# Target Curve Comparison



## pionkej

This thread may spur some discussion, or it may not. I often see people ask about what final "curve" they should tune their system to. You see responses range from things like: flat, "smiley face", ELC (equal-loudness contour), gentle slope downward, the "JBL Curve" (provided by Andy W.), etc. It just so happened I decided to do a bit of research on the topic while I had some down-time recently and wanted to share my findings. Everything below was obtained from simply using Google Search. 

So, let's start with the curves written out. I ended up settling on five different curves. Any explination/logic I found about why these curves exist will be shared below said curve. 

*1.) JBL/Andy W. Curve:*

-20-60hz: +9db
-60-160hz: Transition to 0
160-3khz: Flat (0)
3khz+: Gradual Roll-off to -6db @ 20khz

* Andy has stated this target response is the "ideal response for a small listening environment" with a bump on the low-end to compensate for typical listener preference.

http://www.diymobileaudio.com/forum...main-andy%20wehmeyers%20target%20response.jpg

*2.) Crutchfield Labs Curve:*

-20-125hz: +6db
-125-200hz: Transition to 0
200-12.5k**: Flat (0)
12.5-16khz: Roll-off to -3db
16-20khz: Roll-off -6db (-9db total)

**This range includes a +1db bump at 400hz, a -1db dib at 10khz, and a +1db bump at 12.5khz.

* This target curve was in a recent edition of Crutchfield Labs. Here is the only comment I found to the logic behind it, "This represent's Jeff's ideal sound curve, one that helps overcome some of the limitations that appear when you listen to music in a moving vehicle."

Crutchfield Car Stereo Proving Ground

*3.) Audyssey Curve:*

20-1khz: Flat (0)
1-3khz: -3db dip
3-10khz: Roll-off to -1.5db
10-20khz: Roll-off -3db (-4.5db total)

* This "popular" curve is the closest I found to flat that some people recommend. I also thought the logic behind the curve was interesting. The roll-off on the top-end is performed as a gated measurement. This eliminates reflections being added to the measured response. Ungated response will be "whatever it is" after reflections are accounted for, but it should be close to flat. This leaves the small dip. It was explained that because of the popularity for 8"/1" and 6.5"/1" speaker combos (both in home and car), we have become accustomed to and prefer the sound of a directivity mismatch, and the dip in power response, and therefore Audyssey "tunes it in" even if it isn't needed. They also flatten the response of the sub up to around 3khz, add the crossover at 80hz, and allow the end-user to adjust sub output if they perfer a boost on the bottom end (similar to all the other graphs)

*4.) Audio Control Curve*

-20-40hz: +6db
-40-250hz: Transition to +1db
-250-2khz: Transition to 0db
-2-20khz: Roll-off to -5db

* It seems this curve was included in the manual with the old Audio Control RTA's. The manual basically said, "Flatten response as much as possible (you won't like it), and then adjust to something approximating this curve." I found this information on diyaudio.com I believe if you want to dig further.

*5.) B&K Curve*

-20-160hz: +3db
-160-2khz: Transition to 0db
-2-20khz: Roll-off to -3db

* There is a long PDF about this curve which I've attached. It seems to be well-received in mimimum phase systems (which the car ISN'T), but I wanted to include it because it also represents the people who like a smooth and steady roll-off. 

http://www.bksv.com/doc/17-197.pdf

And for those of you who are visual learners...a graphical representation of all the curves and an average of all the curves:


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## pionkej

If this thread does generate some discussion, I'd like to point out up front that this is just one helpful tool in the "game" of tuning. There are MANY other factors out there besides a target curve that need to be considered and I suggest people read up on them before aiming for this. Things like phase response, polar response, and power response all need to be considered. 

There are many ways to get to the "finish line" and if you choose poorly you could end up with a "perfect curve" and system that sounds like crap.

For example, I could cross the 6.5" midbass in my door at 50hz and 5khz. I then boost the low end flat (and beyond xmax) to meet the sub and the top-end to flat (to compensate for beaming/off-axis response) to meet the tweeter. The graph may look nice, but I've introduced distortion from exceeding xmax (and may kill the speakers too) and created a terrible mismatch in power response (because the midbass is beaming and the tweeter is omin-directional).


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## Libertyguy20

great right up....i posted a thread yesterday similar to this in terms of (among other things) trying to understand the logic behind a few of the curves (JBL and Crutchfield)....didn't even know about these other curves however.

Please note that on your graph, you placed the 400hz 1 db boost of the crutchfield curve incorrectly at 4000k mark instead of 400.


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## pionkej

Libertyguy20 said:


> great right up....i posted a thread yesterday similar to this in terms of (among other things) trying to understand the logic behind a few of the curves (JBL and Crutchfield)....didn't even know about these other curves however.
> 
> Please note that on your graph, you placed the 400hz 1 db boost of the crutchfield curve incorrectly at 4000k mark instead of 400.


Good catch. I've edited the original post and moved the bump to 400hz.

Also, I wanted to point out that I personally aim for my frequency response to not vary more than 3db per octave from my "target curve". I do aim for less than that, but 3db is my "threshhold". I say this because I'd be hard pressed to care about any of the 1db peaks or dips in the Crutchfield response personally, but I included it anyways.


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## jcollin76

This is perfect! Ive been researching this exact topic... And not having the greatest luck.
Ive recently started "trying" to dial in my front stage with an rta. 
I wont be much help, but looking forward to what others have to add.

Thank you for posting this.


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## jcollin76

This is what I was reading yesterday. I know its geared for home audio, but some of the "small room" stuff could carry over... Or I could be totally wrong. 
http://www.hometheatershack.com/forums/rew-forum/96-house-curve-what-why-you-need-how-do.html
I get kinda lost between curves, equal loudness, etc. being new to Rta based tuning doesnt help either. Lol


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## smellygas

Nice post. The one key piece of information you're missing is the METHOD by which you're measuring your loudspeakers.

Example: Is your mic directional? Omnidirectional? Or were they binaural microphones that take into consideration the directivity of the sound source/reflections and the shape of the listener's ear? Was it gated (i.e. you cutoff later reflected sounds that are ignored by the ear)? And are you measuring in a diffuse field or a free field? The relative intensity and direction of the different sound waves that strike your ear (i.e. direct + reflected and arriving at an angle) makes a BIG difference in the sound that ultimately strikes your eardrum. 

You can take identical speakers in an identical room, but change around HOW you measure, and subsequently, you could "come up with" a whole bunch of different "target curves" that describe the exact same listening environment. *That's why it's useless to talk about target curves without specifying the precise method/environment of the measurement*.

If you're interested, here's another curve to add, it's for free-field measurement and it's based on blinded listener preferences to loudspeakers, including expensive or well-regarded ones. 
http://www.aes.org/tmpFiles/elib/20120609/5270.pdf
It's doesn't really apply that well to the diffuse-field you get in a car, but it's still good for comparison. It would be nice if anyone knows of any JAES papers that talk about listener preference curves for in-car sound systems.


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## james2266

I have researched this quite a bit myself over the course of the past 2 years or so but I must say I don't think I have seen as many curves discussed so well all in one place. Subscribed for sure. I, too, would like an answer to the above post on how to measure for these curves. It is something I have always wondered myself. I use an omnidirectional mic (ECM8000) mounted flat and aimed straight ahead. I try to get the mic as close to where the center of my head usually is. I actually find that difficult as the mic is rather long and the seat headrest usually gets in the way. Maybe there is a better more accurate way to be aiming/placing the mic?


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## james2266

I have also read that taking multi- readings at different angles/positions and averaging them is necessary (spacial averaging). I have not really played with that too much as it is time consuming enough for me. The couple times I did, I noticed the high frequencies change immensely between readings (above 5 Khz or so).


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## highly

smellygas said:


> <snip>...*it's useless to talk about target curves without specifying the precise method/environment of the measurement*.


I'll agree with your statement up to this point. It's only useless based on the assumption that the person measuring the listening environment is ignorant to the process and the choices they have when doing so. I think a discussion of the curves themselves and the perspectives behind them brings a separate and useful discussion to bear. Again, I agree, the process of measuring is as much or more important than the data it gathers but assuming a fundamental understanding of the measurement process this discussion stands freely and in its own right.


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## ErinH

I'm more interested in the curves provided and how they were obtained. Sure, knowing how to measure is important, but knowing how a given was measured is at least equally important and arguably moreso. That's one thing I really see. And then when people try to lump in the equal loudness curve... It's just nebulous to discuss it without knowing the procedures taken to arrive at any result. 


Sent from my iPhone. Pardon the grammar.


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## tyroneshoes

Just curious,

How accurately have phone rta apps been when compared to m-audio/true rta and other methods?

I have surprisingly similar results using true rta and the droid app RTA Pro


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## stereo_luver

bikinpunk said:


> I'm more interested in the curves provided and how they were obtained. Sure, knowing how to measure is important, but knowing how a given was measured is at least equally important and arguably moreso. That's one thing I really see. And then when people try to lump in the equal loudness curve... It's just nebulous to discuss it without knowing the procedures taken to arrive at any result.
> 
> 
> Sent from my iPhone. Pardon the grammar.


Agreed.

Chuck

BTW...thanks John


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## smellygas

highly said:


> I'll agree with your statement up to this point. It's only useless based on the assumption that the person measuring the listening environment is ignorant to the process and the choices they have when doing so. I think a discussion of the curves themselves and the perspectives behind them brings a separate and useful discussion to bear. Again, I agree, the process of measuring is as much or more important than the data it gathers but assuming a fundamental understanding of the measurement process this discussion stands freely and in its own right.


Let me clarify. If you plan to EQ your system to match a particular target curve, but you don't know the method by which the target curve was obtained, then YOU CAN'T DO IT = useless. But great for discussion, I guess.

Example: Let's say I take the world's best sounding car stereo. And I record the freq response curve from pink noise using an [unknown measuring technique], then publish my curve for others to duplicate my incredible sound. Problem is, depending on the measurement technique used by the tuners trying to copy this "target curve," you will obtain a completely different final equalization. For instance, take the ubiquitous ECM8000. Aim it up and take a spatial average. Now aim it at each speaker and take an average. Quite different. Take binaural mics and take a spatial average. Different. And what's worse is that some of the curves above were measured in the free-field with mostly direct sound arriving from directly in front of the listener and reduced amplitude reflected sound coming from the sides. Car sound is direct sound coming more from the sides with near-equal amplitude early reflected sound coming from all around in a diffuse field. Completely different. So unless you match the technique, you can't reproduce the original sound signature. i.e. useless. 

...and the result is people complain that XYZ Target Curve doesn't sound right, it's too bright, etc. It's not the target curve, it's the failure to match the measurement technique.


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## ousooner2

tyroneshoes said:


> Just curious,
> 
> How accurately have phone rta apps been when compared to m-audio/true rta and other methods?
> 
> I have surprisingly similar results using true rta and the droid app RTA Pro


Here is a good thread that someone just recently did. Used an Iphone4 w/ Studio Six and the mic/etc used in the first post

Portable RTA Setup - AcuraZine Community


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## tyroneshoes

much like my experiences. The smartphone RTA apps work surprisingly well.


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## avanti1960

pionkej said:


> If this thread does generate some discussion, I'd like to point out up front that this is just one helpful tool in the "game" of tuning. There are MANY other factors out there besides a target curve that need to be considered and I suggest people read up on them before aiming for this. Things like phase response, polar response, and power response all need to be considered.
> 
> There are many ways to get to the "finish line" and if you choose poorly you could end up with a "perfect curve" and system that sounds like crap.
> 
> For example, I could cross the 6.5" midbass in my door at 50hz and 5khz. I then boost the low end flat (and beyond xmax) to meet the sub and the top-end to flat (to compensate for beaming/off-axis response) to meet the tweeter. The graph may look nice, but I've introduced distortion from exceeding xmax (and may kill the speakers too) and created a terrible mismatch in power response (because the midbass is beaming and the tweeter is omin-directional).


OK, thanks for the info. How about a little more on how to best set up one's system so that RTA is more effective? Maybe choose your crossovers and slopes wisely, set the levels on your drivers to match the target curve as close as possible to avoid excessive EQ, avoid boosting levels and EQ bands so that you do not drive the amplifier into clipping, etc?


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## smellygas

Hey, guys, can we stay on topic here. The discussion is about target curves, not smartphone RTA's. There's a thread about that here:
http://www.diymobileaudio.com/forum...ussion/71240-rta-analyzer-droid-platform.html
Thanks.


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## avanti1960

Having spent many hours in my car over the past weeks with my new RTA toy this thread is very interesting and timely. 
I also researched the topic and found the JBL curve, house curve, etc. Basically the target curve is just a starting point. The important thing is to be consistent in your measuring as you develop and refine your own curve to your own liking. Here are some takeaways-
*Mic position averaging. I did this at first by averaging multiple mic positions. However to simplify the process I did find a single position that duplicated the "average" curve. I use this mic position every time I fine tune for an RTA curve. Basically it's ear level, dead center in the driver's seat facing directly forward. 
*Source. I use correlated pink noise full spectrum. Track 43 on the shefield lab disk. 
*Software settings. Find what works and keep them consistent. Your are attempting to reshape a curve over time based on tuning, listening over a few days, re-tuning etc. It's not so important the shape of the curve but that you create the curve in the same way each "session". This way you can understand the relationship to the visual curve and the sound you are experiencing. 
My first curve was way too bass heavy. I liked it at first but then had to re-tune it. Having the RTA available and using it the same way each time guarantees that I can go in and refine the bass part of the curve and possibly other frequency zones without affecting other areas- it is tuning with vision, not tuning blindly. You draw a line- if you don't like the sound, it's easy to reshape parts of the curve based on what you are hearing or not hearing. 

Here is my latest curve- it is kind of radical but I like it so far. I'll live with it for a week and see if it needs more work.

Another important factor is that too much EQ (even if there is no boosting) can sound very bad at times. I've made more of an attempt lately to adjust to a given curve by setting crossovers, slopes and levels to minimize the amount of EQ needed. This definitely improves the SQ of the results no matter the curve shape. 

-
One final comment- that crutchfeld curve article is registering high on my BS meter. With the way car interiors are these days it is highly doubtful they were able to achieve their resulting curve with only some aftermarket speakers and a receiver without advanced EQ or processing controls. 

Make a curve- listen over a few days and note what you like / don't like as it relates to the frequency octaves/ refine your curve by measuring the same exact way and by adjusting to those findings/ repeat as necessary / pray that some day you can put away the microphone and cables. peace.


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## pionkej

Smellygas-

I understand and appreciate your comments on how a curve isn't worth much without knowing how to get there. However, I would contest that it ISN'T nearly as confusing or difficult as you imply. I'd also contest that knowing how to properly achieve your target curve is more important than how you measure for it.

Let's look at it this way. If you dig deep though this forum, you'll find many people are happy with a tune that is "level" within +/-3db using 1/3oct smoothed resolution. The variance of the curves above look big because of the scale, but they are, in reality, all very close. In fact, outside of the two outliers (Audyssey & JBL) on the low-end (20-80hz) every curve is within 3db of the "average" I plotted. Even the outliers are only 4.5db out at that range. What does this mean? To me, it means that if you chose the average curve and accepted a +/-3db range mentioned above, you could satisfy nearly all of the curves.

