereophiles, we have some bizarre fixation on getting our really big drivers to move alot and we convince ourselves that tubby bloat is really impact because we want a "bang" but we settle for a "blormp" because we want to reduce the midrange because we don't like what a saxophone REALLY sounds so we cut 1-3k. Then we decide that we like the sound of the toms and the conga drums so we boost 80-300 because we think that's where impact comes from. Then we feel our pant legs move and say, "DAMN! That midbass kicks ass" even though there no definition left in any percussive anything.
> 
> *Oh, and because in order to get bass in the front, you have to put in big midbass drivers and drive them with big amps and turn them way up because installing them was a lot of work.*


I was joining the mob until this part. Something is not quite right here. The belittled stereophiles are the kinda guys who install an 8" sub in a cupholder and fear bass altogether. Maybe it's because the pot and stick music hasn't really prepared them for this type of material. 

If they really are installing truly large midbass drivers and putting in the work to reinforce the poor car, power to them. They must be a dying breed because I can hardly count more than a hand would allow over the last 6 years.


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## highly (Jan 30, 2007)

cvjoint said:


> I was joining the mob until this part. Something is not quite right here. The belittled stereophiles are the kinda guys who install an 8" sub in a cupholder and fear bass altogether. Maybe it's because the pot and stick music hasn't really prepared them for this type of material.
> 
> If they really are installing truly large midbass drivers and putting in the work to reinforce the poor car, power to them. They must be a dying breed because I can hardly count more than a hand would allow over the last 6 years.


I have to admit I am in the *BBW* camp.

*B*ig *B*eautiful *W*oofers, you pervert.

6.5" midranges. 8" woofers. The subwoofer isn't really necessary unless you are on the highway at 80 MPH...
Transients are as they should be. Visceral when that's called for, but subtle and detailed otherwise. Was there supposed to be a downside to that mindset? I certainly don't recall being told my midbasses were overpowering, but when that sax gets down and gritty and honks at you, you KNOW it.

If I could manage to shoehorn a pair of 12s IB in the footwells I'd be done.


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## cvjoint (Mar 10, 2006)

We always say we need more women in this hobby. Gotta be careful what we wish for I guess!


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## sqnut (Dec 24, 2009)

MarkZ said:


> I'm not Erin, but I have a couple comments.


I'm glad that you replied directly to my post i/o picking and sniping at parts of what I said while replying to someone else . It's all good though.





MarkZ said:


> First, masking is (mostly) frequency dependent, so it's difficult for high frequencies to mask lower end. At least in the traditional sense of the word. Yes, your top end can be so ugly that it distracts from the low end, but that's really something else.


The frequencies are not masking out the lower end, your ears are. Since your ears are most sensitive in the 1-4khz range and if there are any issues here your ears are going to highlight this and forget about whats happening at the lower end. 



MarkZ said:


> Anyway, I don't really think we should be guided by our ear's sensitivity, necessarily. The engineers already did that when they put the album together. If you're the "listen to it the way the engineer intended" type, then you want a completely flat FR.


What the engineer so painstakingly recorded goes out the window thanks to the environment you're listening in and this obsession with RTA flat. RTA flat would sound like 'weak low end, boomy midbass and overly bright midrange.' I'm quite sure that is not how the engineer wants you to hear it. The ears sensitivity is critical when setting up sound in a car.





MarkZ said:


> *Yeah, but it's hard to mimic the reflections and occlusion that your legs (and head!) provide*. I think positioning the mic at ear level is a very good approximation. I think the biggest problem is that you're overestimating some of the reflections of the side windows when you don't have a head in the way.


Which is why you have to do this bit by ear and not RTA. I'm sure you could get good results by placing the mic near your ear BUT you DON'T want to set it flat.


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## rc10mike (Mar 27, 2008)

If you dont compete to try to impress someone elses ear, then at the end of the day whats really more important to you?

Actually liking what you hear or having a system that measures flat on a RTA?

To me RTA seems like one of those "peace of mind" things, that as long as it measures flat then it must sound as good as it gets, the end. Essentially tricking yourself into believing that it sounds the best it could, even if you really dont like it.


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## cvjoint (Mar 10, 2006)

1. Erin did not in fact use an RTA

2. Tuning with a mic is not synonymous to tuning to a flat target curve


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## rc10mike (Mar 27, 2008)

cvjoint said:


> 1. Erin did not in fact use an RTA
> 
> 2. Tuning with a mic is not synonymous to tuning to a flat target curve


1. Ok, refer to post 1 word 21

2. Never said it was or wasnt, just making a general statement of what seems to be the common goal of "audiophiles" on this forum.


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## cvjoint (Mar 10, 2006)

rc10mike said:


> 1. Ok, refer to post 1 word 21
> 
> 
> 
> 2. Never said it was or wasnt, just making a general statement of what seems to be the common goal of "audiophiles" on this forum.


Yes. I see it.


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## ErinH (Feb 14, 2007)

Damn. You guys really know how to pick apart each others' posts just to say something contrary for the sake of it, don't ya?

I appreciate those who took the time to see what the OP was: a heads up thread regarding using both your ears and a mic to analyze your system with the goal of making it better. 

I'm sorry that some of you have chose. To use it for something it's not and make it it an unfounded basis for your own viewpoints while highlighting the difficulty of using either method alone. 

Erin


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## cvjoint (Mar 10, 2006)

FWIW I thought we were getting sidetracked by Mike in either competition talk, or target curves. That was an attempt to get it back on track. The RTA thing is well founded and I'm afraid it's collateral damage at this point. 

The OP doesn't prove anything as far as your ears as a tuning device as far as I can tell. It could be nonlinear distortion as I mentioned in earlier posts. Without eliminating HD differences before and after boosting you can't claim it sounds bad and you should not EQ. What I mean is that you can claim whatever you want, but I'm not buying it.

Andy made a good post about reflections. That was a great theoretical addition but there is no proof as of yet. This is the most notable stride towards proving "EQ. is bad." Show me the money!


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## stereo_luver (Oct 30, 2007)

bikinpunk said:


> Damn. You guys really know how to pick apart each others' posts just to say something contrary for the sake of it, don't ya?
> 
> I appreciate those who took the time to see what the OP was: *a heads up thread regarding using both your ears and a mic to analyze your system with the goal of making it better. *
> I'm sorry that some of you have chose. To use it for something it's not and make it it an unfounded basis for your own viewpoints while highlighting the difficulty of using either method alone.
> ...


That's what I took from it. Thanks Erin.

Chuck


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## sqnut (Dec 24, 2009)

cvjoint said:


> The OP doesn't prove anything as far as your ears as a tuning device as far as I can tell.


The original curve doesn't prove anything for tuning by ears because:

1. It doesn't cover all 10 octaves.

2. It wasn't done by ear. 

The first point is more relevant though. It would be interesting if Erin would post the FR of his system as it sits across all 10 octaves.


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## MarkZ (Dec 5, 2005)

sqnut said:


> I'm glad that you replied directly to my post i/o picking and sniping at parts of what I said while replying to someone else . It's all good though.


Ha, it's a forum dude. Folks are gonna chime in. Be thankful I didn't bribe ant to let me intrude on your PMs.



> The frequencies are not masking out the lower end, your ears are. Since your ears are most sensitive in the 1-4khz range and if there are any issues here your ears are going to highlight this and forget about whats happening at the lower end.


That's not how masking works. 



> What the engineer so painstakingly recorded goes out the window thanks to the environment you're listening in and this obsession with RTA flat. RTA flat would sound like 'weak low end, boomy midbass and overly bright midrange.'


It really doesn't sound like that at all.



> I'm quite sure that is not how the engineer wants you to hear it. The ears sensitivity is critical when setting up sound in a car.


Then why didn't he engineer it not to sound like that?

Look, I'm not an engineer-knows-best kinda guy, as I too have some preferences that depart from the mainstream. But I think flat is a very good approximation to what I like (I tend to have a very shallow decrease in output at the high end).


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## ErinH (Feb 14, 2007)

cvjoint said:


> The OP doesn't prove anything as far as your ears as a tuning device as far as I can tell.





sqnut said:


> The original curve doesn't prove anything for tuning by ears because:
> 
> 1. It doesn't cover all 10 octaves.
> 
> ...



Guys, I really think you're reading too much in to this. The purpose wasn't to tell you that one is better than the other. In fact, the purpose was quite the opposite. I discuss using the RTA as a tool but also say in the OP that a quick hearing check resulted in a terrible sound. Sure, it won't be the same for everybody but if you sit back and realize:
The purpose of the thread was to highlight a common problem in car audio and highlight one way that people often go about fixing it and my results (as well as general results) when I applied that method.

Another goal of this thread was to also discuss just how important install is. Unfortunately I can't provide data for that but the fact of the matter is that modes do occur and you can't do anything about it. However, placement will yield varying results. I wish someone else would pick up the ball here and do some quick testing/analysis in their car and report back. There's a lot of single dudes here with nothing better to do than mess with their car stereo (this isn't a dig... I might just envy your free time) and a lot of them have an RTA, so let's get crackin, folks! 

I chose not to show the entire spectrum because I wanted to hone in on midbass/subbass transition. We have 3 pages of discussion already on < 500hz alone... imagine if I had shown you guys 20-20khz!


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## 14642 (May 19, 2008)

Erin, are your original graphs the left side WITH the sub and the right side WITH the sub? It appears that 80Hz or something like that is your crossover frequency. If you reverse the polarity of the sub, does that improve the left side response? Second question, if you sit in the passenger's seat, is the problem reversed? If you turn off the sub, do the two channels look more similar?What I'm trying to find out here is whether the problem can be improved by moving the SUB, changing the crossover point or polarity or if the problem is relative phase between left and right.


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## sqnut (Dec 24, 2009)

Look, I genuinely think that the solution to your midbass lies in the octaves unseen. 

I would like to see if, what worked for me can also work for you. Just try what I'm suggesting. Best case scenario, you have better sound and are hooked on tweaking, worst case scenario I look like a fool. 

Dude you measure speakers and derive appropriate inferences, but you won't try something that may be a bit different? No I'm not baiting you .


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## ErinH (Feb 14, 2007)

You're making wrong inferences.
You're trying to answer a question that wasn't asked.


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## pionkej (Feb 29, 2008)

bikinpunk said:


> Guys, I really think you're reading too much in to this. The purpose wasn't to tell you that one is better than the other. In fact, the purpose was quite the opposite. I discuss using the RTA as a tool but also say in the OP that a quick hearing check resulted in a terrible sound. Sure, it won't be the same for everybody but if you sit back and realize:
> The purpose of the thread was to highlight a common problem in car audio and highlight one way that people often go about fixing it and my results (as well as general results) when I applied that method.
> 
> Another goal of this thread was to also discuss just how important install is. Unfortunately I can't provide data for that but the fact of the matter is that modes do occur and you can't do anything about it. However, placement will yield varying results. I wish someone else would pick up the ball here and do some quick testing/analysis in their car and report back. There's a lot of single dudes here with nothing better to do than mess with their car stereo (this isn't a dig... I might just envy your free time) and a lot of them have an RTA, so let's get crackin, folks!
> ...


Erin, 

I felt your OP was perfectly clear on its intent. All it's takes, however, is one divergent view to "fan the flame" so to speak. 

I'm not trying to muck thinks up further, but any install I've done involves setting forth a good plan/layout (and having "backup" plans in mind), selecting the best drivers for my install (this means models well in the intended enclosure, and measures well for its intended frequency range--so driver testing DOES matter to me), measuring with an RTA to see what everything looks like, make adjust by level/TA/EQ from the RTA (and I listen after a change is made to determine if it was beneficial), and finish everything by ear. 

The only reason I'm pointing this out is because it incorporates what many have said both does and doesn't matter in this very thread. It's my opinion that it ALL matters and you have to know which tool to use to fix the problem to the best of your ability. This may seem like common sense to many, but I bring it up because some of these polarizing arguments could easily scare the hell out of the uninitiated that may stumble into this thread.


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## sqnut (Dec 24, 2009)

I'm guessing its either a phase issue like Andy mentioned, either between the sub and the mids or between the two mids themselves. If the image is really pulling to one side then you need to look at L/R balance for all 10 octaves not just the low end. You need to do this first for each pair of drivers then combine 2 and then all three. Then you need to level match (not flat) but for a curve that sounds good in your car to your ears. You know what good sound in a car is, that's why I'm using the ears bit.


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## sqnut (Dec 24, 2009)

bikinpunk said:


> You're making wrong inferences.
> You're trying to answer a question that wasn't asked.


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## chad (Jun 30, 2005)

I'm just pissed off that this has me thinking about attacking this suck-out I have in my listening space at home and I really don't have much time to get at it this weekend.

So screw you people that just argue with each other, I'm gonna go in the corner and chase my tail for a while, maybe lick my balls for a little while.


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## kyheng (Jan 31, 2007)

Someone were chasing for his own shadow and proudly says he can catch it.....


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## sqnut (Dec 24, 2009)

chad said:


> I'm gonna go in the corner and chase my tail for a while, maybe lick my balls for a little while.





kyheng said:


> Someone were chasing for his own shadow and proudly says he can catch it.....


But that's the whole point. You'll never catch the tail or the shadow, but you'll keep getting closer :laugh:


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## quietfly (Mar 23, 2011)

chad said:


> I'm just pissed off that this has me thinking about attacking this suck-out I have in my listening space at home and I really don't have much time to get at it this weekend.
> 
> So screw you people that just argue with each other, I'm gonna go in the corner and chase my tail for a while, maybe lick my balls for a little while.


lol 
+++ FTW++++


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## chad (Jun 30, 2005)

kyheng said:


> Someone were chasing for his own shadow and proudly says he can catch it.....


I run from my shadow.....


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## vitvit (May 3, 2011)

rc10mike said:


> Actually liking what you hear or having a system that measures flat on a RTA?


I think we do not talk about_flat_ RTA, but measuring to help our listening that we can't printout and analyse later.
Why should we contradict one to other? I, personally, hear and feel things becomes better after changes in system shows better measurements. Not looking at FR alone: check your phase, group delay graphs, waterfall and impulse.


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## Hanatsu (Nov 9, 2010)

Hm the best use for FR measurements (imo) is to set L-R channels equal and to adress problems in response. Every system I've tuned sounds lot better after I measured and adressed irregularities in FR. Never had a system that measure anything close to flat, it doesn't sound good to me. I use to have 10dB+ between 20-80Hz then falling down to reference level at approx 160Hz, from here I care mostly about having the same response from both sides. Most important imo, is the response between 1,5-3,5kHz, rather have this area a few dBs lower than the rest. I tweak the last settings by ear.


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## Hanatsu (Nov 9, 2010)

Had a picture of a target response I found quite pleasing in my car, of all the testing and listening I've done I found this to be the best one. (Note, I simulated this response in a program using my real in-car FR)










Edit: Used, 16 mic locations, averaged all, smoothed 1/3. Simulation app probably smoothed it again =/


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## ErinH (Feb 14, 2007)

Looks an awful lot like the equal loudness curve...


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## MarkZ (Dec 5, 2005)

Huge differences in what people like. I could never live with that much energy <100Hz and that dip from 200-500. 

Agree with you on the importance of FR measurements in getting L/R balance correct though. It's really the easiest way.


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## sqnut (Dec 24, 2009)

Hanatsu said:


> Edit: Used, 16 mic locations, averaged all, smoothed 1/3. Simulation app probably smoothed it again =/


Can you measure from one location i.e. where you sit. Let's see how that graph shapes up. Even with a 16 mic average it looks good.



MarkZ said:


> Huge differences in what people like. I could never live with that much energy <100Hz and that dip from 200-500.


It is not about how it looks, it's about how it sounds. I guess thats too complicated a difference to comprehend.


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## MarkZ (Dec 5, 2005)

sqnut said:


> It is not about how it looks, it's about how it sounds. I guess thats too complicated a difference to comprehend.


Those of us with experience looking at such things can use the data to predict certain aspects of what it will sound like. In ALL my previous cars, the FR always ends up having pretty much the same profile.


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## 14642 (May 19, 2008)

Hanatsu said:


> Had a picture of a target response I found quite pleasing in my car, of all the testing and listening I've done I found this to be the best one. (Note, I simulated this response in a program using my real in-car FR)
> 
> 
> 
> ...


In order to understand what this curve means, it's necessary to know whether the 16 mic locations were arranged around the seating area for the driver and passenger or whether these 16 locations were all over the car. IN general, I'd say that this curve pretty closely matches my proposed target with the exception of the 3dB dip in the lower midrange and the 4dB dip at the tweeter crossover. More information about the measurement condition would be helpful in determining the reason for these two dips, although neither is very big.


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## sqnut (Dec 24, 2009)

Thank you Andy for validating that curve. You're validating another avenue for people to explore.

I think a slight dip around 2-5khz works, because in a car you will always have issues in this range, no matter what you do. It's also the range where the ears are most sensitive. So any artifacts / defects will stand out even more. By cutting this range a bit you're reducing the perception of those defects a bit. I have a similar 3db dip as well. 

I'd actually cut a bit in the 6-8hz to handle sibilance and then open it up at around 12khz and let things roll of from there. Overall I think it's a pretty neat curve. 

Of course each environment/install will have its own unique ideal curve but what strikes me is how close the curves mimic the equal loudness curves. I too am curious how this was measured. 

While this thread has had it's share of snapping and sniping and that includes me, I just think people should be maybe be more open to different ideas and possibilities. If you don't try it you'll never know for sure.


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## chad (Jun 30, 2005)

sqnut said:


> I think a slight dip around 2-5khz works, because in a car you will always have issues in this range, no matter what you do.


I think that's painting with a pretty broad brush, unless we all drive the same exact vehicle... 



sqnut said:


> It's also the range where the ears are most sensitive.


THIS on the other hand, is spot on.


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## MarkZ (Dec 5, 2005)

I don't understand the significance of equal loudness curves on this discussion. Both you and Erin have brought it up, and maybe one other person. Equal loudness curves are already accounted for during production. The FR plot is just a transfer function (by freq).

What might be more relevant than the equal loudness curve is the spacing between the contours in the Fletcher-Munson curves. That's an indicator of the _change_ in SPL required to elicit a _change_ in perceived loudness. That would be an indirect measure of jnd vs. freq (not really, but same idea). IIRC, that's mostly flat across the entire band except at the edges.


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## ErinH (Feb 14, 2007)

MarkZ said:


> I don't understand the significance of equal loudness curves on this discussion. Both you and Erin have brought it up, and maybe one other person. Equal loudness curves are already accounted for during production. The FR plot is just a transfer function (by freq).
> 
> What might be more relevant than the equal loudness curve is the spacing between the contours in the Fletcher-Munson curves. That's an indicator of the _change_ in SPL required to elicit a _change_ in perceived loudness. That would be an indirect measure of jnd vs. freq (not really, but same idea). IIRC, that's mostly flat across the entire band except at the edges.



How can it be? The equal loudness curve changes with volume. 

F-M is one subset of ELC's.


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## sqnut (Dec 24, 2009)

chad said:


> I think that's painting with a pretty broad brush, unless we all drive the same exact vehicle...


......and have the same placement, agreed. But for the average install where drivers are separated and tweeters mounted up high, near reflective surfaces etc......I should have qualified my statement better.




chad said:


> THIS on the other hand, is spot on.


Tks, at least I got something right


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## sqnut (Dec 24, 2009)

bikinpunk said:


> How can it be? The equal loudness curve changes


....but the shape of the curve remains similar. You tune at a fixed volume one that you normally like listening at. Then when you turn the volume up or down a bit, the sound is still nice but slightly different, sure. It will be best at the volume you tuned it at.


