# Sticky  On-axis vs off-axis



## 14642

*Re: Is off-axis better for front stage? - Hybrid Audio*

Someone really needs to add something to this discussion of on and off axis. OK...I'll do it. 

There's no mystery here and the differences between on and off axis placement are simple.

1. Sound is reflected from a bunch of surfaces in the car. We hear those reflections MOSTLY as changes in frequency response to the direect sound. They also contribute significant crosstalk (left ear hears right information and right ear hears left information). That crosstalk reduces the system's ability to sound "larger than the car".

2. The difference between on and off-axis sound from your speakers is very simply defined by the diameter of the cone. Frequencies that have wavelengths that are long compared to the diameter of the cone are radiated everywhere--to the front, the side and the back. Frequencies that are short relative to the diameter are radiated frontward. 

2b. the high frequency response of almost all speakers has a peak. This is caused by cone distortion-a small part of the cone moves differently than the rest of the cone. That peak is "played" by a smaller part of the diaphragm, so it has a different dispersion than the rest of the cone. If you look at the off axis response of such a speaker, you'll see that the peak is not attenuated at the same rate as the rest of the high frequency response. This can be a HUGE problem and it's one of the criteria for choosing a crossover point.

3. If you mount a speaker on axis, the high frequencies will arrive at your ears direcetly and the lower frequencies will too, but they will ALSO arrive at your ears after being reflected off ADJACENT boundaries. The high frequencies will also be reflected by boundaries near your ears (side glass) but NOT from adjacent boundaries (because they are radiated FORWARD). 

4. Reflections are attenuated because of the increase in pathlength (6dB for every doubling of distance). They are also modified by the material. Carpet doesn't reflect super high frequencies but glass does, for example.

5. So...a tweeter mounted off axis will direct more high frequencies into the reflecting surfaces and less into the direct sound. The same thing happens with a midrange (or a wide-bander). 

6. When you equalize, you can't equalize the reflection differently than the direct sound from the speaker. That doesn't matter if your head is completely stationary because for every point in space, we hear the sum of the direct and reflected sound. When we move our head, we hear a different combiination. It's helpful to have the direct and reflected sound as similar as possible to be effectively equalized. This isn't possible in a car, so no matter how we mount speakers we'll still be confronted with this problem. 

6. The problem is the worst when the off-axis response has a big hole and the on-axis response has a peak. This is common with 6-1/2" conponent systems where the woofer doesn't quite reach the tweeter. Sometimes, crossover designers who are focused on the on-axis response and ignore the directivity (off axis response) build a high-Q crossover to boost the response at the crossover. This makes this problem worse and can make the car sound bad when you listen despite a good curve.

All of this is why I suggest mounting tweeters on axis, using a small mid between a 6 and a tweeter, and keeping speakers away from the junction of the dash, side window and windshield. 

Widebanders should ALWAYS be mounted on-axis if no tweeter will be used.


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## hpilot2004

How would you go about adding a midrange to an existing two way component set. My component set has midrange/bass in factory position; front lower half of door, and my tweeters are mounted high on the door panel above the mid about 8 to 10 inches above my mid/bass. My tweeter is a dome type. I have thought about moving my tweeters to my sail panels and using my existing tweeter location for my midrange.

Any advice on how I should be approaching this?

Thanks for the helpful sticky. Very well explained, Sir.


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## pocket5s

I guess there are always those few exceptions out there.


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## asawendo

What do you think about dipole drivers Andy? That radiated front and back....it it impossible in the car? Thx


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## Cparker1989

You say keep the tweeters away from the junction of dash,windshield, and side window. Where exactly/and how far from this junction do you feel are ideal locations? I'm also wondering how important it is for a small mid range to be mounted on axis, how many degrees off axis should we try not to surpass?


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## 14642

pocket5s said:


> I guess there are always those few exceptions out there.


OF course one can make a good sounding car by breaking all the rules. I'm just trying to make suggestions that add a measure of predictability and simplify this for as many people as possible. Winning IASCA contests means you win contests, it doesn't necessarily mean it's the best way to build a car that sounds correct (or as close to correct as is possible).


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## 14642

asawendo said:


> What do you think about dipole drivers Andy? That radiated front and back....it it impossible in the car? Thx


Of course, anything is possible, but what's the reason for this? In home theater, they're used to create a diffuse field.


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## 14642

cajunner said:


> I think there might be a problem with the wording in the second number 6.
> 
> I'm going to assume that the crossover in question is the 6.5" low pass, and the high Q means a slight bump in frequency response at the upper end of the 6.5" response.
> 
> If the problem is a peak in the on-axis (combing/break-up), and a drop-off in the off-axis, (narrowed response from beaming/cone diameter function), then building a high Q in the response is going to accentuate the peak, and raise the off-axis response.
> 
> If building a high Q in the crossover is actually meant as creating a high Q filter, and is being used to create a notch at the response peak, then it makes sense that the designer is paying attention to the on-axis response.
> 
> I guess what that means is the notch will cause the off-axis response to drop further and increase the effect of the 6.5" not meeting up with the tweeter.
> 
> But, if building a high Q filter into a crossover doesn't work for the on-axis response because it pushes the off-axis down, is it better to let the peak stay in the on-axis?
> 
> And, are we building crossovers with passive components or pushing software sliders?


Well, I suppose there is a problem: there are two number sixes.

My point is that if the woofer begins to roll off lower than the lowest frequency we can count on the tweeter to play, then there's a hole in the response. The hole will be deeper farther off axis. If we boost the output of the woofer with a high Q crossover so that the on-axis response is flat, then the off axis response will still have a hole. When you adjust the response with an EQ, you'll adjust the power response because the car is reflective and then the on-axis response will have a peak and the off axis response will still have a smaller hole. 

Doesn't matter whether this is a passive or active network.


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## 14642

Cparker1989 said:


> You say keep the tweeters away from the junction of dash,windshield, and side window. Where exactly/and how far from this junction do you feel are ideal locations? I'm also wondering how important it is for a small mid range to be mounted on axis, how many degrees off axis should we try not to surpass?


Tweeters are not as big a problem as midrange speakers in that location.


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## subwoofery

cajunner said:


> I don't understand what you're saying to do, to fix this issue.
> 
> if we can't add some high-side boost to the woofer to "meet" up with the tweeter, because the hole's still there, what else is there?
> 
> are you advocating the use of ellipsoid tweeter faceplates and/or bringing the crossover down to meet the woofer, thereby pushing more sound out of the tweeter but controlling the directivity/dispersion, and leaving the woofer's roll-off alone?
> 
> I saw Pioneer (PRS components) bring the crossover down and introduce a low-playing tweeter, but it seems like a lot of people didn't care for it crossing that low. They preferred the higher crossover with active control, letting the woofers play up higher and crossing steeper than the passives.
> 
> 
> Now, the use of an ellipsoid horn load, seems like a bit of a tussle when mounting these suckers, where and how is the question?
> 
> optimum mounting locations, "tastefully done" implementation of the idea, and accessible vehicles, likely suspects for this kind of install?
> 
> because, horns add a bit of directivity and well, directing the output means it would be easier to mount the faceplates on-axis somehow, I haven't seen this done...
> 
> has it been done, and unobtrusively?
> 
> I did almost take a sledge and body hammer to the wheelwell/dead pedal area, once..
> was going to put a cheap compression midrange bolted from the engine compartment, but it seemed a little crazy, so...
> 
> anyways, looking for solutions/stopgaps, for dealing with uneven power response in the front of the car.
> 
> My install consists of a 5.25" mid and a ribbon tweeter but I'm wanting to cross the ribbon a bit higher than the mid wants to "reach" so any input...


I thought that waveguides (ellipsoid tweeter faceplates) on a tweeter was also to widen dispersion down low in order to better "meet" the midrange around the Xover point... 

Don't really know what your question is...
If the off-axis response has a dip, you add a high-Q boost on the midranges upper end to flatten the response up to the tweeter - then you also add some boost to the reflected energy which as Andy stated, isn't really a good thing. 
Also, the high-Q boost usually works well with the driver's side (closest to you) - however that same high-Q boost accentuates the peak on the passenger's side (more on-axis than the driver's side)

Kelvin


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## 14642

subwoofery said:


> I thought that waveguides (ellipsoid tweeter faceplates) on a tweeter was also to widen dispersion down low in order to better "meet" the midrange around the Xover point...
> 
> Don't really know what your question is...
> If the off-axis response has a dip, you add a high-Q boost on the midranges upper end to flatten the response up to the tweeter - then you also add some boost to the reflected energy which as Andy stated, isn't really a good thing.
> Also, the high-Q boost usually works well with the driver's side (closest to you) - however that same high-Q boost accentuates the peak on the passenger's side (more on-axis than the driver's side)
> 
> Kelvin


No, in fact, they do just the opposite. They narrow the tweeter's dispersion at low frequencies to hopefully match the narrowing dispersion of the midrange at the crossover point. The result should be a power response with gradually diminishing high frequency response without peaks or dips. The "roundover" at the edge of the waveguide (if it exists) helps to scatter the high frequencies from the tweeter to widen dispersion at those frequencies. 

The rest of this is correct.