Also, you mention directional mics...why? I don't think I have EVER seen anyone mention using a directional mic for measurements. That goes for pro audio, home audio, or car audio. So again...why? If you take that away, you are left with a omnidirectional mic and a binaural mic. If you use spatial averaging, neither will give you much difference in results. Ask Erin. Not to put him on the spot, be he bought binaurals and has gone back to using a single omni. From what I understand, it's because it's easier to use and when using spatial averaging, the results are NOT very different. If I'm wrong about that and there was a big difference, I'll eat my words and apologize.

So, on to where to measure and how to measure. Well, I vote for measuring at the listening position. This doesn't change for me, or most people that I know of, whether in the home or the car. You are right that the car is more reverberant than the home, and depending on how you measure (gated or ungated) it WILL affect what the final sound is. Fortunately, because of the size of the listening space, nothing below the treble range changes much anyway (see image below). In fact, with a 5msec gated test vs an ungated one, I have no difference in FR from below 10khz. Granted, there is a 15db difference between the two at 20khz, but odds are the only speaker affected is the tweeter, so it isn't like trying both options and seeing what you prefer would affect any tuning beyond said tweeter.

All of this brings me back to the fact that I, PERSONALLY, feel that measuring system response is the easy part. Getting to the target is the difficult part.


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## pionkej

bikinpunk said:


> I'm more interested in the curves provided and how they were obtained. Sure, knowing how to measure is important, but knowing how a given was measured is at least equally important and arguably moreso. That's one thing I really see. *And then when people try to lump in the equal loudness curve... *It's just nebulous to discuss it without knowing the procedures taken to arrive at any result.


Erin,

From all that I've read about the ELC lately, I feel there is ZERO need to factor it in IMHO. I know you already know this, but I thought it was a good time to share why since I feel I've read some good stuff on it lately. First off, it isn't accurate to material such as music. The ELC is based on people listening to individual pure tones and ranking them based on when they "equal" a 1khz tone in output. If anybody wants to know more about this part, go look at "A Weighted Curve" on wikipedia. Next, jcollin76 gave a useful link to "House Curves" from HTS. Here is a take on why tuning for a target curve doesn't degrade how the recording was mastered or why the ELC doesn't need to be incorporated. It is one man's opinion, but I felt there was enough logic behind it that I've jumped on board.

*Part Three
Answering house curve critics


Every theory in audio has its proponents and detractors. However, as we’ll see, room curve detractors typically don’t have a good understanding of what it is, nor of its function.


A house curve built into recordings?
One thought critical of house curves is based on a rather idealistic concept of the recording studio environment and exactly how it affects our program material. The following is from a house curve discussion thread a few years ago on another Forum:

”Consider a properly set up mixing booth in a studio. The mixing engineer is listening to either nearfield monitors or other speakers when he is laying out the final 'sound' of the music that is being mixed down to two (or more) channels. If the physical space and hardware has been designed properly (including the choice/location/EQ of the monitoring speakers), the frequency response at the mixing position should be flat from 20 Hz to 20 kHz. Neither the booth nor the mixing electronics should add or subtract from the sound on the master tape. If you wish for your home system to be accurate, it needs to be as flat as the one they used in the studio.”

Here’s the problem with this idea: If the mixing engineer’s monitoring system is as flat as all that, it will sound as bad to him as it does in your living room! There’s no way around it; a properly-tuned studio monitoring system will also have an appropriate house curve for the room it’s in. It has to. If not, the engineer is simply going to compensate with equalization. Good engineers know that their room and speakers of choice will affect their final mix. That’s why they usually demo it in different environments before they finalize it.

Another thought critical of house curves acknowledges and indeed embraces the fact that they come into play in the production stage. It holds that a room curve at home isn’t necessary because it’s built into the product’s final mix. Therefore – once again - we should set up our systems with response as flat as possible, otherwise nothing will sound right.

Nice idea, but as we’ve established, very few people actually think flat in-room response sounds good on their playback system. 

Furthermore, the question needs to be asked: which house curve are they using in that mixing studio – small room, large room, or something in between? As we saw in Part Two, room size matters tremendously, and once again this can’t be understated. After all, the engineer can reasonably expect that his CD will be played back in cars, dorm rooms and living rooms. What about the DJ spinning tunes in a huge hotel ballroom or at an outdoor event? What a dilemma: Which house curve is our hapless engineer supposed to “build in?” Obviously something fundamental is missing from the built-in curve theory: an industry standard.


A Fletcher-Munson house curve?
Other room curve skeptics base their doubts on the Fletcher-Munson curves, which show deficiencies in human hearing at the lowest and highest frequencies. They claim that studio engineers, being human themselves with the same auditory deficiencies, compensate for that in the recording process. The following was also presented on a discussion thread a few years ago:

“The engineer who mixed the material you are listening to has the same hearing response you do, that is less sensitive to lower bass frequencies. Do you think he would increase them to compensate? Of course he will.

“Now, enter a concept like a house curve to this equation. If your playback system has a curve attempting to compensate for a frequency response associated with human hearing, what do you think the results will be when you play back material that was mixed and prepared on a flat system? 

“Well, you'll be re-compensating, adding again the same compensation curve that the engineer added.”

This critic’s disapproval is fundamentally flawed because it’s based on the notion that a house curve is synonymous with the Fletcher-Munson curves. It isn’t. The Fletcher-Munson curves show how our perception of bass and treble frequencies change with variations in volume levels. That is a wholly separate phenomenon that has virtually nothing do with a house curve, other than the fact that it's best to calibrate your system at the volume level you use most. As we’ve thoroughly established, a house curve is compensation for the room, not the ear.

Along the same lines we have this complaint:

The problem with a "house curve" is that it's a static solution which only works at one playback volume. It may be inadequate at lower volumes, and it may be overly intrusive at higher playback volumes.

I have not found this to be the case at all. Calibrate your system and house curve for the level you normally listen and you’ll find that it will be adequate for most listening from that point, except perhaps for extreme level variations. With extreme changes from your normal settings you aren’t doing critical listening anyway – e.g. ultra-low levels for background music, or ultra high when you’re “showing off” the system's capabilities. In these instances, all that’s needed (if anything) is a simple level adjustment of the sub, not a total re-curving.

Read more: House curve: What it is, why you need it, how to do it! - Home Theater Forum and Systems - HomeTheaterShack.com 

*


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## pionkej

See my comments below:



avanti1960 said:


> *Mic position averaging. I did this at first by averaging multiple mic positions. However to simplify the process I did find a single position that duplicated the "average" curve. I use this mic position every time I fine tune for an RTA curve. Basically it's ear level, dead center in the driver's seat facing directly forward.
> 
> I wouldn't do this personally. It is stupid easy to take averages with TrueRTA (which I see you use) and it WILL be more representative of your system if you take averages. Just start measurement, stop, hit Alt+1, repeat for six measurements. Go to Utilities and average all six (I like to save as 20). I do all of this at 1/6 octave. After it's done, I go back to utilities smooth the response to 1/3 octave and evaluate from there.
> 
> Here is my latest curve- it is kind of radical but I like it so far. I'll live with it for a week and see if it needs more work.
> 
> Try what I said above about 1/3 smoothing and repost. You may find it isn't so radical.
> 
> Another important factor is that too much EQ (even if there is no boosting) can sound very bad at times. I've made more of an attempt lately to adjust to a given curve by setting crossovers, slopes and levels to minimize the amount of EQ needed. This definitely improves the SQ of the results no matter the curve shape.
> 
> Many times if you try and "fix" high Q peaks with EQ (like those found on 1/6 octave tuning), you can ruin the sound. It is another reason I prefer 1/3 octave smoothed. The only exception to this is when looking for modes (below around 300hz). There, I would use something like 1/24octave, a slow sine sweep, and peak hold settings. I haven't done this part yet, but I know others who have with success, I plan to do it myself on my next tune, and that's why I feel comfortable recommending it.
> 
> Make a curve- listen over a few days and note what you like / don't like as it relates to the frequency octaves/ refine your curve by measuring the same exact way and by adjusting to those findings/ repeat as necessary / pray that some day you can put away the microphone and cables. peace.
> 
> Pretty much truth here. Make sure when tuning you try and do it in small doses and you step back and evaluate. Some of my worst tunes came from sitting in the car too long at one time. I end up "fixing" things that were fine and I hate the sound the next day. So, take your time and make small adjustments, evaluate, and repeat until happy (if you're ever happy).


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## smellygas

pionkej said:


> Smellygas- Let's look at it this way. If you dig deep though this forum, you'll find many people are happy with a tune that is "level" within +/-3db using 1/3oct smoothed resolution.


Thank you for the thoughtful reply. My opinion is that +/-3dB at 1/3 oct smoothing, depending on where the peaks/valleys are, can sound okay to pretty bad. My personal goal is to get something close to what I can get from a reference home audio setup.



> The variance of the curves above look big because of the scale, but they are, in reality, all very close. In fact, outside of the two outliers (Audyssey & JBL) on the low-end (20-80hz) every curve is within 3db of the "average" I plotted.


Having done a lot of EQ for years, my experience is that much smaller corrections over smaller bandwidths can make BIG differences in sound quality. My perspective is that those curves are completely difference. Even a wide bandwidth boost/cut of +2dB over the treble can make a big difference in "brightness."



> Also, you mention directional mics...why? I don't think I have EVER seen anyone mention using a directional mic for measurements.


Keep in mind that even mics we call "omnidirectional" are actually quite directional. Take the ubiquitous ECM8000. It's polar response is not flat. Unless sound is a single point source (it's not due to reflections), you're going to have off-axis sound striking the ECM8000 and the mic's response will be different. So when you take that spatial average of sound striking the mic at all different angles, the curve you get is mic-dependent. 



> That goes for pro audio, home audio, or car audio. So again...why? If you take that away, you are left with a omnidirectional mic and a binaural mic.


You cannot use identical measurement techniques in home and car audio. Car audio, again, has a sound field consisting of direct/early-reflected sound at similar amplitude. Home audio is direct with lower-amplitude early+late-reflected sound. Perceived sound flatness varies based on the direction at which is strikes your outer ear. This is why I don't think the home audio curves are applicable to car. It's the same reason why headphones do not have a flat frequency response (because otherwise they would sound terrible). They are diffuse-field corrected because just like in car audio, the sound comes from the sides and all around, not primarily from the front of the listener. 



> If you use spatial averaging, neither will give you much difference in results. Ask Erin. Not to put him on the spot, be he bought binaurals and has gone back to using a single omni. From what I understand, it's because it's easier to use and when using spatial averaging, the results are NOT very different. If I'm wrong about that and there was a big difference, I'll eat my words and apologize.


I'd be interested i knowing why this person didn't prefer using binaurals. But my first question is, was he/she equalizing towards a curve that was specifically derived from binaural measurement to begin with? If not, I don't see how you can get good results. 



> So, on to where to measure and how to measure. Well, I vote for measuring at the listening position.


Of course, where else would you measure from?



> Fortunately, because of the size of the listening space, nothing below the treble range changes much anyway (see image below). In fact, with a 5msec gated test vs an ungated one, I have no difference in FR from below 10khz. Granted, there is a 15db difference between the two at 20khz, but odds are the only speaker affected is the tweeter, so it isn't like trying both options and seeing what you prefer would affect any tuning beyond said tweeter.


If you're referring to the car cabin environment, then yes, this is known already that gating makes no difference because reflected sound arrives very shortly after the direct sound (i.e. a diffuse field)



> All of this brings me back to the fact that I, PERSONALLY, feel that measuring system response is the easy part. Getting to the target is the difficult part.


There are many harmful ways to EQ to a target curve. And a target curve doesn't capture all the problems with your system, like high-Q high amplitude peaks in the midbass...can't see that with 1/3 octave


----------



## pionkej

See below:



smellygas said:


> Thank you for the thoughtful reply. My opinion is that +/-3dB at 1/3 oct smoothing, depending on where the peaks/valleys are, can sound okay to pretty bad. My personal goal is to get something close to what I can get from a reference home audio setup.
> 
> I agree that the +/-3db at 1/3 I mentioned can sound great to terrible. I find it pretty bold to say "okay" at best. Fact is, it is a good range to consider acceptable IMHO and many of the best sounding cars I've heard target it as such. That also doesn't mean there aren't problems that need to be fixed by using higher resolution or your ears. Spot treatments don't discredit a general +/-3db range of "acceptability".
> 
> Having done a lot of EQ for years, my experience is that much smaller corrections over smaller bandwidths can make BIG differences in sound quality. My perspective is that those curves are completely difference. Even a wide bandwidth boost/cut of +2dB over the treble can make a big difference in "brightness."
> 
> Again, you're right that a 2db change can make a difference. Hell, a .5db change can make a difference. Point is, I put up several different curves (yes, I agree they are different) that all have VERY similar trends. They are similar enough that if you chose the "average" response of them and accepted a +/-3db range, you could touch on almost all of them within the same tune. I didn't say that tune would sound good/great either, but I think it's worth noting since they LOOK to be very different when, in fact, they aren't.
> 
> Keep in mind that even mics we call "omnidirectional" are actually quite directional. Take the ubiquitous ECM8000. It's polar response is not flat. Unless sound is a single point source (it's not due to reflections), you're going to have off-axis sound striking the ECM8000 and the mic's response will be different. So when you take that spatial average of sound striking the mic at all different angles, the curve you get is mic-dependent.
> 
> I think you're clutching at straws here personally. I'm not saying that accuracy isn't important, and I certainly think you should have a calibrated mic, BUT to imply that using the ECM8000 is worthless because of polar response issues is a bit misleading too. Take 6, or more, measurements and average them and I promise it's going to paint a pretty good picture of what your system is doing. Again, I'm not trying to be a jerk with the "clutching straws" comment, but your posts seem to be awfully "doom and gloom" towards generally accepted methods of tuning while sharing very little on what you think is the proper way to measure. It just contributes very little and I feel that if somebody wants to challenge what is being shared here, having a valid response with support is required.
> 
> You cannot use identical measurement techniques in home and car audio. Car audio, again, has a sound field consisting of direct/early-reflected sound at similar amplitude. Home audio is direct with lower-amplitude early+late-reflected sound. Perceived sound flatness varies based on the direction at which is strikes your outer ear. This is why I don't think the home audio curves are applicable to car. It's the same reason why headphones do not have a flat frequency response (because otherwise they would sound terrible). They are diffuse-field corrected because just like in car audio, the sound comes from the sides and all around, not primarily from the front of the listener.
> 
> I don't really have anything to back up my disagreement here other than the fact that the curves above are similar. The "JBL Curve" comes from Andy W. and is recommended for cars. So is the "Crutchfield Curve". Neither are that different than the other "home curves" I've included. I understand you feel differently, but as it stands, you have not shared any suggestions and so I'll stick with what I've got in front of me.
> 
> I'd be interested i knowing why this person didn't prefer using binaurals. But my first question is, was he/she equalizing towards a curve that was specifically derived from binaural measurement to begin with? If not, I don't see how you can get good results.
> 
> They are a member here. In fact, they have already commented in this thread. If they feel like sharing more, they can. Anything beyond what I've already said would be purely speculation. All I do know is they had the means and have moved back to a single omni with spatial averaging.
> 
> Of course, where else would you measure from?
> 
> I'm not sure. I was thinking you might have implied we should measure right at the speaker to avoid reflections, which is not an accurate picture of the sounds that reach your ears.
> 
> If you're referring to the car cabin environment, then yes, this is known already that gating makes no difference because reflected sound arrives very shortly after the direct sound (i.e. a diffuse field)
> 
> Actually it does make a large difference in the treble (which I believe I just showed). What I'm saying is that you have no way of separating the reflections below that point and therefore they are included in the response. So you tune with them included. Now if you have an adjusted target response for the car, I'm all ears. Right now, you're still playing like you hold all the keys, but you're holding them all above our heads.
> 
> There are many harmful ways to EQ to a target curve. And a target curve doesn't capture all the problems with your system, like high-Q high amplitude peaks in the midbass...can't see that with 1/3 octave
> 
> You're right again, but I actually just shared how to look for modes (the high Q peaks you speak of) in another reply. It's funny how we both know the answers, but only one of us seems willing to help others by sharing them.