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## sqnut (Dec 24, 2009)

MarkZ said:


> I don't understand the significance of equal loudness curves on this discussion. Both you and Erin have brought it up, and maybe one other person. Equal loudness curves are already accounted for during production. The FR plot is just a transfer function (by freq).
> 
> What might be more relevant than the equal loudness curve is the spacing between the contours in the Fletcher-Munson curves. That's an indicator of the _change_ in SPL required to elicit a _change_ in perceived loudness. That would be an indirect measure of jnd vs. freq (not really, but same idea). IIRC, that's mostly flat across the entire band except at the edges.


It's relevant because what is recorded is not what you're hearing in a normal car setup. One look at Andy's FR graphs for speaker level and ear level will tell you that. So now that curve that was so painstakingly recorded by the engineer, is shot to hell. If you know the curve that you need to dial back in, you're ahead of the curve. 

Of course there's more to good sound than just the FM curves. You still need to account for the anomalies of the car part of which you'll do while dialing in the curve and the balance you'll have to do by ear. You need to dial in tonality by level matching. All that is over and above the FM. Applying how we hear to what we're hearing is very important to my mind.


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## ErinH (Feb 14, 2007)

sqnut said:


> ....but the shape of the curve remains similar. You tune at a fixed volume one that you normally like listening at. Then when you turn the volume up or down a bit, the sound is still nice but slightly different, sure. It will be best at the volume you tuned it at.


The point of the curve is to illustrate how hearing is perceived at _varying _levels. And it does change. I realize it's similar, otherwise I wouldn't have said what I did in reply to the graph given. But, my point is that an engineer can't technically adjust to an equal loudness curve because it, by nature, varies. He can adjust to some curve at a given phon based on the ELC but it can't be dynamic because a recording isn't dynamic on the CD. See what I'm saying?


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## sqnut (Dec 24, 2009)

I think one other thing that needs to be mentioned is that this graph is 'averaged', that is what is giving it the smoothness. I think if one were to measure the same car and plot a graph for 1/3 octaves, the broad shape of the curve might remain similar, but the ride would be bumpier. 

That would differ from car to car and that is something you have to set by ear.


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## 14642 (May 19, 2008)

sqnut said:


> Thank you Andy for validating that curve. You're validating another avenue for people to explore.
> 
> I think a slight dip around 2-5khz works, because in a car you will always have issues in this range, no matter what you do. It's also the range where the ears are most sensitive. So any artifacts / defects will stand out even more. By cutting this range a bit you're reducing the perception of those defects a bit. I have a similar 3db dip as well.
> 
> .


This is also the region where the midrange and tweeter are crossed over in most systems. For two-way systems that use 6" mids, this is the area where the directivity (dispersion) of the mid and tweeter are not well matched. The result of flat response in the on-axis measurement is a dip in the response of the off axis measurements. So, I'd guess that's what contributes the dip and is why you like it.


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## ErinH (Feb 14, 2007)

FWIW, I don't really believe in one curve as an end all be all. I use varying degrees of every curve I've seen. A-weight, B-weighting, ELC, Flat, etc. That's ultimately because I'm tuning to some degree of preference. However, I maintain that a TRUE reproduction system should NOT alter the response in any way; this means a _dead flat_ FR because, again, what you put in is exactly what you should get out. If you put in ABCD, you should get ABCD. You should not get AbCd. All hearing preference aside, it's as simple as signal in = signal out and the methods you use to get there, whether it be by choosing the correct drivers and using them in their best passband or using DSP to help correct for some anomalies. 

The difference, and often undistiguishable part in car audio discussion, is that to attain a 'flat' response in _our_ environment you have to alter the _true_ response. What I mean is simply this: If you were to take a great speaker in the home environment and put it in the car, the FR changes significantly. Then folks attack it with the EQ often in erroneous manners to 'fix' it, not fully realizing what they're doing to not only the acoustic response but the mechanical response as well. This is NOT saying that a bad driver sounds good in the car; this is saying that this is why you should start with the best baseline you can, whether that be based on install requirements or simply price.

In my OP I somewhat highlighted this by mentioning the boosting of given frequencies via EQ resulted in a bad sound. The reason is simply because you're having to correct not only for the driver response but the effect of the environment on the response to a MUCH larger degree than a non-car audio environment.
This is why I cringe when people say generic things like "flat doesn't sound good". It's not that it doesn't sound good... it's that the means taken to achieve it are (more often than not) not good (for a lack of better words). Folks grab the EQ and start boosting and cutting without really understanding what they're doing. Connecting the dots isn't adequate and doesn't guarantee a good sound. You have to use the RTA and your ears together to gain a better understanding of what exactly you're changing and better yet, what exactly is causing the problem so you can then make the correct changes to make the response better.


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## sqnut (Dec 24, 2009)

bikinpunk said:


> *But, my point is that an engineer can't technically adjust to an equal loudness curve because it, by nature, varies.*


So he picks one level and records based on that level. You could be listening at a different level. Which is why you tune for the volume you listen at and a curve that will make most well recorded cd's sound good. BUT even then some cd's will sound better than others. They will all sound good but not equally good. That's fine. 



bikinpunk said:


> He can adjust to some curve at a given phon based on the ELC but it can't be dynamic because a recording isn't dynamic on the CD. See what I'm saying?


Does my explanation above somewhat answer this question?


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## ErinH (Feb 14, 2007)

sqnut said:


> I think one other thing that needs to be mentioned is that this graph is 'averaged', that is what is giving it the smoothness. I think if one were to measure the same car and plot a graph for 1/3 octaves, the broad shape of the curve might remain similar, but the ride would be bumpier.
> 
> That would differ from car to car and that is something you have to set by ear.


I agree to an extent. 1/3 resolution is often good enough. I see a lot of folks trying to fix problems they really can't because they use 1/24. 

I actually use something similar to what Andy said above; >1/3 below 500hz and 1/3 above 500hz. This shows me where the problems are with the bass area and helps me figure out ways to combat modes created by pressurization of the cabin. Above that, it's really reflection driven


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## sqnut (Dec 24, 2009)

Andy Wehmeyer said:


> This is also the region where the midrange and tweeter are crossed over in most systems. For two-way systems that use 6" mids, this is the area where the directivity (dispersion) of the mid and tweeter are not well matched. The result of flat response in the on-axis measurement is a dip in the response of the off axis measurements. So, I'd guess that's what contributes the dip and is why you like it.


Thank You, that makes a lot of sense. Yes this is where most people (including me) cross the two ways.


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## ErinH (Feb 14, 2007)

sqnut said:


> So he picks one level and records based on that level. You could be listening at a different level. Which is why you tune for the volume you listen at and a curve that will make most well recorded cd's sound good. BUT even then some cd's will sound better than others. They will all sound good but not equally good. That's fine.
> 
> 
> 
> Does my explanation above somewhat answer this question?


I understand how the ELC works. I've been basing tunes off it for years and have spent the better part of 6 months specifically working on methods to implement an ELC in my car with pots (but that's for another thread) just to see what results I get. It doesn't change the fact that a cd is pressed at a static "volume". That signal will ALWAYS remain the same no matter what volume you turn it up. Our hearing perception is what changes. 

You can tune for the volume you listen at and I do. I agree it's probably the best method. I've taken the ELC and plotted it at a given dB and then based my dynamic curve off that SPL (85dB @ 1khz, fwiw).
Let's say the engineer mixed based off the curve. What volume was it? Was he at 85dB or 90dB? These are pretty trivial in response, I agree. But what if he mixed at something more extreme... say 60dB or 100dB? The point is simply: you don't know what he did. So, like I said above, realistically what we _should _be doing - if our goal is true reproduction of the original signal - is aiming for flat and making sure the way we get there is correct. Please see my above post for further explanation. It really is simple as signal in (should equal) signal out.

Everything else regarding ELC really is just semantics. I mean, really, what are we arguing here?


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## sqnut (Dec 24, 2009)

bikinpunk said:


> However, I maintain that a TRUE reproduction system should NOT alter the response in any way; this means a _dead flat_ FR


I don't have science to back me on this but, a dead flat measured response is different from a dead flat perceived response, thanks to the ELC and the way we hear. 

A dead flat measured response sounds like not enough low end (which could be one reason people going for a flat response will xover the subs ~100-150hz, just to get better perception of the lower end) and an overly bright midrange/highs. 

A perceived flat response is based on how we hear and gives you a much better sense of balance across the different ranges and allows us to better integrate the ranges to more believable 'whole'. 


Hey, we're actually having a civilized discussion........


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## chad (Jun 30, 2005)

sqnut said:


> So he picks one level and records based on that level. You could be listening at a different level. Which is why you tune for the volume you listen at and a curve that will make most well recorded cd's sound good. BUT even then some cd's will sound better than others. They will all sound good but not equally good. That's fine.


Lots of fantastic info here Audio CD Mastering, Mixing & Replication

touching more on what you speak of: Honor Roll


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## 14642 (May 19, 2008)

bikinpunk said:


> Connecting the dots isn't adequate and doesn't guarantee a good sound.


That's the gold right there, fellers. 

A great sounding system will NOT measure like poop, but a system that measures nicely may sound like poop. There are a thousand ways to connect the dots in every system and most of them will sound like a$$. It's not THAT the dots are connected is HOW the dots are connected.


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## 14642 (May 19, 2008)

chad said:


> Lots of fantastic info here Audio CD Mastering, Mixing & Replication
> 
> touching more on what you speak of: Honor Roll


Wow. Great links. Thanks Chad.


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## sqnut (Dec 24, 2009)

chad said:


> Lots of fantastic info here Audio CD Mastering, Mixing & Replication
> 
> touching more on what you speak of: Honor Roll


Tks for posting these. The first time I saw the second link, it was more for identifying good recordings, stuff that would sound good .


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> The point of the curve is to illustrate how hearing is perceived at _varying _levels. And it does change. I realize it's similar, otherwise I wouldn't have said what I did in reply to the graph given. But, my point is that an engineer can't technically adjust to an equal loudness curve because it, by nature, varies. He can adjust to some curve at a given phon based on the ELC but it can't be dynamic because a recording isn't dynamic on the CD. See what I'm saying?


Hence the loudness button on your head unit. But unless you're using a dynamic EQ of some sort, you can't compensate for it in the tuning process either.


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## 14642 (May 19, 2008)

MarkZ said:


> Hence the loudness button on your head unit. But unless you're using a dynamic EQ of some sort, you can't compensate for it in the tuning process either.


This discussion of ELCs makes no sense to me in this thread. This is about tuning a system for accurate (or believable) reproduction. While we percieve sound differently at different levels, it's silly to make an audio system that adjusts the frequency response according to ELC if your objective is accuracy. The loudness button on the radio is so you can hear the bass in the music when you turn the volume down BECAUSE YOU'RE FOCUSED ON SOMETHING ELSE.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

Sub'd to make it easier to check in.

All I'm going to say is it all depends on what you want. Do you want it to sound "nice" or do you want it to sound "real". There are plenty of people who dont like the way live music sounds and like recorded music played over a tube amp better. Me, I want as close to live sound as reasonably possible. As Erin stated earlier, that means signal in = signal out for a good recording.

I just have a long way to go learning to best ways to get it there.


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## Hanatsu (Nov 9, 2010)

Andy Wehmeyer said:


> In order to understand what this curve means, it's necessary to know whether the 16 mic locations were arranged around the seating area for the driver and passenger or whether these 16 locations were all over the car. IN general, I'd say that this curve pretty closely matches my proposed target with the exception of the 3dB dip in the lower midrange and the 4dB dip at the tweeter crossover. More information about the measurement condition would be helpful in determining the reason for these two dips, although neither is very big.


Eh, sorry should have told that. Response was taken with a ECM8000 mic at left seat. Eight points each side (I wasn't in the seat, but I did put a fake leg to simulate blocking the left mid), 2,5inch or so between points sideways and approx 1,25" between every point forward. Input was made in TrueRTA, avaraged all results. From there I took the measured curve and inputted it into a self made visualbasic app which tells me how to EQ each point to compensate and this is the result of that (well kinda smoothed but overall response looks like this). Speakers are mounted at dash level, all frequencies between 200Hz-20kHz are completly onaxis. Door speakers handle 40-160Hz more or less (little gap here aswell). Havn't EQed more than 3dB+ or more than -5dB each band. Gap between 2,5kHz-3,15kHz in crossovers with 6dB filters both ways between midrange and tweeters. Might create a buildlog here later on, hehe 

Edit: Pretty sure I measured this at about 90-93dB (around there, need my damn laptop where all pictures and results are saved. But I'm like 500km away from it atm lol..)

Sorry for my drawing skillz...


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## sqnut (Dec 24, 2009)

Hanatsu said:


> Gap between 2,5kHz-3,15kHz in crossovers with 6dB filters both ways between midrange and tweeters. Might create a buildlog here later on, hehe


JI'm sure you have tried this but just curious what happens if you don't leave gap, but put both drivers on like a 24db slope? This would also help if you're getting lobing in this range.


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## ecbmxer (Dec 1, 2010)

Wow, thats a lot of averaging. How do some of you other guys position your mic to do RTA? And how many points are averaged?


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## cvjoint (Mar 10, 2006)

ecbmxer said:


> Wow, thats a lot of averaging. How do some of you other guys position your mic to do RTA? And how many points are averaged?


I usually do 10 points around the left ear, 10 around the right, and 5 up front. In reality I just move the mic around the head earL cheekL front cheekR earR until I average in 30+ measurements. After about 15 or so the FR plot stops moving erratically and settles to a nice average.


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## MarkZ (Dec 5, 2005)

Have you guys analyzed differences in mic positions before averaging?


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## cvjoint (Mar 10, 2006)

MarkZ said:


> Have you guys analyzed differences in mic positions before averaging?


Yeah, especially as it pertains to this suckout. It's worse by the left ear near the side of the car. 

I also can't average CSD plots and HD plots.


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## Hanatsu (Nov 9, 2010)

sqnut said:


> JI'm sure you have tried this but just curious what happens if you don't leave gap, but put both drivers on like a 24db slope? This would also help if you're getting lobing in this range.


I've changed it since then this is like 3 month old, this response was taken with DLS Iridium8, Audison Voce3 and DLS Iridium1i. Now I run DLS Iridium8/Fountek FR88EX and DLS Nobelium1. Got them crossed like this now. Mid: Pass/[email protected] - Midrange: [email protected] HP/2,[email protected] (Phase inverted) - Tweet: 3,[email protected] HP/[email protected] LP.

My tweets have pretty low Fs, around 850Hz. For some reason the staging was better with 1st order filters before, now I run 12dB filters with phase inverted instead. Overall response looks similar now, I will post a build log next week or so. Then I'll upload all the graphs and testing I've done, it's a huge amount. I think I've done over 50-60 different comparasion plots.

Edit: Leaving a gap in the 2,5-3kHz area because I have some wierd reflection here causing 6-7dB jump in this area. The gap flattens it down without the EQ


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## ErinH (Feb 14, 2007)

Toole's research showed that 6 mic positions is adequate in car. He started with 18. Read his white paper if you want the details. Given that, I don't really see the real benefit of all the extraneous mic points for averaging.


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## Hanatsu (Nov 9, 2010)

You probably right, the response doesn't change that much anyway between the points, I could try 4 points each side instead next time. Probably won't be much difference. Guess I was too thorough then... :thinking:


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## ErinH (Feb 14, 2007)

Actually, I think it was Geddes. That's my bad.


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## BigRed (Aug 12, 2007)

bikinpunk said:


> Toole's research showed that 6 mic positions is adequate in car. He started with 18. Read his white paper if you want the details. Given that, I don't really see the real benefit of all the extraneous mic points for averaging.


I agree Erin. I've done both and 6 seems to be plenty


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## cvjoint (Mar 10, 2006)

With the Omnimic you get to see the average. If it settles and doesn't move after a few measurements you are set. No reason to use a rule of thumb here, you get to observe the outcome. 

Anyway, you can have 400+ takes it doesn't actually hurt.


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## ErinH (Feb 14, 2007)

at the risk of bringing back the dead, here's some fun stuff.


I got my 'reference' system set up upstairs finally. Zaph zrt 2.5 (scanspeak 2.5 way). In room response is +/-1dB in the room above about 130hz. Great for reference listening.









^You can see the klippel in the background if you look! 

Spent the past couple days listening to it off and on in between my daughter's naps. It brought some things to my attention that I hadn't noticed or had questions about before. One being, if you listen the Livingston Taylor track "Grandma's Hands", the finger snap on the left moves pretty much all over the place. It's not stagnant like I was told it was sometime ago and I've since wondered how much it moved. When I listened to the setup upstairs it quickly became evident just how much and how far. 
Also noticed some stage things and overall tonality things that I'd never heard before. 

Took the knowledge out to the car to do some work and wound up doing a bit more with the RTA. I spent about an hour working on left/right balance alone.
This is the measured difference between left and right. Single point at my nose with me in the car. Panned right, measured, panned left, measured. Did this for about an hour working on the EQ until I got things balanced to what you see. I'm withing 0.5dB for most everything above 300hz except for the area around 1khz where I'm about 1dB off. The overall curve needs work to get the sound just right. My goal wasn't that; my goal was balancing the two sides. It paid off in full. Final listening session proved that it worked very well. So, tonight, the mic won for efficiency. 
Like I said, the curve needs work, of course, but I've gotten some of that resolved already. I modeled the HRTF and used that as a guide to tune by; much like what Andy provided way back when in the JBL MS-8 thread and like Helix provides via a Praxis frd file on their site. The big bumps are gone and the result is the next step in the evolution of my car and my learning. 


Again, just to show the match between left & right. *Pay no attention to the shape of the curves.* The picture was taken before I started working on the summed curve shape. 








(yet, I'm sure there will be at least one person who tells me how to adjust my curve)


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## thehatedguy (May 4, 2007)

I know of a couple of guys who use two EQs- one to match l/r and one for fine tuning tonality.


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## SouthSyde (Dec 25, 2006)

thehatedguy said:


> I know of a couple of guys who use two EQs- one to match l/r and one for fine tuning tonality.


A rane rpm88 could do that all in one.


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## garysummers (Oct 25, 2010)

View attachment 33828


Real Time Analysis utilizing Timed Spatial Averaging


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## ErinH (Feb 14, 2007)

That's a lotta mics, Gary!
Must be nice. 

Curious what you use. Figure it's not the run of the mill stuff knowing your occupation. 

You may have just made me your number one stalker via email with that picture. We need to talk RTA...


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## garysummers (Oct 25, 2010)

Welcome to GOLD LINE - Home page

I use the DCPCIW with the MX4 multiplexer and 4 of the TEF04 mics.
The mount is something I put together rummaging at Guitar Center. This system was recommending by a friend who ran the Home THX program for LucasFilm. It is very simple to use and I can have the Alpine F1 software running in the same window on my PC. Makes tuning manageable.


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## sqnut (Dec 24, 2009)

bikinpunk said:


> (yet, I'm sure there will be at least one person who tells me how to adjust my curve)


Except for that bump at ~1.5khz that is a fairly close mirror of the FM graph. You preach RTA flat but your curve isn't flat. Your curve mirrors the FM graph yet you choose to ignore it's relevance. No, I'm not going to tell you how to adjust your curve, I really could not care less.


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## MarkZ (Dec 5, 2005)

I like the color scheme in your room.


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## ErinH (Feb 14, 2007)

sqnut said:


> Except for that bump at ~1.5khz that is a fairly close mirror of the FM graph. You preach RTA flat but your curve isn't flat. Your curve mirrors the FM graph yet you choose to ignore it's relevance. No, I'm not going to tell you how to adjust your curve, I really could not care less.



O

M

G


Seriously, does no one read anymore? 

You quoted me, deleted text and yet managed to delete the text that makes your reply completely irrelevant. Again, read what I wrote. I had bolded it before... I'll leave it bolded again.