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## 14642

cajunner said:


> Off-axis will almost always have a dip with a component mid/woofer and tweeter combination.
> 
> I don't know if Andy is advocating for 3-way implementation or some other format that deals with the off-axis hole/narrow dispersion issue.
> 
> and how are you implementing this "high-Q boost" if you don't have parametric equalization and adjustable crossover with level controls?
> 
> just want to understand where the traditional fail modes in installs are being corrected, and by what tools/methodology, since it's important enough to create a thread to discuss the observation/occurrence?
> 
> As it stands, most higher-end metal and sandwich cones and kevlar based woofers are going to have some amount of snap at their roll-off.
> 
> 
> so, going high-tech elevates the region where paper-based drivers smooth out the peak, but we want to enjoy that nice flat region as far out as possible, the issue is that peak is identifiable and noticeable when using active crossovers that do not have extra control, or DSP built-in.
> 
> so, a passive can easily have a notch filter that tames the out-of-band response, and that wonderful smooth response from the filter makes it hard to throw out that network when going active, but that's a drift...
> 
> back to the issue of beaming and narrowing dispersion, is this really that big of a deal?
> 
> Is the multi-element approach consistently able to outperform most 2 way installs?
> 
> the hard question for me is integration, the premium sound package available from JBL had the ellipsoid faceplates and I don't remember ever seeing them used, where they were actually same plane, same axis as a recording monitor might be, as a time-aligned active speaker might be.


Same plane. same axis isn't so critical. The GTi waveguides were designed for use at 35 degrees off axis, to facilitate installation in the doors.


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## subwoofery

cajunner said:


> how did this happen?
> 
> I understand the waveguides aren't off-center, they are symmetrically formed and have no adjustment of any kind, (at least, that's what they look like on an internet screen)
> 
> is the passive network adjusted for off-axis, or is the shape of the guide itself, the angle/pattern coverage tested for 35 degrees of uniform distribution, and that's the cut-off point at which one might be able to perform a door installation?
> 
> And, using the waveguides in the classic format seems like they would be best installed with their flange flush with the existing door panel, this is hard to achieve high in the door without really chopping up the panels, or maybe there's something I'm missing?
> 
> I always liked the clever idea/implementation for using a waveguide but finding them in use has been a bit of a unicorn thing...
> 
> 
> maybe hang them from the bottom corner of the dash, like the ID horns but flush to the dash?
> 
> it's interesting and it's fitting the universal theme of recording monitors of today with a front baffle that has a smooth integrated guide for tweeter control, but in the car the placement options are so limited, and putting them in the dash, what about then? Is the reflection of a controlled dispersion tweeter off the glass going to coherently produce an image with the mid in the door locale?
> 
> is that why same plane/same axis is not as important?
> 
> I've never used the faceplates so I am unaware of their success in various install locations..


If you download the 660Gti manual, there's a good explanation about how to use the waveguide - not sure if it answers your questions but it's worth the read  

Kelvin


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## subwoofery

Not sure in which thread I should write this so I'm writting it here: 


> A room that has a significant amount of reflected energy will often be perceived as more "spacious", and have more of a "they are here" characteristic. A monopole with controlled directivity involves the room less and tends to be more of a "You are there" characteristic.


Taken from: On Loudspeaker Directivity Part 2 Article By Jeff Poth

It's exactly what I've experienced with my 2 cars - Conventional cone and dome drivers VS horns

Kelvin


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## asawendo

subwoofery said:


> Not sure in which thread I should write this so I'm writting it here:
> 
> Taken from: On Loudspeaker Directivity Part 2 Article By Jeff Poth
> 
> It's exactly what I've experienced with my 2 cars - Conventional cone and dome drivers VS horns
> 
> Kelvin


Thanks for the link Bro..


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## subwoofery

asawendo said:


> Thanks for the link Bro..


Thanks for the bump  Hope we can get some reply in this thread  

Kelvin


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## 14642

What kind of a reply are you looking for? I'd agree with the suggestion in theory. the use of a spherical waveguide on a tweeter isn't going to substantially change the perception of ambience, and there's very little opportunity to do any real pattern control in a car over a wide band of frequencies. Acoustic crosstalk is the big problem in cars if "you are there" is the objective. I find that "we're all are somewhere larger than this car" is a pretty good illusion for car audio.


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## subwoofery

Andy Wehmeyer said:


> What kind of a reply are you looking for? I'd agree with the suggestion in theory. the use of a spherical waveguide on a tweeter isn't going to substantially change the perception of ambience, and there's very little opportunity to do any real pattern control in a car over a wide band of frequencies. Acoustic crosstalk is the big problem in cars if "you are there" is the objective. I find that "we're all are somewhere larger than this car" is a pretty good illusion for car audio.


It just that you made such a great first post but I've yet to see people jump into this thread to give their point of view, agree with you or contradict some points in your post...

Guess I'm just bored 

Kelvin


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## AAAAAAA

So are we saying a good place for midrange and tweet is the kick pannel?

Some of us liking both seats sounding good would have to go 35degree for both sides for a compromise.

In regards to center channels, it's pretty much always going to be close to one of those junctions.


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## 14642

There's a HUGE difference between mounting a small mid in the top of the door and mounting it in the dash or the A-Pillar. Kick panels have a couple of advantages and a couple of disadvantages. One of the advantages is that in some cars, the pathlength differences are reduced enough to provide good imaging in the midrange. The second is that they are FAR away from the junction of the windshield, dash and side window.

The disadvantage is that the shape of the footwell often produces a big cancellation in the mottom part of the midrange. The second disadvantage is that there are plenty of opportunities for obstruction from legs, etc. The third disadvantage is that it's difficult to make an enclosure that's big enough to allow the midbass to have flat response and good bass extension.


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## Orion525iT

I am no expert, but I can at least comment on my experience. I originally had 6.5 plus tweeter crossed 24db slopes at 2500hz passive angled in the kicks to get good center stage. I was experiencing a hole in response due to the angle of the 6.5 in the kicks. If I placed the 6.5 further forward, more on axis at the firewall, the hole was gone but the stage pulled to the drivers side. I attribute this stage change mostly to near reflections off the pedal assembly, but intensity differences also come into play here too.

Tried 5" mids in the kicks, and found that the hole was smaller at the crossover, but I lost mid bass output and made sub integration more difficult. 5" at the firewall, and I still had the same near reflection issues as with the 6.5s

As it sits now, I have 8" midbass, 5" mids and tweeter. I am cramming all this into the kick area, away from the pedal assembly to avoid near reflection issues. I have no idea crossover/slopes at this point. But I should be able to run the 8" from 50-1000hz before off axis response begins to diverge greatly, 5" mids should do well from 250-3000hz before off axis response diverges. Tweeters from there. Ideally I would use a 3-4" mid to push the mid/tweet crossover higher and then use a smaller tweet, but its not in the budget.

6.5" plus tweeter may have worked, but the trick would have been to find a tweeter that is comfortable crossing at 1200-1400hz, and there are only a few that can do that. Even so, I felt like there would be zero flexibility in xover and driver placement. It would either work or not.

Going 3-way, for me, adds flexibility to xover and slopes that I could not get with 2-way. This is important because I found a had the best results crossing below the region where a particular driver begins to beam. Even with kick panel location, near reflections were a significant component for me. EQ, TA, whatever would not change that.

I have done all my initial setup specifically without TA or EQ to make sure I am not masking issues like off axis response. Granted my situation is exceptional in regards to placement and the size of drivers I can use, but hopefully it serves as a good example.


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## 14642

Yup. You're on the fight track. A 6", 3" and tweeter might also be sufficient.


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## AAAAAAA

Small midrange basically means something that can play down to where? The last few years all the rage was about paying 3" down to200hz or so. But I'm thinking that low isn't necessary. 800-1k perhaps... Maybe A bit Higher for a dome midrange that needs no enclosure.


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## BuickGN

I'm always playing with crossovers to try and solve my problems that way first. I have the 9s in the doors playing up to 600hz. There was a null there with the 3.5" in the kicks thats not as bad with the 9s covering the same range. 

Instead of the 3.5s playing 4khz and higher, they're at 2,800hz sitting on the dash on axis and pretty far forward (toward me, away from the windshield). I noticed when the 3.5s were playing out past 4khz, response would change severely as I moved my head. I guess it's because the passenger side mid is on axis and the driver's side is 30 degrees off. 

I guess my only point is things seem to change less with each speaker nowhere near it's beaming point. That includes less change when I have passengers' legs blocking the mids or shifting my head one way or the other with the driver's side being off axis.


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## Boostedrex

Great post Andy. I do have some questions though.

1. What is it about the dash/windshield/side window junction that is so bad? I've seen this location work out plenty of times, but it took a LOT of work with acoustical treatments, driver aiming, and tuning.

2. Is it possible to have the drivers up high (dash level) and still pull off a car that sounds correct without having to re-design the better part of the dash?


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## thehatedguy

The part about a lot of acoustical treatments to get it right would probably be the main thing...you are so close to 3 highly reflective surfaces.


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## DonH

great read Andy. thank you for taking the time to post this up. I too have always been a fan of on axis mounting of tweeters. was never able to articulate my reasons as to why. This can now help me!


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## Orion525iT

BuickGN said:


> I guess my only point is things seem to change less with each speaker nowhere near it's beaming point. That includes less change when I have passengers' legs blocking the mids or shifting my head one way or the other with the driver's side being off axis.


That is pretty much were I am with this. I spent months messing with endless configurations to figure this out, although there was already plenty of sound science behind it.

The other thing of note is that having the drivers fully on axis didnt work out exactly either. One would think this would be better, as it you get more direct sound from the driver than reflections. But what I noticed was that the more on axis the speaker was, the more I could localize it. In a room, where one is relatively far away from the drivers, this may not be an issue. But in my experience, at near field things begin to change. Maybe I am picking up on harmonics? Place the drivers off axis, and the harmonics are attenuated along with high frequency dispersion? This may also explain why my stage shifted so drastically to the drivers side when I placed the drivers more on axis; it wasn't just near reflections off the pedal assembly. 