For now, I'm done with this thread. I simply started it to share some information I had recently acquired doing some searching of the web. I felt it was better than the typical "what midbass/sub should I use" threads that pop up daily. It seems that instead my sharing is being challenged by a person who knows a bunch and shares very little. The point of this forum, to me, is to share and dispel dogma...if it isn't happening...I'm not interested.


----------



## smellygas

pionkej said:


> See below:
> 
> 
> 
> For now, I'm done with this thread. I simply started it to share some information I had recently acquired doing some searching of the web. I felt it was better than the typical "what midbass/sub should I use" threads that pop up daily. It seems that instead my sharing is being challenged by a person who knows a bunch and shares very little. The point of this forum, to me, is to share and dispel dogma...if it isn't happening...I'm not interested.


I was done with this thread when I received 2 personal attacks (deleted by a mod) when I simply requested that people not talk about their smartphone RTA's here. 

I'm flattered that you think I know the answers. I don't. That's why I'm trying to ask questions that usually don't get asked in the bimonthly target curve thread. Obviously that's not acceptable. So never mind. Everyone appreciates your efforts in compiling the different target curves. Clearly, nobody appreciates me pointing out that the curves are not reproducible without duplicating or accounting for the way the target curve was measured. 

And hey, maybe I'm completely wrong! But explain how I can measure my car's FR with an ECM8000 and with binaural mics and obtain completely different curves (and both are almost completely flat on-axis 20-20k). Even 2 different ECM8000's won't measure the same without calibration. But hey, never mind, let's just talk about the normal stuff we talk about in these threads. By all means. 

There are people out there who've determined a "preferred" freq resp curve using a reference car stereo system and have generated a target curve using their measurement technique. For instance, any company with a DSP cabin response correction feature (like the MS-8, Alpine's Imprint, and the Audissey solution for car) knows...they just haven't published it AFAIK in JAES, and it remains somewhat proprietary. (Interesting, the Harman Group HAS published the "target curve" of home loudspeakers including their measurement technique). Andy has published his target curve for cars, but I'd be curious how to duplicate his results - i.e. if I EQ to that curve, what measurement equipment would I use? binaural mics, spatially averaged? Standard dummy head with binaural mics? Spatially averaged omnidirectional mic? 

I obviously offended some people, and my contributions are not appreciated, so cya later. Perhaps someone who knows the answer can chime in so we can stop having these repetitive target curve threads.


----------



## 14642

OK...here goes.

I arrived at my target curve after years of using it to make customers smile. What's clear (and some of our guys are now doing some work to determine the best target curve for a broad range of listeners) is that the shape is correct. The AMOUNT of boost at low frequencies is subjective. The width of the transition band (I use 60-160) is also subjective (as the midbass freaks here will attest) and the amount of high frequency attenuation is also subjective. Three knobs that adjusted those three things would make great bass midrange and treble controls. 

The suggestion that a gated measurement should be used at high frequencies is valid in a large room, but invalid in a small reflective room. Fortunately, that part of the curve is the least objectionable if it isn't exactly right, so it doesn't really matter. 

No bass boost is also invalid in a small environment and especially in one where ambient noise is concentrated at low frequencies.


----------



## avanti1960

Andy Wehmeyer said:


> OK...here goes.
> 
> I arrived at my target curve after years of using it to make customers smile. What's clear (and some of our guys are now doing some work to determine the best target curve for a broad range of listeners) is that the shape is correct. The AMOUNT of boost at low frequencies is subjective. The width of the transition band (I use 60-160) is also subjective (as the midbass freaks here will attest) and the amount of high frequency attenuation is also subjective. Three knobs that adjusted those three things would make great bass midrange and treble controls.


Thanks for your contributions. The detailed write-ups about MS-8 mentioned the target curve and helped me in defining mine in my vehicle. 
I believe the subjectivity part of the equation is influenced by personal preference but also by having to adjust for variables in recordings, music type and vehicle speed. 
If there were a system that could maintain one's "curve" (more or less) by real time compensation for recording mix, road speed and volume level it would be very desirable. Or at the very least, give one an easy means to manually compensate. 
In my area we have high speed highways and long stretches of stop and go driving. Leaving the "curve" alone would result in extreme bass at a stoplight and a weak thin sound at highway speeds. 
On the fly manual compensation and adjustment is something I just cannot escape from and it is not user friendly on a head unit with multiple menu layers and selections. 
The OEMs have done a service by providing easy access tone adjustment. I wish my head unit had it (although now I am prompted to use the stored EQ memory presets, it's just a lot of work).


----------



## james2266

Andy Wehmeyer said:


> OK...here goes.
> 
> I arrived at my target curve after years of using it to make customers smile. What's clear (and some of our guys are now doing some work to determine the best target curve for a broad range of listeners) is that the shape is correct. The AMOUNT of boost at low frequencies is subjective. The width of the transition band (I use 60-160) is also subjective (as the midbass freaks here will attest) and the amount of high frequency attenuation is also subjective. Three knobs that adjusted those three things would make great bass midrange and treble controls.





avanti1960 said:


> Thanks for your contributions. The detailed write-ups about MS-8 mentioned the target curve and helped me in defining mine in my vehicle.
> I believe the subjectivity part of the equation is influenced by personal preference but also by having to adjust for variables in recordings, music type and vehicle speed.
> If there were a system that could maintain one's "curve" (more or less) by real time compensation for recording mix, road speed and volume level it would be very desirable. Or at the very least, give one an easy means to manually compensate.
> In my area we have high speed highways and long stretches of stop and go driving. Leaving the "curve" alone would result in extreme bass at a stoplight and a weak thin sound at highway speeds.
> On the fly manual compensation and adjustment is something I just cannot escape from and it is not user friendly on a head unit with multiple menu layers and selections.
> The OEMs have done a service by providing easy access tone adjustment. I wish my head unit had it (although now I am prompted to use the stored EQ memory presets, it's just a lot of work).



First, I'd like to also thank Andy W. for stepping in a bit here and hopefully keep this thread useful. I, too, use your 'curve' as my base curve. You see I am one of those mid-bass freaks you talk about:laugh: so, I have mine increasing ever so slightly starting around 350 Hz or so. I have also talked to Avanti recently on his measuring techniques amongst other things as we have the same vehicle. I don't know if I mentioned it but this vehicle is a prime example of one that needs a serious dose of sound deadening. If you have not yet, I wouold invest in about 100 ft2 of mlv and ccf and line that floor and sides up to the windows at least. You will notice a massive difference in that annoyance on the highways. I know I sure did. I got rid of about 30% of the up front wind noise too by lining the inside of my a-pillars with ccf when I had them off too. I need to do the b pillars (between the main doors) now. Don was so truthful in saying that noise is like water it just seems to find the weakspot and seep through.


----------



## smellygas

Andy Wehmeyer said:


> OK...here goes.
> 
> I arrived at my target curve after years of using it to make customers smile. What's clear (and some of our guys are now doing some work to determine the best target curve for a broad range of listeners) is that the shape is correct. The AMOUNT of boost at low frequencies is subjective. The width of the transition band (I use 60-160) is also subjective (as the midbass freaks here will attest) and the amount of high frequency attenuation is also subjective. Three knobs that adjusted those three things would make great bass midrange and treble controls.


Thank you for sharing details of your target curve, Andy. So, I guess the next question is, what measurement technique can we use so that we can reproduce your ideal curve? (or at least come close before adjusting the width of the transition band and the HF attenuation)


----------



## subwoofery

smellygas said:


> Thank you for sharing details of your target curve, Andy. So, I guess the next question is, what measurement technique can we use so that we can reproduce your ideal curve? (or at least come close before adjusting the width of the transition band and the HF attenuation)


(binaural mic) Look straight forward, select _Go_, look pass the driver's side mirror, select _Go_, look @ the passenger's side mirror, select _Go_, select _done_  

Kelvin


----------



## Martin

Hey there,

very nice thread!

The target response I use is very similar to Andys. 

(Measured with driver in seat with spacial averaging close to both ears, omnidirectional mic)

It is flat from 20Hz to 50Hz (+10dB), falls steep to 70Hz (0dB), then flat to 600Hz, then falls off to 20kHz (-6dB)

I measured my subwoofer in near-field and at the drivers seat to determine the cars transfer function.



The high frequency attenuation I derived from this picture:



When measuring directly at the ears the signal at the contralateral ear is attenuated by a few decibels. So the sum of both sides must be attenuated to.

My left side speakers are at -25° on the horizontal plane, the right side speakers are at +60°. This leads to about 6dB attenuation at 20kHz.

The thing i do not understand excactly is how to determine the level of the midrange. It seems to be at +10dB, because if i add the woofers response up from the 0dB level (270Hz, full 20db peak from 40Hz down) the bass sounds definitely to loud.
Maybe that's caused by the power response in the cars small cabin, where you do no only hear the on axis sound, but the on axis sound AND all reflections together. It seems the "normal level" IS already at +10dB?!

Martin


----------



## james2266

Martin said:


> Hey there,
> 
> very nice thread!
> 
> The target response I use is very similar to Andys.
> 
> (Measured with driver in seat with spacial averaging close to both ears, omnidirectional mic)
> 
> It is flat from 20Hz to 50Hz (+10dB), falls steep to 70Hz (0dB), then flat to 600Hz, then falls off to 20kHz (-6dB)
> 
> I measured my subwoofer in near-field and at the drivers seat to determine the cars transfer function.
> 
> 
> 
> The high frequency attenuation I derived from this picture:
> 
> 
> 
> When measuring directly at the ears the signal at the contralateral ear is attenuated by a few decibels. So the sum of both sides must be attenuated to.
> 
> My left side speakers are at -25° on the horizontal plane, the right side speakers are at +60°. This leads to about 6dB attenuation at 20kHz.
> 
> The thing i do not understand excactly is how to determine the level of the midrange. It seems to be at +10dB, because if i add the woofers response up from the 0dB level (270Hz, full 20db peak from 40Hz down) the bass sounds definitely to loud.
> Maybe that's caused by the power response in the cars small cabin, where you do no only hear the on axis sound, but the on axis sound AND all reflections together. It seems the "normal level" IS already at +10dB?!
> 
> Martin


Cool graphs and I like the way you came up with the car's transfer function.


----------



## MarkZ

pionkej said:


> Erin,
> 
> From all that I've read about the ELC lately, I feel there is ZERO need to factor it in IMHO. I know you already know this, but I thought it was a good time to share why since I feel I've read some good stuff on it lately. First off, it isn't accurate to material such as music. The ELC is based on people listening to individual pure tones and ranking them based on when they "equal" a 1khz tone in output. If anybody wants to know more about this part, go look at "A Weighted Curve" on wikipedia. Next, jcollin76 gave a useful link to "House Curves" from HTS. Here is a take on why tuning for a target curve doesn't degrade how the recording was mastered or why the ELC doesn't need to be incorporated. It is one man's opinion, but I felt there was enough logic behind it that I've jumped on board.
> 
> *Part Three
> Answering house curve critics
> 
> 
> Every theory in audio has its proponents and detractors. However, as we’ll see, room curve detractors typically don’t have a good understanding of what it is, nor of its function.
> 
> 
> A house curve built into recordings?
> One thought critical of house curves is based on a rather idealistic concept of the recording studio environment and exactly how it affects our program material. The following is from a house curve discussion thread a few years ago on another Forum:
> 
> ”Consider a properly set up mixing booth in a studio. The mixing engineer is listening to either nearfield monitors or other speakers when he is laying out the final 'sound' of the music that is being mixed down to two (or more) channels. If the physical space and hardware has been designed properly (including the choice/location/EQ of the monitoring speakers), the frequency response at the mixing position should be flat from 20 Hz to 20 kHz. Neither the booth nor the mixing electronics should add or subtract from the sound on the master tape. If you wish for your home system to be accurate, it needs to be as flat as the one they used in the studio.”
> 
> Here’s the problem with this idea: If the mixing engineer’s monitoring system is as flat as all that, it will sound as bad to him as it does in your living room! There’s no way around it; a properly-tuned studio monitoring system will also have an appropriate house curve for the room it’s in. It has to. If not, the engineer is simply going to compensate with equalization. Good engineers know that their room and speakers of choice will affect their final mix. That’s why they usually demo it in different environments before they finalize it.
> 
> Another thought critical of house curves acknowledges and indeed embraces the fact that they come into play in the production stage. It holds that a room curve at home isn’t necessary because it’s built into the product’s final mix. Therefore – once again - we should set up our systems with response as flat as possible, otherwise nothing will sound right.
> 
> Nice idea, but as we’ve established, very few people actually think flat in-room response sounds good on their playback system.
> 
> Furthermore, the question needs to be asked: which house curve are they using in that mixing studio – small room, large room, or something in between? As we saw in Part Two, room size matters tremendously, and once again this can’t be understated. After all, the engineer can reasonably expect that his CD will be played back in cars, dorm rooms and living rooms. What about the DJ spinning tunes in a huge hotel ballroom or at an outdoor event? What a dilemma: Which house curve is our hapless engineer supposed to “build in?” Obviously something fundamental is missing from the built-in curve theory: an industry standard.
> 
> 
> A Fletcher-Munson house curve?
> Other room curve skeptics base their doubts on the Fletcher-Munson curves, which show deficiencies in human hearing at the lowest and highest frequencies. They claim that studio engineers, being human themselves with the same auditory deficiencies, compensate for that in the recording process. The following was also presented on a discussion thread a few years ago:
> 
> “The engineer who mixed the material you are listening to has the same hearing response you do, that is less sensitive to lower bass frequencies. Do you think he would increase them to compensate? Of course he will.
> 
> “Now, enter a concept like a house curve to this equation. If your playback system has a curve attempting to compensate for a frequency response associated with human hearing, what do you think the results will be when you play back material that was mixed and prepared on a flat system?
> 
> “Well, you'll be re-compensating, adding again the same compensation curve that the engineer added.”
> 
> This critic’s disapproval is fundamentally flawed because it’s based on the notion that a house curve is synonymous with the Fletcher-Munson curves. It isn’t. The Fletcher-Munson curves show how our perception of bass and treble frequencies change with variations in volume levels. That is a wholly separate phenomenon that has virtually nothing do with a house curve, other than the fact that it's best to calibrate your system at the volume level you use most. As we’ve thoroughly established, a house curve is compensation for the room, not the ear.
> 
> Along the same lines we have this complaint:
> 
> The problem with a "house curve" is that it's a static solution which only works at one playback volume. It may be inadequate at lower volumes, and it may be overly intrusive at higher playback volumes.
> 
> I have not found this to be the case at all. Calibrate your system and house curve for the level you normally listen and you’ll find that it will be adequate for most listening from that point, except perhaps for extreme level variations. With extreme changes from your normal settings you aren’t doing critical listening anyway – e.g. ultra-low levels for background music, or ultra high when you’re “showing off” the system's capabilities. In these instances, all that’s needed (if anything) is a simple level adjustment of the sub, not a total re-curving.
> 
> Read more: House curve: What it is, why you need it, how to do it! - Home Theater Forum and Systems - HomeTheaterShack.com
> 
> *


The part in blue is garbage. :/


----------



## subwoofery

MarkZ said:


> The part in blue is garbage. :/


Please explain why you feel that way... 