And, no, just because it has that shape it doesn't mean that's what it was like. The mic was in front of my face. The result would be different from the mic in free space. Why you insist on trying to start an argument with the above is beyond me. If you had actually read the post and took it for what it was worth you wouldn't have even had to reply. 
Furthermore, the rise in response from 300-1khz is the complete opposite of the FM curve. Just pointing it out. So, there are actually 2 things in my curve that don't mimic the fm curve. 





bikinpunk said:


> Again, just to show the match between left & right. *Pay no attention to the shape of the curves.* The picture was taken before I started working on the summed curve shape.
> 
> 
> 
> ...



This was right below the picture, which you did actually manage to not delete in the quote.


bikinpunk said:


> (yet, I'm sure there will be at least one person who tells me how to adjust my curve)


Looks like I was right.




Edit: 
When have I EVER "chosen to ignore" the relevance of the F-M curve? Show me one time that I've said it's irrelevant. I've started threads on here regarding how to tune around it and have provided users the f-m curve in numerous posts. I just stand firmly by that ultimately it's tuning based on a preference. A true audiophile (not the a-holes you see posting from on high); one who seeks reference playback understands that you should not alter the signal from flat. Honestly, with the screenname "sqnut", I would think you would at least concede this point. Truthfully, I would expect that if anyone here is shooting for that, it would be you. Sound quality as a true-to-the-original reference should not alter the signal in any form. The hard part is achieving flat in a way that doesn't screw things up. I've said it numerous times in this thread: signal in should always equal signal out IF your goal is to remain true to the recording. That's why people are so keen on drivers that have a flat response and you see Zaph and other testers praise drivers that can do this in a given bandpass. Your ELC curve (and mine in the past) as well as others' tweaks are all based on PERSONAL taste. I'm not going to tell you it's wrong; it's your choice. I will say that by simple logic of a playback system that is designed to do nothing except recreate the source it fails on face value alone. But, again, we all do things a bit differently for whatever reason. You'll never see me blast that. 

You seem hell bent on righting your tuning curve. I never blasted it. I don't know why you have such a chippy attitude.


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## ErinH (Feb 14, 2007)

MarkZ said:


> I like the color scheme in your room.


Thanks.


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## MarkZ (Dec 5, 2005)

So the difference between left and right is maximal below 300Hz and above 10kHz (although not by much). Is this something you decided just wasn't important to improve, or did you try but there was some obstacle?

I can understand that L/R level differences aren't a big deal below 300Hz, but I would think that >10k might be worth trying to perfect. Not that there's much energy up there, but people usually refer to that range as contributing to "ambience", which I would think would be important to balance.

Edit: again, you're within a couple dB already so I doubt it matters. I find it pretty remarkable how close you came with the rest.


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## ErinH (Feb 14, 2007)

MarkZ said:


> So the difference between left and right is maximal below 300Hz and above 10kHz (although not by much). Is this something you decided just wasn't important to improve, or did you try but there was some obstacle?
> 
> I can understand that L/R level differences aren't a big deal below 300Hz, but I would think that >10k might be worth trying to perfect. Not that there's much energy up there, but people usually refer to that range as contributing to "ambience", which I would think would be important to balance.
> 
> Edit: again, you're within a couple dB already so I doubt it matters. I find it pretty remarkable how close you came with the rest.


Oh, certainly, Mark. That's a very valid point. I worked a tad bit more after this picture on L/R matching and got that pretty good. The real problem is that I started chasing my tail. The wavelength is so short that with every iteration I just kept getting to about the same thing. I don't have a picture of the most recent iteration to show but the L/R response above 10khz is better now than in the picture above.

Below 300hz was also something that was worked on after the fact. The response matches MUCH more closely now there as well. I'll try to post up new plot today if I get the time. Daughter's still sleeping right now on the couch next to me which is the only reason I'm here typing now. 
(Side Note: It's amazing how an episode of Little Einsteins can be ingrained in your brain even when it's on as background noise ).

Regarding how close they match now, it took much less work than I had expected. I contribute it to install. Drivers are on axis and treatment in the pillars helped smooth some filtering out. Took me about an hour of straight panning and matching to get what you see above. That's really not long at all compared to how long it's taken me to get (not even) as close with previous installs/tunes. I'm very pleased with it right now but still plan to work on the overall curve a bit.


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## BigRed (Aug 12, 2007)

Love your curves Erin


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## ErinH (Feb 14, 2007)

BigRed said:


> Love your curves Erin


You so crazy!


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## sqnut (Dec 24, 2009)

bikinpunk said:


> This was right below the picture, which you did actually manage to not delete in the quote..Looks like I was right...


I kept that quote in on purpose. Technically you were wrong cause I did not tell you how to tweak your curve.







bikinpunk said:


> Edit:
> When have I EVER "chosen to ignore" the relevance of the F-M curve? Show me one time that I've said it's irrelevant. I've started threads on here regarding how to tune around it and have provided users the f-m curve in numerous posts. I just stand firmly by that ultimately it's tuning based on a preference. A true audiophile (not the a-holes you see posting from on high); one who seeks reference playback understands that you should not alter the signal from flat. Honestly, with the screenname "sqnut", I would think you would at least concede this point. Truthfully, I would expect that if anyone here is shooting for that, it would be you. Sound quality as a true-to-the-original reference should not alter the signal in any form. The hard part is achieving flat in a way that doesn't screw things up. I've said it numerous times in this thread: signal in should always equal signal out IF your goal is to remain true to the recording. That's why people are so keen on drivers that have a flat response and you see Zaph and other testers praise drivers that can do this in a given bandpass. Your ELC curve (and mine in the past) as well as others' tweaks are all based on PERSONAL taste. I'm not going to tell you it's wrong; it's your choice. I will say that by simple logic of a playback system that is designed to do nothing except recreate the source it fails on face value alone. But, again, we all do things a bit differently for whatever reason. You'll never see me blast that.
> 
> You seem hell bent on righting your tuning curve. I never blasted it. I don't know why you have such a chippy attitude.


Ok, let's put the FM curves aside for a bit. Let's talk about 'reference' sound. For me, it's accurate reproduction of whats on the cd. I'm looking at getting say the Diana Krall - Live in Paris cd to sound and feel the same in my car as it does in my 2ch setup at home (dynamics, tonality, imaging, spatial qualities etc). My biggest limitation in the car is the environment itself. I have accepted that my car will never sound like my home 2ch, given that I don't compete and just don't have the time to throw at this addictive crack pot hobby. 

I am using eq curves to correct what I can for the environment and the way we hear. I'm running drivers that are fairly linear in a wide bandpass. I am definately not tuning for driver deficiencies.

Last but not least, let's look at how music is recorded. Is the engineer building a curve into the recording? Is 50hz recorded as loud as 3khz? If not, why not? If there is an eq curve built into the recording and then we level things off to 'flat' at the reproduction stage, are we in fact hearing 'reference' sound? I think it goes beyond personal preference.

The longer I spend in this hobby, the more I'm forced to question my mindsets. The point is, this is a really complicated hobby and sometimes we further complicate things. If it sounds good or closer to my home setup, then it's good. As is the curve that dialed it in. If another curve or straight line moves the sound further away from my ref sound then the sound and curve aren't good for me.

Edit: One last point, when equalising for L/R your RTA or the SPL meter may tell you that at a given setting L&R is balanced. Your ears however may tell you that the side from where early reflections hit you first, is still louder. Who would you believe and what would you do? The point is at the end of the day your ears will validate or reject whatever you dial in. I'm assuming ears that have a certain level of training, hours spent tweaking. I'm not talking about golden ears


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## 14642 (May 19, 2008)

This thread is now bordering on the ridiculous, so i'm going to add to it.

I hereby postulate that once you've finished tweaking using test equipment and the various tools at your disposal (filters, delay, position, etc) to achieve the CORRECT response, a final check and readjustment using your ears as the test gear is simply an exercise in finishing the job of adding in your personal preference. If you're frustrated with your hobby, maybe it's because your personal preference is for something other than "correct" response and the disconnect between truth and belief and the history of your diatribes and postulates is too much to bear.

No, Erin, this is not directed at you nor anyone in particular.


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## sqnut (Dec 24, 2009)

For the record, while my FR curve is close to the FM curves, I too have a slight bump ~ 300 and 1khz. #00 hz for better vocal clarity and around 1-1.5khz for better overall dynamics.


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## sqnut (Dec 24, 2009)

Andy Wehmeyer said:


> This thread is now bordering on the ridiculous, so i'm going to add to it.
> 
> *I hereby postulate that once you've finished tweaking using test equipment and the various tools at your disposal (filters, delay, position, etc) to achieve the CORRECT response, a final check and readjustment using your ears as the test gear is simply an exercise in finishing the job of adding in your personal preference.* If you're frustrated with your hobby, maybe it's because your personal preference is for something other than "correct" response and the disconnect between truth and belief and the history of your diatribes and postulates is too much to bear.
> 
> No, Erin, this is not directed at you nor anyone in particular.


That is exactly what I am saying. Use equipment to get to a point but let your ears decide do the final tweaking. Thats what I said in my edit.

It's ok, you can tell me it's aimed at me . Just out of curiosity, what is the curve that the MS-8 is programmed to dial in?


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## mattyjman (Aug 6, 2009)

:snacks:


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## ErinH (Feb 14, 2007)

Andy Wehmeyer said:


> This thread is now bordering on the ridiculous, so i'm going to add to it.
> 
> I hereby postulate that once you've finished tweaking using test equipment and the various tools at your disposal (filters, delay, position, etc) to achieve the CORRECT response, a final check and readjustment using your ears as the test gear is simply an exercise in finishing the job of adding in your personal preference. If you're frustrated with your hobby, maybe it's because your personal preference is for something other than "correct" response and the disconnect between truth and belief and the history of your diatribes and postulates is too much to bear.
> 
> No, Erin, this is not directed at you nor anyone in particular.


Where do I sign?


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## omegaslast (Nov 4, 2010)

Does omnimic only throw out really rectangular graphs??


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## ErinH (Feb 14, 2007)

omegaslast said:


> Does omnimic only throw out really rectangular graphs??


Yep. I'm not a fan of the snapshot tool but it is what it is.


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## MarkZ (Dec 5, 2005)

sqnut said:


> Last but not least, let's look at how music is recorded. Is the engineer building a curve into the recording? Is 50hz recorded as loud as 3khz? If not, why not?


We don't listen to white noise. So it's hard to tune to a curve, per se. Music is dynamic and has different spectral content from one song to the next, and from one passage to the next. It's been said that "natural sounds" exhibit spectral content that approximates 1/f (estimates of some forms of music usually exhibit 1/f^N, where N is somewhere between 1 and 2). So, he certainly doesn't want the 50Hz component of a song to have, on average, the same loudness as the 3kHz component, because it would sound unnatural.

The F-M curves are accounted for because, presumably, the engineer is adjusting the spectral content of the music to achieve some sort of end goal -- to sound "natural", or "good", or "loud", or whatever the goal may be. I agree, it's not always great sounding to everyone, and it probably doesn't match your personal preferences. But your preferences have nothing to do with F-M curves. If they do, it's only a coincidence.


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## 14642 (May 19, 2008)

bikinpunk said:


> Where do I sign?


I must be thick today. I don't get it.


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## ErinH (Feb 14, 2007)

Andy Wehmeyer said:


> I must be thick today. I don't get it.


I agree and want to sign up to your camp.


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## Hanatsu (Nov 9, 2010)

Offtopic: Erin, can you take a pic of the klippel, can't seem to find any good images of them. Never seen one, a bit curious how they look and how you operate it 

Btw, nice home setup!


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## Hanatsu (Nov 9, 2010)

MarkZ said:


> So the difference between left and right is maximal below 300Hz and above 10kHz (although not by much). Is this something you decided just wasn't important to improve, or did you try but there was some obstacle?
> 
> I can understand that L/R level differences aren't a big deal below 300Hz, but I would think that >10k might be worth trying to perfect. Not that there's much energy up there, but people usually refer to that range as contributing to "ambience", which I would think would be important to balance.
> 
> Edit: again, you're within a couple dB already so I doubt it matters. I find it pretty remarkable how close you came with the rest.


I found that equal L-R is most important between 700Hz-12kHz. Below and above I notice the center shift very little. Lower freq is understandable but why not above 12kHz? Perhaps my ears sucks...?


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## 14642 (May 19, 2008)

Hanatsu said:


> I found that equal L-R is most important between 700Hz-12kHz. Below and above I notice the center shift very little. Lower freq is understandable but why not above 12kHz? Perhaps my ears sucks...?


'Cause there ain't nothing up there.


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## ErinH (Feb 14, 2007)

one more round of left vs. right. Spent about 45 minutes on this. 9 averages for each panned side (left or right). Overall the 2 curves match pretty well. +/-1.5dB under 1khz and +/-1dB above that. Pretty dang hard to get better than this with a mic unless the locations are dead on the same each time.


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## omegaslast (Nov 4, 2010)

bikinpunk said:


> Yep. I'm not a fan of the snapshot tool but it is what it is.


Its such a weird ratio and the y axis throws me for a loop, its so hard for me to mentally stretch the picture into what a full-range frequency response graph usually looks like. 

Have you ever thought about using REW?


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## ErinH (Feb 14, 2007)

I've used every program under the sun at this point. From $free to $1k (klippel). OM, to me, is just a simple to use program. It's not cheap but it's a great all-in-one solution that's stupid easy to use. I have a few complaints but overall I'm happy with the product.

I don't have an issue with the ratio of the x vs y axes. I just wish the import resolution was higher than it is.


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## garysummers (Oct 25, 2010)

"Pretty dang hard to get better than this with a mic unless the locations are dead on the same each time"

IMHO this is paramount if you want take this type of data. If you don't have absolute accurate repeatable measurements, then you are not comparing apples with apples. This is why I use the 4 mic mount with the multiplexer. The mics can be placed and re-placed with precision accuracy every time. If you do an RTA tweak on say L&R, then you take the mics out for a session of listening. Now you want to slightly, accurately modify your target curve. If the mics are not precisely where they were the last measurement, it all becomes a crap shoot. 100% repeatable measurements every time. If you are taking 6 separate measurements each time and averaging the results, the chances you will duplicate precisely those six positions next time is slim.
Just MHO.


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## cvjoint (Mar 10, 2006)

garysummers said:


> "Pretty dang hard to get better than this with a mic unless the locations are dead on the same each time"
> 
> IMHO this is paramount if you want take this type of data. If you don't have absolute accurate repeatable measurements, then you are not comparing apples with apples. This is why I use the 4 mic mount with the multiplexer. The mics can be placed and re-placed with precision accuracy every time. If you do an RTA tweak on say L&R, then you take the mics out for a session of listening. Now you want to slightly, accurately modify your target curve. If the mics are not precisely where they were the last measurement, it all becomes a crap shoot. 100% repeatable measurements every time. If you are taking 6 separate measurements each time and averaging the results, the chances you will duplicate precisely those six positions next time is slim.
> Just MHO.


Gary,

What about the human torso/body? I would imagine there is a lot of reflecting and absorbing done by the driver himself. In a large venue or even a large living room I can see why testing with the listener in the seat is not necessary, they are a small part of the signal jamming. In a car, particularly the driver side output, takes quite a beating depending on how your legs sit even let alone body/no body.

I'm with you on the measurement needing to be repeatable but it's also repeatable if I use one mic and place it right by one of the speakers in the same exact spot. It's a necessary condition but not sufficient. With 30+ averages the Omnimic is within 1 db between measurements at most with me in the seat.


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## garysummers (Oct 25, 2010)

If you are in the seat , where is the mic? Theoretically you should be measuring at ear position, correct? Depending on where you have located your speakers and what part of the audio spectrum they are reproducing, how much effect the body will have on the perceived response at the exact listening position. If you have a mid and tweeter in the A-pillar with a measured response down to say 200hz, your legs and lower torso will have very little affect in this frequency range. The mid bass is in the door or kick and playing say, 70 to 200hz. As the frequency becomes lower omni-directional perception becomes greater. So I think the perceived affect becomes less.


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## omegaslast (Nov 4, 2010)

bikinpunk said:


> I've used every program under the sun at this point. From $free to $1k (klippel). OM, to me, is just a simple to use program. It's not cheap but it's a great all-in-one solution that's stupid easy to use. I have a few complaints but overall I'm happy with the product.
> 
> I don't have an issue with the ratio of the x vs y axes. I just wish the import resolution was higher than it is.


Havent used the omnimic or its software, is the main advantage over REW no SPL meter needed?


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## BigRed (Aug 12, 2007)

omegaslast said:


> Havent used the omnimic or its software, is the main advantage over REW no SPL meter needed?


I've found it MUCH easier to use


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## ErinH (Feb 14, 2007)

garysummers said:


> "Pretty dang hard to get better than this with a mic unless the locations are dead on the same each time"
> 
> IMHO this is paramount if you want take this type of data. If you don't have absolute accurate repeatable measurements, then you are not comparing apples with apples. This is why I use the 4 mic mount with the multiplexer. The mics can be placed and re-placed with precision accuracy every time. If you do an RTA tweak on say L&R, then you take the mics out for a session of listening. Now you want to slightly, accurately modify your target curve. If the mics are not precisely where they were the last measurement, it all becomes a crap shoot. 100% repeatable measurements every time. If you are taking 6 separate measurements each time and averaging the results, the chances you will duplicate precisely those six positions next time is slim.
> Just MHO.


Oh, I agree. Unfortunately, I just don't have a contraption rigged up just yet. I did... just a piece of MDF with holes drilled out on a stand... but I threw it away last year. 



Regarding body/mic measurements, also keep in mind the effect of the headrest when you sandwich your mic between it and your seat back. When folks measure a speaker, they do so in free space. 
I have yet to really study the difference with and without a headrest in place but I keep meaning to. I'm a forgetful dude. Too much going on upstairs at once. 
Depending on the size, shape, and material makeup of the headrest and the seat, you could have varying results from any nominal measurement (regardless of what you deem 'nominal'). It's something to consider.
Not only that, but any vibration carried through your seat will show up in measurements. 
These are things you have to be at least aware of when looking at measurements.

That's one reason why a binaural measurement seems to make more sense. Or at least a measurement with you in the seated position. This requires a new curve with some sort of deviation from flat to account for head shadowing (think JBL uses this in their target curve for the ms-8 with a rolloff above 2.5khz).



Furthermore, even response deltas between ears due to the nearfield positioning of the speakers will affect any sort of target curve due to their own shadowing. In other words, the drivers aren't really out in front and even when on axis, their positioning relative to your head aren't the same. This means, for example, that a driver on axis on the right side won't reach the left ear as wholly as a driver on the left side on-axis will reach the right. 
This is really where you get in to the muck of things and where it really gets confusing. I haven't had time to do due diligence to the topic.


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## garysummers (Oct 25, 2010)

KEMAR Manikin Type 45BA

Tom Holman and the THX folks did extensive research into the use of the KEMAR Manikin for measuring of acoustical data. He was never convinced the transfer function they arrived at to compare the data to conventional RTA analysis was correct and they abandoned the concept. I don't know anyone who is using this idea for studio alignment either. Even though the KEMAR link says it is the standard I have not seen it used in years. The mixing rooms and recording studios I work in are all tuned using RTA w/ timed spatial averaging using multiple mics. Not familiar with the MS-8 and what they are doing, not to say that it isn't valid. New developments are always happening. Just not the convention in my world.


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## ErinH (Feb 14, 2007)

Another wrench ... Not all mics have the same response when pointed differently. IOW, facing the mic up vs at a speaker can yield different results. That's why a cal curve is needed. Cross spectrum provides this if asked. A mic is essentially a speaker and we know what happens when you turn a speaker off axis.


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## 14642 (May 19, 2008)

bikinpunk said:


> Another wrench ... Not all mics have the same response when pointed differently. IOW, facing the mic up vs at a speaker can yield different results. That's why a cal curve is needed. Cross spectrum provides this if asked. A mic is essentially a speaker and we know what happens when you turn a speaker off axis.