The above observation was repeatable for both the 6.5" and 5" mids. On axis, I could hear slight driver separation. Off axis, they blended and could not pinpoint origin of sound. There seems to be a balance here, and my experience pushed me in the direction mitigating near reflections, crossing well before beaming, with somewhat off axis placement.


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## sqnut

While we are talking about driver placement and axis, is there a particular placement or mounting axis that will bring out greater depth in the stage? Eg mid range in kicks etc.


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## subwoofery

Now we're talkin'  

Kelvin


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## 14642

sqnut said:


> While we are talking about driver placement and axis, is there a particular placement or mounting axis that will bring out greater depth in the stage? Eg mid range in kicks etc.


There are several things that can help to create depth in the stage. First, it's important to separate the stage from the room ambience. The stage is where the musicians are and the room is where you are. Think of an auditorium--the stage dimensions are not the same as the room dimensions. In a bar, it's all one space. This may or may not exist in the recording. If it does, it may be real or fake--doesn't matter so long as it's there. 

To leep it relatively simple, early reflections describe the area around the musicians and late reflections describe the listening space. For studio recordings, these reflections may or may not be added to the mix. IF they're added, then they're often the result of a room synthesis algorithm. many of these are very effective. 

So...first, these reflections have to be included in the recording for you to reproduce them. If you have access to the EMMA disc and the IASCA disc, check out two tracks. Listen to the 7 drum beats track on the IASCA disc and then listen to the track on the EMMA disc where the guy speaks as he walks around the stage. These are good examples of tracks do and don't include these cues. No matter what you do (well, almost--but I'll get to that later), the 7 drum beats will NOT appear far outside the left and right speakers because the recording is simply panned from left to right using simple level controls in the recording. 

The cues do exist in the track on the EMMA disc and they aren't synthesized. With this track it's possible to hear the room larger than the car. 

Then, listen to a third track. Check out "I Will Rise Up" by Lyle Lovett. It's on "It's Not Big, It's Large". I'm not sure whether this is a studio track with room synthesis or recorded live, but it's a good example of a recording that includes a stage and a room. It seems close-miced so it will appeal to those of you who like live recordings and those who don't. 

OK, now think about what you hear when you listen to a concert--choose an auditorium for this mental exercise. The musicians are on stage. You hear the sound directly from the musicians, the sound that's reproduced over the mains (the big speakers on the stage that point AT you) and the sound of those reflected from the side and back walls of the room. You also hear the sound of the musicians and the stage monitors reflected from the surfaces that make up the stage. 

Think about what it would take to ACCURATELY reproduce that even using a recording and speakers placed on the stage if you were in sitting in the auditorium. If you had a speaker located at the position of each of the musicians and those were miced and piped into the house system, that might do it. If you placed two stereo speakers on the stage and piped the output of those through the house system, that would require those speakers to reproduce the space of the stage. Hmmm...

In both of these scenarios, you'd hear the room. The reflected sound would come from all around you, just as it did in the live recording. You'd probably hear a pretty good approximation of what you heard live.

Now, take those two speakers and place them in your live-in room. Hmmm...now the reflected sound you hear is defined by the boundaries of the room. Early reflections come from the space around the speakers and late reflections come from the back and side walls. All the sound from the speakers is reflected by those walls--the sound of the room isn't separated from the sound of the musicians. The early and late reflections are all included in the sound from the front speakers. You may sense from the recording that there was a room, but it won't be reproduced AS a room. 

Now, what if we move to a car. The space is tiny. So tiny that there are no late reflections generated by the "room". We hear the car and the speakers as the same event. Acoustic crosstalk makes this worse. 

OK, so what can we do? Eliminating reflections will get us back to the two stereo speakers in a dead room, but it isn't practical because we have to be able to see through the windshield and the windows. Kick panel mounting helps because the speakers are moved away from the glass. That helps, but low frequencies are still reflected--no matter the surface material--carpet doesn't eliminate low frequency or midrange reflections very well. Much of the ambient information is high frequency stuff, though. OK. So that's an improvement. Now we're closer to good 2-channel. 

But what about the room? For recordings that don't include a room, we're now OK. Dry, studio recordings will sound dry. Images will be small and located between the speakers.90% of the cars I listen to and 99% of competition cars I listen to sound like this. When judges and competitors say, "The musicians aren't behind you when they play live", this is what they're after. When they turn their head to determine if something is coming from behind them so they can take points away, this is what they're after. I don't think those guys have ever been to a live show, and if they have, they weren't listening to the room. 

If you want to win competitions, this is the way to do it. Figure out how to generate a bunch of early reflections in your car. Mount the speakers off axis in the kick panels and bounce **** around all over the place. Maybe you'll get lucky. You may have to remove the dash, cut a big hole in it so the sound of the speakers can bounce off the windshield with the longest path length you can pull off. this will increase the sense of "depth". This is a matter of trial and error and will seem like magic when you get to something you like. 

If you use only front speakers and mount the speakers on your a-pillars and point them at the listeners, you'll NEVER get there. Someone will blast me and say that their car does it, but I'd postulate it's because they've never heard a room or never paid any attention to what live music sounds like. 

So, what else can we do to approximate a room? Simple. Use an upmixer and rear speakers. Most of the upmixers (PL2, DTS Neo, Logic7) help this by attempting to remove the ambient sounds and steer those to the rear. You have to have rear speakers and they have to play loudly enough to be heard as real events. Fortunately, gain controls on the amp that drive the rear speakers make this simple. With this method, if the recording includes a room, it will be better approximated in your car. JBL's MS-8 does this. Other processors with PL2 also do this. It's very effective, but there are some artifacts. Get used to it. 

The third way is to use a room synthesis algorithm that GENERATES a fake room. Early reflections can be added to the front speakers and late reflections can be added to the rear speakers. this can make the car sound larger than it is no matter the recording. This is what I used to use in my Volvo. It also works and I managed to win IASCA at SBN with it. Judges said, "I've never heard a car that REPRODUCED the ambience in the recording the way yours does." I didn't tell them that the ambience didn't EXIST in the recording until after I collected my trophy. There are no car audio processors that include this, yet. I did it with a PC and some custom software, courtesy of a Harman colleague. 

So, after all this, my suggestion is--if you want depth, you have to have a system that can either reproduce it or create it. Two speakers on the a-pillars won't do it. You need rear speakers and you need the right information to be played by those rear speakers.


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## Guest

Andy

What you just so eloquently explained is why I'm so excited to install the MS-8 in my system.... I want the entire vehicle to solidify and anchor the front stage.....

If you have any tips or suggestions PLEASE send me a PM with them...

Thanks again for sharing your vast knowledge.


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## AAAAAAA

Thank you andy


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## sqnut

Andy thanks for your detailed response. I was typing this post while you replied. Took a while to rethink and correct the lines below so as not to come across as the proverbial cocky hammer:blush:. I really want to learn more about depth.

No way to absorb your post in one go, so I'm going to go over it a few more times before coming back with questions.

"The reason I ask about the depth is because, I feel that is one of the issues I haven't been able to resolve, even as everything else got better over six years of tuning. Width, height, tonality and accuracy all improved over six years of tuning. But depth was one thing that never stood out. On the track where the voice locates different points on the stage, deep into the stage images up just beyond the windshield, I feel with good depth this should image over the hood. 

Install is something that has remained constant for me over this period. So all gains have basically come via learning to use the dsp. But depth is one parameter that hasn't improved in line with everything else. In my two way the mids are mounted in the doors but up high, about 8" below the windows. The near mid is pretty much firing into the steering column. The tweeters are mounted in pods near the base of a pillars and are cross firing.

So I'm wondering if depth perception is somehow limited by how the drivers are mounted / angled and if there are other options that would yield better depth."


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## subwoofery

sqnut said:


> Andy thanks for your detailed response. I was typing this post while you replied. Took a while to rethink and correct the lines below so as not to come across as the proverbial cocky hammer:blush:. I really want to learn more about depth.
> 
> No way to absorb your post in one go, so I'm going to go over it a few more times before coming back with questions.
> 
> "The reason I ask about the depth is because, I feel that is one of the issues I haven't been able to resolve, even as everything else got better over six years of tuning. Width, height, tonality and accuracy all improved over six years of tuning. But depth was one thing that never stood out. On the track where the voice locates different points on the stage, deep into the stage images up just beyond the windshield, I feel with good depth this should image over the hood.
> 
> Install is something that has remained constant for me over this period. So all gains have basically come via learning to use the dsp. But depth is one parameter that hasn't improved in line with everything else. In my two way the mids are mounted in the doors but up high, about 8" below the windows. The near mid is pretty much firing into the steering column. The tweeters are mounted in pods near the base of a pillars and are cross firing.
> 
> So I'm wondering if depth perception is somehow limited by how the drivers are mounted / angled and if there are other options that would yield better depth."


One thing that can help is get your tweeters away from the windshield and install them either just above the midrange (high up in the door) or in the sails. 
Second thing that might help is to work on your tweeter's T/A relative to the midrange - I seem to remember (read that many times in a few of your posts) that you added T/A to the tweeter because you "liked" how your system sounded with a late tweeter response. 
It might sound good the way you did it but that might prevent you from having perfect phase in your system. 

One thing I've noticed when tuning is that tweeter phase has a lot to do about how we perceive bass notes - I could aim my Focal tweeter one way and the bass response would drop and sound strained when aiming another way would make the system bloom (when needed) and make the system much more enjoyable...

Kelvin


----------



## sqnut

Andy Wehmeyer said:


> There are several things that can help to create depth in the stage. First, it's important to separate the stage from the room ambience. The stage is where the musicians are and the room is where you are. Think of an auditorium--the stage dimensions are not the same as the room dimensions. In a bar, it's all one space. This may or may not exist in the recording. If it does, it may be real or fake--doesn't matter so long as it's there.