Kelvin


----------



## MarkZ

Andy Wehmeyer said:


> Three knobs that adjusted those three things would make great bass midrange and treble controls.


I like that you included this line.

My view, which I understand is pretty unpopular around these parts, is that a single curve will not make you happy unless you're trying to reproduce a relatively small cherry-picked selection of music. This drives perfectionists nuts, as it should.

Different engineers and artists do things differently from one another. Sometimes intentionally, sometimes not. But regardless, if your interest is music and not just audio systems, then one of your goals should be to reproduce a wide selection of music independently of how the engineers recorded those pieces of music. And this is why what you say rings true: it's not just about using the tools a single time to achieve a particular curve, but rather, it's about the accessibility you have to those tools during playback. _That requires that you identify the most important tools in your tool chest, or create more powerful tools using lumped signal processing routines._

IMO, more important than achieving a target curve is achieving balance, a reasonable image, and reducing discontinuities and odd behaviors in your response. Those are things you're probably not going to change during playback. But this makes the properties of the "target curve" pretty uninteresting to me. What I'm more interested in are the properties of the _differences_ between the curves required for playback of different musical selections.

In my personal (and admittedly far from perfect) implementation of this, I've found that it's important to have ready access to:

* two bass bands ("sub" bass <50Hz, and overall bass level < ~200Hz)
* tweeter level 
* center level relative to L & R
* midbass "bloat" (which is a broad bandwidth boost or attenuation in the ~150-500Hz area) 

90% of the manipulations that I feel are necessary during playback can be accommodated by these four controls, that I have readily accessible in the VST plugins that I use. This probably satisfies the variations I find in the music that I, personally, tend to listen to. And it also allows me to mimic some of the tonality that I've experienced in live settings for different musical genres, which can be very different.

Edit: I should also point out that when I used delayed bandlimited rear fill (L-R), I found that the optimal level varied quite a bit based on recording as well. There were many recordings where I turned it off altogether.


----------



## smellygas

MarkZ said:


> I like that you included this line.
> 
> My view, which I understand is pretty unpopular around these parts, is that a single curve will not make you happy unless you're trying to reproduce a relatively small cherry-picked selection of music. This drives perfectionists nuts, as it should.
> 
> Different engineers and artists do things differently from one another. Sometimes intentionally, sometimes not. But regardless, if your interest is music and not just audio systems, then one of your goals should be to reproduce a wide selection of music independently of how the engineers recorded those pieces of music. And this is why what you say rings true: it's not just about using the tools a single time to achieve a particular curve, but rather, it's about the accessibility you have to those tools during playback. _That requires that you identify the most important tools in your tool chest, or create more powerful tools using lumped signal processing routines._
> 
> IMO, more important than achieving a target curve is achieving balance, a reasonable image, and reducing discontinuities and odd behaviors in your response. Those are things you're probably not going to change during playback. But this makes the properties of the "target curve" pretty uninteresting to me. What I'm more interested in are the properties of the _differences_ between the curves required for playback of different musical selections.
> 
> In my personal (and admittedly far from perfect) implementation of this, I've found that it's important to have ready access to:
> 
> * two bass bands ("sub" bass <50Hz, and overall bass level < ~200Hz)
> * tweeter level
> * center level relative to L & R
> * midbass "bloat" (which is a broad bandwidth boost or attenuation in the ~150-500Hz area)
> 
> 90% of the manipulations that I feel are necessary during playback can be accommodated by these four controls, that I have readily accessible in the VST plugins that I use. This probably satisfies the variations I find in the music that I, personally, tend to listen to. And it also allows me to mimic some of the tonality that I've experienced in live settings for different musical genres, which can be very different.
> 
> Edit: I should also point out that when I used delayed bandlimited rear fill (L-R), I found that the optimal level varied quite a bit based on recording as well. There were many recordings where I turned it off altogether.


Interesting. My only comment is that in home audio, if you have a reference-quality system that is set up properly, nearly all good recordings will sound fantastic without having to change around your bass and tweeter tone controls for each song. I'm not sure why you think that's necessary in car audio. 

In fact, what I've found was that when my car equalization curve wasn't optimal, that's when I started to notice that certain musical recordings sounded better than others. That's because certain musical recordings, based on their frequency content, accentuate the EQ problems with my system more than others. I know that changes to me EQ "target curve" are beneficial when more of the songs in my collection sound "right." 

Now, as predicted, this thread still hasn't been able to provide us with a complete target curve based on a reference car stereo system (or based on based on formal listener preference tests or perhaps extensive experience) AND a measurement methodology that can be used to reproduce the curve.


----------



## MarkZ

smellygas said:


> Interesting. My only comment is that in home audio, if you have a reference-quality system that is set up properly, nearly all good recordings will sound fantastic without having to change around your bass and tweeter tone controls for each song. I'm not sure why you think that's necessary in car audio.
> 
> In fact, what I've found was that when my car equalization curve wasn't optimal, that's when I started to notice that certain musical recordings sounded better than others. That's because certain musical recordings, based on their frequency content, accentuate the EQ problems with my system more than others. I know that changes to me EQ "target curve" are beneficial when more of the songs in my collection sound "right."
> 
> Now, as predicted, this thread still hasn't been able to provide us with a complete target curve based on a reference car stereo system (or based on based on formal listener preference tests or perhaps extensive experience) AND a measurement methodology that can be used to reproduce the curve.


You're of course correct that a poorly calibrated system will sometimes be more sensitive to differences between program material. But there are differences that are specific to the program material itself. This should be obvious to anyone who listens to 90s era gangsta rap, follows it up with folk music, and then proceeds to listen to modern shoegaze at deafening levels. There are characteristics to genres, artists, and even record labels that are fairly stereotypical. Whether this comes from trends in the engineers typically chosen within genres; or something more intrinsic to the genre itself is definitely a debatable topic. But, regardless of its cause, it's there.

You're one of many who don't seem to want to acknowledge that. Instead, you qualify it by using the term "good recordings", as though any recordings that don't fit a very particular template are "bad recordings". This reasoning is circular.


----------



## smellygas

MarkZ said:


> You're of course correct that a poorly calibrated system will sometimes be more sensitive to differences between program material. But there are differences that are specific to the program material itself. This should be obvious to anyone who listens to 90s era gangsta rap, follows it up with folk music, and then proceeds to listen to modern shoegaze at deafening levels. There are characteristics to genres, artists, and even record labels that are fairly stereotypical. Whether this comes from trends in the engineers typically chosen within genres; or something more intrinsic to the genre itself is definitely a debatable topic. But, regardless of its cause, it's there.
> 
> You're one of many who don't seem to want to acknowledge that. Instead, you qualify it by using the term "good recordings", as though any recordings that don't fit a very particular template are "bad recordings". This reasoning is circular.


Oh well let me clarify then. Obviously there are differences among recordings - i.e. ambience, mixing, compression, etc. That's common knowledge. But in my experience, almost all tracks will sound fantastic on a reference-quality home stereo. And I'm including 80's, 90's, pop, dance/trance, top40, whatever. Even if a recording has have over-boosted bass and there's some clipping distortion, they all sound excellent on such a stereo system. On the other hand, when you're playing various music back on a car stereo, where EQ curves are not optimized and in need of tuning, I find that many of these same tracks sound just terrible. Sure, there are "bad recording" with noise, hiss, major clipping distortion, highs rolled off or overboosted, whatever - I'm not talking about those. I'm talking about 90-95% of the major recording studio releases out there. 

Think about it - is it common for people to sit and adjust 3-4 tone controls on their $20,000 home stereos for each track that gets played? NO. And the reason is the frequency response curve of high-end speakers, properly positioned in a room, is optimal for most of the recordings out there.


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## MarkZ

That doesn't make any sense. For the example that you provided of a recording that has "over-boosted bass", wouldn't it make sense to reduce the amount of bass during playback? If not, then what exactly do you mean by "over-boosted"?

I can't tell you why people with very expensive home audio systems don't adjust tone controls. In my experience, it might be because they're notorious for trying to fit square pegs into round holes, sometimes even throwing the square pegs into the garbage can labeling them "bad recordings". I guess I don't consider the home audio crowd -- the ones that spend hundreds of thousands of dollars on audio equipment to listen to a limited selection of recordings confined to a tiny spot in the room -- the group that everybody should mimic.


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## smellygas

MarkZ said:


> That doesn't make any sense. For the example that you provided of a recording that has "over-boosted bass", wouldn't it make sense to reduce the amount of bass during playback? If not, then what exactly do you mean by "over-boosted"?
> 
> I can't tell you why people with very expensive home audio systems don't adjust tone controls. In my experience, it might be because they're notorious for trying to fit square pegs into round holes, sometimes even throwing the square pegs into the garbage can labeling them "bad recordings". I guess I don't consider the home audio crowd -- the ones that spend hundreds of thousands of dollars on audio equipment to listen to a limited selection of recordings confined to a tiny spot in the room -- the group that everybody should mimic.


Okay so to make sure I understand, you believe that tone controls should be adjusted individually while listening to each song because you think each recording engineer is incompetent, and you have absolutely no appreciation for home audio, or rather, your criticism is more of the prototypical opinions of certain home audio ppl with 100k systems who criticize recordings (which does not describe me). 

We are so far apart on perspective, I don't see any point in continuing this discussion. So, YOU'RE RIGHT ABOUT EVERYTHING. I take back everything I said. I agree that all recording engineers are morons and we should re-equalize all tracks to match our perfect car stereo systems (because god forbid your imperfect target curve is actually making some recordings sound worse than others), and your car stereo sounds way better than even a modest home audio set up. There. Happy? End of discussion. 

Now let's see if we can talk about target curves again.


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## MarkZ

smellygas said:


> Okay so to make sure I understand, you believe that tone controls should be adjusted individually while listening to each song because you think each recording engineer is incompetent, and you have absolutely no appreciation for home audio, or rather, your criticism is more of the prototypical opinions of certain home audio ppl with 100k systems who criticize recordings (which does not describe me).
> 
> We are so far apart on perspective, I don't see any point in continuing this discussion. So, YOU'RE RIGHT ABOUT EVERYTHING. I take back everything I said. I agree that all recording engineers are morons and we should re-equalize all tracks to match our perfect car stereo systems (because god forbid your imperfect target curve is actually making some recordings sound worse than others), and your car stereo sounds way better than even a modest home audio set up. There. Happy? End of discussion.
> 
> Now let's see if we can talk about target curves again.


You really seem to have a pretty big problem when it comes to people challenging your assertions. You did it with pionkej, and even promised to leave the thread, and now you're playing the same card with me. How many times are you going to say you're done with a topic before you _actually_ leave? Because that's pretty annoying.

Now, if you can put the condescension away, and consider other possibilities aside from me being incompetent, then please read on.

I never said that anyone's a moron. I don't know where you got this.  I said that artists and engineers do things differently from one another. They're not all cut from the same cloth. Therefore, to achieve your particular goal for _re_production, you need to take into account the differences in production. *By virtue of admitting that there is such a thing as a "target curve", and that it tends to deviate from flat, everybody in this thread is actually acknowledging that this is true.* Since the aggregate target curve (however you want to measure it...) has a particular characteristic, then this implies that there's a bias (ie. error) in the way engineers tend to record music. This doesn't mean they're incompetent and it doesn't mean they're morons. It means that their goals -- whatever they may be -- are different from the goals of the group with the non-flat "target curves"... _us_. We can hand-wave all day long about why that is. That's exactly what pionkej's long quote in blue is doing, actually. But I don't think that discussion is very relevant for the end user.

Anyway, so we have a target curve based on a transfer function that _transforms_ the signal into something that you find more palatable. But you reject all other transformations, making the claim that program material that requires a different transformation to achieve the same subjective standard must be a "bad recording". That appears to be the main point where we differ. It's also the point where you're using circular logic. You're suggesting that a recording is intrinsically good or bad based on whether or not it can be transformed to your liking with an _arbitrary_ transfer function. You're justifying the EQ curve with the "goodness" of the recording, even though the "goodness" of the recording is determined by the EQ curve! See the circular reasoning?

Let me give you an example. Suppose you consider a certain recording to be "high quality". You achieve your "target curve" by boosting 500Hz by 3dB (at a given Q, bw, etc). And you find that a lot of other albums in your collection are also similarly improved by boosting 500Hz by the same amount. Suppose, then, that the record company releases a "remastered" version of that high quality album, where the only change is that they boost 500Hz by 3dB. You could therefore achieve the _same output_ by changing your EQ settings to account for the fact that they already boosted 500Hz. In this example, you would argue that this recording is a "bad recording" because you have to individually account for this change, despite the fact that a simple correction can be applied to achieve the exact same end result.


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## ErinH

I think the entire argument can be easily resolved by determining goals which come down to two options: 
Reference or preference. 

Neither is bad. Just know what your goal is and go from there. 

If you're trying to achieve a reference playback system then any change to a spec curve (whatever that is determined to be; see: anechoic measurements and the whole logic of signal in = signal out) is then altering the original recording in the way it was out on the CD by the engineer(s). 
Everything else is pure preference. You're altering the recording to fit your tastes. That's not true to the cd. I think we all understand this. 

So, is your goal reference - where you make futile efforts to achieve outputting and hearing (two solely different tasks) what is only on the disc? Or is the goal to have the ability to tweak the sound system to your liking? NOTE: Some may focus on the "to your liking" portion, though, I find that a single curve really has done a great job at pleasing my tastes - no matter the source material - as I continue to try to understand how to achieve a one curve fits all solution much like an attempt at a system that does not alter the output. Tuning on the fly, or to the ELC*, is a preference (unless someone has been able to correlate ELC to a proper** curve which I've not yet seen). 