Well, yes, but consider the size of the micropone diaphragm, which mostly determines the polar plot--it's 1/4" or so. In any case, any deviation would only happen at the highest frequncies, and that isn't critical.

So, the reason for the spatial average is to eliminate the comb filtering in the measurement at midrange and high frequencies that we don't hear and that's caused by all of those reflecting surfaces. The high frequency tilt should be included in the target curve to accommodate head masking of high frequencies. I used to use a 6-mic array very similar to the one in the picture and it worked well too. No high frequency tilt in the target is necessary with that one. We used the wearable mic in MS-8 because the person doing the setup needs to be in the car to operate the unit. We correlated the target curve for the head mic to my measurements using the mic array and included correction for the measured effects of the plastic enclosure. 

Since then, we've developed a spectral averaging routine that makes the spatial average unnecessary. the wearable mic solves the non-acoustic problem of a single operator running setup. 

many types of measurements are valid so long as the conditions are understood and the results can be correlated or corrected. Some types are better than others.


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## ErinH (Feb 14, 2007)

I was t talking so much about directivity as the response. I have seen cal files for the behringer in bring degrees and they've differed. Probably not enough to be a deal breaker but different. 


I'm more interested in how my post above regarding head shadowing, proximity to drivers and their orientation and even the headrest may change the measured response and how/if they should be addressed.


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> Regarding body/mic measurements, also keep in mind the effect of the headrest when you sandwich your mic between it and your seat back.


I had thought about this before too. I've hung my microphone through a crack in the subroof before. 

It might be worth making separate measurements for high and low frequencies, as many of the tradeoffs correct one at the expense of the other.


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## cvjoint (Mar 10, 2006)

garysummers said:


> If you are in the seat , where is the mic? Theoretically you should be measuring at ear position, correct? Depending on where you have located your speakers and what part of the audio spectrum they are reproducing, how much effect the body will have on the perceived response at the exact listening position. If you have a mid and tweeter in the A-pillar with a measured response down to say 200hz, your legs and lower torso will have very little affect in this frequency range. The mid bass is in the door or kick and playing say, 70 to 200hz. As the frequency becomes lower omni-directional perception becomes greater. So I think the perceived affect becomes less.


Ear level moving around the head 30+ times. Most of the positions are by the ears themselves since I'm looking forward for the most part while driving. The human body is about as large as the center console and that makes a difference. The left door speaker in particular gets a lot of variation depending on body location, even crossed 200hz down. By lots I mean up to 5 times more variation than I get over repeated measurements with the same body location. 5 times larger than estimation error in other words. 

Maybe the optimal way would be a spliced methodology. Based on what Andy is saying I could improve my method by using yours from 1khz up. 

Is this true Andy? What target curve should I go for using the wearable mic setup?


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## SSSnake (Mar 8, 2007)

A "quick note" that goes 11 pages.  not too bad. 

Can't tell on my iPhone but is Gary's mic array behind the headrest? I have always tried to place the mics in front of the headrest because I assumed there would be large response differences behind the headrest. 

Btw I am currently using six mic locations and that seems to provide reasonable repeat ability and resolution. However, the measurement variation between mic location is pretty ugly at least for the left side. I am trying to examine different mounting locations to reduce the variation but with the current two system I am not having a lot of luck. Any ideas as to whether or not this is an attainable goal or am I just chasing my tail?


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## vitvit (May 3, 2011)

How should one perform averaging correctly? I use REW and it's "average". But shouldn't we discard phase information from measured signals before averaging? Any paper to read?


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## garysummers (Oct 25, 2010)

"Can't tell on my iPhone but is Gary's mic array behind the headrest?"
In front because thats where my ears are.


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## ErinH (Feb 14, 2007)

SSSnake said:


> A "quick note" that goes 11 pages.  not too bad.
> 
> Can't tell on my iPhone but is Gary's mic array behind the headrest? I have always tried to place the mics in front of the headrest because I assumed there would be large response differences behind the headrest.
> 
> Btw I am currently using six mic locations and that seems to provide reasonable repeat ability and resolution. However, the measurement variation between mic location is pretty ugly at least for the left side. I am trying to examine different mounting locations to reduce the variation but with the current two system I am not having a lot of luck. Any ideas as to whether or not this is an attainable goal or am I just chasing my tail?


Gary's mic array is in front of the headrest. 

Yea, a quick note sometimes turn in to more than I bargained for. 



vitvit said:


> How should one perform averaging correctly? I use REW and it's "average". But shouldn't we discard phase information from measured signals before averaging? Any paper to read?


I'd have to break out REW to say for sure. but the basic idea is to measure the system in x number of locations all in the head area and then average those individual measurements in to one final curve. 

I do this for each side: left and right. That way I can independently match the curves to each other via dsp.
After I match them, I start working on the final curve to get it how it needs to be. Easier than trying to get a target curve overall and then screwing yourself over by re-EQ'ing the individual bands.


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## Hanatsu (Nov 9, 2010)

bikinpunk said:


> I do this for each side: left and right. That way I can independently match the curves to each other via dsp.
> After I match them, I start working on the final curve to get it how it needs to be. Easier than trying to get a target curve overall and then screwing yourself over by re-EQ'ing the individual bands.


Same here, best way of doing it imo.


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## garysummers (Oct 25, 2010)

What every methodology we use to acoustically align our car audio systems is not really the issue. the issue is what is the result. The desired result is that all channels are aligned to a specific target curve and to the ear they sound level and timbre matched. If you do your tune and then you play full bandwidth pink noise bursts alternating between left and right, say in 2 second intervals, do they sound timbre matched to your ear. If they do your system is properly tuned and your music will sound good, providing your target curve is valid. If they do not sound the same your music will sound, to quote Big Red, "like ASS!" 
IMHO


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## cvjoint (Mar 10, 2006)

I would love to compare results using the two methods. If you bring your toy to the meet this Saturday I'll bring mine. 

Otherwise I could get creative to replicate a multi-mic rig. If I do top down I can test it the usual way and then step out and move the mic around with some sort of extension. I hope no one will be watching lol


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## ErinH (Feb 14, 2007)

What are you looking to find out, George?


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## vitvit (May 3, 2011)

I'm asking this question because I suspect that simple milti-mic rig people use in this thread might output something but hardly "average" if their output just electrical "mix". If you take output from, say, two mikes, and combine it by resistive matrix, at some frequencies you can get the sum values lesser then each mike output. That is because of phase difference might go over 90 degree.
The only correct way to average I can think of is an average FR only, ignoring signal's phase.
(REW allows us to do this).


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## cvjoint (Mar 10, 2006)

bikinpunk said:


> What are you looking to find out, George?


Whether testing with the listener in the car makes a lot of difference.


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## garysummers (Oct 25, 2010)

Do the pink noise test I mentioned and let me know if your method is successful. If so no need to compare. Again its not the method but the result.
If it is not successful, method modification may be required.


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## ErinH (Feb 14, 2007)

cvjoint said:


> Whether testing with the listener in the car makes a lot of difference.


I think the biggest thing to consider is how the FR *should* look in the two different scenarios. To me, that is key.


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## garysummers (Oct 25, 2010)

I assume by" FR" you mean "Frequency Response".


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## cvjoint (Mar 10, 2006)

garysummers said:


> Do the pink noise test I mentioned and let me know if your method is successful. If so no need to compare. Again its not the method but the result.
> If it is not successful, method modification may be required.


Spoken like a true artist! A quick note, the same argument can be used by the lazy and ignorant to dispel any need for testing of any kind or pink noise. In the limit this is "I don't care what it tests like, all I care about is what it sounds like." 




bikinpunk said:


> I think the biggest thing to consider is how the FR *should* look in the two different scenarios. To me, that is key.


Ha! I agree with you here because I know what you are trying to get at. I am also curious on what target curve to achieve in the two different scenario. Me thinks the head shadowing is what the focus is here. 

Part of the question however is not theoretical. The impact of neck down seems like an empirical question. Not all human bodies are the same so you couldn't possibly predict the outcome with certainty. There is a stochastic component to this.


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## ErinH (Feb 14, 2007)

garysummers said:


> I assume by" FR" you mean "Frequency Response".


correct.


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## garysummers (Oct 25, 2010)

For this discussion the "FR" is synonymous with "Target Curve" Correct?


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## ErinH (Feb 14, 2007)

cvjoint said:


> Ha! I agree with you here because I know what you are trying to get at. I am also curious on what target curve to achieve in the two different scenario. Me thinks the head shadowing is what the focus is here.
> 
> Part of the question however is not theoretical. The impact of neck down seems like an empirical question. Not all human bodies are the same so you couldn't possibly predict the outcome with certainty. There is a stochastic component to this.


Glad you got me. I tried to delve in to it a bit in an earlier post but fear it may have gotten glossed over.
hrtf is a factor for sure but in my studies it seems to be mainly when discussing binaural recording (or, in general, how we hear) whereas a speaker is usually measured in free space... and that's also how we RTA; mic at the headrest sort of thing.
The material of the headrest and the shape could also impact the result of the RTA. 

These kind of things are what I wonder: is there a different curve in a scenario with the mic in front of you in the seated position vs the mic in free space (with you out of the car). If so, how different are the two? 
How does the headrest influence the result? If, for example, you tune flat with the headrest attached to the seat and then tune flat without the headrest, will the sound be the same? Probably not, but to what extent. 

In a nutshell, I'm wondering what works 'best' and how a target curve should be applied if flat isn't the real goal in that given situation. Keep in mind that flat with a mic in free space isn't flat with a binaural measurement. These are the differences I'm focusing on. 



garysummers said:


> For this discussion the "FR" is synonymous with "Target Curve" Correct?


Yep. I interchange them quite a lot. It keeps people confused so I can feel superior. 
Here's another one:
RTA. 
:laugh:

^obviously, I'm kidding.


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## garysummers (Oct 25, 2010)

"A quick note, the same argument can be used by the lazy and ignorant to dispel any need for testing of any kind or pink noise. In the limit this is "I don't care what it tests like, all I care about is what it sounds like." 

I would be very surprised if the "lazy and ignorant" would be able to build a accurate audio reproduction system without some sort of testing and listening. As a matter of fact I have heard a few of those systems. To quote Jim Becker again, "Ass"


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## garysummers (Oct 25, 2010)

So I think the real question that we have arrived at is "How do we determine our target curve?" This curve may look different based on the methodology of testing used but nonetheless we are trying to achieved the same result. No compromise accurate audio reproduction! Correct? So how do we determine our target curve?


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## ErinH (Feb 14, 2007)

Easier to quote myself. 



bikinpunk said:


> Regarding body/mic measurements, also keep in mind the effect of the headrest when you sandwich your mic between it and your seat back. When folks measure a speaker, they do so in free space.
> I have yet to really study the difference with and without a headrest in place but I keep meaning to. I'm a forgetful dude. Too much going on upstairs at once.
> Depending on the size, shape, and material makeup of the headrest and the seat, you could have varying results from any nominal measurement (regardless of what you deem 'nominal'). It's something to consider.
> Not only that, but any vibration carried through your seat will show up in measurements.
> ...


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## cvjoint (Mar 10, 2006)

That is perhaps Jim's best quote. Kidding Jim! 

Binaural:









Should go with this target curve:









Large room should go with this curve:

______________________________

Question is, in a car with the mic going around the head should we still go for:

______________________________

Sorry I'm a visual guy :blush:


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## garysummers (Oct 25, 2010)

Step away from the analytical world for a second, take a deep breathe and think. How do we arrive at our target curve?


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## ErinH (Feb 14, 2007)

Depends on what your goal is. 
My first answer is you arrive at the final curve by tuning to what sounds right. 
But this topic is in driven toward those who don't have the experience to know what to shoot for or a proper reference. 

Flat in the free field is the "curve" of choice. It doesn't alter the signal. That means you get out what you should. No more. No less. 
I wonder what changes in the car when adding variables such as a headrest or body. No way to really discern direct from reflected sound.


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## cvjoint (Mar 10, 2006)

garysummers said:


> Step away from the analytical world for a second, take a deep breathe and think. How do we arrive at our target curve?


This one is easy. When I watch the Titanic in IMAX I want to hear Celine Dion and the water splashing. And therefore:

________________________

The lazy and ignorant will sometimes prefer a dubstep remix of Celine Dion and some machine guns for good measure. Well...except they can't get either the line above or the remix without some skill!


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## garysummers (Oct 25, 2010)

"My first answer is you arrive at the final curve by tuning to what sounds right."

Your first answer is correct! A+

How do we know what sounds "right"?


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## ErinH (Feb 14, 2007)

garysummers said:


> "My first answer is you arrive at the final curve by tuning to what sounds right."
> 
> Your first answer is correct! A+
> 
> How do we know what sounds "right"?


That's where this topic hits a stalwart. You need a proper reference. Then you question that reference. Lol. 

Without that reference, what do you do? 
The problem I've always found with trusting myself is that you become complacent. The "oh, it sounds great to me" complex until you hear something better ...
so, you need a reference.


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## cvjoint (Mar 10, 2006)

bikinpunk said:


> That's where this topic hits a stalwart. You need a proper reference. Then you question that reference. Lol.
> 
> Without that reference, what do you do?
> The problem I've always found with trusting myself is that you become complacent. The "oh, it sounds great to me" complex until you hear something better ...
> so, you need a reference.


Well put. We could assume proper reproduction or the sound as it was intended to be heard. This simplifies the exercise with no loss of generality. Sadly we lost half the steam in the thread to this point.


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## garysummers (Oct 25, 2010)

"so, you need a reference.

BINGO!!

If you do not have a accurate mental reference (aural memory) of what that music should sound like down to the smallest detail, you are just chasing your tail and will spend much wasted time in your efforts. I beat this drum all the time with regards to an accurate reference system, whether it be a calibrated home audio system or some real good headphones, to base our tuning on. If all you ever do is listen to your car and that is your reference you will only achieve the goal mentioned before, by luck if ever. Just before I do a tuning session in my car I do a refresher listen session in my home. Aural memory is very short even for the most trained ears. How do you think Mark gets his Nascar to have that remarkable sound. I know Mark is a huge proponent of the need for an accurate reference system to base you tuning on. I assume you all have good home reference systems. Listen on your reference system then into the car and make it sound like that. How you do it and the methods employed are up to you but the goal and results will be the same. IMHO


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## garysummers (Oct 25, 2010)

"Sadly we lost half the steam in the thread to this point."

IMHO where we have arrived in the thread is the most important point and the rest of it is just technical **** which I don't understand anyway!:laugh:


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## ErinH (Feb 14, 2007)

I actually just got my custom molds in for my etymotic headphones today. 

World of difference. Finally, low end without stupid room modes!


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## Niebur3 (Jul 11, 2008)

FWIW, I have noticed that using a mix of music you know REALLY well and music you have never heard before seems to keep the senses fresh when doing those reference/car listening/tuning sessions. 

BTW, since this thread touched on RTA curves....I just have to comment that I had a vehicle in the mid '90's that would score a 19/20 or 20/20 every time in IASCA competitions for the RTA portion.....and this car had NO equalizer of any kind.


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## schmiddr2 (Aug 10, 2009)

garysummers said:


> "Sadly we lost half the steam in the thread to this point."
> 
> IMHO where we have arrived in the thread is the most important point and the rest of it is just technical **** which I don't understand anyway!:laugh:


Most people who care to read all this know about having a reference and know that their ideal sound cannot be found by imagining a line of a graph. I found the first few pages of the thread much more educational.


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## cvjoint (Mar 10, 2006)

bikinpunk said:


> I actually just got my custom molds in for my etymotic headphones today.
> 
> World of difference. Finally, low end without stupid room modes!


Nice dood. I've been using mine for half a decade now. The inserts are still as smooth as they were on day one. Etymotic is some amazing stuff, engineering wise, quality wise, durability wise, and hell, even price. 

I was just reading some stuff the other day on subwoofer frequency stereo separation. I never really thought about it but with headphones you get stereo separation down to the last hz. That's something you don't get in car audio or even HT.


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## cvjoint (Mar 10, 2006)

garysummers said:


> "so, you need a reference.
> 
> BINGO!!
> 
> If you do not have a accurate mental reference (aural memory) of what that music should sound like down to the smallest detail, you are just chasing your tail and will spend much wasted time in your efforts.* I beat this drum all the time with regards to an accurate reference system, whether it be a calibrated home audio system or some real good headphones, to base our tuning on.* If all you ever do is listen to your car and that is your reference you will only achieve the goal mentioned before, by luck if ever. Just before I do a tuning session in my car I do a refresher listen session in my home. Aural memory is very short even for the most trained ears. How do you think Mark gets his Nascar to have that remarkable sound. I know Mark is a huge proponent of the need for an accurate reference system to base you tuning on. I assume you all have good home reference systems. Listen on your reference system then into the car and make it sound like that. How you do it and the methods employed are up to you but the goal and results will be the same. IMHO


Ok, so let me see if I get this right. 

1.We find a good pair of headphones.
2.We play a familiar track through them.
3.We use aural memory to capture the track in its pristine condition.
4.We get in the car and tune to what's in our head.
5.We get a car that sounds as good as the headphones.

So the work-horse here is this:









And it works because of this:









Namely, someone that understands the technical stuff went through the trouble to find what accurate reproduction looks like as a target curve in a known and controlled reproduction setting. 

Is 1-5 really easier than Andy or someone with the technical expertise spoon feeding us a target curve and a plan for mic location? I mean look at the alternative, to get to 5 you not only rely on this reality of someone doing the hardwork already (step 1.)but you must also be able to follow all the other steps. In particular:
3.We use aural memory to capture the track in its pristine condition.

The mind is a fickle thing...


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## rc10mike (Mar 27, 2008)

Aural memory, I never thought I would see that term on here again, based on how little my "Aural Memory" thread moved...


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## garysummers (Oct 25, 2010)

cvjoint said:


> Ok, so let me see if I get this right.
> 
> 1.We find a good pair of headphones.
> 2.We play a familiar track through them.
> ...


All I can say is "too each his own." I have been trusting my ears for the last 32 years in my mixing career and they have never let me down yet! Methodology is not the question here, but the end result will either justify or disprove that method. IMHO


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## ErinH (Feb 14, 2007)

Yes, Gary, and it certainly works for you. I think my main concern is for those who don't have a reference system. I'd suggest a set of headphones + molds like I have, but some avoid that, too.

If we can find some way to capture what should be a reference curve and use that to help us further our stereo system, I think we take a big step. Flat may still work but for the reasons I mentioend previously, it may hinder you as well if you don't understand exactly what the RTA is telling you. It gives you a line; it doesn't tell you how it arrived at that line and that's the hardest part about tuning with a mic.


This thread is indeed a bit all over the place now. With the talk in another thread about helmholtz absorbers I'm going to build one in the coming weeks and see how it helps against a suck out in my car. The problem is finding a way to actually place it in the car. Maybe that can kick this thread in another direction.


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## Hanatsu (Nov 9, 2010)

"Aural memory" is short lived at best. Learn how a specific song should sound like on a reference home audio system. An alternitive is to measure a true SQ home audio system and match FR somewhat in car. Headphones have this unreal zero crosstalk, you'll never be able to reproduce that in a car. It's like the direct opposite, I understand the point but the point is kinda lost when you can't make it sound anywhere close to what you hearing in those phones.


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## BigRed (Aug 12, 2007)

Most final mixes from most recording engineers are not flat. Google it if u want some broad information regarding that topic. So Gary is absolutely right IMO. Some that have an rta might want to try this. Rta your home system with pink noise. Just one channel. Is it flat? Report back your findings


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## MarkZ (Dec 5, 2005)

Educate me, guys. You're saying that flat is an unsuitable "reference curve" because the masses, on average, prefer some deviation from flat that shares some common characteristics from person to person?