Using the auditorium example, in the car the perception is that of being seated 3 ft from the stage, half way between the mid point of stage edge and right wing. The actual stage depth is not more than 12-18 beyond the front edge. Even on tracks that I know exhibit depth on my home 2ch. At home I'm seated 10 feet from stage and stage depth seems another 8-10' from the edge on tracks that show depth. 

The size of the two rooms is very different so the stage in the car would be scaled down in all three dimensions by the smaller space. But the loss of depth in the car seems out of proportion with the other two dimensions. It would be great if I could push the edge of the stage a couple of feet further and then have 2-3' of stage depth. 



Andy Wehmeyer said:


> To keep it relatively simple, early reflections describe the area around the musicians and late reflections describe the listening space. For studio recordings, these reflections may or may not be added to the mix. IF they're added, then they're often the result of a room synthesis algorithm. many of these are very effective. So...first, these reflections have to be included in the recording for you to reproduce them.


I believe while recording, depth is added by rolling off the highs of what you want to show as deep in the stage, while adding delay or some reverb to that sound. So the late reflections define these delayed rolled off sounds. It's funny how you can know something without really understanding it . That makes a lot of sense. 




Andy Wehmeyer said:


> OK, now think about what you hear when you listen to a concert--choose an auditorium for this mental exercise. The musicians are on stage. You hear the sound directly from the musicians, the sound that's reproduced over the mains (the big speakers on the stage that point AT you) and the sound of those reflected from the side and back walls of the room. You also hear the sound of the musicians and the stage monitors reflected from the surfaces that make up the stage.
> 
> Think about what it would take to ACCURATELY reproduce that even using a recording and speakers placed on the stage if you were in sitting in the auditorium. If you had a speaker located at the position of each of the musicians and those were miced and piped into the house system, that might do it. If you placed two stereo speakers on the stage and piped the output of those through the house system, that would require those speakers to reproduce the space of the stage. Hmmm...


Still absorbing this. If I understand correctly what youre saying is that even in the auditorium the depth of the stage is defined by the ability of the speakers to deliver that depth, since what you're hearing is primarily from the speakers and not the actual instruments themselves........never thought of it that way. Inspite of 'being there' you're not really hearing 'live' sound. Not sure if I'm reading this right



Andy Wehmeyer said:


> In both of these scenarios, you'd hear the room. The reflected sound would come from all around you, just as it did in the live recording. You'd probably hear a pretty good approximation of what you heard live.


The reflected sound defines the physical boundaries of the space. Will come back with questions on the other half of your post. Thank you for helping me understand a lot of stuff tonight.


----------



## sqnut

subwoofery said:


> One thing that can help is get your tweeters away from the windshield and install them either just above the midrange (high up in the door) or in the sails.
> Second thing that might help is to work on your tweeter's T/A relative to the midrange - I seem to remember (read that many times in a few of your posts) that you added T/A to the tweeter because you "liked" how your system sounded with a late tweeter response.
> It might sound good the way you did it but that might prevent you from having perfect phase in your system.
> 
> One thing I've noticed when tuning is that tweeter phase has a lot to do about how we perceive bass notes - I could aim my Focal tweeter one way and the bass response would drop and sound strained when aiming another way would make the system bloom (when needed) and make the system much more enjoyable...
> 
> Kelvin


The way I have it setup is to have the tweeters and mids on each side in phase with each other. When hearing the mid and tweeter on one side, the tweeter is in phase with the mid when 95% of the sound seems to come from the tweeter with only the very low end pulling down towards the mid. Rough sketch description. I agree that having the mid and tweeter in phase is essential tobring out the brass response. While the bulk of fundamentals on bass notes are in the ~60-300 zone, the attack and hence presence are in the harmonics ~1.5-4khz. This is often the transition range between mid and tweeter. Hence both drivers will have an impact here. Having your tweeter out of phase with the mids will take the bite out of the low end.

My sails won't take the Scan tweeters. Will have to open up the door panels to see f something can be done there, but it looks unlikely.

PS You got your wish of livening up this thread


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## sqnut

Based on what Andy mentioned about hearing it live, hearing it live in an auditorium, hearing it in your living room and hearing it in your car, this pink floyd cover seems to put things in perspective........................way past my bed time


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## subwoofery

sqnut said:


> The way I have it setup is to have the tweeters and mids on each side in phase with each other. When hearing the mid and tweeter on one side, the tweeter is in phase with the mid when 95% of the sound seems to come from the tweeter with only the very low end pulling down towards the mid. Rough sketch description. I agree that having the mid and tweeter in phase is essential tobring out the brass response. While the bulk of fundamentals on bass notes are in the ~60-300 zone, the attack and hence presence are in the harmonics ~1.5-4khz. This is often the transition range between mid and tweeter. Hence both drivers will have an impact here. Having your tweeter out of phase with the mids will take the bite out of the low end.
> 
> My sails won't take the Scan tweeters. Will have to open up the door panels to see f something can be done there, but it looks unlikely.
> Which car do you have? Have a pic of your doors with the speaker installed?
> 
> PS You got your wish of livening up this thread  Yep, mission accomplished!!!!! :thumbsup:


One thing that might help you get more depth is to play with your subwoofer's T/A - try adding something like 8ms (maybe even 10ms) to your subwoofer and play with polarity. <-- this will help with the depth of the stage, not the ambience 

Kelvin


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## 14642

Try this experiment at home. Set up a pair of speakers and sit in between them in the standard equilateral triangle. Listen for awhile so you get a good sense of depth. Then, gradually move your chair forward until you are nearly on the same plane as the speakers. As you move the chair forward, reposition the speakers so that they're basically on-axis. 

Hmmm...

This exercise suggests to me that door mounted speakers can contribute better depth and width too. Putting the speakers farther out in front of you changes your listening position relative to the position of the stage, but that isn't image depth. Despite the IASCA rules' attempt to differentiate these two things, many judges and competitors confuse them. I think that's because they don't know what rooms sound like. 

Before you can even go for stage depth, there has to be a stage. That means TA has to be right and the bass has to sound like it comes from the front. Then, the bass needs to be tuned so low frequencies sound like they come from an instrument rather than just from some point in front of you. Bass to midbass integration is 95% EQ and 5% phase, if you ask me. With enough EQ (separate bands for left and right midbass and the sub) I can do it with any crossover point or slope, so long as the sub and the stuff around it don't rattle. I can't do it with a big overlap between the midbass and the sub. In fact, I've never heard it done really well by anyone using a big overlap.

Of course, someone will blast me for that and say theirs does it, but I'd counter by saying that no matter how good you think it is, it could be made better without the overlap.

On-axis, off-axis, aiming, blah blah blah has far more to do with frequency response than it does width of stage, depth of stage, etc. One exception to that is in my first suggestion above--bouncing **** all over the front of the car.


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## Orion525iT

sqnut said:


> Based on what Andy mentioned about hearing it live, hearing it live in an auditorium, hearing it in your living room and hearing it in your car, this pink floyd cover seems to put things in perspective........................way past my bed time


Lol...Ummagumma

My first PF album. I didnt test the waters , I jumped right in. Was hooked ever since.


----------



## asawendo

Hi Andy glad to see you more active in this forum. Regarding your explanation about "The Room Acoustic" I always appreciate when I heard properly executed rear fill in the car with decent processor. Especially for Classical/Orchestra Recording. I like the ambience, sense of spaciousness as long as they are not exaggerated. But the problem is...sometimes its not consistently reproduced between some recording. There are the ones with great ambience and there are the ones with weird ambience. The one with great result usually coming from Telarc, Sheffield and Chesky recording. Maybe you can explain this phenomenon. Thx a lot


----------



## Orion525iT

Andy Wehmeyer said:


> This exercise suggests to me that door mounted speakers can contribute better depth and width.


I think my experiments with different kick panel placements concur with this. I can change position of the speakers fore and aft without change in PLDs, but it does change distance to the ear. Moving the drivers closer seems to widen the stage, and also deepens the stage, and sound is "fuller" But it also sounds like I am a 6" away. Further forward, and the stage narrows, overall sound is drier, distance to stage increases. I cant decide what I like best.



> On-axis, off-axis, aiming, blah blah blah has far more to do with frequency response than it does width of stage, depth of stage, etc. One exception to that is in my first suggestion above--bouncing **** all over the front of the car.


Interesting. At the dash, too many reflections to tame. At the kicks, some reflections needed to create a "room". I have started to second guess using sound absorbing materials under the dash. The main reason is that it pulls the stage. Having some reflections may actually help to keep the stage centered in my case.

I will say, for my personal preference, I tend to like a more cohesive sound. I like tons of ambiance, but if things start to get busy, it actually makes me a bit nauseous. Happens with visual things too. Might just be a brain thing.


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## sqnut

subwoofery said:


> One thing that might help you get more depth is to play with your subwoofer's T/A - try adding something like 8ms (maybe even 10ms) to your subwoofer and play with polarity. <-- this will help with the depth of the stage, not the ambience
> 
> Kelvin


The car is a 07 Ford Fiesta. It's an ugly install, but I'll take some pics and post. 

I measured impulse response and got a bearing on the delay settings for each driver. I think of this as mechanical phase. I used these settings for a long time, didn't mess with them. Getting the drivers in phase helps in disconnecting the sound from the physical drivers, its very easy to pick drivers that are out of phase on that criteria alone, assuming FR is corrected for L/R. Then went to work on the response curve.