I know that leaves a very wide gap but ultimately this thread was started to discuss what that "reference curve" is and how it's achieved and how we can get closer to it. The first part is understanding it. That's the incredibly hard part. Luckily the concept of achieving an unaltered signal from the source is extremely easy to grasp. In a signal world it's input equals output. Period. But in the acoustic world everything gets altered due to (mainly) environment and speakers. 


*don't forget the ELCs are dynamic. People often act as if it's static. It changes with volume and, thus, for one to rightfully claim it as a curve, it should really be dynamic by changing form with volume a la audyssey's dynamic EQ. 
Also, keep in mind I was once a huge proponent of this method and no longer am. The reason is simple: if I hear a sound, I hear it the same way, whether it be recorded or live. If the playback system can accurately mimic the real sound, adjusting it to mimic the ELC only alters it and they no longer sound the same. ELC is only a way to quantify human hearing thresholds and IMO should not be used to adjust an EQ. 

**again, whatever "proper" is. Which is the subject of this thread. 


Sent from my iPhone. Pardon the grammar.


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## smellygas

MarkZ said:


> *By virtue of admitting that there is such a thing as a "target curve", and that it tends to deviate from flat, everybody in this thread is actually acknowledging that this is true.*


Yeah, you're not getting it. The reason there is a "target curve" in a car is because the car environment exists as a diffuse soundfield vs. the free-field in a listening room. Therefore, in order for the frequency response in a car to be perceived as flat/neutral, you need to correct the EQ curve to compensate for the DIFFUSE FIELD that exists. Did you know that headphones also have what is essentially a "target curve?" That's because they, too, require diffuse field equalization because...they reproduce sound in a diffuse field. 

The problem we have in car audio, is many people use measurement techniques designed for the free field. With the exception of binaural mics, they don't account for the various angle of incidence that the sound strikes the ear. And so that's why you get all sorts of different supposed "target curves" that supposedly are trying to describe the exact same most-pleasing cabin response. 

Guess what. In home audio, the concept of the best FR curve, measured using a reproducible technique and listening room, has already been validated. It's not arbitrary. They took a large group of blinded listeners, sat them down in front of various loudspeakers and played various types of recordings. The loudspeakers that consistently sounded the best all tended to have very similar FR curve characteristics. It's published in JAES, a peer-reviewed engineering journal (as opposed to the opinion of an internet forum user who likes his tone controls). Again, this is why you can take high-quality loudspeakers, stick them in your living room, and almost all recordings sound fantastic, regardless of what free-reign the audio engineer used when mixing the track.


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## pionkej

Erin hit the nail on the head, the purpose of this thread was to show that there is a prevailing "trend" among people as to what a PREFERRED system playback is. No matter where the transition, it appears boosted on the low end, transitions to flat, and then rolls-off at the top. The fact that they fall so close to each other was the most surprising part to me. Please note that this DOESN'T mean that a 3db or 5db or etc. doesn't matter, but I felt as I was looking and writing these curves down there was a prevailing similarity that I wanted to graph and overlay. 

I'll also say that I totally understand where Mark is coming from. He admitted that he aims for "flat" response and that it isn't the prevailing popular choice (which I believe is evident between seeing/hearing members tunes and finding these various house curves), HOWEVER, I also see where is coming from with having the ability to ajust certain parameters to ones taste and to the current song playing. I would actually venture to say that in a very basic form, many people do this already. I do. I tune to my generally preferred response and I, like Erin, want to have a solution that leaves pretty much every song enjoyable without having to make adjustments all the time. HOWEVER, I also use my remote gain knob when I want things a little more or less bass heavy. The funny thing is, this also adjusts the transition point from midbass to subs, so I'm pretty much altering the bottom end of my target response curve. I have a mark to know how to get back "home" and I tweak on the fly from there.


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## jcollin76

@smellygas:
Then why don't you go to a forum, or section of this forum, geared for home audio... beings all your examples and proof are in that realm.

It seems your goals are different from the goals of others in this thread. I'm all for discussion and learning, but your killing this thread by being argumentative and arrogant.


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## pionkej

smellygas said:


> Yeah, you're not getting it. The reason there is a "target curve" in a car is because the car environment exists as a diffuse soundfield vs. the free-field in a listening room. Therefore, in order for the frequency response in a car to be perceived as flat/neutral, you need to correct the EQ curve to compensate for the DIFFUSE FIELD that exists. Did you know that headphones also have what is essentially a "target curve?" That's because they, too, require diffuse field equalization because...they reproduce sound in a diffuse field.
> 
> The problem we have in car audio, is many people use measurement techniques designed for the free field. With the exception of binaural mics, they don't account for the various angle of incidence that the sound strikes the ear. And so that's why you get all sorts of different supposed "target curves" that supposedly are trying to describe the exact same most-pleasing cabin response.
> 
> Guess what. In home audio, the concept of the best FR curve, measured using a reproducible technique and listening room, has already been validated. It's not arbitrary. They took a large group of blinded listeners, sat them down in front of various loudspeakers and played various types of recordings. The loudspeakers that consistently sounded the best all tended to have very similar FR curve characteristics. It's published in JAES, a peer-reviewed engineering journal (as opposed to the opinion of an internet forum user who likes his tone controls). Again, this is why you can take high-quality loudspeakers, stick them in your living room, and almost all recordings sound fantastic, regardless of what free-reign the audio engineer used when mixing the track.


Smelly, I hope you understand that there is nothing wrong with wanting to learn. But, to me, you come across as wanting to piss in everyone's cheerios with your "but's" and then contribute ZERO usuable input. 

I understand all mics are different. I understand all producers and their studios are different. But hell man, having a direction to head is better than nothing and that's what we're trying to get here. You, however, don't come across as genuine but accusatory. Seriously, Andy has said that the MS8 uses binuaral mics because of ease for consumers**, and the MS8 uses his target curve. Never once have I seen him say, "I suggest this curve, but ONLY if you use the JBL MS8's binaural mics (or binarual mics in general)". Never once have I seen him say, this curve is useless with a Behringer mic. I think you are clutching at straws with these comments. YES, THERE ARE DIFFERENCES. YES, THEY MAY BE AUDIBLE. But after hitting the "preferrred curve" you SHOULD be tuning to preference and, IMHO, that should be done by ear anyways.

Part of the problem here is that there is no "paint by numbers" approach to audio, but I personally think you are looking at everything wrong. Instead of being anal retentative about what mic to use, why don't you look at methods to make mic difference nearly a moot point? I see two ways to do this. One is to cross all speakers before they begin beaming. This should insure that off-axis response is nearly the same as on-axis and therefore the sound the mic(s) picks up is irrelvant if it is direct or reflected. Second, operate all speakers beyond their beaming point, use heavy acoustic treatments to reduce reflections, or both, so the mic(s) picks up only the direct sound. I personally think the former is easier and has the benefit that I don't have to keep my head in a vice for good sound...so it's the approach I personally take.

**Each time somebody can put the headphones on, turn their head twice, and the mic has averaged six points of reference. Nobody has to aim an omni and tell the MS8 to take a reading...ease of use.


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## MarkZ

smellygas said:


> Yeah, you're not getting it. The reason there is a "target curve" in a car is because the car environment exists as a diffuse soundfield vs. the free-field in a listening room. Therefore, in order for the frequency response in a car to be perceived as flat/neutral, you need to correct the EQ curve to compensate for the DIFFUSE FIELD that exists. Did you know that headphones also have what is essentially a "target curve?" That's because they, too, require diffuse field equalization because...they reproduce sound in a diffuse field.
> 
> The problem we have in car audio, is many people use measurement techniques designed for the free field. With the exception of binaural mics, they don't account for the various angle of incidence that the sound strikes the ear. And so that's why you get all sorts of different supposed "target curves" that supposedly are trying to describe the exact same most-pleasing cabin response.
> 
> Guess what. In home audio, the concept of the best FR curve, measured using a reproducible technique and listening room, has already been validated. It's not arbitrary. They took a large group of blinded listeners, sat them down in front of various loudspeakers and played various types of recordings. The loudspeakers that consistently sounded the best all tended to have very similar FR curve characteristics. It's published in JAES, a peer-reviewed engineering journal (as opposed to the opinion of an internet forum user who likes his tone controls). Again, this is why you can take high-quality loudspeakers, stick them in your living room, and almost all recordings sound fantastic, regardless of what free-reign the audio engineer used when mixing the track.


Wow. Yes I'm aware of the jAES, peer review, and some of the studies that have examined what you're describing. Really, I know you're new here, but I genuinely think you would be doing yourself a favor keeping some of the condescension in check.

You're veering slightly off course here, which is ok, but I'll address all your points since you decided to stick around. 

1) You're failing to acknowledge that the "target curve" is not a simple psychoacoustic transformation or a byproduct of measurement, but rather it also absorbs the bias/error that I referred to in my last post. I didn't make this **** up. Really. It's the very same bias/error that pionkej's reference aimed to address!

2) You're conflating measurement and true response functions, which I believe is the same problem that others in this thread had with you earlier. You're absolutely correct that measurement methodology is something important to consider in the general scheme of things, but I also think you're sweeping a lot of variability under the rug and blindly chalking it up to measurement error.

3) You totally disregarded everything I wrote in my last response to you. Which is a problem, because you didn't address the very basic logical fallacy that serves as the central tenet of your position.


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## smellygas

MarkZ said:


> Really, I know you're new here,


I've been a member since 2008. How many more years to I need to be a member before I'm not considered "new" by your standards?



> but I genuinely think you would be doing yourself a favor keeping some of the condescension in check.


That's funny, I was going to say exactly the same of you a few posts ago. To be honest, I'm not sure what your "central tenet" was because I was busy sorting through all the personal attacks (I'm being serious here). So if there's something relevant that I missed, feel free to post it again. On the other hand, don't.


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## smellygas

Back on track, I'm pretty happy with the response curve in my car. It sounds pretty good on almost all of my music. The MS-8's DSP equalization got me most of the way there, and fine-tuning the EQ curve based on RTA and listening comparisons to a good home system was very helpful. 

So just for fun, I measured a response curve in my car using spatially averaged measurements with a calibrated ECM8000 using pink noise. I then took the exact same measurement with binaural mics, also spatially averaged. The two curves looked completely different.  Thus, if I were to pick any of the curves in the OP, and EQ to it based on using the ECM8000, and then EQ it again based on the binaural mics, I would obtain completely different sound signatures. And this is very convincing empirical data that shows the measurement technique is so important that not accounting for it makes it nearly impossible to reproduce someone else's "target curve." You people can believe whatever you want, but I invite you to repeat this experiment before continuing the acrid responses.


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## MarkZ

This is probably a silly question, but I'm going to give you the benefit of the doubt: do you plan to address _any_ of the points I made in my last two responses to you? Or was your tactic all along strawman->strawman->obfuscation->snipe? Because that's not cool man.


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## ErinH

smellygas said:


> Back on track, I'm pretty happy with the response curve in my car. It sounds pretty good on almost all of my music. The MS-8's DSP equalization got me most of the way there, and fine-tuning the EQ curve based on RTA and listening comparisons to a good home system was very helpful.
> 
> So just for fun, I measured a response curve in my car using spatially averaged measurements with a calibrated ECM8000 using pink noise. I then took the exact same measurement with binaural mics, also spatially averaged. The two curves looked completely different.  Thus, if I were to pick any of the curves in the OP, and EQ to it based on using the ECM8000, and then EQ it again based on the binaural mics, I would obtain completely different sound signatures. And this is very convincing empirical data that shows the measurement technique is so important that not accounting for it makes it nearly impossible to reproduce someone else's "target curve." You people can believe whatever you want, but I invite you to repeat this experiment before continuing the acrid responses.



What was the measurement setup for both? Details, please. 


Sent from my iPhone. Pardon the grammar.


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## pionkej

bikinpunk said:


> What was the measurement setup for both? Details, please.
> 
> 
> Sent from my iPhone. Pardon the grammar.


Big 2nd. You were obviously sitting in the car with the binaural, were you doing the same with the omni? How many readings did you take and average with these mics (AFAIK 6 is the suggested number)?

Also, pictures go a long way. You may have very valid points, but right now you're doing ZERO to back it up. I made the point that a 5ms gated response only affects frequencies above around 10khz. Some people may take me on my word, but attaching a simple picture (like I did) adds a lot to the credibility of my statements. 

So, a few more details of your method and an overlay between the two averaged responses would be huge in helping forward this part of the conversation.


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## avanti1960

weighing in on the debate-

1) there is a target curve that most people would find enjoyable but it is not so easy to achieve in one's car and there are other variables that must be clearly defined before the curve will achieve its desired results. it most definitely includes higher levels of bass, a flat or shallowly dropping midrange and a more aggressive downward slope in the higher frequencies. 

2) this curve is not everyone's preference but will serve a meaningful purpose as a starting point. the key is that you listen and refine over time and be absolutely scientifically and systematically consistent about measuring as you refine the curve. the goal IS to define your curve of preference- your own curve. 

3) i have a nice home stereo. i never adjust the EQ or ever have a reason to. I do adjust the volume on the subwoofer occasionally. 
however- i have not found a need to keep upgrading hardware, add a digital signal processor or even come close to finding a reason to pop in a pink noise CD and get the mic and RTA software up and running. 
there is obviously something quite challenging about car audio that makes it more vulnerable to variations in music and recordings as to exaggerate the differences somehow, throw them over our threshold for acceptability and make us want to adjust things all the time.


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## ErinH

Sdit: 
I want to state up front the goal of this post is NOT to discuss my response curves. Only to discuss the differences in measurement results between measurement methods. 
For the love of all that is good, please focus on the forrest and not the dang trees!
Moving on...

Since the discussion got sidetracked (and, to some degree, rightfully so) with how one measures, it's good to have data to go with it.

The following was taken tonight in my car. 
Binaural mics using a stereo recording input device (whereas most forget this is essential and wind up only recording in mono off the laptop's sound card, not realizing it doesn't have stereo recording capabaility) vs the dayton omnimic results.

The conditions of the test are listed below. look at the number/color in the TrueRTA window pane and match that up with the number below so you can determine the test method. 

Ask questions if my explanations are too brief or you have any general questions. 

The omnimic results are calibrated with the standard cal file provided with the mic. No, unfortunately, the binaurals aren't. If you have a _realistic _way of achieving this, lmk because it's not easy at all*; though, the panasonic capsules have a pretty good track record for being flat, with a minor bump around 10khz (might explain the ones in the results), in all the research I've done.


Test Conditions:
1)	Binaural - Left only
2)	Binaural - Right only
3)	Binaraul - Left+right
4)	Binaraul - Left & right averaged
5)	Binaraul - Spatial average of binaural
6)	N/A on purpose
7)	OM average (Mic at head position, me in the backseat, no headrest)
8)	OM average (Mic at head position, me in the backseat, headrest in place)
9)	OM average (Me in driver's seat holding mic vertically)

Note 1: 1, 2, & 3 were done to see individual vs combined results
Note 2: 5 is simply an 'average' of the two sides (1 & 2). The measurement was averaged by me looking at each mirror and combining the results. Doing more point measurements between those bounds would probably have smoothed the graph, but the overall result stands as is.
Note 3: Why headrest vs no headrest? Because I wanted to see how much it mattered. In this particular case, not much as you can see below.
Note 4: OM mic was placed vertically to show the difference in horizontal vs vertical measurement. The OM does not have a polar response cal file provided; only an on-axis response. 