Or are you guys talking about something specific to car audio, because of the inherent limitations of the environment (e.g. reducing the amplitude of frequencies that generate the most unpleasing reflections)?

Or both?

If I'm understanding this discussion, then I hate to throw a monkey wrench into the works by suggesting that music is often recorded so differently that ideal reproduction requires a different "reference curve" for each album... 



BigRed said:


> Most final mixes from most recording engineers are not flat. Google it if u want some broad information regarding that topic.


As I mentioned earlier in the thread, "flat" in this context doesn't make sense to me. Flat in reference to what?


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## Niebur3 (Jul 11, 2008)

MarkZ said:


> Educate me, guys. You're saying that flat is an unsuitable "reference curve" because the masses, on average, prefer some deviation from flat that shares some common characteristics from person to person?
> 
> Or are you guys talking about something specific to car audio, because of the inherent limitations of the environment (e.g. reducing the amplitude of frequencies that generate the most unpleasing reflections)?
> 
> ...


What is funny is at Finals I went around to many of the top cars and I used "regular" music. Several CD's that I know very well. Only 1 or 2 reference songs and the rest were recorded for the masses. It is hard for even the best systems out there to sound good on so many different recordings.


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## ErinH (Feb 14, 2007)

MarkZ said:


> Educate me, guys. You're saying that flat is an unsuitable "reference curve" because the masses, on average, prefer some deviation from flat that shares some common characteristics from person to person?
> 
> Or are you guys talking about something specific to car audio, because of the inherent limitations of the environment (e.g. reducing the amplitude of frequencies that generate the most unpleasing reflections)?
> 
> ...


No, what I'm saying is that "flat" is always measured in free space. All my FR testing is done at a given distance with the mic in the open field. Zaph, et al, do the same. Mfg's included.
A speaker should measure flat within some tolerance and some bandpass to be a notedly good performer. This is logical; signal in, signal out (I feel stupid that I continually say this, but I hope you guys understand where I'm coming from). But, again, speakers and drivers are measured in an open field. Not with a seat behind them.

When you put the mic in the car environment with a headrest behind it does the nominal - flat - curve then change to some other shape; one that still sounds 'flat' but isn't actually flat? 
Much like how hrtf changes the 'curve', does one account for the seat makeup/geometry when measuring in the car because you're no longer measuring in free space?
That's my question.


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## ErinH (Feb 14, 2007)

BigRed said:


> Most final mixes from most recording engineers are not flat. Google it if u want some broad information regarding that topic. So Gary is absolutely right IMO. Some that have an rta might want to try this. Rta your home system with pink noise. Just one channel. Is it flat? Report back your findings


it certainly should be.

a mix is different than the way a speaker reproduces a sound. if a speaker changes from a flat response it is a coloration on the original source to some degree.


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> No, what I'm saying is that "flat" is always measured in free space. All my FR testing is done at a given distance with the mic in the open field. Zaph, et al, do the same. Mfg's included.
> A speaker should measure flat within some tolerance and some bandpass to be a notedly good performer. This is logical; signal in, signal out (I feel stupid that I continually say this, but I hope you guys understand where I'm coming from). But, again, speakers and drivers are measured in an open field. Not with a seat behind them.
> 
> When you put the mic in the car environment with a headrest behind it does the nominal - flat - curve then change to some other shape; one that still sounds 'flat' but isn't actually flat?
> ...


Gotcha. Hence the whole 'leg' conversation.

Free space should be irrelevant. All the reflecting surfaces in the car are going to alter the measured response. They don't disappear when you listen to your audio system. It seems the question should be more about the temporal window you use to capture energy that makes up the FR curve. Near reflections should probably be absorbed in your curve, late reflections probably not. Is that what you guys do now?


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## ErinH (Feb 14, 2007)

Power response.


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## sqnut (Dec 24, 2009)

1. Headphones are a good ref for tonality, but will do nothing for imaging/staging. Even the headphones don't have a flat response curve.

2. There is a big difference between sitting in the drivers seat and measuring and measuring with an empty seat. If you balance L/R without sitting in the seat and then sit and listen, the image is no longer centred but pulls towards you. Cvjoint is right, the absorbtion, reflections, cancellations with you in the seat will have a major effect on your near side response.

3. It's tough to get accurate repeatability sitting in the drivers seat because how you sit, where your legs are etc can never be 100% same everytime. The variations will be nominal but noticable. How you sit, how your legs are placed, your heads position will all effect different ranges and hence your overall perception. Again nominal but noticeable. 

4. IMHO a decent 2ch setup is a good reference for tonality, staging and imaging. Aural memory is indeed shortlived, but if you go back and forth between the car and the 2ch with the same cd about a zillion times, you can get a fairly accurate idea of what's right and wrong. You will still need to go back and measure from time to time, specially when you mess up the sound by over tweaking. But even then, it's your ears telling you that the sound sucks. Just like they will tell you when its good.

5. At the end of the day it's about measuring and hearing. But how it sounds, trumps how it measures. You won't get it sounding good if it measures like crap but it doesn't have to measure perfect to sound great. 

6. Measured flat and percieved flat are two different things. Percieved flat will always have a curve. Well recorded music will have a built in curve. When your ears 'percieve' the sound as flat, that will actually bring out the recorded curve in the music and you will get your reference sound, i.e. actually hear the way the cd is recorded.


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## ErinH (Feb 14, 2007)

sqnut said:


> 1. Headphones are a good ref for tonality, but will do nothing for imaging/staging. Even the headphones don;t have a flat response curve.
> 
> 2. There is a big difference between sitting in the drivers seat and measuring and with an empty seat. If you balance L/R without sitting in the seat and then listen, the image is no longer centred but pulls towards you. Cvjoint is right, the absorbtion, reflections, cancellations with you in the seat will have a major effect on your near side response.
> 
> ...


Good summary of this thread so far. 

I'd like to take note of #2 again. Please see my post before regarding near side speakers and the angle/positioning of the left and right side drivers to us in the near field.


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## pionkej (Feb 29, 2008)

sqnut said:


> 6. Measured flat and percieved flat are two different things. Percieved flat will always have a curve. Well recorded music will have a built in curve. When your ears 'percieve' the sound as flat, that will actually bring out the recorded curve in the music and you will get your reference sound, i.e. actually hear the way the cd is recorded.


Since this thread has been a huge hodge-podge of topics, I have a question about the part where everyone was discussing flat vs. FM curve vs. your preference. 

Forgive me if this is an ignorant question, but shouldn't we be striving for what the baseline is INSIDE the mastering studio? Is there anything remotely close to a "standard" within that industry? 

We all concede that our stereo is just medium for reproducing sound. The argument is that we don't know if it is accurate because we have no standard to reference. Even a home "reference" system isn't certain to be completely accurate, so how do we compare to that? So I'm wondering what a system playing pink noise in a mastering studio would measure like. Does it measure flat? Does it measure "perceived flat" (ELC)? We can't be certain of how something was recorded and we can't be certain of how something was mastered...BUT...if we could try and match what a mastering studio's FR looks like, I think we would have a faithful reproduction of music.

Let's say, for sake of simplicity, that the "standard" was "measured flat". If we matched that, we would hear what the producer hears when listening to the unmastered recording (we're true to the source here). If the producer changes anything, the changes he makes are based off a "measured flat" system, and so our flat system would faithfully reproduce his changes. This statement should hold true for perceived flat, or "smiley face", etc since mastering changes would be on top of whatever FR was being used for mastering.

Which brings me back to the question...is there a standard? I'm certain the answer is no, because that would be too simple and we would know what to aim for faithful reproduction. I'm also sure that if there ever was anything close to a standard, it has long since left with the introduction of things like Pro Tools where people can produce an album in their "home studio".

But let's say for one second there IS a standard, it also brings us back to the very first post Erin made, when you are trying to achieve a desired response...most sound bad, few sound good, and there are a million different ways to get there.


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## MarkZ (Dec 5, 2005)

Pionkej and others,

What does "flat" mean in that context? If I play a saxophone for you (I can't play a sax, but pretend I can...), and you record it, what is "flat"? An unfiltered version of it? Yuck! You don't put that on a CD. Every engineer and his brother will add a compressor, which I guarantee will alter the frequency response of the sax, and will probably do so in a dynamic way. What if I play an (amplified) guitar and my buddy plays the drums? How, exactly, do you define "flat" in that case?

The production process is entirely different from the reproduction process. "Flat", in the context of reproduction, is shorthand for "flat transfer function". There's, in effect, no transfer function during production, so you're asking for the impossible.


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## cvjoint (Mar 10, 2006)

Hanatsu said:


> "Aural memory" is short lived at best. Learn how a specific song should sound like on a reference home audio system. An alternitive is to measure a true SQ home audio system and match FR somewhat in car. Headphones have this unreal zero crosstalk, you'll never be able to reproduce that in a car. It's like the direct opposite, I understand the point but the point is kinda lost when you can't make it sound anywhere close to what you hearing in those phones.


Amen. Two great points. 

Aural memory test:
http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/115577-test-prove-whether-testing-ear-any-good.html

This is one way to prove that aural memory is good enough for tuning. I would also buy any other evidence if the test is properly carried out. For all the people that swear on by ear tuning the lack of response is staggering. I will go in with my mic and test it's repeatability on demand, I believe in it. 

No amount of tuning will get a car to sound like headphones or HT, period.



BigRed said:


> Most final mixes from most recording engineers are not flat. Google it if u want some broad information regarding that topic. So Gary is absolutely right IMO. Some that have an rta might want to try this. Rta your home system with pink noise. Just one channel. Is it flat? Report back your findings


Any sucker can get an RTA snapshot, but do they know the usefulness of it all?

So what if it's not flat? If I give you my RTA plot will you know whether the deviations from flat are my coffee table? Will you know if it's not my fridge running beside the floorstander? Will you know whether the speaker engineer intended humps in the response? Is it a matter of choice, a matter of price point (and therefore compromise) or ideal? 

The mixing done by the recording engineer is not in question. For us to talk about target curves we must first be able to tune to A target.


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## ErinH (Feb 14, 2007)

MarkZ said:


> Pionkej and others,
> 
> What does "flat" mean in that context? If I play a saxophone for you (I can't play a sax, but pretend I can...), and you record it, what is "flat"? An unfiltered version of it? Yuck! You don't put that on a CD. Every engineer and his brother will add a compressor, which I guarantee will alter the frequency response of the sax, and will probably do so in a dynamic way. What if I play an (amplified) guitar and my buddy plays the drums? How, exactly, do you define "flat" in that case?
> 
> The production process is entirely different from the reproduction process. "Flat", in the context of reproduction, is shorthand for "flat transfer function". There's, in effect, no transfer function during production, so you're asking for the impossible.


Mark, again, think of the playback system. Leave the sound engineer out of it. What should be the goal of a TRUE, _reference _playback system?
To provide an unaltered playback of the source media. 

That simply means that if you were able to record the waveform of the media itself and then the waveform of the speaker's output the two should be the exact same; ideally. I understand ideal isn't very realistic but that doesn't make the goal any less true. 

That's all I mean by "flat". A one to one of the source media to the output of the speaker.
Anything else is just preference (and that's fine if that's what you want; I don't' give a **** either way).


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> Mark, again, think of the playback system. Leave the sound engineer out of it. What should be the goal of a TRUE, _reference _playback system?
> To provide an unaltered playback of the source media.
> 
> That simply means that if you were able to record the waveform of the media itself and then the waveform of the speaker's output the two should be the exact same; ideally. I understand ideal isn't very realistic but that doesn't make the goal any less true.
> ...


Erin, that's exactly my point. Reproduction has a well-defined definition for "flat". But when people start talking about how the engineer recorded it, and other aspects of the production phase, then you can no longer use the same concepts.

I think pionkej was talking about the FR for the person mastering an album, but that's still part of the production process. The goals during the mastering stage are not necessarily goals that we want to mimic. sqnut was using similar terminology ("perceived flat"), in support of the idea that F-M is useful here. My argument is that it's not useful.

Maybe I'm nitpicking over the use of the term "flat"?

But I'd again like to point out that albums are mixed and mastered completely differently, making it unavoidable that you have to adjust for each album. I was reminded of this recently when listening to a band who released three albums, all pretty much the same musical content. The first album is completely deficient in the low end. It usually requires a 3dB boost below ~150Hz and I usually give it a few more dB <45Hz. The third album has way too much low end, usually requiring that I give the entire sub a broad CUT in gain by a whopping 6dB (a quick google search reveals that Steve Albini had a hand in recording this one :/ ). The second album is just right. 

Three albums, same band, similar music, wildly different spectral content.

How important is it, then, that the end-target curve is precise, when I'm turning knobs while driving down the road?  It seems the most useful aspect of quantifying FR, to me, is achieving L/R balance.


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## ErinH (Feb 14, 2007)

I agree with what you're saying. We need to define what curve we're talking about.

But, again, to me it's as simple as A = A. Not A = AxYz. 
Anything else is simply not a true reproduction either on purpose on by fault (ie: "I want it to sound like this" or "I can't tune worth a flip").
I don't care if someone brings in preference.

What I'm more concerned about is achieving the equivalent of flat in the free, open field measurement method in the car. How does a headrest or a body position shape that flat response?
I agree with what someone said earlier. One way to achieve this could be to measure with the mic in front of you while RTA'ing a set of well known speakers; some that have a great frequency response (let's be honest, nothing is perfect). Does the location of your head change the sound? In the car the direct to reflected sound is very low. So, I'd say no. In a home, I'd say you have more opportunity to get a well behaved shape due to the less reflective nature. Especially if you use an impulse window. 

And, furthermore, the physical location of a home set is out in front of you. In a car, you're skewed and the angle of the sound to your ears is dramatically affected moreso than in the home environment when both speakers are (typically) aimed at your ears/head. Make sense?


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## Mic10is (Aug 20, 2007)

This whole thread has gone in so many freaking directions.....

everyone's ears are different--YES. everyone hears slightly differently--YES
everyone has different preferences -YES

But if we all hear a piano played and heard certain notes played--we should all agree that its a Piano.
Same with just about every single other instrument.
That is a reference.
and its basically a common shared reference that everyone should know and understand.

Now If I play a Piano and you guess its a harpsichord or a violin...then there are some issues


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## 14642 (May 19, 2008)

vitvit said:


> I'm asking this question because I suspect that simple milti-mic rig people use in this thread might output something but hardly "average" if their output just electrical "mix". If you take output from, say, two mikes, and combine it by resistive matrix, at some frequencies you can get the sum values lesser then each mike output. That is because of phase difference might go over 90 degree.
> The only correct way to average I can think of is an average FR only, ignoring signal's phase.
> (REW allows us to do this).


Yes. A correct spatial average is an average of the "frequency" response without the phase response. A simple electrical sum doesn't work.


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## cvjoint (Mar 10, 2006)

vitvit said:


> I'm asking this question because I suspect that simple milti-mic rig people use in this thread might output something but hardly "average" if their output just electrical "mix". If you take output from, say, two mikes, and combine it by resistive matrix, at some frequencies you can get the sum values lesser then each mike output. That is because of phase difference might go over 90 degree.
> The only correct way to average I can think of is an average FR only, ignoring signal's phase.
> (REW allows us to do this).


Here is a great quote from Bill Waslo, the brain behind the Omnimic some of us use:
_"No, the averaging is not applied to the impulse wave, nor would you want it to. Averaging of impulse responses can result in comb filtering and cancellations. Imagine if you were different distances from the speaker when making two measurements to be two averaged -- the average of those impulse responses would have two impulses, one after another, each half as high, which wouldn't be very useful and would have a meaningless spectrum. The averaging in the frequency domain is 'power averaging', where phase information is tossed out so that waves can't cancel or interfere, you only get an average of the magnitude curves."_

Aka the Omnimic passes the vitvit critique! Good point though.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

Mic10is said:


> This whole thread has gone in so many freaking directions.....
> 
> everyone's ears are different--YES. everyone hears slightly differently--YES
> everyone has different preferences -YES
> ...


I was going to say this earlier. If two people listen to a live violin at the same time, sitting right next to each other, they are hearing the same thing. Even though it may not sound the same to each of them, its the same sound reaching their ears. 

Now, throw them both in rooms, with the recording of that some performance they just listened to, and have them play with an rta to get it to sound like it did live. The end result should be the same, as long as they both tune to make it sound like the live violin sounded. Because even though their brain interpreted it differently, they both heard the same sound. 

Now, if they both tune to preference, then thats a whole other can of worms, (and is completely ok, if thats what your going for).


Another thing I was thinking about. I may be way off base here, but here it is. Its been said that aural memory is short lived. If that was the case, how are singers able to hit the same pitch over and over. If you tell a good singer to high a certain note within their range, they can usually hit it right on. If aural memory was truly that short, how would they be able to do that?


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## highly (Jan 30, 2007)

bikinpunk said:


> I agree with what you're saying. We need to define what curve we're talking about.
> 
> ...to me it's as simple as A = A. ...Anything else is simply not a true reproduction either on purpose on by fault


Therein lies my definition of 'flat response'. What it takes for me to get as close to the perception of equality between the signal and the result. I do not think it is possible to get to the point of realism that evokes true believability - that you are actually present at the point of recording. That to me would be the ultimate goal, and I concede that it is unlikely to the point of impossibility. In Cvjoint's 'three albums' argument, The crappy ones SHOULD sound like crap. If they were mixed and mastered poorly, the system shouldn't 'fix' them. They are just crap recordings. I similarly don't expect a Drunk ****** track to magically come out of my stereo clean and polished all of a sudden. A system that does that may indeed sound better on more material, but that is an injection of preference, not 'truth to the source'. 

Is there a One True Curve? I would argue 'no'. I do not think that there exists a curve or response that produces the same result for every listener. Beyond that of preference, every person's personal listening environment (head, ears, pinnae, brain, etc.) differs to such a degree that the best you can hope for is a 'Curve of Average Acceptance' - and according to Toole that will be good to some, very good to many, and abhorrent to a few. Even if there WERE One True Curve, I'd be willing to bet that no two cars that had a measured response that matched that curve would sound the same by any strech of the imagination. There are far too many other variables - impulse response, decay, dynamicism, distortion, detail as just a short list - that are at least as important to the end result.


Aural memory isn't great, but we are quite good at aural deltas if A/B'd. That doesn't mean we can't train ourselves to do a better job at it. We most certainly can. That's not the same thing as pitch recognition (which can also be learned), or muscle memory (again, learned). I'd suspect that the singer leverages a combination of these things to accomplish their goal. Just as my fingers can play the guitar without me thinking about fingering the next chord, and I can tell immediately when the instrument is out of tune. Can I tune it to within the hertz by ear on a string-by-string basis? No, but I suspect if I trained for it I could learn to.


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## Hanatsu (Nov 9, 2010)

To me "flat response" is when the speaker outputs the same amplitude at every audiable frequency as the source material. Whether the recording is "flat" or not doesn't matter, the speaker should reproduce the same amplitude vs frequency as the source output. 

Having said that, take two different enviroments. Even if they measure as flat as you get, there's no guarantee that they actually will sound the same. Perhaps that's more likely in home audio where you control the enviroment better. But all the reflections, resonances and crap in a car adds distortion. What you see on a RTA are basicly primary signal reproduced by the speakers + THD+N+IMD (dunno if you can include rattling, resonances etc in this). Everything which resonates should have overtones both as HD and IMD. At small levels ofc, but everything adds up. That's probably why "flat" transfer function in a car doesn't sound good to many people. The "real" transfer function in which I include primary sound source (speaker) and early reflections might actually be somewhat flat, until the soundwave hits a piece of plastic and bounce off another surface and so on. Cabin gain is another factor to concider, this happens in home audio aswell but at a smaller level (if you not sitting in the closet lol). 

Interested to see the difference between really short gated measurements vs RTA over say 300Hz. How much the car enviroment changes the curve in midrange/HF...