I reached a point where I had the isolation of each instrument everything in proportion to the overall stage size. Sound that was close to accurate but something wasn't right. A bit dull and missing the last 10%. This was about 2 years into tweaking. I'd reach a point where I knew I just needed to make a small jump but the eq just would not give that jump. Compared my home audio to the car and realized that the disconnected sound is what was missing in the car. Went back and played with TA on the drivers. Bang!! That is when I learn't that FR and phase are linked. As you change the response curve on the eq you are changing the relative phase between the drivers. So, tweak on the eq and then come back and tweak on the TA. Get that disconnected and dynamic sound that is accurate. This is acoustic phase. 

The range in which I tweak the TA is within +/- 0.5-0.7ms of the readings from the impulse response. Phase and TA is something best set by ear, once you know what you're listening for.

So are you suggesting that I add another 10ms of delay on the sub from where I have t now? Also by adding that delay I'm putting the sub and mids out of phase in any case and you still want me to reverse polarity on the sub? Gonna try it and will let you know.


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## 14642

How are you measuring impulse responses and where do you pick the peak in the impulse response of your subs and your midbass?


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## 14642

asawendo said:


> Hi Andy glad to see you more active in this forum. Regarding your explanation about "The Room Acoustic" I always appreciate when I heard properly executed rear fill in the car with decent processor. Especially for Classical/Orchestra Recording. I like the ambience, sense of spaciousness as long as they are not exaggerated. But the problem is...sometimes its not consistently reproduced between some recording. There are the ones with great ambience and there are the ones with weird ambience. The one with great result usually coming from Telarc, Sheffield and Chesky recording. Maybe you can explain this phenomenon. Thx a lot


Well, I'd say that some recordings simply don't include much ambience. Check out that silly pink panther track on the IASCA disc and then listen to Boom Boom Pow by the Black Eyed Peas. Those are two completely differnt kinds of recordings and shouldn't sound the same. With an upmixer, the Pink Panther will sound big, especially when the full orchestra is playing. Boom Boom Pow won't. With a room synthesis algorithm, everything will sound a little bigger than the car and the Pink Panther will be even bigger.


----------



## sqnut

Andy Wehmeyer said:


> How are you measuring impulse responses and where do you pick the peak in the impulse response of your subs and your midbass?


I set this with the holmimpulse and initially set everything by aligning peaks. A while after I dialed in the acoustic response by ear, I checked again and found that I was closer to aligning initial response.


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## 14642

exactly, but how do you determine the initial impulse for midbass and subs? By picking the top of the hump (which is not a sharp peak)?


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## sqnut

By initial response I'm thinking the base of the curve. So the initial alignment was where the curve started flattening out and down the line when I did this by ear it was about 1/3 way up the initial slope of the peak.


----------



## subwoofery

sqnut said:


> So are you suggesting that I add another 10ms of delay on the sub from where I have t now? Also by adding that delay I'm putting the sub and mids out of phase in any case and you still want me to reverse polarity on the sub? Gonna try it and will let you know.


I got that info from Mic - tried it and it works  

Take notes of your settings then change the T/A setting on the subwoofer to the max. Listen to a well known track with a good beat and work your way down with T/A (on the subwoofer) until it's spot on... 
If that doesn't work, change the polarity of your subwoofer and try again. 

Kelvin


----------



## sqnut

Just carrying the discussion further....



Andy Wehmeyer said:


> Try this experiment at home. Set up a pair of speakers and sit in between them in the standard equilateral triangle......
> This exercise suggests to me that door mounted speakers can contribute better depth and width too.


Not sure if this is correct but, by moving closer to the speakers I would think that the late reflected energy would reduce while early reflections would increase. 



Andy Wehmeyer said:


> Bass to midbass integration is 95% EQ and 5% phase, if you ask me. With enough EQ (separate bands for left and right midbass and the sub) I can do it with any crossover point or slope, so long as the sub and the stuff around it don't rattle. I can't do it with a big overlap between the midbass and the sub. In fact, I've never heard it done really well by anyone using a big overlap.
> 
> Of course, someone will blast me for that and say theirs does it, but I'd counter by saying that no matter how good you think it is, it could be made better without the overlap.


I have tried both underlap and overlap between the sub and mids and neither has worked. I use the eq tailor the response of sub and mids and aim for a transition ~70hz. This with a sub/mid xover at 50hz. Beyond 60hz I'm using the eq to get the sub response to basically fall off a cliff. Any reason why the phase is less important than response? Considering this range ~30-80hz is more sensitive to phase rather than amplitude. 



Andy Wehmeyer said:


> One exception to that is in my first suggestion above--bouncing **** all over the front of the car.


I guess that's a given with most cars



Andy Wehmeyer said:


> With a room synthesis algorithm, everything will sound a little bigger than the car and the Pink Panther will be even bigger.


Ok I have a question here. From an accuracy standpoint should we be adding ambiance / a room by using the algorithm dsp, even though said ambiance may not be on the recording?

My assumption has always been that the objective of car audio is to reproduce a recording as close to whats on the recording.


----------



## sqnut

cajunner said:


> Andy stated the car is too close of an environment to produce the physical delay of reflected sound that you can do in a home environment.


I get that, I was asking about recordings that don't have that space or ambiance recorded in. If you use dsp to add space and ambiance to them are you making things less accurate even though they may sound better. But then again he won using it


----------



## quietfly

silly question, SOTA?


----------



## sqnut

quietfly said:


> silly question, SOTA?


State of the art


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## quietfly

cool thanks!


----------



## destinationfer2

What if I placed my morel supremos about 2-3 inches above my dash on my A-Pillars facing each other out of phase while my Morel CDM-54 4 inch Dome mids and Morel Elate 6.5 on the stock door location about 12-16 inches away from the tweeter location. I've heard a lot of members have had good results with a little tweaking on the DSP..Is this a good Idea?

As for dash reflections I was thinking about a dash mat..
I already have all the equipment but haven't pulled the trigger on the install labor


----------



## eclampsium

Andy Wehmeyer said:


> There are several things that can help to create depth in the stage. First, it's important to separate the stage from the room ambience. The stage is where the musicians are and the room is where you are. Think of an auditorium--the stage dimensions are not the same as the room dimensions. In a bar, it's all one space. This may or may not exist in the recording. If it does, it may be real or fake--doesn't matter so long as it's there.
> 
> To leep it relatively simple, early reflections describe the area around the musicians and late reflections describe the listening space. For studio recordings, these reflections may or may not be added to the mix. IF they're added, then they're often the result of a room synthesis algorithm. many of these are very effective.
> 
> So...first, these reflections have to be included in the recording for you to reproduce them. If you have access to the EMMA disc and the IASCA disc, check out two tracks. Listen to the 7 drum beats track on the IASCA disc and then listen to the track on the EMMA disc where the guy speaks as he walks around the stage. These are good examples of tracks do and don't include these cues. No matter what you do (well, almost--but I'll get to that later), the 7 drum beats will NOT appear far outside the left and right speakers because the recording is simply panned from left to right using simple level controls in the recording.
> 
> The cues do exist in the track on the EMMA disc and they aren't synthesized. With this track it's possible to hear the room larger than the car.
> 
> Then, listen to a third track. Check out "I Will Rise Up" by Lyle Lovett. It's on "It's Not Big, It's Large". I'm not sure whether this is a studio track with room synthesis or recorded live, but it's a good example of a recording that includes a stage and a room. It seems close-miced so it will appeal to those of you who like live recordings and those who don't.
> 
> OK, now think about what you hear when you listen to a concert--choose an auditorium for this mental exercise. The musicians are on stage. You hear the sound directly from the musicians, the sound that's reproduced over the mains (the big speakers on the stage that point AT you) and the sound of those reflected from the side and back walls of the room. You also hear the sound of the musicians and the stage monitors reflected from the surfaces that make up the stage.
> 
> Think about what it would take to ACCURATELY reproduce that even using a recording and speakers placed on the stage if you were in sitting in the auditorium. If you had a speaker located at the position of each of the musicians and those were miced and piped into the house system, that might do it. If you placed two stereo speakers on the stage and piped the output of those through the house system, that would require those speakers to reproduce the space of the stage. Hmmm...
> 
> In both of these scenarios, you'd hear the room. The reflected sound would come from all around you, just as it did in the live recording. You'd probably hear a pretty good approximation of what you heard live.
> 
> Now, take those two speakers and place them in your live-in room. Hmmm...now the reflected sound you hear is defined by the boundaries of the room. Early reflections come from the space around the speakers and late reflections come from the back and side walls. All the sound from the speakers is reflected by those walls--the sound of the room isn't separated from the sound of the musicians. The early and late reflections are all included in the sound from the front speakers. You may sense from the recording that there was a room, but it won't be reproduced AS a room.
> 
> Now, what if we move to a car. The space is tiny. So tiny that there are no late reflections generated by the "room". We hear the car and the speakers as the same event. Acoustic crosstalk makes this worse.
> 
> OK, so what can we do? Eliminating reflections will get us back to the two stereo speakers in a dead room, but it isn't practical because we have to be able to see through the windshield and the windows. Kick panel mounting helps because the speakers are moved away from the glass. That helps, but low frequencies are still reflected--no matter the surface material--carpet doesn't eliminate low frequency or midrange reflections very well. Much of the ambient information is high frequency stuff, though. OK. So that's an improvement. Now we're closer to good 2-channel.
> 
> But what about the room? For recordings that don't include a room, we're now OK. Dry, studio recordings will sound dry. Images will be small and located between the speakers.90% of the cars I listen to and 99% of competition cars I listen to sound like this. When judges and competitors say, "The musicians aren't behind you when they play live", this is what they're after. When they turn their head to determine if something is coming from behind them so they can take points away, this is what they're after. I don't think those guys have ever been to a live show, and if they have, they weren't listening to the room.
> 
> If you want to win competitions, this is the way to do it. Figure out how to generate a bunch of early reflections in your car. Mount the speakers off axis in the kick panels and bounce **** around all over the place. Maybe you'll get lucky. You may have to remove the dash, cut a big hole in it so the sound of the speakers can bounce off the windshield with the longest path length you can pull off. this will increase the sense of "depth". This is a matter of trial and error and will seem like magic when you get to something you like.
> 
> If you use only front speakers and mount the speakers on your a-pillars and point them at the listeners, you'll NEVER get there. Someone will blast me and say that their car does it, but I'd postulate it's because they've never heard a room or never paid any attention to what live music sounds like.
> 
> So, what else can we do to approximate a room? Simple. Use an upmixer and rear speakers. Most of the upmixers (PL2, DTS Neo, Logic7) help this by attempting to remove the ambient sounds and steer those to the rear. You have to have rear speakers and they have to play loudly enough to be heard as real events. Fortunately, gain controls on the amp that drive the rear speakers make this simple. With this method, if the recording includes a room, it will be better approximated in your car. JBL's MS-8 does this. Other processors with PL2 also do this. It's very effective, but there are some artifacts. Get used to it.
> 
> The third way is to use a room synthesis algorithm that GENERATES a fake room. Early reflections can be added to the front speakers and late reflections can be added to the rear speakers. this can make the car sound larger than it is no matter the recording. This is what I used to use in my Volvo. It also works and I managed to win IASCA at SBN with it. Judges said, "I've never heard a car that REPRODUCED the ambience in the recording the way yours does." I didn't tell them that the ambience didn't EXIST in the recording until after I collected my trophy. There are no car audio processors that include this, yet. I did it with a PC and some custom software, courtesy of a Harman colleague.
> 
> So, after all this, my suggestion is--if you want depth, you have to have a system that can either reproduce it or create it. Two speakers on the a-pillars won't do it. You need rear speakers and you need the right information to be played by those rear speakers.