*First, binaural comparison between left ear only, right ear only, and a spatially averaged measurement:*











*Second, results between OM vs Binaural measurements. * This pits the averaged binaural results (#5) vs the OM measurements (#7-9). 
Note: The results were shifted so the data would be easier to see. Having a bunch of lines on top of each other makes it hard to compare multiple graphs. For two or three graphs, it's okay. more than that and it's too tough to be useful.









Same as above, just zoomed in and shown from 200-20khz.














It took me about 30 minutes to do this. It took more time to post the results than actually capture the data. I encourage others to do this as well because not only will you get some experience and possibly learn something about your setup, you can then speak on that experience. it's easy to spitball ideas and shoot down discussion but apparently pretty damn hard to get off a computer and try to experiment. if this offends you, I'm talking about you. 


Now that we have some sort of understanding of the various measurement techniques and their respective resultant, maybe we can move forward in this thread. The more who contribute their own results, the better we can possibly draw some correlation and rule out the nebulous discussion and focus on what matters. 
If you decide to post your data, MAKE SURE to explain the how and why. Try to do a better job than me... it's late and I'm tired. 



- Erin


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## smellygas

bikinpunk said:


> What was the measurement setup for both? Details, please.


Here's what I did, just to demonstrate the magnitude of differences you get using different measurement techniques, I arbitrarily picked the following 2 techniques, both with stereo pink noise, both L&R channels playing simultaneously:

1) ECM8000 pointed up, handheld in drivers seat head position, with me sitting in back seat, tweeters approx 120deg polar off-axis, 6 measurements taken a few cm apart with a total width slightly wider than my head, M-audio mobile-pre, each measurement average of 8, then all averaged on Room EQ Wizard (REW)

2) SP-TFB-2 binaural mic from soundprofessionals.com in my ears, sitting in driver's seat, 6 measurements total, 3 from each side with head neutral, and head slightly left and slightly right (maybe 15 degrees), andrea-usb-sa sound card [credit to bikinpunk post 5/7/10 for this setup], each measurement avg of 8, then all averaged in REW

Rather than post the two curves, which I don't feel like doing, I'm going to post the DIFFERENCE between 1) and 2), both smoothed to 1/3-oct and without calibration correction.

*Hz - DIFFERENCE between 1) and 2) in dB*
20 - 20
40 - 12
80 - 20
100 - 10
200 - 4
400 - -2
800 - 0
1k - 1
2k - 5
4k - 6
8k - 2
16k - 4

Side notes: Using the binaural mic and turning my head further (looking at each tweeter) made a difference of about 1dB throughout on the 1/3 oct smoothed curves. Pointing the ECM8000 directly at tweeters in 3 different positions per tweeter (i.e. on-axis, but with mic element perhaps 5cm closer to the front because the seat back gets in the way), yields a completely different curve compared to pointing straight up. 

And there you go. You have my data and the graphs from bikinpunk above. Who still believes that you can try to reproduce someone else's target curve without taking into account the measurement/mic methodology? I'm accepting apologies starting....now...


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## jcollin76

smellygas said:


> Here's what I did, just to demonstrate the magnitude of differences you get using different measurement techniques, I arbitrarily picked the following 2 techniques, both with stereo pink noise, both L&R channels playing simultaneously:
> 
> 1) ECM8000 pointed up, handheld in drivers seat head position, with me sitting in back seat, tweeters approx 120deg polar off-axis, 6 measurements taken a few cm apart with a total width slightly wider than my head, M-audio mobile-pre, each measurement average of 8, then all averaged on Room EQ Wizard (REW)
> 
> 2) SP-TFB-2 binaural mic from soundprofessionals.com in my ears, sitting in driver's seat, 6 measurements total, 3 from each side with head neutral, and head slightly left and slightly right (maybe 15 degrees), andrea-usb-sa sound card [credit to bikinpunk post 5/7/10 for this setup], each measurement avg of 8, then all averaged in REW
> 
> Rather than post the two curves, which I don't feel like doing, I'm going to post the DIFFERENCE between 1) and 2), both smoothed to 1/3-oct and without calibration correction.
> 
> *Hz - DIFFERENCE between 1) and 2) in dB*
> 20 - 20
> 40 - 12
> 80 - 20
> 100 - 10
> 200 - 4
> 400 - -2
> 800 - 0
> 1k - 1
> 2k - 5
> 4k - 6
> 8k - 2
> 16k - 4
> 
> Side notes: Using the binaural mic and turning my head further (looking at each tweeter) made a difference of about 1dB throughout on the 1/3 oct smoothed curves. Pointing the ECM8000 directly at tweeters in 3 different positions per tweeter (i.e. on-axis, but with mic element perhaps 5cm closer to the front because the seat back gets in the way), yields a completely different curve compared to pointing straight up.
> 
> And there you go. You have my data and the graphs from bikinpunk above. Who still believes that you can try to reproduce someone else's target curve without taking into account the measurement/mic methodology? I'm accepting apologies starting....now...


Yeah, not going to happen.

I don't care if your right, or wrong, my issue is your being quite the Richard about it.

Its been stated how you measure is important, and that you have valid points. 
Its the presentation, being argumentative and arrogant that's the issue.
But, I guess you'd have to care what other people thought, and actually read what they post to get that... as its been stated more than once.

Btw, thanks for sharing how you measured.


----------



## highly

smellygas-

It seems fairly straightforward that the measurement techniques measure vastly different things. Was this the intent of the choices? 

Why did you choose to measure two different axes (straight up at a soft surface with one mic, then straight out at glass and including your pinna, head, and body with the second) and expect any correlation of signifigance? Given that even gated measurements in a car below about 200 Hz are suspect, the measurements of the frequencies above that show what I would expect to see given the difference in techniques. Nothing here seems particularly surprising.


----------



## pionkej

highly said:


> Given that even gated measurements in a car below about 200 Hz are suspect, the measurements of the frequencies above that show what I would expect to see given the difference in techniques. Nothing here seems particularly surprising.


I agree 100%. The measured differences above 2khz, or so, are completely explained by the fact he included head/body shadowing with the binaural and didn't with the omni (and it didn't help he aimed it towards the headliner). 

The differences below 300hz, however, don't make sense at all. The wavelengths at those frequencies are so long that the different methods should not have results that vary so widely. That leads me to believe this is a user error of some sort. 

Smelly, if your entire point was to use vastly different methods to show how "if you don't specify, you can get drastically different results"...congrats, you are correct in regards to the tweeter. Everything else you're trying to "prove" really points more towards flaws in your measurement system and so I don't think I'll be apologizing quite yet.

EDIT: Smelly, I will eat my words a little and say it is possible that aiming a omni-directional mic up at the ceiling can affect the midrange a bit in addition to the tweeter. So it is probably not an accurate method if you are trying to mimic a curve somebody else ahieved by measuring the system with a mic pointed forward or using binaural mics. I say possible because I have the overlay between the measurements #5 and #9 (*binaural average *vs. *omni average*) and the differences do appear to begin in the midrange (around 2khz). You can argue that they begin around 500hz, but the binaural is the average of only 4 points, not 6, and I don't accept that difference because of the large swings in the 4 point measurements *(#1* and *#2*) show that an additional 2 points with the binaural could bring the 500-2khz range much closer to what is shown with the omni. The overlay does show two important factors though: first is that you need to exercise common sense when aiming the mic**, and second that the area below 200hz doesn't (and SHOULDN'T) vary by 10-20db like you implied it does. So..."I'm accepting apologies starting...now..." 










**I personally like to sit in the diver seat when measuring the system response. I also take 8 measurements (I know 6 is generally accepted as adequate) with my omni mic. One is aimed toward the ceiling, one as aimed to the front of the car, one is aimed back to the point where my ears are at the headrest, and one across the bridge of my nose (pointed at the glass). That is 4 measurements that are performed for each side of my head (for a total of 8) and then averaged.


----------



## ErinH

smellygas said:


> Here's what I did, just to demonstrate the magnitude of differences you get using different measurement techniques, I arbitrarily picked the following 2 techniques, both with stereo pink noise, both L&R channels playing simultaneously:
> 
> 1) ECM8000 pointed up, handheld in drivers seat head position, with me sitting in back seat, tweeters approx 120deg polar off-axis, 6 measurements taken a few cm apart with a total width slightly wider than my head, M-audio mobile-pre, each measurement average of 8, then all averaged on Room EQ Wizard (REW)
> 
> 2) SP-TFB-2 binaural mic from soundprofessionals.com in my ears, sitting in driver's seat, 6 measurements total, 3 from each side with head neutral, and head slightly left and slightly right (maybe 15 degrees), andrea-usb-sa sound card [credit to bikinpunk post 5/7/10 for this setup], each measurement avg of 8, then all averaged in REW
> 
> Rather than post the two curves, which I don't feel like doing, I'm going to post the DIFFERENCE between 1) and 2), both smoothed to 1/3-oct and without calibration correction.
> 
> *Hz - DIFFERENCE between 1) and 2) in dB*
> 20 - 20
> 40 - 12
> 80 - 20
> 100 - 10
> 200 - 4
> 400 - -2
> 800 - 0
> 1k - 1
> 2k - 5
> 4k - 6
> 8k - 2
> 16k - 4



Your results are certainly different than mine. FR aside, you can take SPL level at any given frequency and match any curve so you can get some sort of ‘spl calibration’. This allows you the ability to look at the differences more easily. FR is FR and doesn’t change with output (that’s what it’s called linear distortion rather than nonlinear distortion), unless you’re in power compression and most mics probably can’t take that high of SPL anyway. Above, you have the difference at 800hz as zero. So, let’s say for the sake of argument that you’ve done an spl calibration. To still have a swing of 20dB is much more than I got. I calibrated the curves at 1khz and the largest difference I have is about 5dB at 16khz. Outside of that, the next largest difference I have is 4dB at 63hz. So, overall, my curves don’t have as wild of a swing as yours (apparently) do. You can see the two together below. 










This is using 1/3 octave, however. 
Since we’re discussing differences in methodologies, let’s discuss resolution of measurement. You gave results that appear to be closer to 1 octave rather than 1/3 octave (maybe you cherry picked these, but without the graphs to go with it, I’m just having to go with you not having finer resolution). If this is indeed the case, you should also know that the differences in measurement resolution can be quite drastic and misleading, depending on how one presents the data. Below you can see my difference in binaural vs omnimic presented in both 1/3 and 1/1 octave. 

*1/3:*










*1/1:*















smellygas said:


> And there you go. You have my data and the graphs from bikinpunk above. Who still believes that you can try to reproduce someone else's target curve without taking into account the measurement/mic methodology? I'm accepting apologies starting....now...


You probably won’t get much of an apology and certainly no pat on the back. No one here (with the exception of a few folks who just haven’t yet tapped the critical thinking side of their brain) thought that different measurement methodologies would garner the same results. Especially not between binaural (body in place, HRTF taking precedent) vs Omni (‘free’ measurement with no body obstruction). As seen in various threads, not only is the body an inhibitor/contributor to the measured curve, but the location of the microphone itself is; thus the whole spatial averaging method, written by Geddes when he worked for Ford Automotive as an acoustical engineer. 
The point was never to say there is no difference. This is where the ol’ noggin comes in to play…
The point of my post above (and others’ before mine) was to learn _what _the difference is. You and I have quantified the difference, and can use this to help ourselves and contribute to the cause if needed. If we all gather as a community and discuss ways to achieve a curve and maybe even all do our own testing to come up with some insight, then what we then have is a way to quantify the differences between methods and can then achieve another’s measurements as long as we know the technique. That’s just one portion of this task. There are many avenues and ways to go about this. Until people are willing to put their egos aside for a bit and quit trying to look smart while regurgitating **** that was published years before we even cared to get in to this, we can’t progress. I’m all for trying to discover some useful ‘one fits all’ curve but the only way to achieve it is as a community. Lord knows none of us here do this for a living (with the exception of Andy). So, let’s put on our engineer hats and see what we can come up with. 
Who knows, we just might come up with something. 


-	Erin


----------



## smellygas

"So, some follow up comments:

- My point, for perhaps the 3rd time, is that you cannot simply EQ to reproduce someone else's target curve without considering the measurement technique (i.e. mic type, placement/orientation, calibration, and processing) used to derive that curve and either a) matching that technique or b) correcting for it...because you'll be applying a completely different equalization.

- For those of you who don't believe this is true, I don't care. If you don't think my simple test and the one posted by bikinpunk is adequate evidence, then nothing I say is going to convince you. To me, it was patently obvious without either test. 

- An ECM8000 pointed up is the method used for Audissey. Look at the Audissey mic used for: 1) home A/V receivers 2) Alpine Imprint for car, 3) the IK Ark system (which includes an ECM8000), and others. 

- Binaural mics with a total of 6 averages is similar to the method used in the JBL MS-8. 
Edit: Yes, I recorded L and R mic channels independently before creating a combined spatial average.

- As you can see, the originally posted target curves were derived using different techniques and equipment, and so not matching the original methodology is going to give you a completely incorrect measurement. 

- I don't know why my binaural mic showed an exaggerated bass response compared to my ECM. I actually repeated the same 2 tests on a high-quality home stereo system, and obtained similar differences between the FR curves in the low-end, so I doubt this is "measurement error," rather than an idiosyncrasy of the measurement technique. But you can believe whatever you want.

- The fact that repeating the binaural test with much exaggerated head turning yielded almost no difference, and aiming the ECM8000 on-axis with the tweeters yielded smooth differences mostly in the midrange but not erratically different [neither data posted], confirms that my car interior has diffuse-field properties 

- If you feel that I was condescending, arrogant, or otherwise rude to you, consider the fact that you probably deserved it or earned it."

*Are you averaging the magnitude response only or does your program also average the phase responses too to come up with the average? If it's using the phase response, that could be th reason you're having a hard time with the bass bump.*


----------



## subwoofery

smellygas said:


> - I don't know why my binaural mic showed an exaggerated bass response compared to my ECM. I actually repeated the same 2 tests on a high-quality home stereo system, and obtained similar differences between the FR curves in the low-end, so I doubt this is "measurement error," rather than an idiosyncrasy of the measurement technique. But you can believe whatever you want.
> You might have missed that part so I'm quoting it again. Is your laptop setup for that?
> 
> 
> bikinpunk said:
> 
> 
> 
> The following was taken tonight in my car.
> Binaural mics using a stereo recording input device (whereas most forget this is essential and wind up only recording in mono off the laptop's sound card, not realizing it doesn't have stereo recording capabaility) vs the dayton omnimic results.
> 
> 
> 
> - If you feel that I was condescending, arrogant, or otherwise rude to you, consider the fact that you probably deserved it or earned it.
> I've pretty much been reading this thread only and understand why people get offended by your posts and replies... I know it is hard to put your pride aside but when you do, you actually learn a lot of things. I think people get your point since a few acknowledged it but you certainly won't be able to communicate (even if your 100% right) with that kind of attitude... Just sayin'
Click to expand...