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## BigRed (Aug 12, 2007)

bikinpunk said:


> it certainly should be.
> 
> a mix is different than the way a speaker reproduces a sound. if a speaker changes from a flat response it is a coloration on the original source to some degree.


I see. We were on two different pages.

I have tested over 30 towers, bookshelfs, waveguides. none had a flat frequency response.


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## ErinH (Feb 14, 2007)

Regarding aural memory, I advise taking notes on certain aspects of a recording while listening to whatever you have as a reference. 
Use those notes to help you tune your car stereo.


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## ErinH (Feb 14, 2007)

BigRed said:


> I see. We were on two different pages.
> 
> I have tested over 30 towers, bookshelfs, waveguides. none had a flat frequency response.


How exactly did you test them? Beginning to end.


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## Hanatsu (Nov 9, 2010)

And the thing is too... when the enviroment changes FR and when we're compensating with EQs/filters we actually dampens the problem NOT removing it, the reflections will still remain. But the reflections + primary source now measure flat but some of the sound will originate from other sources, screwing up staging and other stuff. That why I like 3-way setups where the drivers are placed pretty much onaxis away from reflecting surfaces as much as possible and running door speakers lowpassed as much as possible. Doors are the biggest issue imo, since the whole door resonates causing distortions and the speaker plays right into your leg and lots of different surface reflections. There's the floor mat, plastic consols, metal inside the door, perhaps leather seats, all these materials have different reflection characteristics. If we only deal with one type of reflection I would like think that the compensation for it would be more effective and precise and eliminate lots of issues. But I might be full of crap, just made a braindump... xD


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## MarkZ (Dec 5, 2005)

highly said:


> Therein lies my definition of 'flat response'. What it takes for me to get as close to the perception of equality between the signal and the result. I do not think it is possible to get to the point of realism that evokes true believability - that you are actually present at the point of recording. That to me would be the ultimate goal, and I concede that it is unlikely to the point of impossibility. In Cvjoint's 'three albums' argument, The crappy ones SHOULD sound like crap. If they were mixed and mastered poorly, the system shouldn't 'fix' them. They are just crap recordings. I similarly don't expect a Drunk ****** track to magically come out of my stereo clean and polished all of a sudden. A system that does that may indeed sound better on more material, but that is an injection of preference, not 'truth to the source'.


That was me. 

So, then you're faced with two options. 1) Set all your suboptimal recordings on fire. 2) Correct them. Sometimes it's difficult to correct a "crap recording". Other times, it's not so bad. Album #3 that I mentioned can be corrected quite easily by simply dialing back the bass (and no, my default bass setting isn't very high to start with). That's really the only major flaw with the recording, and it's one that seems to be pretty amenable to a simple gain correction in a single band.

Gonna go listen to that album now actually. Thanks guys!


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

^curious what artist that is. I have an artist I really like that has sort of the same thing. Of the 5 cds I have from them, #2 is best, #3 is second, #4 is third, #1 is fourth, and #5, which came out two weeks ago, is worst. Its the most compressed, and the bass is cranked. Cd #2 from them is the most dynamic, and sounds the most like they do in concert.

If you want, PM me to keep the thread on track.


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## SSSnake (Mar 8, 2007)

It seems to me we are trying to address to many variables at once and that is why the discussion is all over the place. Several topics have been brought up but if we could address this in an organized manner maybe we could make more headway. IMO - It seems as if one of the major topics of discussion is:

Is there a standard measured frequency response curve that we should be trying to attain?

If we can agree on an answer then we will have accomplished something. 

For me we have to start with a simple statement of goals. If we can't agree on the goal then even this simple question can't be answered with a consensus by the community. If we make the assumption that the goal of an ideal audio system is to act as a simple transformer (transforming electrical signals into sound waves) without introducing any system specific biases then we can take the first step. Basically this is Erin's statement of A=A.

For this case the measured frequency response FR and phase for the system when measured in a perfectly anechoic environment would be flat and level throughout the entire passband (20hz to 20khz). Basically whatever you put on the input side electrically would come out of the speaker as sound without any alteration (this ignores any discussion of distortion and other noise products and their effect of FR but it is a good point of departure for discussion). Because we are measuring in a perfectly anechoic environment we are only measuring the sound eminating from the speaker without any reflections (there could and likely would be some difraction effects but these should be very minor for even a modestly capable design) . I think this should be a fairly defensable and accepted position. Let me know if I missed the boat.

If we buy off on all of this then the measured FR goal for an audio system measured in an anechoic environment has to be flat and level response.

From here we need to move into a more complicated situation. Measured FR in a car. In the car we are far from an anechoic environment (as we have said many times) so the measured response will include all of the nasty reflections that play havoc on the what we hear. But they also play havoc on what we measure. To further complicate things, the tools, measurement conditions, and measurement techniques/settings can and do vary what we measure as well. 

For example there has been some mention in this thread of measurement gating. The gates, or measurement beginning and end times, drastically effect what we measure (at least in a highly reflective environment). Without including what gate settings are used in the measurement how can we hope to define a standard target curve? 

Remember we haven't even discussed the possibility that the reflections effect what we hear yet just what we measure and we have only touched on one small variable in what we measure. 

I'll let everyone beat this up before writing more.


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## Neeoo (Dec 13, 2011)

SSSnake said:


> Is there a standard measured frequency response curve that we should be trying to attain?
> 
> If we can agree on an answer then we will have accomplished something.


Exactly. And in order to do this, each must achieve flat frequency response with the *exact same source material*. At THIS point, each system would be tuned to a reference baseline. Then, and only then, could any comparison be drawn between listening experiences (keeping in mind that each system was tuned to a baseline reference curve despite the unique nuances of each environment). Will having each system tuned to a similar baseline allow for comparison of the quality of the listening experience? No. Reflections, imaging cues etc will 'color' each system uniquely. This being said, a baseline frequency response will only ever allow for a common point from which to discuss other aspects. Ill proffer that it is impossible for 2 systems to ever sound exactly the same UNLESS they are exactly the same ie... same vehicle, same components, same installation.


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## MarkZ (Dec 5, 2005)

Neeoo said:


> Exactly. And in order to do this, each must achieve flat frequency response with the *exact same source material*.


What does this mean? Do you mean "flat" using noise vs. sweeps vs. impulses, etc? I don't understand what "same source material" means in this context.


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## Neeoo (Dec 13, 2011)

MarkZ said:


> What does this mean? Do you mean "flat" using noise vs. sweeps vs. impulses, etc? I don't understand what "same source material" means in this context.


Good point. Probably a poor choice of words, but essentially - if the 'standard' for tuning a system is to achieve a flat response using a 20-20k hz pink noise, then a system tuned to flat response using a 20-20k pink noise signal has reached the target 'baseline'. Peaks and nulls have been eliminated (or compensated for) and the system is capable of reproducing the most accurate sound that IT is capable of reproducing. 

What have we achieved by this flat 'standard' response though? I assert that we have achieved nothing other than a reproducible baseline from which we can begin tuning to our individual preferences. Nothing more, nothing less.


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## Neeoo (Dec 13, 2011)

Ill venture out a little further as well. Audio is completely subjective. Why? The frequency of the sound from a hi-hat can be caught, measured and determined by an RTA. Its amplitude can be measured as well. But there is no instrument that can tell us how accurate that sound was. Was it real? Was it reproduced from a recording? Was it too bright? Too mellow? Did it sound real or muffled? 

An 'accurate' system cannot be quantitatively determined.


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## garysummers (Oct 25, 2010)

Some people were posting earlier in the thread asking if there were any room equalization reference standards in the audio production industry. This link is to a SMPTE paper that some may find an interesting read, others may find it worthless, but I will post it none the less. It is a paper by Ioan Allen, a gentleman who has been with Dolby laboratories since Ray Dolby invented noise reduction. It describes how the motion picture industry arrived at the current reference standard for theatrical mixing rooms and cinemas worldwide. This is the exact standard employed today in all cinemas and film mixing studios.

http://www.dolby.com/uploadedFiles/...essional/Dolby_The X-Curve__SMPTE Journal.pdf

FYI


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## ErinH (Feb 14, 2007)

Neeoo said:


> Ill venture out a little further as well. Audio is completely subjective. Why? The frequency of the sound from a hi-hat can be caught, measured and determined by an RTA. Its amplitude can be measured as well. But there is no instrument that can tell us how accurate that sound was. Was it real? Was it reproduced from a recording? Was it too bright? Too mellow? Did it sound real or muffled?
> 
> An 'accurate' system cannot be quantitatively determined.


I disagree entirely.


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## MarkZ (Dec 5, 2005)

Neeoo said:


> Good point. Probably a poor choice of words, but essentially - if the 'standard' for tuning a system is to achieve a flat response using a 20-20k hz pink noise, then a system tuned to flat response using a 20-20k pink noise signal has reached the target 'baseline'. Peaks and nulls have been eliminated (or compensated for) and the system is capable of reproducing the most accurate sound that IT is capable of reproducing.
> 
> What have we achieved by this flat 'standard' response though? I assert that we have achieved nothing other than a reproducible baseline from which we can begin tuning to our individual preferences. Nothing more, nothing less.


I could get on board with that. "Flat" as a baseline lets you know what your dialed-in preferences are after you dial them in. That's how mine is set up for the most part. 

The problem, as some people in this thread have addressed, is that "flat" can vary based on things like mic position, the "leg problem", and how you gate the measurements.



Neeoo said:


> Ill venture out a little further as well. Audio is completely subjective. Why? The frequency of the sound from a hi-hat can be caught, measured and determined by an RTA. Its amplitude can be measured as well. But there is no instrument that can tell us how accurate that sound was. Was it real? Was it reproduced from a recording? Was it too bright? Too mellow? Did it sound real or muffled?
> 
> An 'accurate' system cannot be quantitatively determined.


Well, it can in the sense that you can compare your recording to the original (which means you need "measurements" of the original). The thing is, it's routine for engineers to alter the signal INTENTIONALLY. You don't want to reproduce the sound room! You want to compress the vocals, you want to compress the **** out of most of the mics on the drum kit, etc. The production process is an opportunity for the engineer and artist to modify the original sound in a way that you LOSE this original "reference". The sound of the hi hat before it hit the mic becomes pretty much irrelevant.

So, I agree with you that "accurate", as you define it, can't be quantitatively determined. But that's just because I don't think your definition has relevance.


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## Neeoo (Dec 13, 2011)

garysummers said:


> ...snip...
> http://www.dolby.com/uploadedFiles/...essional/Dolby_The X-Curve__SMPTE Journal.pdf
> 
> FYI


From this journal: 

"One remark is well worth quoting: “Whenever such conditions exist that the particular characteristic recommended does not give satisfactory results, it is recommended that the acoustic characteristics of the auditorium be corrected.” This was an acknowledgement that the acoustic behavior of the auditorium significantly affected the sound quality. But it seems probable that after-the-fact acoustic corrections were as rare 60 years ago as they are today. *Most likely, the installation engineer checked the electrical response at the power amplifier, using a frequency response test film. He would then listen to some typical program material. If the tonal balance seemed wrong, he would make a subjective judgment and adjust “the padding.” *


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## garysummers (Oct 25, 2010)

That was the fastest read of a SMPTE paper in history!!!


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## Neeoo (Dec 13, 2011)

garysummers said:


> That was the fastest read of a SMPTE paper in history!!!


I found Cliffs Notes lol!
Seriously though, I've been reading Floyde Tools book "Sound Reproduction - Loudspeakers and Rooms" for the last few days. My brain is thinking in this mode already.


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## sqnut (Dec 24, 2009)

garysummers said:


> That was the fastest read of a SMPTE paper in history!!!


Confirmation bias?


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## Neeoo (Dec 13, 2011)

There's more here. The paper describes the process that theaters went through to achieve full range, noiseless sound (Dolby B noise reduction anybody?). The response curves that the standardization committee agreed on were arrived at by a combination of instrumentation and subjective tuning. 
Quote: *"A surprising development was the discovery that the best subjective match still showed an apparent slight HF droop*. A slope of around 3 dB per octave from about 2 kHz seemed to give the best results, along with a slight limitation to low-frequency bandwidth, as seen in Fig. 11. The low-frequency limitation is easy to explain—more low-frequency energy would probably overload the loudspeaker and generate distortion components. The reason for the apparently desirable HF droop is not very easy 
to explain. There are three possibilities, singly or in combination: 
(1) Some psychoacoustic phenomena involving faraway sound and picture. 
(2) Some distortion components in the loudspeaker, making more HF objectionable. 
(3) The result of reverberation buildup, as described below"

By beginning with known 'ideal' eq settings, and adding subjectively driven adjustments to the curve, the engineers arrived at the settings that yielded the most desirable subjective results. By applying this curve, using exactly the same 'standardized' equipment, a theater may achieve what is acceptable by 'standard' sound. Yet, each theater would 'sound' different to an audience member. Why?


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## ErinH (Feb 14, 2007)

Neeoo said:


> There's more here. The paper describes the process that theaters went through to achieve full range, noiseless sound (Dolby B noise reduction anybody?). The response curves that the standardization committee agreed on were arrived at by a combination of instrumentation and subjective tuning.
> Quote: *"A surprising development was the discovery that the best subjective match still showed an apparent slight HF droop*. A slope of around 3 dB per octave from about 2 kHz seemed to give the best results, along with a slight limitation to low-frequency bandwidth, as seen in Fig. 11. The low-frequency limitation is easy to explain—more low-frequency energy would probably overload the loudspeaker and generate distortion components. The reason for the apparently desirable HF droop is not very easy
> to explain. There are three possibilities, singly or in combination:
> (1) Some psychoacoustic phenomena involving faraway sound and picture.
> ...


This coincides with Toole's power response.

Thanks for taking the time to read the doc. I brought it up while taking a lunch break but haven't had a chance to view it. might be a couple days before I have a chance to sit down and read it in a quiet environment.


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## sqnut (Dec 24, 2009)

garysummers said:


> Some people were posting earlier in the thread asking if there were any room equalization reference standards in the audio production industry. This link is to a SMPTE paper that some may find an interesting read, others may find it worthless, but I will post it none the less. It is a paper by Ioan Allen, a gentleman who has been with Dolby laboratories since Ray Dolby invented noise reduction. It describes how the motion picture industry arrived at the current reference standard for theatrical mixing rooms and cinemas worldwide. This is the exact standard employed today in all cinemas and film mixing studios.
> 
> http://www.dolby.com/uploadedFiles/...essional/Dolby_The X-Curve__SMPTE Journal.pdf
> 
> FYI


I'm not very technical and I just speed read the SMPTE file. It seems that audio for movies is recorded keeping in mind the characteristics of the reproduction environment in mind. The sound is recorded and mixed in a much smaller room, but for playback in a larger room with its unique characteristics. I look at reverbrations as reflections and in a large space the lower end is more prone to reverbrations and there is a roll off above about 2khz. The way we hear is also factored into the equation.

If the above is correct, then I'm curious how 2ch music is recorded. Here perhaps the average recording and playback environments are closer in size and characteristics. Again, the way we hear is probably factored into the 
recording. Just looking for confirmation on this.

It's really tough to keep up with this thread


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## cvjoint (Mar 10, 2006)

I sit down at a restaurant and order some steak. I decide it's missing that certain something so I sprinkle it with some salt. Does that make me a cook? Would you say you are eating salt now and not a steak?

I use objective methods to arrive at a reference sound system. I decide I'm a basshead and add some boost down low. Does that make me an artist? Would you say now car audio is subjective and not objective?

I use objective methods to arrive at a reference sound system. I have 100 guys go in and make each tune to taste. I record output adjustments in DB and HZ increments. I record time alignment adjustments in MS increments. I average the results and create a final map for tuning. Would you cal the final curve subjective? Keep in mind, the difference in output, frequency and time arrival are quantifiable. Keep in mind with 100 subjects asymptotics kick in really nicely to make inference. Keep in mind the sample mean is an unbiased estimator of the population mean.


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## Neeoo (Dec 13, 2011)

cvjoint said:


> I use objective methods to arrive at a reference sound system. I decide I'm a basshead and add some boost down low. Does that make me an artist? Would you say now car audio is subjective and not objective?


This is my (and from what I understand, the OP's) point. The objective methods that you use to arrive at a reference sound system. Are they standardized? Are they broadly applicable? Will applying those same methods to Car A and Car B result in being able to say both Car A & B are now 'reference' systems? Or does it require something more applied to each (subjectively) to truly yield a reference system? 




cvjoint said:


> I use objective methods to arrive at a reference sound system. I have 100 guys go in and make each tune to taste. I record output adjustments in DB and HZ increments. I record time alignment adjustments in MS increments. I average the results and create a final map for tuning. Would you cal the final curve subjective? Keep in mind, the difference in output, frequency and time arrival are quantifiable. Keep in mind with 100 subjects asymptotics kick in really nicely to make inference. Keep in mind the sample mean is an unbiased estimator of the population mean.


This is an interesting scenario from a mixed statistical/applied subjectivity angle. If each participant was A) reasonable with their adjustments B) of a set of similar music taste individuals and C) had a solid background in tuning, then it would be fun to imagine that the end result would be a mean average that would be pleasing to at least 80% of them. The final curve would be completely subjective however as it would be the sum of 100 peoples tweaks. I see what you are getting at though and I would assert that each person has a unique view of what something 'should' sound like. So even though the final curve would be the sum of each participants adjustments, or even the average, it would not satisfy the individual, and may likely not even satisfy the group.


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## Neeoo (Dec 13, 2011)

MarkZ said:


> So, I agree with you that "accurate", as you define it, can't be quantitatively determined. But that's just because I don't think your definition has relevance.


Totally agreed. We are not really discussing the 'accuracy' of a reproduced sound. So then what are we talking about? The accuracy of a recording or the ability of a speaker or system to accurately reproduce the recorded material. This is like the turtle in infinite regression, except the turtles are replaced by 'reference systems'. We say 'oh its accurate because it sounds like reference system xyz.'. And how do we know xyz is a reference system, 'oh because it sounds like system zyz1. 





> A well-known scientist (some say it was Bertrand Russell) once gave a public lecture on astronomy. He described how the earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: "What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise." The scientist gave a superior smile before replying, "What is the tortoise standing on?" "You're very clever, young man, very clever," said the old lady. "But it's turtles all the way down!"


I'm not attempting to be the guy that asks difficult and ambiguous questions. But the foundation for having a scientific discussion about audio is yet to be laid IMO. It may never be. This is sort of parallel to best tasting food, or best wine or best cigar where a thing's quality is proclaimed based on its likeness to another thing of quality. A standard. Unfortunately, I dont know if we have reached that standard yet.


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## cvjoint (Mar 10, 2006)

Neeoo said:


> This is my (and from what I understand, the OP's) point. The objective methods that you use to arrive at a reference sound system. Are they standardized? Are they broadly applicable? Will applying those same methods to Car A and Car B result in being able to say both Car A & B are now 'reference' systems? Or does it require something more applied to each (subjectively) to truly yield a reference system?
> 
> The only way for me to answer that is to switch majors and devote a good chunk of my life to engineering. Or, I can rely on acoustical engineers to get me up to the cutting edge without actually understanding the intermediary steps. What I do know, is that if there is a way to get car A and car B to sound as equal as they can be they are the guys who know or have a methodology that enable them to find out eventually. Us low skilled guys turning bass knobs and knocking heads are not going to get two cars on equal footing. The worse thing we can do is claim it's not possible, or it's *all *subjective. This undermines not only our effort but also the effort of the ones who know to contribute.
> 
> ...


I see where you are coming from with subjectivity enter into the equation and there are two ways to tackle it. 
Head on:
Use objective methods to directly achieve the final curve (an average, self catered, etc)
Indirectly by using a reference and adding on to it.

Either way, you need to quantify and formally conceptualize to make the most of it. To say all is subjective you are either throwing most of the tools you have to start from scratch or denying that your reference (may be a good pair of headphones) was objectively created.