Wow, wow, wow! Now you cleared my toughts!!! Off course, having a jbl bit one or MS8 and a very good head unit coupled to top notch speakers will help everyone, but, after reading this, i'm pressed to tell a litle,bit about some off my last cars and how i ended up having a good soundstage in the last two with a very good linearity on the frequency spectrum and integration among the hy/mids/lows on all speakers.

about 1996-1997 i bought my first good head unit. It was a very expensive pioneer deh?? 9250 with DEQ hide away unit, DSP... It was able to cut high and low on each channel and a parametric 3 point adjust on 9 bands sepparately for the front and the rear channels. It could add trough the dsp some ambience too with some sophisticated algoritims (more than those comon off today head units) but i didn't have much good speakers and amplifyers at that time, but that was able to amuse me and to make me know how much important a goos head unit can be. I'm until today searching for such nigh capable headunit coupled to modern days stuff... that head unit walked with me for nothing less than 3 cars, while the rest off the equipment evolved to a nicer system... good quality, but no gorgeous soundstage at that time... 

Later i finnaly had the cash to make a complete new system arround 2006, wich consisted off a JVC kdavx2 headunit capable off dolby prologic 5.1 channels (more on that later), wich was used to create a truly 5.1 channles system in my litle peugeot206 at that time, with a mtx tcx6.1 kit in the fronts, a tcx5.1 kit on the rears, two 3 inch full,range speakers boxed in a litle space in my console ahead of the gear knob. All the speakers were on axis, the sub was an Kicker 10inch square L7 in a small sealed box. The aplyfyer was a 5.1 channel Audiobahn with an exquisite but nice power arrangement off 2x150 to the front, a bit less for the rears, a 75-115 rms center channel and a 300-500-800 sub chanel all with the required normal stuff (i missed that amp). The result was a 28 points out off 30 possible on the rta test in my first local IASCA competition and a 1st place begginer trophy (Ok, the local competition in the begginer class was easy  ) The car had a reasonably good soundstage with a clearly focused voice singing in front off me, was nice on that drums test from left to right, but despite the good linearity, absence off frequency gaps between the mid's and high's, it was clear that the soundstage was being upgraded becouse off the dolby prologicII processing and when it was "on" it significantly handicaped my low mids in the door panels, despite adequate door panel treatments, if i backed to normal stereo mode, it would give back my midbass authority but disable the center channel and dismantle my sharp focused soundstage... that remained for 3 years, when i changed the car for a fiat Punto T-Jet Abarth, wich carried over all the sound system...

On this car, i continued evolving the system, made even better door treatment and angled a bit more the door midbass towards the passengers, mounted the tweeters on axis again but in a dedicated space a bit upp and front off the A pillars above the dash (Had to add - 4,5 db on the tweeters to please my ears). This time i put my dual 3 full ranges in a custom box just above the dash, off axis this time. Wow! the soundstage increased it's size and gained a bit more off depth wich wasn't there in the last build. The L7 was ported and gave me much more bass in this build, but, i remained with the trade off, nice soundstage with excellent frequency covering range but a litle gap between the door midbass and the sub, despite my better instalation on that car... That remained 2 years...3 then i had the idea off correcting that with 2 small amplifyed subs from pioneer, under the front seats, that came with dedicated crossovers making a nice blend among them and the door midbass and the rear sub. Now i had a punchy midbass and a total off 670RMS being unleashed in the front part off the car... Man... Coupled with that high positioned centerchannel creating a spacious soundstage in front off me... In a warm bassy configuration (my preference) that could be adjusted on the fly to very neutral with the knobs in front off me without needing to enter any menus off the head unit... God! i was in automotive sound heaven for the first time....

then, with a knee problem, i had to change my manuat trans car to a automatic, and sold everything together for a BMW 328i Sport-M wich came with a very good sound from factory, not much powerfull, but very linear, with a good soundstage, thanks to a nice center channel up there in the dash, off axis, just like my old car use to have, but the bmw one seems punchy there. I just added a Morel Ultimo SC10 sub in a sealed box with a jbl DSP controled MS-5001 sub amplifyer and it was done... a nice factory 3 - way system plays cleanly in the front, with mid bass under the seats, midrange up on the door panels and tweeter in A pillars. Perhaps that's the trick... you just need the right equipment and on axis kit, and an off axis center channel to create the "illusion" off a wider soundstage. Maybe, using an old pionner external DEQ connected only to the rear speakers can create the ambience we are looking for, increasing the car size... Or maybe, it could be connected only to an off axis mid speaker above the dash and in the rear off the car... Man... The rest, straight from the head unit and on -axis based mount... Am I traveling too much??? :laugh:


----------



## eclampsium

destinationfer2 said:


> What if I placed my morel supremos about 2-3 inches above my dash on my A-Pillars facing each other out of phase while my Morel CDM-54 4 inch Dome mids and Morel Elate 6.5 on the stock door location about 12-16 inches away from the tweeter location. I've heard a lot of members have had good results with a little tweaking on the DSP..Is this a good Idea?
> 
> As for dash reflections I was thinking about a dash mat..
> I already have all the equipment but haven't pulled the trigger on the install labor


Maybe try just temporarily placing them in different points before finally putting them... the mid bass may just go there i think, with good door treatment...


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## eclampsium

Orion525iT said:


> Th...
> 
> The above observation was repeatable for both the 6.5" and 5" mids. On axis, I could hear slight driver separation. Off axis, they blended and could not pinpoint origin of sound. There seems to be a balance here, and my experience pushed me in the direction mitigating near reflections, crossing well before beaming, with somewhat off axis placement.


Exactly!!! Maybe not totally on axis nor totaly off axis.... Analyzing my bmw factory sound and taking in consideration what you are saying and Andy, i understand why the factory uses a 3 way kit with on axis tweeters (so it doesn't get much reflections, distortions and frequency bumps/gaps) and the mid's are in the door in an mid to upper portion but slightly off axis, one door facing the other, so that it's not totally on axis, helping to create a wider soundstage and a bit off ambience, the midbass they put under the seat and, as it plays lower frequency, less directional frequencies, it seems to blend perfectly with the door mids, making it seems that there is bass coming from "somewhere" in the fornt off the car, but you can't locate well exacly where... And then comes the center channel in an off axis position above the dash, helping to construct the soundstage trough a bit off disperse waves off sound in a broad spectrum off frequencies... Making it looks like the sound is,coming from somewhere in front you, without you being able to pinpoint exactly where is the speaker... I'm starting to think about using a sepparate dsp just to add effects on the off axis, above the dash speakers and back speakers on my next build, letting the rest alone...


----------



## MetricMuscle

I've read through this a few times to let it all sink in. Some of this I was aware of, some sort of but didn't think as deeply about it, some not so much.

I wonder if we might at this point try to summarize most of this discussion and make some determinations about priorities when designing a system, compromises that can't realistically be avoided but can be corrected or cannot be corrected, etc. 

If I have understood this thread correctly up to this point:

1. Positioning of drivers On-Axis relative to the listener is always desired.
2. Positioning of drivers to avoid early reflections is always desired.
3. Positioning of drivers Horizontally for Equal Path Length from listener is always desired but not easily/realistically accomplished in automotive environment. Vertical height differences are not as big an issue.
4. Positioning for single point source is always desired but not always easily/realistically accomplished in automotive environment. Will TA correct issues of non-point source positioning like combing etc. ?

A DSP can correct:
1. Path Length Differences
2. Phase - Doesn't phase just affect time alignment?
3. EQ
4. More intricate crossover control to experiment with.
5. Combing?

A DSP can not correct:
1. TA issues due to reflections.
2. Combing?

I think it is very unrealistic to try to compare home audio to car audio because:
1. On-Axis is easy in home audio.
2. Avoiding early reflections is easy and later reflections will actually add to the spaciousness of home audio. Floor, ceiling, walls and windows are the culprits.
3. Do later reflections even exist in car audio due to small environment?