Kelvin


----------



## smellygas

bikinpunk said:


> Since we’re discussing differences in methodologies, let’s discuss resolution of measurement. You gave results that appear to be closer to 1 octave rather than 1/3 octave (maybe you cherry picked these, but without the graphs to go with it, I’m just having to go with you not having finer resolution).


Bikinpunk, to answer your questions, all original measurements were made at 1/12 octave. I used 1/3 oct smoothing because that's how a lot of target curves are presented. The difference I published were based on eyeballing the difference between curves at 1/3-oct smoothing and me reporting them at arbitrary intervals. 



> As seen in various threads, not only is the body an inhibitor/contributor to the measured curve, but the location of the microphone itself is; thus the whole spatial averaging method, written by Geddes when he worked for Ford Automotive as an acoustical engineer.


It's funny that you mention that. I made reference to Geddes' paper in one of my posts here in 2009 when people were still taking single mic readings and I was advocating the need for spatial averaging. See:
Link: http://www.diymobileaudio.com/forum/684334-post4.html
(although according to MarkZ, I'm still a "new" member...)
Yes, the presence of a human body will affect FR measurements - yet another reason to consider the measurement technique of the desired target curve. 



> If we all gather as a community and discuss ways to achieve a curve and maybe even all do our own testing to come up with some insight, then what we then have is a way to quantify the differences between methods and can then achieve another’s measurements as long as we know the technique. Erin


Hopefully we can start talking about the measurement technique ALONG with each target curve, which would be a complete change from every other "target curve" thread I've seen here over the past 4 years.


----------



## ErinH

smellygas said:


> It's funny that you mention that. I made reference to Geddes' paper in one of my posts here in 2009 when people were still taking single mic readings and I was advocating the need for spatial averaging. See:
> Link: http://www.diymobileaudio.com/forum/684334-post4.html
> (although according to MarkZ, I'm still a "new" member...)
> Yes, the presence of a human body will affect FR measurements - yet another reason to consider the measurement technique of the desired target curve.
> 
> 
> Hopefully we can start talking about the measurement technique ALONG with each target curve, which would be a complete change from every other "target curve" thread I've seen here over the past 4 years.


It's ironic you link that particular post in your reply. 

First off, the fact that you mentioned the paper* years ago doesn't make you any more knowledgeable or above it all (as they say) than the rest of the community. You found a paper someone else wrote and referenced it. 
Few of us here offer ingenuity. We offer recycled ideas and sometimes bring fresh perspective. Myself included, certainly. You weren't the first to suggest spatial averaging, so while it's cool you were hip to it years ago, the fact is others were hip to it long before then. Nyugen was posting about it in 2007.The paper itself was written in 1988. I doubt that in 2009, you were the first to suggest reading the paper. 


The attitude you present with your posts is what has seemed to cause so much disdain for your posts. Fact is, a lot of what you say has truth to it but you:

Aren't coming up with these ideas on your own. Yet, you present an air of narcissism like nothing I've seen (in a while) here. Are you here to help or make yourself look smart? That's a genuine question, though, rhetorical. 
Aren't necessarily being challenged on the ideas; rather your unwillingness to discuss the topic and further knowledge. So, while you toss out the skepticism and look down on those invested in the discussion, you have yet to offer anything new, much less of real merit. This isn't a personal attack by any means. It's an observation based on how you've presented yourself here. If you don't like my observation, then adjust your attitude. 


The real irony is in the post you linked (what I've bolded and highlighted in Red):



smellygas said:


> This isn't a stupid question. In fact, I've had the same question for at least 5 years, and there's a lot of misinformation out there, and I learned a lot of things the hard way. I ended up reading about 10 key articles published in JAES and everything kind of fell into place. A lot of the following will sound like voodoo, and I'm sure the people who repeat the same misinformation will chime in soon, but here goes:
> 
> a) *you absolutely must take several measurements in slightly different locations and average them together to get a valid measurement. This is called spatial averaging.* Geddes in an older JAES article found that taking one random time-averaged (not spatial) RTA measurement gave you a measurement accuracy window of about +/- 8dB or so...which basically is almost useless. You'll find that just moving your mic a few inches changes your RTA curve completely. He found that you required a minimum of 6 measurements in 6 strategic locations to yield a precision of +/- 0.5dB.
> b) *A flat RTA with a pink noise signal is NOT desirable. It will sound overly bright. * Ignore the IASCA metric. Everybody who has done RTA work will say "flat sounds terrible." The reason, very briefly, is that you're measuring the power response, which includes direct and reflected sound. A flat power response sounds too bright. *What you want is a flat ANECHOIC response. You can't measure anechoic response without sophisticated software. TrueRTA doesn't do it. So the next best thing is to model the power response curve (what you measure) after what a flat anechoic response speaker would sound like. This has been studied. It is a downsloping line from about 100-400Hz to 10-20kHz at a rate of 1-1.7db/octave. That's your target. *
> 
> SG



Which contrasts with your posts here, such as this one:



smellygas said:


> you cannot simply EQ to reproduce someone else's target curve without considering the measurement technique (i.e. mic type, placement/orientation, calibration, and processing) used to derive that curve and either a) matching that technique or b) correcting for it...because you'll be applying a completely different equalization.


At one point you recommended a curve and encouraged the audience to tune to that curve and made no mention of measurement gear/technique/whathaveyou. Instead, you suggested that one should tune to the power response curve. Now curves are terrible. Yep, that was years ago... but it doesn't make the point any less valid. The point being: at one point you suggested a generic curve with no caution and no constraints. Also, the curve you describe seems similar to some of the curves presented by the OP.

The other ironic part is that you were very willing to help and did so in a very non-condescending way. Honestly, I read your reply and thought it was kickass. I wish you had that kind of tact here. If you did, we'd probably be a LOT further along in this thread than we are right now.

As I and others have already said, what you say regarding measurement techniques and methods is absolutely true. I don't think anyone here is really arguing that at all. The issue comes down to those who are trying to use a target curve and those who think it's useless. As seen above, at one point, you thought there was merit. Something has changed your mind (or, maybe you just like being contrary; I don't know). I think it might be more interesting on your part to say "I used to recommend this, but I don't now and here's why" rather than taking the naysaying approach you have above. I've learned a whole, whole lot from my own past mistakes. Anyone who looks in to my post history can see I've come a long way from my nooB days and I can share a lot of my own experiences with others. At the end of the day, most of us are here to help or learn. Outside of that you have folks who are advertising or just plain bored at work. John's attempt to get some discussion going may have been poorly worded in the title but that doesn't mean we can't run with the ball toward discussion that bears fruit.

The focus of this thread is to discuss curves, yes, but moreso to discuss how one can _achieve_ it. So far, however, this thread has been derailed by jibber-jabber from many camps.

I'm game for discussing ideas and determining some methods on how we can come up with a useful curve that would work for individuals. This entails much more than "what mic do you have". I have some thoughts on cabin influence, sound power vs power response, and other random things that I've been wondering and have been wanting to get that discussion going but the SNR level here is too high, yet, to do so. No, none of these are original... just trying to think of ways how we can take what has been presented to us by Toole, Geddes, Linkwitz, etc and applying some of the basics to a new environment. If you've got ideas to discuss to help further this thread then let's proceed with that rather than this endless back and forth pseudo-debate. Otherwise, I'll politely ask you to refrain from posting and further derailing this thread. It started off with some merit and has really taken a side road from a potentially cool direction. I'll do my best to clean up anything further off topic so you don't feel under attack but I ask you to refrain from posts that aren't OT or useful in some manner. If you want to continue a tirade, do so in the off-topic section. I'll be happy to provide a link in this thread to it, if you'd like.

- Erin






*Note:
I've attached a copy of the The Localized Sound Power Method in this thread for those who want to see it. I mentioned it in my tutorial here as well, so if you want to know how to implement it, check it out.


----------



## smellygas

Bikinpunk, thank you for pointing out the irony of my post from 2009. In that thread, people were pleasant and did not warrant my current attitude in this thread. It was enjoyable to have a conversation, whether or not I was right or wrong. 

Fastforward to this thread. Each subsequent response in this thread has made me less and less willing to participate in a personable manner, beginning with the two obscene posts that I reported (and were deleted by a mod) and ending with another profane post that I also just reported (and was censored by a mod).

Obviously, in real life, if I communicated with people in like manner, I would have zero friends and no job and probably end up getting shot. It's easy to make that assumption rather than to consider the fact this was simply a reactionary response to the inflammatory remarks made by others here. It's very easy to point fingers at the "new guy" as the troublemaker, but consider for a moment how the offensive responses here have influenced the tone of my responses. To be honest, I do have other ideas and explanations for how to enhance reproducibility of target curves and to achieve reference-level sound in the car. However, I just don't see how I can possibly discuss them here in this environment. 

So, I am confident that you all can figure it out and have a productive dialogue, and I wish you all the best. Perhaps the conversation should return to a comparison of the target curves rather than focusing too much on how the target curves were measured.


----------



## ErinH

smellygas said:


> Bikinpunk, thank you for pointing out the irony of my post from 2009.


no problem. but, really, you should thank yourself since you linked it. 




smellygas said:


> So, I am confident that you all can figure it out and have a productive dialogue, and I wish you all the best.


Sounds good. See ya' in other threads.

Oh, and thanks for recognizing the work of the mods who have reacted to your reported posts. I didn't personally see the reports, but another mod must have since it was dealt with. Good job, mods!


- Erin




Everyone else, let's get back OT. Any further digression of this thread will be deleted without warning. So, stay on point. 

Reeeeeaaaaaaaaddddddyyyyyyyyyy?.....

GO!


----------



## Wy2quiet

bikinpunk said:


> no problem. but, really, you should thank yourself since you linked it.
> 
> 
> 
> 
> Sounds good. See ya' in other threads.
> 
> Oh, and thanks for recognizing the work of the mods who have reacted to your reported posts. I didn't personally see the reports, but another mod must have since it was dealt with. Good job, mods!
> 
> 
> - Erin
> 
> 
> 
> 
> Everyone else, let's get back OT. Any further digression of this thread will be deleted without warning. So, stay on point.
> 
> Reeeeeaaaaaaaaddddddyyyyyyyyyy?.....
> 
> GO!


I just want to say that I saw your advice (I do not remember which thread) about moving the mic in a constant figure 8 while using averaging (I use the REW, until about 200 measurements are made and use that average, like 2 minutes) and I can see the curve moving massively, sometimes 8-12db difference in some frequency ranges. I cannot see how anyone could get a solid tune from a couple spots, or even a single. 

I find it best if I do the figure 8 motion (or circle) around my left ear and then my right. Then I sit in the drivers seat and try the same thing. Obviously your head/body, and in my case since I use my arm to move the mic, will all cause reflections.


----------



## avanti1960

I'd like to add one to the mix and revive this thread. I'll call it the "bose" curve. I purchased some Bose computer speakers after being astonished at their pleasing SQ after an in-store demo. I measured with my RTA (magenta curve) and mirrored the response in my car with a little more bass (blue curve). 
Although I tweaked the bass a bit it has remained as the basis for my favorite sounding curve. It even has a little fletcher-munson built in- notice the valley between 2.5 and 6K? 
Also shown is my version of the Andy curve (gold). No offense but this one simply did not last a day. It was too hot and bright. Maybe I need to taper the high end more? 
Good stuff these RTA curves.
Reference, uncorrelated pink noise, 6 position mic average at the listening position, body in car.


----------



## james2266

avanti1960 said:


> I'd like to add one to the mix and revive this thread. I'll call it the "bose" curve. I purchased some Bose computer speakers after being astonished at their pleasing SQ after an in-store demo. I measured with my RTA (magenta curve) and mirrored the response in my car with a little more bass (blue curve).
> Although I tweaked the bass a bit it has remained as the basis for my favorite sounding curve. It even has a little fletcher-munson built in- notice the valley between 2.5 and 6K?
> Also shown is my version of the Andy curve (gold). No offense but this one simply did not last a day. It was too hot and bright. Maybe I need to taper the high end more?
> Good stuff these RTA curves.
> Reference, uncorrelated pink noise, 6 position mic average at the listening position, body in car.


Interesting. Ya still gots that big dip from ~60-~80 Hz tho. You really should try out some nice 8-9 inch midbasses in that Rav


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## avanti1960

james2266 said:


> Interesting. Ya still gots that big dip from ~60-~80 Hz tho. You really should try out some nice 8-9 inch midbasses in that Rav


No dip in the "andy curve" though! Yes, I did add some boost. Sounds full- I kept that part of the curve. 

Still might go 8" though, the dyn 172. 

YOU have lots of work to do!


----------



## james2266

avanti1960 said:


> No dip in the "andy curve" though! Yes, I did add some boost. Sounds full- I kept that part of the curve.
> 
> Still might go 8" though, the dyn 172.
> 
> YOU have lots of work to do!


Understatement of the decade. It will most definitely keep me busy once I get everything together to get going. I am thinking out what to do for a subwoofer currently this morning. My problem is I want it to look not out of place - that is the tricky part. I think the plan is coming right along for the rest of the build tho. 

I was told by quite a few that the Dyn 172 was the best option for me when I had the Rav. You will be impressed. For me, I have WAY more room in my doors this time. I can get the Morel 8s into the doors with no metal cutting at all I think (came with 6x9). I can see me getting a set of mw182 in there when there is money again too


----------



## avanti1960

Refined curves shown in the attached pics. the "andy curve" was too bright on the mid-high end. the "bose curve" did not have enough bass given the noise and other cancellations on the road. 
My final "hybrid" curve smooths out the bass end by dropping from 50 to 160, not the previous slope from 100 to 200 hz- i.e. a misrepresented andy curve- and merges with the bose curve from there up the register. 
I also dropped the boosting below 50 hz in used to flatten out the deep bottom end. It doesn't seem right to boost the low end. 
Regardless, the new refined hybrid curve sounds radically different than any curve I've run to date. 
A nice solid bass foundation with an "oomph peak" and zero coloration / muddiness to the overall sound, which is clear and open.


----------



## therapture

avanti1960 said:


> *In my area we have high speed highways and long stretches of stop and go driving. Leaving the "curve" alone would result in extreme bass at a stoplight and a weak thin sound at highway speeds. *
> On the fly manual compensation and adjustment is something I just cannot escape from and it is not user friendly on a head unit with multiple menu layers and selections.
> The OEMs have done a service by providing easy access tone adjustment. I wish my head unit had it (although now I am prompted to use the stored EQ memory presets, it's just a lot of work).


*WARNING*_* dead thread revival in process.*_



I find myself tuning a bit bass and midbass heavy. For sitting and critical listening I dial my sub remote level down to about 30% of max, and also a -1 or -2 head unit bass cut to clean up the mids. That way on the highway at 75mph I can crank it back up and still get that presence and impact from the midbass and sub. Even a +1 on the head unit for the tweeters if there is a lot of wind noise.