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## Neeoo (Dec 13, 2011)

cvjoint said:


> I see where you are coming from with subjectivity enter into the equation and there are two ways to tackle it.
> Head on:
> Use objective methods to directly achieve the final curve (an average, self catered, etc)
> Indirectly by using a reference and adding on to it.
> ...


I understand what you are saying and from a biased perspective, may agree with it. From an objective perspective though, I have to return to my point about the turtles. Person A tunes a system based on Reference headphone 1, Person B then uses Reference headphone 1 to confirm the accuracy of the system. Can it be said that Person B will never feel compelled to 'tweak' the system? If not, then does that mean the system is 'correct'?


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## BigRed (Aug 12, 2007)

garysummers said:


> Some people were posting earlier in the thread asking if there were any room equalization reference standards in the audio production industry. This link is to a SMPTE paper that some may find an interesting read, others may find it worthless, but I will post it none the less. It is a paper by Ioan Allen, a gentleman who has been with Dolby laboratories since Ray Dolby invented noise reduction. It describes how the motion picture industry arrived at the current reference standard for theatrical mixing rooms and cinemas worldwide. This is the exact standard employed today in all cinemas and film mixing studios.
> 
> http://www.dolby.com/uploadedFiles/...essional/Dolby_The X-Curve__SMPTE Journal.pdf
> 
> FYI


Wow Gary , you have a new nickname .... Mr. X factor!! Lol


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## BigRed (Aug 12, 2007)

Let me ask this question, if 2 different vehicles, say a small Honda civic, and a big van, have their target curve set to flat, perfectly flat from 20hz to 20k and you play the same song in both, will they sound the same? If you have ever tuned more than one vehicle in your life you should have the answer


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## Mic10is (Aug 20, 2007)

BigRed said:


> Let me ask this question, if 2 different vehicles, say a small Honda civic, and a big van, have their target curve set to flat, perfectly flat from 20hz to 20k and you play the same song in both, will they sound the same? If you have ever tuned more than one vehicle in your life you should have the answer


YES both will sound like ass perfectly flat from 20-20


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## sqnut (Dec 24, 2009)

BigRed said:


> Let me ask this question, if 2 different vehicles, say a small Honda civic, and a big van, have their target curve set to flat, perfectly flat from 20hz to 20k and you play the same song in both, will they sound the same? If you have ever tuned more than one vehicle in your life you should have the answer





Mic10is said:


> YES both will sound like ass perfectly flat from 20-20


How come it took you'll 13 pages to say that . I got slammed for saying the same thing earlier in the thread.


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## ErinH (Feb 14, 2007)

sqnut said:


> How come it took you'll 13 pages to say that . I got slammed for saying the same thing earlier in the thread.


Again, it's not what the curve looks like as much as it is how you got there. 

So, I disagree with the two above. And that's EXACTLY what I say in the OP. 13 pages later and I'm still ringing the same bell.


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## sqnut (Dec 24, 2009)

bikinpunk said:


> Again, it's not what the curve looks like as much as it is how you got there.


Well I got there by trial and error and kinda hearing my way there. That and finally figuring out what the FM curves really meant. 



bikinpunk said:


> So, I disagree with the two above. And that's EXACTLY what I say in the OP. 13 pages later and I'm still ringing the same bell.


This thread needs a 5 star rating for the varying opinions that everyone has given. I agree 100% with those 2 posts.


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## SSSnake (Mar 8, 2007)

Unfortunately I don't have the time that I would like to dedicate to this thread but Big Reds comments were exactly where I was going with my earlier post. The size of the room/car makes a difference in what we measure and what we hear. So IMO you've more to do than just come up with some one size fits all curve. You have to take into account the room size/dimensions and the measurement methods/settings. To get started down that path I was trying to establish a commonly accepted baseline for the discussion. Flat anechoic response.


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## ErinH (Feb 14, 2007)

Yea. This thread really is all over the place. I'm involved. 

Think I'm bowing out.


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## sqnut (Dec 24, 2009)

SSSnake said:


> The size of the room/car makes a difference in what we measure and what we hear. So IMO you've more to do than just come up with some one size fits all curve. You have to take into account the room size/dimensions and the measurement methods/settings. To get started down that path I was trying to establish a commonly accepted baseline for the discussion. Flat anechoic response.


I think the size of the vehicle was a bit of red herring in Big Reds post. I think he was talking more WRT a flat curve. A flat FR will sound crappy irrespective of vehicle size. No one is saying that there is one exact mother of all curves that will work in all cars. Each car is different and will have different acoustics. You will have to tune for that. BUT Good sound in car A and B can have *similar* and yet NOT exactly the same curve.


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## SSSnake (Mar 8, 2007)

I'll let Red speak to the point of his post but the statement I am referencing is that two flat curves in two different sized vehicles sound DIFFERENT. Which i believe completely. My posts only suggest that accurate in an ANECHOIC environment would be flat. Even the largest cars are FAR from an anechoic environment. I have not and will not suggest that flat response in the car is the most accurate. In point of fact I don't believe it is. But the reason for this belief is the effects of reflections and their subsequent effect on what we hear and what we measure. 

I am not even suggesting that the subjectively best sounding response curve for anechoic measurements would be flat response. It would just be the most accurate.


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## MarkZ (Dec 5, 2005)

sqnut said:


> A flat FR will sound crappy irrespective of vehicle size.


I think you're really going too far with this point. A lot of people, myself included, find flat to be pretty pleasing for a lot of program material.



SSSnake said:


> I'll let Red speak to the point of his post but the statement I am referencing is that two flat curves in two different sized vehicles sound DIFFERENT. Which i believe completely.


So do I. But there's a lot more to sound than measured FR responses. If you changed the measurement methodology -- such as the temporal window you use -- the once-identical FR curves start to diverge in the two vehicles. You guys must remember that FFTs are approximations.

Rather than focus on this idea of a "reference curve", which I think is total BS , you guys should be discussing the idea of a "reference methodology" for capturing a curve.


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## Neeoo (Dec 13, 2011)

SSSnake said:


> I'll let Red speak to the point of his post but the statement I am referencing is that two flat curves in two different sized vehicles sound DIFFERENT.


This has been proven, and even mentioned in Tooles book (Loudspeakers and Rooms). He speaks of sizes and shapes of rooms affecting the sound in different ways. Its simple physics. Sound bounces off of surfaces, and in bouncing it 'sounds' different when it gets to our ear drums. Two vehicles may very well have flat curves, but due to the differences in interiors, 'flat' will sound different in each. Its a really ambitious goal that those who have started this discussion have. I admire their efforts and respect them for the progress that they have made.


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## masswork (Feb 23, 2009)

sqnut said:


> BUT Good sound in car A and B can have *similar* and yet NOT exactly the same curve.


Agree.

I have yet to see *exactly* same curve in 2 cars (or even 2 places).
Be it flat, or not flat.

1/3 similar is easy, but 1/24, 1/48 exactly similar? really doable?
That's why "same" FR curve sounds different - because our measurement is not detail enough.

And that's just FR, what about other? group delay maybe? 
exactly same too?


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## cvjoint (Mar 10, 2006)

masswork said:


> Agree.
> 
> I have yet to see *exactly* same curve in 2 cars (or even 2 places).
> Be it flat, or not flat.
> ...


Bingo, and that whole topic of nonlinear distortion.


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## masswork (Feb 23, 2009)

Neeoo said:


> This has been proven, and even mentioned in Tooles book (Loudspeakers and Rooms). He speaks of sizes and shapes of rooms affecting the sound in different ways. Its simple physics. Sound bounces off of surfaces, and in bouncing it 'sounds' different when it gets to our ear drums. Two vehicles may very well have flat curves, but due to the differences in interiors, 'flat' will sound different in each. Its a really ambitious goal that those who have started this discussion have. I admire their efforts and respect them for the progress that they have made.


Totally agree.

The room is always a very important factor.

Say sound from speaker with flat FR curve radiates into our listening space.
After it, whatever reverberant sound field that exists begins to decay.
And because reverberation has the effect of prolonging acoustical events, reverberation time is an important influence on how we hear music.

So, if we wonder why exactly same FR curve (if it's really doable at all) will still sound different in different room, might need to take a look at the waterfall plot.​


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## garysummers (Oct 25, 2010)

One comment:

With reference to the "Target Curve". What it is and how it is arrived at will still require some more discussion but it is just that a "target". Something to aim for. Will it require further adjustment in the individual application? Absolutely! This IMHO is where the "Trained Human Ear" comes in to play to fine tune the individual system to its environment. Just as was noted in the SMPTE paper that the curve was set to the target but was listened to and adjusted based on individual room size and acoustics. Target curves are nothing new. Audessey, Imprint, MS-8 and any other auto-alignment technology has to have an internal programed target curve or how would the computer know what to do. Maybe Andy can share with us how the MS-8 folks arrived at their target curves. I have email to Tom Holman about the Audessey and imprint technologies and how the target curves were arrived at. Hopefully its not that secret and we can add this info to our discussion.


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## Tendean17 (Feb 23, 2009)

Almost all my knowledges about car audio are coming from this forum, it means from all of you guys .. so when i found something to better understanding .. i always read my collection threads. If it comes about RTA and Flat Response i go to this thread :

http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/11579-flat-response.html

And this from Andy Wehmeyer i think very usefull :



Andy Wehmeyer said:


> The point isn't the WAY you measure, rather it's whether what you measure correlates to what you hear. If you're able to use ANY tool to repeat the procedure of going from a bad-sounding car to a good one, then your measurement is valid. The confusion arises when you attempt to explain that tool to others, so they can use it successfully.
> 
> Npdang's method will yeild a very different target curve at high frequencies than the method I use. One thing is for certain, though, and that is that you understand the tool you use so you aren'tchasing problems that don't exist. I find that 1/3rd octave analysis isn't enough resolution if I'm tuning a single speaker. However, if you tune both sides at once because you don't have separate left and right EQ, using finer resolution will expose a response that doesn't correlate to what you hear because the steep and narrow peaks and dips that result from the constructive and destructive interference are far less audible than the measurement suggests (unless you know what you're looking at). A spatial average helps to reduce those peaks, but a spectral average helps too. IF you're using 1/3rd octave analysis and measuring all the speakers at the same time, then you shold avoid using high Q filters to fix problems and target the general shape instead because the picture of those high Q peaks and dips isn't valid.
> 
> ...


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## Tendean17 (Feb 23, 2009)

garysummers said:


> One comment:
> 
> With reference to the "Target Curve". What it is and how it is arrived at will still require some more discussion but it is just that a "target". Something to aim for. Will it require further adjustment in the individual application? Absolutely! This IMHO is where the "Trained Human Ear" comes in to play to fine tune the individual system to its environment. Just as was noted in the SMPTE paper that the curve was set to the target but was listened to and adjusted based on individual room size and acoustics. Target curves are nothing new. Audessey, Imprint, MS-8 and any other auto-alignment technology has to have an internal programed target curve or how would the computer know what to do. Maybe Andy can share with us how the MS-8 folks arrived at their target curves. I have email to Tom Holman about the Audessey and imprint technologies and how the target curves were arrived at. Hopefully its not that secret and we can add this info to our discussion.


About JBL MS-8 Target Curve .. 

http://www.diymobileaudio.com/forum/1236176-post21.html


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## cvjoint (Mar 10, 2006)

Tendean17 said:


> Almost all my knowledges about car audio are coming from this forum, it means from all of you guys .. so when i found something to better understanding .. i always read my collection threads. If it comes about RTA and Flat Response i go to this thread :
> 
> http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/11579-flat-response.html
> 
> And this from Andy Wehmeyer i think very usefull :


That's it, Andy's going into my bromance category. I always intend to read DIYMA by nickname but you seem to be able to do this much better than I can.


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## sqnut (Dec 24, 2009)

masswork said:


> Agree.
> 
> I have yet to see *exactly* same curve in 2 cars (or even 2 places).
> Be it flat, or not flat.
> ...


No one said the curve would be exactly the same. Broadly similar maybe, but different enough to account for different environments, installs etc. Delays would be different in the same vehicle for different placements. So obviously they are going to vary a lot from vehicle to vehicle. The main point is that flat does not work in a car.


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## masswork (Feb 23, 2009)

Yeah, personally, i don't like ruler flat either (in small space like car)
I tend to like curve like ELC, audyssey, or Harman's as posted above.

Don't know why...
Maybe it's related to background noise.
My car's background noise, measured as quite as possible without excitation signal 
shows big increase in frequency below 200Hz.
Above 200Hz looks pretty flat.


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## sqnut (Dec 24, 2009)

Probably because all those curves are similar and its about playing around in that range to find something that works for your environment and install. Also because they compensate/correct for how the ears work and parts of the curve are probably recorded into the music. The curves also helps a bit with the impact of the environment in the 2-4khz range. They work on several levels.

You're basically addressing a lot of issues with these curves. Issues that would be common to all ears in all cars. I'm a bit surprised by the number of people struggling with this concept. Its easy to try if you have the dsp.


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## mattyjman (Aug 6, 2009)

cvjoint said:


> Ok, so let me see if I get this right.
> 
> 1.We find a good pair of headphones.
> 2.We play a familiar track through them.
> ...


I didn't think it was worthwhile bringing up a new thread, but i had a question about reference set ups...

i was looking at purchasing some headphones so i can do what's said above... i have a great home system with b&w speakers, and office system with KRK recording monitors, but i don't trust either of them as i have not equalized the space they are in? 

with that said, for headphones, is it a must to go for "in ear" type headphones? i know some people in the headphone world prefer the audiotechnica ath-m50, which is an over the ear headphone but with a supposed good response? 

are there pro's and cons for each when it comes to a reference, or is one simply not comparable to the other when it comes to "in ear" vs "over ear" headphones?


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## ErinH (Feb 14, 2007)

Honest to goodness, I love the ety hf3's I have. However, without the custom molds they were alright. The molds set them apart from anything else I've ever used. and it's incredibly easy. Just find an audiologist from the ety site and have them create te molds. Wait a couple weeks and go pick up the new tips. All said and done I'm in about $250 on mine and I like them more than the $400 IEMs I used previously and more than anything else I've heard. they're very neutral and perfect for a reference. I don't detect any frequency response anomalies The low end response is absolutely SUPERB. 
Plus, they're a whole lot more diverse than traveling or using over head cans.


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## highly (Jan 30, 2007)

Whereas I <hate> using in-ear phones as a reference. I'm not even fond of closed back headphones as they sound claustrophobic and constrained to me. Yes, you can absolutely use whatever it is you trust. 

...Though with your home setup I would seriously consider what it would take to learn to trust them. You have the makings of what could be an excellent reference sitting right in front of you that can give you a much more complete picture than any headphone could...


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## ErinH (Feb 14, 2007)

highly said:


> Whereas I using in-ear phones as a reference. I'm not even fond of closed back headphones as they sound claustrophobic and constrained to me. Yes, you can absolutely use whatever it is you trust.
> 
> ...Though with your home setup I would seriously consider what it would take to learn to trust them. You have the makings of what could be an excellent reference sitting right in front of you that can give you a much more complete picture than any headphone could...


I agree with the last paragraph wholeheartedly. That would be a great side discussion. 

I use both the headphones and speakers in home. It gives me a well rounded reference. The separation in headphones is so much more definitive. Almost to a fault because attaining that anywhere else is so far removed. Plus you don't get reflections to help give you a better sense of space. Still, I love them for the ability to give low end response without being affected by room modes.


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## mattyjman (Aug 6, 2009)

well, honestly, based on the previous discussion, i was planning on using the home speakers to give me a good inclination of staging, depth, etc, where headphones don't give you a realistic goal... whereas the tonality of the headphones will help in the tuning side of things...

using the pair as a reference was my goal.

my issue with the b&w's is my room response. i have a nice pio elite receiver, with an auto eq wizzard, and despite going through it multiple times, adjusting the location and angle of the mic, it still doesn't sound quite right, it doesn't sound wrong, just not absolutely perfect. staging is amazing though... they are incredible speakers. maybe i'll need to get moving on putting together an actual rta and start playing with the manual eq options.


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## Mic10is (Aug 20, 2007)

mattyjman said:


> well, honestly, based on the previous discussion, i was planning on using the home speakers to give me a good inclination of staging, depth, etc, where headphones don't give you a realistic goal... whereas the tonality of the headphones will help in the tuning side of things...
> 
> using the pair as a reference was my goal.
> 
> my issue with the b&w's is my room response. i have a nice pio elite receiver, with an auto eq wizzard, and despite going through it multiple times, adjusting the location and angle of the mic, it still doesn't sound quite right, it doesn't sound wrong, just not absolutely perfect. staging is amazing though... they are incredible speakers. maybe i'll need to get moving on putting together an actual rta and start playing with the manual eq options.


space the speakers about 6 feet apart then sit about 6 feet away in the middle.

keep the speakers as far away from a wall.

easiest way without going through more hassles


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## its_bacon12 (Aug 16, 2007)

The only worry I have about you using balanced IEMs as reference is if your headphone output is higher than a few ohms.

Give this blog a read if you're really into headphones: NwAvGuy

Tons of great info - I built his O2 Headphone amp and I absolutely love it. Amazing.


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## subwoofery (Nov 9, 2008)

bikinpunk said:


> Honest to goodness, I love the ety hf3's I have. However, without the custom molds they were alright. The molds set them apart from anything else I've ever used. and it's incredibly easy. Just find an audiologist from the ety site and have them create te molds. Wait a couple weeks and go pick up the new tips. All said and done I'm in about $250 on mine and I like them more than the $400 IEMs I used previously and more than anything else I've heard. they're very neutral and perfect for a reference. I don't detect any frequency response anomalies The low end response is absolutely SUPERB.
> Plus, they're a whole lot more diverse than traveling or using over head cans.


Just wondering if the fit is really tight - will it hold on while doing some jogging? 

Kelvin


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## ErinH (Feb 14, 2007)

Yep. They don't move at all when I run.


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## subwoofery (Nov 9, 2008)

bikinpunk said:


> Yep. They don't move at all when I run.


Sweet... Thanks  

Kelvin


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## ErinH (Feb 14, 2007)

just to clarify, I'm talking with the molded tips. without them, they fall out. at least using the supplied tips.


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## subwoofery (Nov 9, 2008)

bikinpunk said:


> just to clarify, *I'm talking with the molded tips*. without them, they fall out. at least using the supplied tips.


I know and was asking about them  

Kelvin


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## ErinH (Feb 14, 2007)

I thought you were but I just wanted to make 100% sure.


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## cvjoint (Mar 10, 2006)

I've used the double seal Etymotic tips for 6 years or so. I go to the gym >200 times a year. They don't fall out. I just change the filters and they keep going and going.


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## mattyjman (Aug 6, 2009)

fwiw... i just picked up a set of audiotechnica m50 cans.... wonderful is all i can say. OMG...


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## myhikingboots (Oct 28, 2010)

mattyjman said:


> fwiw... i just picked up a set of audiotechnica m50 cans.... wonderful is all i can say. OMG...


Wait till they break in.


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## ErinH (Feb 14, 2007)

figured it's time to update and see if I can get some convo going again. not for the sake of me seeking help, but to share some insight and maybe make some folks go "hmmm"...


I long ago said that my midbasses make the system perform much better when they have no HPF enabled. People are apalled to learn I rock 7" drivers all the way to 20hz. Been doing it for about 1.5 years now and so far, so good.

I did, however, recently try a stint at using a HPF on them at 50hz and using the sub around the same point. Sub with a 36dB slope and midbasses with 24dB slopes. Got it?
Okay...

The problem arose whenever I'd get a midbass guitar or kickdrum; you'd feel it in the back. Grrrr. 
I played around with varying the sub to midbass transition in a multitude of ways (changing the crossover points, changing the slope, flipping phase, etc). Nothing really worked as well as when they midbasses were played with no low end filter. I had an idea why but I wanted to see if it held up. I popped in a track that makes everyone's car do the nasty: Spanish Harlem. Yes, I know you hate it, but it does a great job at highlighting deficiencies in a stereo system. 