This leads me to believe if I commit to using a DSP I can de-prioritize:
1. PLD
2. ?

....but I will still need to:
1. Avoid early reflections by not placing any drivers near glass, the dash, console, my six-pack abs, any hard reflective surface.
2. Position all drivers On-Axis except for those producing below XXHz frequency?

When stating the above in a factual like manner, I am asking as much as stating, please make any necessary corrections.


----------



## Jepalan

Nice summary. I am a total NOOB compared to the experts on this forum, but I don't think DSP can completely correct for combing. Not where combing is caused by complex phase interactions from multiple reflections reaching the ear via different delay paths. I could be wrong on this - I am sure the experts will chime in. 

This is why positioning, aiming, and deadening are critical. Getting the physical space impacts "out of the way" first allows you to fine tune the rest with EQ & TA.


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## Hanatsu

Combing caused by reflections will not be "fixed" with any type of processing. You can however compensate for the effects the reflections have by EQing away the peaks in the frequency response. Combing due to destructive interference/interaction from two speakers can be altered with T/A though (this will also have an effect on the FR). 

You alter phase with T/A, a linear phase shift vs frequency. 

Avoiding early reflections are basically near impossible to archive, might be able to pull it off with waveguides/horns to some point. Still, avoiding early reflections in the lower midrange will not be possible for all practical intents and purposes. It's easier to EQ the reflections together with the direct sound, i.e "spread the chaos around". 

If you don't got a DSP I suggest you get one. Channel independent EQ together with T/A is a good recipe to improve the soundstage. Active crossovers are great to have as well. ^^


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## Jepalan

Hanatsu said:


> <snip>
> You alter phase with T/A, a linear phase shift vs frequency.
> 
> Avoiding early reflections are basically near impossible <snip>... It's easier to EQ the reflections together with the direct sound, i.e "spread the chaos around".


Re phase & T/A: Agree. T/A only "fixes" phase of the direct paths. Which is a good thing. And as you said, T/A can reduce destructive/constructive interference from multiple sources (i.e. multiple speakers) reaching the ears as long as you have independent T/A control for each source.

I am not sure I understand your second point re "EQ the reflections together with direct sound to <sic> spread the chaos". I guess you just mean to reduce constructive peaking where you can with the EQ? Can you elaborate? The constructive/destructive effect of reflected sound can change so easily with head position, it seems this would only be useful with large room effects that are quite "static" in nature - i.e. low freqs.


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## Hanatsu

Jepalan said:


> Re phase & T/A: Agree. T/A only "fixes" phase of the direct paths. Which is a good thing. And as you said, T/A can reduce destructive/constructive interference from multiple sources (i.e. multiple speakers) reaching the ears as long as you have independent T/A control for each source.
> 
> I am not sure I understand your second point re "EQ the reflections together with direct sound to <sic> spread the chaos". I guess you just mean to reduce constructive peaking where you can with the EQ? Can you elaborate? The constructive/destructive effect of reflected sound can change so easily with head position, it seems this would only be useful with large room effects that are quite "static" in nature - i.e. low freqs.


Below the Schroeder frequency (~200-300Hz) the response won't vary much at all if you move your head - these frequencies will be dominated by room modes. At higher frequencies as the wavelengths get smaller, any smaller head movement will change the FR. This doesn't matter as much as you might think, normally when you measure that range, you average with 1/3oct smoothing and use the appropriate EQ settings to tame the smoothed response plot. 

What I meant by EQing the reflections together with the direct sound is that all reflections basically are phantom speakers with their own phase/FR. These phantom speakers (reflections) will blend much better with the source (and yield a better stage) if their response is similar to that of the direct sound (the speaker). The areas where the reflections are in phase with the direct sound the SPL will add, wherever the reflections is near 180deg out of phase with the source, there will be a null. The constructive interference can be EQed out, the nulls however can not. Also, if you mount the speaker on-axis, the off-axis response will be crucial how the near reflections "behave" - you want the offaxis response as similar to the on-axis response as possible (beyond the speaker's beaming point the offaxis dispersion will be more and more attenuated, it's important that the overall shape of the FR is similar, not the absolute SPL).


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## MetricMuscle

Jepalan said:


> I am not sure I understand your second point re "EQ the reflections together with direct sound to <sic> spread the chaos". I guess you just mean to reduce constructive peaking where you can with the EQ? Can you elaborate? The constructive/destructive effect of reflected sound can change so easily with head position, it seems this would only be useful with large room effects that are quite "static" in nature - i.e. low freqs.


I think he means where you have peaks and/or holes from the sum of both direct and reflected sound you can use EQ to increase or decrease the actual output so the summed response is level.

The combing I'm more worried about is when two drivers that crossover to each other are not close to each other. Response at or near the crossover point will produce combing as the sound is being split between the two. In home HiFi this is a bigger issue the higher the crossover point is, like where a mid crosses to a tweeter. There is an actual equation to determine how far away the two drivers can be. This distance gets to be so small at some point the drivers need to be coincident or co-axial or you have to lower the crossover point. A mid-bass to a mid crossing around 300Hz is no issue, you can have many inches of separation. 

I've read in other threads that the vertical height differences between the left and right front speakers is not very discernible to human hearing like the actual distance horizontally is. So, the driver arrangement on the passenger side doesn't necessarily have to look just like the driver's side. What is important is the horizontal distance each driver is from the listening position regardless of height, to a point. What gives you image, stage, depth width etc. is the timing of arrival be it from equal path lengths or time alignment. 

With this in mind, the whole concept of pillar mounted mids and/or tweeters provides little if no benefit and causes most of the uncorrectable issues a car has. Reflection and combing unless the mid is up there too and crossed to the midbass low enough. Door mounting becomes a good alternative since the path length distance kick panels provide can be handled by the DSP. 

Advantages of pillar mounted mid and/or tweeter:
1. On-Axis driver positioning.
2. ?

Disadvantages of pillar mounted mid and/or tweeter:
1. Reflection.
2. Combing due to separation distance to mid-bass or tweeter.
3. Path Length Difference.
4. More intrusive and limited enclosure size/realistic driver sizes.

Advantages of kick panel mounted mid and/or tweeter:
1. Path Length Distance.
2. Point source driver positioning.
3. On-Axis driver positioning.
4. Less early reflection.

Disadvantages of kick panel mounted mid and/or tweeter:
1. Easy to block driver path with foot, leg, arm etc.
2. Fitment issues like emergency brake or clutch pedal, enclosure volume, no actual kick panel area in some cars.

Advantages of door mounted mid and/or tweeter:
1. Point source driver positioning including the mid-bass in a 3-way.
2. Already OE locations.
3. Lotsa room for enclosure volume and actual driver sizes.
4. Less reflection.

Disadvantages of door mounted mid and/or tweeter:
1. On-Axis mounting not always easy, especially if using OE location.
2. Path length distance.
3. Possible to block driver path with foot, leg, arm etc.


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## eclampsium

I'm planning to make a test in mu current build and will post the result someday here by the end off the year... I'm restoring an old C-10 truck and as it is in bare metal right now, i'm building locations for the midbass and midhy in the door, sealed. Maybe a litle bit off on axis tilt on them to avoid reflections from the dash, as i need to place them more forward to avoid much distance difference from the tweeters mounting in the pillar (i'll mess sith the position before placing them definetly...). These will be handled by an amp. I'll make an experiment, placing two 3" full ranges (the paper dual cone types, without a proper tweeter) in the dash reflecting they're sound to the windshield connected in the own main unit Front channels (ore rear channels to make easy to correct distance adjustments i think) and will play with the Rar channel crossover point and channel volume and see how will it blend with the 3-way kit and helps construct (or deconstruct) the soundstage... If i don't like the end result, i'll simply turn down the channel volume trough fader... As i don't plan using rear speakers becouse it's a single cab... and it's in bare metal, the time to make 2 aditional holes is right now... My best experiences, are with good headunits and a mix off on-axis/off-axis placements and as previously sayd here the thread, a DSP with time and mic frequency analysis and correction is a strong bet...


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## Jepalan

Hanatsu & Metric - thanks for the clarifications re EQ and combing. Makes complete sense. I'm learning a great deal following this thread. Dang it, now I want to go make some angled rings for my front mid-bass drivers and get them more on-axis. (That and cover my entire interior with anechoic foam)


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## MetricMuscle

So, to minimize reflections:
1. Mount drivers On-Axis.
2. Select drivers that do not have a wide dispersion pattern.
3. Mid-bass woofer can be Off-Axis if low passed around 300Hz.
4. Sub woofers are not an issue either.
5. Can wave guides be used on all frequencies?


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## Hanatsu

Dispersion is related to cone size. A standard 6,5" driver is omni directional far beyond 300Hz. A driver with 6,5" cone area should be good to about 2,5kHz. This frequency goes down as cone area goes up. 

A widebander got one serious issue, you want to reproduce a wide range of frequencies - some are within its omni-directional dispersion range and frequencies (for a 3" driver, 4-6kHz) some are not. The sound power will not be even in the entire range, the lower frequencies get reflected into nearby surfaces and creates phantom speaker sources. The higher frequencies however, they are "only" coming from the speaker without much reflected energy reaching the listener, the sound power won't be even at all frequencies. The effect this has is that a widebander will have a "boosted" midrange and a lacking high-end (generally speaking), if you look a measurement at listening position - it will look like there's a lowpass filter applied around 4-5kHz. You basically have to make severe cuts with EQ or carefully place crossovers to counteract this. A waveguide/horn works in the same way, larger = lower frequency "working range". At some point the wavelengths will be so long that narrowing them are impossible because the horn/WG won't fit inside a car. Horns/waveguides might be somewhat practical to implement down to 1kHz if I have to mention some arbitrary number...