----------



## 14642

The target curve I published depends a little bit on the mic, but only the high frequency tilt. That's really a matter of preference. MS-8 uses a spatial average and a microphone that goes on your head. High frequency tilt in the target for that technique MUST be greater than for a single mic. 

Spectral averaging at high frequencies is almost as effective as the spatial average. In the midrange, it's helpful to look at several mic placements.


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## cajunner

the push towards quieting the vehicle is also the push towards retaining some mid bass coherency, as the 250 hz rumble through the chassis from the tires is going to affect your perceptual "suspension of disbelief" that augments the stereo image.

Notice when you are apt to boost the bass/mid bass at speed, it's usually because you notice that something's not right with the music, and that 'not right' feeling is the dissolution of clarity in the band of frequencies that we are attuned, for survival.

the stereo image collapses the most significantly when those frequencies are affected, I would imagine it's part of the hearing mechanism's designed in traits, that probably also produce a Fletcher-Munson curve's biased or non-flat bearing.

and that's probably why OpSoDis is successful as well, in that there is a greater panorama between speakers that lie 180 degrees to our sides, than at any other point forward in the image.

so bringing all of these keywords and catch phrases together, I propose that it's okay to boost the mid bass when riding down the highway.

Or, quiet the car, that's pretty good too.


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## pionkej

I agree 100% that mitigating road noise helps lesson need/desire to have different setting for driving and stationary. My stereo isn't perfect but I have pretty well tamed road noise to the point that at my listening levels (which ARE a bit loud), I don't feel the need to have two different settings. 

And since I have learned a good bit since starting this thread a year and a half ago, I'd like to update it a bit from my end. First, my personal tune is quite similar to the JBL tune, except the rise starts around 215hz (instead of 160hz) and carries higher (up about 18db a 35hz). What I ultimately ended up tuning for was "ear flat". What this means is that using by using 31 bands of pink noise, I adjusted levels until things were perceived as flat (I interlaced a 1khz tone between each band for "level reference"). Let me also state that this IS NOT easy to achieve. In the three years of building this car what I ended up with was a 12" sub tuned to 18hz (crossed at 60hz), 10" midbass in each footwell (crossed at 60hz and 180hz), 6.5" midranges (crossed at 180hz and 2.5khz), and tweeters covering the remainder. How does that compare to "the norm". Well, I cross a 10" midbass where I see many cross a 6.5" (63hz) and I cross a 6.5" midrange where I see some cross a 3" (180hz). Sub and tweeter are pretty typical. My reason for this is because I feel speakers being played outside their ideal range kills realism more than the system response and getting that increase from 215hz down to 35hz is critical. 

Look at the response of most 6.5" speakers and they are rolling off with no filter by 80hz or so. So the speaker's response is going down as your response curve should be going up! I worked around this by crossing high. Even though I "cross" at 180hz between midbass and midrange (the drivers responses cross at this point), I actually cross the midrange around a "typical" 80hz. This is because combining the flatness of the midrange with the rolled off midbass creates a rise in response (just like we want for the increase in the curve). I do the same with the midbass to sub. Basically, I overlap but only with the response of the smaller speaker. It still makes integration tricky, but it keeps subs from playing too high and keeps midbass from playing too high as well.

If you really want to get a good idea of what I'm talking about you need to play around with REW. Set a simple house curve that is +20 at 20hz and -20 at 20khz (you can hone this in later). Now load it up. You can set the speaker to "small speaker" and set the crossover at 80hz. This will show you what you NEED a speaker to do to handle an 80hz crossover with "ear flat" tuning. It is not easy.

If any of this was unclear, I apologize as I quickly typed it on my lunch break. If you need any clarity or help, I'll be glad to do what I can. Also, my experience is not all inclusive and does not mean you can't achieve a great sounding system with a 6.5" midbass or 3" midrange or whatever...I'm just sharing and I hope it helps.


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## mooch91

pionkej said:


> What I ultimately ended up tuning for was "ear flat". What this means is that using by using 31 bands of pink noise, I adjusted levels until things were perceived as flat (I interlaced a 1khz tone between each band for "level reference").


Very cool technique. I've often used pink noise for similar purposes and never thought to throw a reference tone in to help overcome the tricks that our minds play with respect to sound. Thanks for the idea!


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## Hanatsu

Interesting thread, nice discussion 

From lots of experimenting with tuning in different cars I found that the low/high frequency tilt is dependent on cabin size, absorbing of highs and directionality of the drivers. With small widebanders practically beaming above 5kHz I found that they need less tilt in the highs to sound balanced. With small tweeters with more dispersion higher up, I needed to decrease the highs slightly to get it to sound balanced. It would seem like the amount of reflections would alter the perception how loud certain frequencies are. Since limited dispersion is hard to attain lower down in frequency, this would apply to the upper midrange and highs. I found that a continuous rise of the frequency below 100Hz sounds best, 20Hz should be about 10dB higher than 100Hz and then pretty flat between 200-250 to about 1kHz and after that downwards tilt towards 20kHz.

Some people mention they tune after the Equal-Loudness-Curves. Imo, that's not a good way of doing it. It won't sound correct from 5kHz and up for starters and often 2-4kHz end up too recessed. To perceive the lowest octave equal at all volume would require some kind of volume dependent bass control (this is the range that our ears sensitivity varies the most in vs volume, i.e "phon" vs frequency relationship.


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## pionkej

Good point on level. I personally use 85-90db for my "ear flat" tuning because I feel it nets the best compromise for competition. 

Previously I only used my miniDSP for tuning which meant I had to break out a laptop to change presets. I now have a P99 as my source so I plan to use the 31-band presets to set up minor changes for higher and lower volumes...eventually.


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## sicride

Yes, I know this is an oldie but goodie thread. There seems to be more and more talk about processing and EQ lately and figured target curves would be relevant information for some of those getting in to tuning.

I also wonder if some people's views on these curves have changed over time?


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## Babs

sicride said:


> Yes, I know this is an oldie but goodie thread. There seems to be more and more talk about processing and EQ lately and figured target curves would be relevant information for some of those getting in to tuning.
> 
> I also wonder if some people's views on these curves have changed over time?


I'm finding, as a newb, I'm having better results leaving a 'curve' idea as for the end, but tuning to general good tonality and balance first, leaving the curve for last. So while I have some idea of the curve I'm looking for, it's only after knocking down individual peaks, bringing sides into balance, centering up the image throughout the bandwidths, and only then being overly concerned about conformity to a curve. If done well, a good balanced curve for the individual car may present itself to you.. Trust ears, and verify by graph.


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## oabeieo

Hanatsu said:


> Interesting thread, nice discussion
> 
> From lots of experimenting with tuning in different cars I found that the low/high frequency tilt is dependent on cabin size, absorbing of highs and directionality of the drivers. With small widebanders practically beaming above 5kHz I found that they need less tilt in the highs to sound balanced. With small tweeters with more dispersion higher up, I needed to decrease the highs slightly to get it to sound balanced. It would seem like the amount of reflections would alter the perception how loud certain frequencies are. Since limited dispersion is hard to attain lower down in frequency, this would apply to the upper midrange and highs. I found that a continuous rise of the frequency below 100Hz sounds best, 20Hz should be about 10dB higher than 100Hz and then pretty flat between 200-250 to about 1kHz and after that downwards tilt towards 20kHz.
> 
> Some people mention they tune after the Equal-Loudness-Curves. Imo, that's not a good way of doing it. It won't sound correct from 5kHz and up for starters and often 2-4kHz end up too recessed. To perceive the lowest octave equal at all volume would require some kind of volume dependent bass control (this is the range that our ears sensitivity varies the most in vs volume, i.e "phon" vs frequency relationship.



That sounds exactly right. 

I've noticed if the HF is closer like on dash and midbass in doors or kicks the highs need be tilted a lot more. Seems the closer they are the more of a shelf is needed. A rta or sweep may show flat but sounds too bright


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## Hanatsu

oabeieo said:


> That sounds exactly right.
> 
> I've noticed if the HF is closer like on dash and midbass in doors or kicks the highs need be tilted a lot more. Seems the closer they are the more of a shelf is needed. A rta or sweep may show flat but sounds too bright


I'd like to add a bit of clarification to my former post, something I really noticed ever since I got my APL DSP. The reason why widebanders need a flatter response than a small tweeter doing the small job is indeed related to the dispersion. It's because of the sound power response. When we measure with the common methods, i.e around the seated position, we don't actually measure the sound power response accurately which is crucial how we perceive loudness. 

I noticed this effect by comparing measurements in RoomEQ and APL. Where RoomEQ showed a flattened downwards sloping response, APL showed a dramatic dropoff above ~3,5kHz for my 3,5" widebanders. This correlated with what I heard pretty much. A tweeter is normally smaller and will have an omnidirectional dispersion much higher up in frequency than a widebander. 

The common method of measuring and equalization based on this data must be performed within the speakers omnidirectional range, i.e full dispersion range to have the required accuracy. 

As seen here, the drivers do indeed drop off beyond 3kHz. To be able to equalize your system properly we want full sound power. If not, it's a bit of a trial and error when you base your tuning upon a target curve (more than usual).


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## oabeieo

Hanatsu said:


> I'd like to add a bit of clarification to my former post, something I really noticed ever since I got my APL DSP. The reason why widebanders need a flatter response than a small tweeter doing the small job is indeed related to the dispersion. It's because of the sound power response. When we measure with the common methods, i.e around the seated position, we don't actually measure the sound power response accurately which is crucial how we perceive loudness.
> 
> I noticed this effect by comparing measurements in RoomEQ and APL. Where RoomEQ showed a flattened downwards sloping response, APL showed a dramatic dropoff above ~3,5kHz for my 3,5" widebanders. This correlated with what I heard pretty much. A tweeter is normally smaller and will have an omnidirectional dispersion much higher up in frequency than a widebander.
> 
> The common method of measuring and equalization based on this data must be performed within the speakers omnidirectional range, i.e full dispersion range to have the required accuracy.
> 
> As seen here, the drivers do indeed drop off beyond 3kHz. To be able to equalize your system properly we want full sound power. If not, it's a bit of a trial and error when you base your tuning upon a target curve (more than usual).


Ya know that makes so much sense. It makes me wonder when , well let's say you have a cancellation somewhere , the energy is still there. Well it would depend on what kind of cancellation , but let's say from a reflection not a nother speaker out of phase.. 

I've had cancelations and even tho it shows a dip on the meter , the energy still seems to be there because I have tryed bumping up the responce in the dip and had it sound like it was too much. 

It's psychoacoustic in another form I guess, lol 

Am I off base? I'm just speculating of course


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## sicride

Sounds possible. Could also be boosting frequencies around a very narrow dip that doesn't show because of the measurement technique or settings. However, that's derailing the topic just like happened originally. Has anyone else had success with variations of these or combinations of these?


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## High Resolution Audio

Subbed for reference.


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## Swaglife81

Seeing the different target curves just comes to show there really isn't no wrong type of curve. It's all listener preference like the pre chosen jazz, rock, live presets. One guy will like one and hate the other. 

I know this is a older thread but the info is great and should help some guys out. You don't have to have a true flat curve going end to end, it just needs to be smoothed to the listeners preference and the setup that ends up sounding the best. Looking at some of those popular curves I can tell I would hate some of them. I do want to see more graphs of other people's target curves to see the differences


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## dcfis

Does somebody have a JBL house curve .txt for REW or any other good curves in .txt for REW? Thanks


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## Justin Zazzi

dcfis said:


> Does somebody have a JBL house curve .txt for REW or any other good curves in .txt for REW? Thanks


You can use the tool in my signature to export a JBL curve or one of a few others into a text file for use with REW. You can also use my tool for a few other neat tricks too.


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## fredswain

The target curve is not only vehicle dependent but also speaker location dependent. I remember tuning a car that had Focal tweets and 6-1/2's in the kicks. They were aimed up at the center of the car, so mostly on axis. That car sounded wonderful flat between 100 and 10k with a 12 dB rise below 100 and a 12 dB fall above 10k. That car eventually had the kicks changed so that everything was off axis and that same curve didn't work anymore. I could never get the sound quality back to where it was even though the rta looked good. The stage was lower and fell on the sides. It's tough to say that any of the above curves would work well but from experience I can say a few things which should make finding the right curve easier. In the 400 hz and below range, aim doesn't matter. Only path length matters. The closer to equal the better. On axis is not as important. From 400-4000, pathlength and aim matter. On axis is better than off. Above 4000, pathlength doesn't matter. Only aim does. On axis being highly preferred. If you can abide by those rules, those general curves will work.


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## HereticHulk

Novice question:

So if I set my gains for a 3 way active system with all EQ settings and levels flat/0db for each network, and using a -5db test tone @ 4khz for tweets, 400hz or 1khz for mids & 40hz for the sub, then start to dial in (for example) the JBL target curve with a +9db between 20-60hz, isn't that much of a boost going to cause a clipped signal?


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## ckirocz28

HereticHulk said:


> Novice question:
> 
> 
> 
> So if I set my gains for a 3 way active system with all EQ settings and levels flat/0db for each network, and using a -5db test tone @ 4khz for tweets, 400hz or 1khz for mids & 40hz for the sub, then start to dial in (for example) the JBL target curve with a +9db between 20-60hz, isn't that much of a boost going to cause a clipped signal?


Maybe. Just subtract 9 db from everything, or set your gains with a 0 db test tone, then subtract 4 db from everything. (Everything in the target curve)


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## bbfoto

HereticHulk said:


> Novice question:
> 
> So if I set my gains for a 3 way active system with all EQ settings and levels flat/0db for each network, and using a -5db test tone @ 4khz for tweets, 400hz or 1khz for mids & 40hz for the sub, then start to dial in (for example) the JBL target curve with a +9db between 20-60hz, isn't that much of a boost going to cause a clipped signal?


Generally, it will not result in a clipped signal because you normally will not need to boost much, if any, in the ~30Hz-70Hz range because the _transfer function_ or natural ''cabin gain'' of the vehicle will provide the approximately ~ 9-12dB of "boost' naturally.

Of course, the amount of natural cabin gain/low-frequency boost will depend on the specific vehicle, what subwoofer & alignment you're using, the subwoofer's placement and loading boundaries, in addition to your listening position relative to the all of the above.

But good car audio subwoofers are designed with specific parameters that take into account the natural cabin gain/transfer function & the resulting low-frequency boost within typical vehicle environments.

If you were to play and measure a particular subwoofer outside in wide open space (an "infinite room" with no boundaries except for the ground or floor) the low frequency output would be much flatter, or severely rolled-off, and perceptively lacking by a large degree.

But that same subwoofer placed inside a vehicle (with no amplitude or EQ adjustments) will have a considerable low-frequency rising response/pressure boost due to the transfer function of the enclosed space.

I tend to always need to cut a bit in this range, and very rarely need to boost to achieve a "balanced" low-frequency response (providing that the subwoofer "system" was chosen and implemented properly to create the desired in-vehicle response).


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