I used my omnimic with TrueRTA and set TrueRTA's "peak hold" to on. I played the first few seconds of Spanish Harlem at a pretty loud level and recorded the sound with the midbass crossover slope enabled and at 24dB/octave.
I then played the track again, this time with the HPF slope inactive (0dB/octave). 
The goal here was to capture the bass resonance of the stand up bass behind Rebecca that often "blooms" in many audio systems and causes the entire audio response to be compromised. Capturing this would allow me to see exactly what was going on with the varying crossover/slopes. 

What you see below is a picture of the response of the first 10 seconds of the track, with Peak Hold set to on with both 'versions' of the system response. 24dB slope is in Green. Slope off is in Purple.









You'll note the large gap in response at 40hz. This means something is out of phase. Surely this sounds bad, right? Well, as it turns out, it seems to do a good job of creating an anti-node. What do I mean? Simple: the car has a modal response driven by geometry at about 45hz. I know this because I did some testing with the omnimic and the OM software using their Bass Decay feature.*
Here's the response of the car's bass decay. This essentially is a means of determining resonance in the 'room' (ie: room modes). 
In the picture below, you can see the scale on the right side that gives you color vs. level of resonance. This level is absolute; it is not given relative to the frequency response. You'll see the large increase in resonance at about 43hz. 








(side note: See that one at 160-200hz? That's a serious issue in my car, too)

As it turns out, while the sub to midbass transition is out of phase here when looking at the FR measured (not pictured here), it actually sounds _very _good. The midbass bloom goes away to a large degree and the upright bass is in front of you. The majority of any tactile feedback in the seatback is removed and the bass shifts up front by a perceptually large amount.

My hunch is that the two drivers being out of phase at/near the crossover is helping to absolve some of the room mode issues and is lending itself to more 'upfront bass' response, rather than 'hit me in the back of the seat'. It seems that I've created an anti-node right where it was needed. Only a theory... 
And, this actually does help prove to some degree my OP even further: don't always solely depend on a graph. You'll recall (before this thread went to hell and back) my goal was discuss room modes, using an RTA, using your ear, and coming up with a helpful discussion on the low end response; the Achilles' heel of car audio (and home audio, too).

I can't say,... won't say..., if this always works for everyone. It is simply a means to further display how tricky this hobby is. Hopefully this will give some folks motivation to try something outside of the norm and possibly have good results.



*Note:
I love the omnimic. Yes, it's expensive compared to other products but it's incredibly simple to use and is packed FULL of great features.


Edit: This post is NOT intended to start a "run your midbasses to the ground with no/low crossover" discussion. Just an observation regarding phase and mode relationship and how they can (possibly) be played against each other with good results.


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## MarkZ (Dec 5, 2005)

Erin, this is probably too obvious of a suggestion, but have you measured the spectral content of the song to see if that's what's actually responsible for the 40Hz thing in your first plot?

Ignorance on my part: what is a "bass decay" plot? Looks like a spectrogram... what do the resonance values correspond to? The way I'm interpreting it, you get more dB of "resonance" over time? That doesn't make sense to me. What is the stimulus?

PS - I don't remember... did you show us a phase response plot? You allude to it...


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## ErinH (Feb 14, 2007)

The bass decay is a simple way of measuring a room mode. Great information here:
Bass Decay



OmniMic Manual said:


> When a bass note is stopped within music, the sound in the room at some frequencies may still continue for some time. That is because the sound reflects back and forth between walls, resonating and forming "modes" before eventually dying down. This is not altogether bad and some reinforcement is normally desirable for natural sounding playback, but you would like to keep it under control and not have some notes sounding muddy or lingering much longer than others.
> 
> The top graph on the Bass Decay display shows the frequency response of the bass range, similar to that shown with the Frequency Response analyzer. The bottom graph shows how long it takes the sound to decay at each frequency. As shown on the legend to the right of the decay graph, the white area extends upward to indicate when the level drops no more than 5 decibels (dB). The light blue indicates when the level has dropped between 5dB and 10dB, etc.



It's a short bass sweep. I believe they have a longer one now. Just a bandlimited sine wave. 

The varying colors are a represnetation of the FR level on the x-axis. The y-axis is milliseconds. Using these two together gives you a very good idea of just how much of a mode there is and at what frequency(ies).

There are two ways of viewing the results of bass decay: absolute or relative to the measured FR (which OM shows in a window above the one I've provided, and you'll see in the link above).

I didn't take an FR or phase measurement tonight. Probably should have but didn't think about it at the time since I had been staring at FR all night anyway.  
There's a dip in response centered @ ~40hz (1/3 octave).


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## ErinH (Feb 14, 2007)

Mark, take a look at about 180hz. See how the 15-20dB resonance lasts for about 75ms? 
That specific area in my car is an issue. I think it's a corner loading effect due to the midbasses mounted in the kicks. I've had problems there since day one and have had to either build the crossover around it or EQ the crap out of 160 & 200hz to bring it down. 

The problem is that a modal issue can't be EQ'd, really. It can to some degree but always an underlying issue. This is where a bass trap would help, but you can't fit them in a normal sized car. The next best thing is an equalizer with adjustable Q and broad levels of attenuation. This is why the Arc PS8, Helix C-DSP, Mosconi, and Zapco DSPs are so nice. You can vary Q. However, the Arc is the only one I know of that allows such a narrow Q of 25 (iirc).

Just posting this to highlight another issue and how useful these kind of measurements can be. I never knew until 15 minutes ago that the issue at 180hz was so obvious. It stands out more than the other issues, to me, because it's such a high resonance with a long decay. It's not something I set out to measure. I've heard it for years... tonight is the first time I've seen it in 2-D.


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## chad (Jun 30, 2005)

bikinpunk said:


> Yep. They don't move at all when I run.


Why do you listen to music when people are chasing you?


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## BigRed (Aug 12, 2007)

I hate 160hz!  good info here Erin!!


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## chad (Jun 30, 2005)

You can't hate it because a right amount is what makes it real.

If you suck it out, you lose a LOT of snap.


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## Lteeples (Feb 19, 2012)

I really like how the title here is "a quick note". I am new here and I haven't read so much in a while. I even skipped most of the thread. Good reading though.


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## MarkZ (Dec 5, 2005)

So it's basically a contour plot of a waterfall, thresholded. [I was thrown by the dB legend being positive and not negative...]


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## ErinH (Feb 14, 2007)

MarkZ said:


> So it's basically a contour plot of a waterfall, thresholded. [I was thrown by the dB legend being positive and not negative...]


Yea. That's a way to look at it.


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## ErinH (Feb 14, 2007)

chad said:


> Why do you listen to music when people are chasing you?


It's the Rocky IV soundtrack. Makes me go faster.


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## cvjoint (Mar 10, 2006)

Sweet find at 180hz. When I had kicks there was a bump there too. EQ. didn't help. I mean it helped a little by downplaying the amplitude but the resonance was still there. If you fix it I'm curious to know how. Nothing I tried worked. 

I was waiting for someone to try this feature out before I do haha.


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## masswork (Feb 23, 2009)

bikinpunk said:


> Mark, take a look at about 180hz. See how the 15-20dB resonance lasts for about 75ms?
> That specific area in my car is an issue. I think it's a corner loading effect due to the midbasses mounted in the kicks. I've had problems there since day one and have had to either build the crossover around it or EQ the crap out of 160 & 200hz to bring it down.
> 
> The problem is that a modal issue can't be EQ'd, really. It can to some degree but always an underlying issue. This is where a bass trap would help, but you can't fit them in a normal sized car. The next best thing is an equalizer with adjustable Q and broad levels of attenuation. This is why the Arc PS8, Helix C-DSP, Mosconi, and Zapco DSPs are so nice. You can vary Q. However, the Arc is the only one I know of that allows such a narrow Q of 25 (iirc).
> ...


Hmm makes me wonder...
Do you gate the measurement at all? Sure, too small time window is no good for bass.
How long is the measurement window btw?


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## ErinH (Feb 14, 2007)

Not gated. Measurement window is a bit longer than duration of the sweep to measure modes. The y axis gives you time ...

Keep in mind typical gating for loudspeaker testig is usually no more than 5-10 seconds in most peoples' homes. 250 ms is a MUCH larger window.


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## slade1274 (Mar 25, 2008)

Sub'd for future reference as to why I won't 'get there' with stock locations.

Damn you DIYMA.


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## BigRed (Aug 12, 2007)

chad said:


> You can't hate it because a right amount is what makes it real.
> 
> If you suck it out, you lose a LOT of snap.


I agree. Let me rephrase that. I hate the 160hz hump in my truck.


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## sqnut (Dec 24, 2009)

I am a bit curious about the 10 db suck out at 400hz when you don't engage the hpf. Not sure how running the mb lower would cause a bigger suck out that high. Or is that your xover point between mb and mids?


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## SSSnake (Mar 8, 2007)

This caused me to go in and look at the spectrograms REW provided. Different graph same info. Time for more measurements (the ones I took only cover part of the areas of interest).


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## masswork (Feb 23, 2009)

bikinpunk said:


> Not gated. Measurement window is a bit longer than duration of the sweep to measure modes. The y axis gives you time ...
> 
> Keep in mind typical gating for loudspeaker testig is usually no more than 5-10 seconds in most peoples' homes. 250 ms is a MUCH larger window.


I see.

Just curious to see the finding in my system... if i may share...
In car response, midbass with 80Hz highpass 24dB.

Same measurement, but different window for analytics.

A.
Impulse:









This is the case with many soundcard i've been using. There's an initial spike at about 6ms after impulse is recorded.

The FR is:










Now, we move the left window so it skip the initial spike which is not caused by the speaker.

B:









With 54ms gate, the frequency resolution is about 18Hz (cmmiw).

The gate is now shorter since we move the left window near speaker impulse. The right window is still the same.
And, the FR will look like this, compared with A.
B is white line, yellow is A.










There's big difference in frequency <60Hz. Above 60Hz is pretty much the same.

And now the third test.
Left window is kept near speaker initial impulse, skipping the first unknown spike.
But the right window is extended.
IR:









FR compared A, B and C:









C is red, B is white line, yellow is A.
Given the speaker is highpassed at 80Hz/24db, i'm not sure if the spike below 50Hz is caused by speaker itself?

This lead me to question:

1. How long should we gate the measurement? The software itself must have put a default number for example 250ms or 500ms if we don't specify. 

2. Am i the only one who receive the unknown initial spike?
If we include this in our measurement, i think it doesn't look right.

Need your advice...

Thanks,
Rizal


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## ErinH (Feb 14, 2007)

On the car, do not gate the measurement. There's no reason to. Everything is reflecting at nearly the same time the sound leaves the speaker.


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## masswork (Feb 23, 2009)

bikinpunk said:


> On the car, do not gate the measurement. There's no reason to. Everything is reflecting at nearly the same time the sound leaves the speaker.


Right.
I can understand if we don't gate to 6-10ms... but 250... 500ms.
But really, no gating at all til 500ms?


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## ErinH (Feb 14, 2007)

masswork said:


> Right.
> I can understand if we don't gate to 6-10ms... but 250... 500ms.
> But really, no gating at all til 500ms?


think of why you have gating.

it's for measuring a driver or speaker and removing the effects of the room. 

in car audio the room is so closely tied to the speaker's response there is no point in removing it in the car. if you want to test the speaker, enclosure, pillar (as I have done) outside of the car then you would gate the response so you understand exactly what that specific item is doing by itself. but, in the car, you have so much stuff so close to the drivers, there's no sense... and no real merit, to removing the room. Hell, you can't, really, unless you do near field and that does nothing for a seated FR.


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## MarkZ (Dec 5, 2005)

Masswork, I believe the difference below 60Hz you're seeing could be an artifact of the window size itself. Change window size and you change FFT resolution, which will be most visible at the lower frequencies. Also, when you compare A vs. B, the dominant low frequency component comes if you evaluate the autocorrelation of the "initial spike" with the remainder of the sound. In other words, the spacing between the envelopes of the two epochs ("initial spike" and late sound) is approximately 20ms, which corresponds to 50Hz. In case A, you're including it. In case B, you're not.

The lesson here is that your low frequency FR is going to be altered by the gating.


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> think of why you have gating.
> 
> it's for measuring a driver or speaker and removing the effects of the room.
> 
> in car audio the room is so closely tied to the speaker's response there is no point in removing it in the car. if you want to test the speaker, enclosure, pillar (as I have done) outside of the car then you would gate the response so you understand exactly what that specific item is doing by itself. but, in the car, you have so much stuff so close to the drivers, there's no sense... and no real merit, to removing the room. Hell, you can't, really, unless you do near field and that does nothing for a seated FR.


Gating is also important for fast automatic sweeps because you don't want resonances/reflections that are specific to one frequency range contaminating another frequency range just because the window is large.

Not sure how your software is measuring energy, but if you simply take the FR of the recorded signal and then assume that it shares the same energy as that which produced it, then you're lumping in harmonics into the wrong bin.

I like bandlimited noise measurements best.


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## ErinH (Feb 14, 2007)

MarkZ said:


> The lesson here is that your low frequency FR is going to be altered by the gating.


Bingo!

When people choose high resulting for a gated impulse, it's misleading because the window really affects the level of resolution.


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## masswork (Feb 23, 2009)

MarkZ said:


> Masswork, I believe the difference below 60Hz you're seeing could be an artifact of the window size itself. Change window size and you change FFT resolution, which will be most visible at the lower frequencies. Also, when you compare A vs. B, the dominant low frequency component comes if you evaluate the autocorrelation of the "initial spike" with the remainder of the sound. In other words, the spacing between the envelopes of the two epochs ("initial spike" and late sound) is approximately 20ms, which corresponds to 50Hz. In case A, you're including it. In case B, you're not.
> 
> The lesson here is that your low frequency FR is going to be altered by the gating.


Hi Mark,
thanks for the explanation.

I was just really curious whether we really shouldn't do gating at all, especially after say 250ms or so. 250ms on 48K is like 4Hz resolution.

As for the initial spike...
Dunno if others experience this

My initial spike is misleading (at least i really think so).
Initial spike is always there, having same amplitude at 6ms.
Regardless of moving mic, lowering the volume of midbass (at the amplifier), flipping midbass polarity - there's always first pulse at 6ms. 

So for me the 1st 6ms is disregarded.

I notice this behaviour using several equipments: m-audio, soundblaster play, laptop internal sound card, denon and ecm8000 mic, HP, Dell and Acer laptop, and ARTA and REW for the software.
All combination shows 1st initial spike that doesn't relate with the measurement.
It doesn't show when measuring loopback connection though.


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## masswork (Feb 23, 2009)

Or we can put it this way...

Measuring tweeter only 5k++, and analyze it with or without gate.
Without gating will show low frequency content, right?
But is it correct?

If we then use it for Eq-ing, it may become a problem.


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## ErinH (Feb 14, 2007)

That first spike may just be the loopback measurement (raw signal).


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## masswork (Feb 23, 2009)

bikinpunk said:


> That first spike may just be the loopback measurement (raw signal).


Yeah, that's what i think too..

Erin, does your equipment have this issue as well?

Have been trying to find equipment (or maybe just software) that doesn't have this issue. 
Sometimes when i forgot to exclude 1st spike, the auto-eq calculation simply sounds terrible...


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## ErinH (Feb 14, 2007)

I've not personally seen that before.


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## thehatedguy (May 4, 2007)

Damn it...you guys are making me want to buy some test gear. The wife would kill me...having a new baby in the fall and buying a new house and all.


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## vitvit (May 3, 2011)

masswork said:


> Have been trying to find equipment (or maybe just software) that doesn't have this issue.
> Sometimes when i forgot to exclude 1st spike, the auto-eq calculation simply sounds terrible...


Try REW (free). Even if you enable "loopback" it will read it from another channel and no "initial" spike will pass to measurement channel.
But "loopbak" is off by default.


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## masswork (Feb 23, 2009)

vitvit said:


> Try REW (free). Even if you enable "loopback" it will read it from another channel and no "initial" spike will pass to measurement channel.
> But "loopbak" is off by default.


Same with REW here.
There's initial spike too... difference is REW put it as 0ms, where ARTA put it on 6ms. But that position depends on REW setting as well.

For example:
Tweeter with 5k highpass crossover:










Initial peak at 0ms.

Tweeter start at around 15ms.

FR without gating (0-500ms)










Notice the lower frequency climbing...
Starting from 200Hz and lower.
I'm not so sure this was the result of tweeter excitation? Or is it just a background noise?

And this one is with windowing. Start at 15ms, and stop 10ms after.










Cleaner. No low frequency detected.


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## SSSnake (Mar 8, 2007)

You've got something strange going on. With REW set to loop back I have never gotten a clean original pulse followed by a decaying impulse. Also with loop back enabled you should not have an impulse at 0 msec.


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## masswork (Feb 23, 2009)

SSSnake said:


> You've got something strange going on. With REW set to loop back I have never gotten a clean original pulse followed by a decaying impulse. Also with loop back enabled you should not have an impulse at 0 msec.


Yeah, something strange.. just can't figure out what it is.

Apparently, i'm not the only one who notice this issue:
http://www.diymobileaudio.com/forum...-i-measure-time-delay-between-speakers-3.html

Loopback is on btw.

Anyway, i just use gating and contine the process...  

REW windowing is very cool btw.
We can see FR changes in every ms.


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## ErinH (Feb 14, 2007)

masswork said:


> REW windowing is very cool btw.
> We can see FR changes in every ms.


You can do this with any windowing program. Keep in mind it's not changes per se. It's the level of resolution.


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## SSSnake (Mar 8, 2007)

But if u r using REW to time align the speakers, which I recommend, r u seeing odd results or r the delays coming in as expected?


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## masswork (Feb 23, 2009)

SSSnake said:


> But if u r using REW to time align the speakers, which I recommend, r u seeing odd results or r the delays coming in as expected?


Delays are ok.
The 2nd impulse (after the 1st weird one) shows correct time arrival.


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## SSSnake (Mar 8, 2007)

Gotcha


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## vitvit (May 3, 2011)

masswork said:


> Delays are ok.
> The 2nd impulse (after the 1st weird one) shows correct time arrival.


Do you need loopback at all? (for this set of measurements)? Do you see initial impulse with lookback OFF?

I think you shouldn't trust the measurement like one you have in any way.

It might be hardware mixing issue. Can you run measurement without speaker connected? Check mixer setting in "recording control" dialog, mute "Stereo Mix" or whatever your mixer has.


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## cvjoint (Mar 10, 2006)

bikinpunk said:


> (side note: See that one at 160-200hz? That's a serious issue in my car, too)


Quoted for comparison. 

Here's my car:










Seems like 125-200hz is a bit high in my car. That's where the FS of the pillar pods is. 

There is another striking feature with this test. As SPL is increased there are clear spikes in the plot. The car's panels are starting to vibrate, i'm guessing it shows up in the tests. This is the highest SPL I could give it before the spikes show up.


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## subwoofery (Nov 9, 2008)

Interesting... Guess I should give it a try in mines  

Kelvin


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## masswork (Feb 23, 2009)

vitvit said:


> Do you need loopback at all? (for this set of measurements)? Do you see initial impulse with lookback OFF?
> 
> I think you shouldn't trust the measurement like one you have in any way.
> 
> It might be hardware mixing issue. Can you run measurement without speaker connected? Check mixer setting in "recording control" dialog, mute "Stereo Mix" or whatever your mixer has.


Ah right.
Haven't tried with loopback off.

Anyway, the rest after 6ms are OK.
It shows all changes in my DSP. For example boosting X by Y dB will shows up correctly. Delaying by x ms... etc...


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