It's either going the horn/waveguide route and avoiding much of the reflections in an extended range OR spread the chaos around, i.e have an even sound power at all frequencies so the reflected sound is similar to the direct sound over an extended range. This is generally easiest to pull off, just don't use drivers beyond their beaming point, use drivers with a well behaved offaxis response and try out different mounting options - sail panels are often great imo.

Sent from my Samsung Galaxy 3 via Tapatalk.


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## eclampsium

Hanatsu said:


> Dispersion is related to cone size. A standard 6,5" driver is omni directional far beyond 300Hz. A driver with 6,5" cone area should be good to about 2,5kHz. This frequency goes down as cone area goes up.
> 
> A widebander got one serious issue, you want to reproduce a wide range of frequencies - some are within its omni-directional dispersion range and frequencies (for a 3" driver, 4-6kHz) some are not. The sound power will not be even in the entire range, the lower frequencies get reflected into nearby surfaces and creates phantom speaker sources. The higher frequencies however, they are "only" coming from the speaker without much reflected energy reaching the listener, the sound power won't be even at all frequencies. The effect this has is that a widebander will have a "boosted" midrange and a lacking high-end (generally speaking), if you look a measurement at listening position - it will look like there's a lowpass filter applied around 4-5kHz. You basically have to make severe cuts with EQ or carefully place crossovers to counteract this. A waveguide/horn works in the same way, larger = lower frequency "working range". At some point the wavelengths will be so long that narrowing them are impossible because the horn/WG won't fit inside a car. Horns/waveguides might be somewhat practical to implement down to 1kHz if I have to mention some arbitrary number...
> 
> It's either going the horn/waveguide route and avoiding much of the reflections in an extended range OR spread the chaos around, i.e have an even sound power at all frequencies so the reflected sound is similar to the direct sound over an extended range. This is generally easiest to pull off, just don't use drivers beyond their beaming point, use drivers with a well behaved offaxis response and try out different mounting options - sail panels are often great imo.
> 
> Sent from my Samsung Galaxy 3 via Tapatalk.


It's exactly the phantom that i'll try to create, but, only with the voice, and subtly... those speakers do not have a proper tweeter (they are not a 2-3way coaxial) and i will mostly work with mid frequencies (voice), wich i like to feel the singer more in front and more disperse... not being pinpointed from the tweeters.... They are very well behaved offaxis as i've used them in two other car's in the past (I'll have to look after them, if they still exists for sale here), and i will try angling it in different directions to see what happens... If it's not good, i'll just shut them down, but i really would like to try it, as i think completely on axis speakers usually produce a very linear response, balanced and well separated frequency ranges, it sometimes just can't seem to simulate ambience too well without artificial DSP settings that create tonal differences/colorations in the soundtrack... The best position for the 3-way kit speakers is something i'm still thinking about...


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## MetricMuscle

Hanatsu said:


> Dispersion is related to cone size. A standard 6,5" driver is omni directional far beyond 300Hz. A driver with 6,5" cone area should be good to about 2,5kHz. This frequency goes down as cone area goes up.


What is the smallest cone size mid that you feel can reproduce from 300Hz up?



Hanatsu said:


> - sail panels are often great imo.


What do you like to mount in the sails, what size, crossover, aiming position etc. ?

One of my projects is a '97 Lexus LS400. It has a 5.25" mid in the doors in a factory enclosure. It is paired with a small maybe 1" diameter dome tweeter in the sail panel aimed across the windshield at the other sail panel.
I've read that this can be used as an "imaging" tweeter but high passed 8KHz or so. 
-Are these reflections not as bad?
-Are they later?
-Is the higher frequency better for less dispersion?

I doubt my factory tweeters are crossed that high since they have to work with the 5.25" mid in the doors.


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## Hanatsu

MetricMuscle said:


> What is the smallest cone size mid that you feel can reproduce from 300Hz up?


The smallest driver that can do 300Hz and up? I recommend a 3" for that, might get away with a really good 2,5" if you don't push it too much.

Scan-Speak 10f is a great widebander from 300Hz+



MetricMuscle said:


> What do you like to mount in the sails, what size, crossover, aiming position etc. ?
> 
> One of my projects is a '97 Lexus LS400. It has a 5.25" mid in the doors in a factory enclosure. It is paired with a small maybe 1" diameter dome tweeter in the sail panel aimed across the windshield at the other sail panel.
> I've read that this can be used as an "imaging" tweeter but high passed 8KHz or so.
> -Are these reflections not as bad?
> -Are they later?
> -Is the higher frequency better for less dispersion?
> 
> I doubt my factory tweeters are crossed that high since they have to work with the 5.25" mid in the doors.


Not sure what you mean with those last two questions. Anyway...

I like to put small widebanders in sail panels, 3" is the best compromise imo (unless you got space for a 4" - those go lower, generally). Usually aim midrange/tweeters somewhat on-axis but it's trial and error mostly. I don't use mine as widebanders but rather as midrange drivers with extended upper range. I recommend pairing a 3" driver with a tweeter crossed around 3-5kHz. The tweeters can be mounted close the widebanders, A-pillars might be a good spot. Just keep the drivers away from the windshield as much as you can. Since you can't avoid reflections altogether your best bet would be to use them to your advantage instead, try out different angles/positions and listen for a while - how's the stage affected by different positions for instance. 

If you go with a 2-way front and you're using 5,25" / 1" drivers I'd start trying out crossovers around 3kHz. Note that the acoustic crossover point (measured) and electric crossover point (DSP, HU, Passive/Amp) often differs quite much, to find the optimal crossovers for specific mounting locations and drivers you really need to measure the system.


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## MetricMuscle

Hanatsu said:


> The smallest driver that can do 300Hz and up? I recommend a 3" for that, might get away with a really good 2,5" if you don't push it too much.
> 
> Scan-Speak 10f is a great widebander from 300Hz+
> 
> 
> 
> Not sure what you mean with those last two questions. Anyway...
> 
> I like to put small widebanders in sail panels, 3" is the best compromise imo (unless you got space for a 4" - those go lower, generally). Usually aim midrange/tweeters somewhat on-axis but it's trial and error mostly. I don't use mine as widebanders but rather as midrange drivers with extended upper range. I recommend pairing a 3" driver with a tweeter crossed around 3-5kHz. The tweeters can be mounted close the widebanders, A-pillars might be a good spot. Just keep the drivers away from the windshield as much as you can. Since you can't avoid reflections altogether your best bet would be to use them to your advantage instead, try out different angles/positions and listen for a while - how's the stage affected by different positions for instance.
> 
> If you go with a 2-way front and you're using 5,25" / 1" drivers I'd start trying out crossovers around 3kHz. Note that the acoustic crossover point (measured) and electric crossover point (DSP, HU, Passive/Amp) often differs quite much, to find the optimal crossovers for specific mounting locations and drivers you really need to measure the system.


What do you like about mounting the mid and tweeter in the sail/pillar? 
What does this do for the stage, image, depth etc.?

I suppose high-passing them around 250-300Hz would minimize any combing between a mid-bass driver. I agree that they should be considered and used as a wide band driver or extended range mid driver.


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## shavis

Right now my ML280s and ML700s are under the factory speaker grills firing straight up at the windshield glass. Sounds pretty good, but not larger than the car (and it's a small car). 

Would removing the factory hard plastic grills in favor of something a little more acoustically transparent make much difference? Or do I really need to build something in the pillars to take them on axis for any profound changes?

Any thoughts anyone?

Thanks!

Cheers!


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## MetricMuscle

The crux of this thread discusses how much damage early reflections can have on an otherwise high SQ car audio arrangement. Splashing off the windshield would be the most direct way to produce early reflections so at least from this thread's point of view, removing the grills will actually have a profoundly undesirable effect.


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## shavis

MetricMuscle said:


> The crux of this thread discusses how much damage early reflections can have on an otherwise high SQ car audio arrangement. Splashing off the windshield would be the most direct way to produce early reflections so at least from this thread's point of view, removing the grills will actually have a profoundly undesirable effect.


So keep the grills? From the drivers seat, there is not a direct line to either pair of speakers, so everything to the ears is essentially reflected. Do you think the grills are not muffling the sound in a fashion? It's like a hard plastic course screen. They had the Bose components in them before, new speakers now, so it's not a situation I can just remove the covers and listen, though that would be nice! Would have to make something completely new.

Keeping the grills certainly looks better to me (I like the stealth appearance). 

Thanks!!


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## MetricMuscle

shavis said:


> So keep the grills? From the drivers seat, there is not a direct line to either pair of speakers, so everything to the ears is essentially reflected. Do you think the grills are not muffling the sound in a fashion? It's like a hard plastic course screen. They had the Bose components in them before, new speakers now, so it's not a situation I can just remove the covers and listen, though that would be nice! Would have to make something completely new.
> 
> Keeping the grills certainly looks better to me (I like the stealth appearance).
> 
> Thanks!!


I'm sure the grills are not helping the situation but this thread was about the benefits of mounting your drivers on-axis and the problems that arise when they are mounted off-axis. How and why those who compete do what they do and what they have found to compensate for issues caused by early reflections. The many issues mounting a small mid or tweeter on the sail panel or A-pillar can create and why the kick panel location is better in most cases.

.....but then, even after all of this cutting edge discussion, Hanatsu posts that he is still gonna mount his stuff on the sail panel and just dismiss all of this brilliant brainstorming we have had from all over the world so, I don't really know what to tell you, I'm feeling kinda broken, like all of my efforts to eradicate early reflections and create superior SQ have fallen on deaf ears, possibly from too much high SPL.


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## Hanatsu

MetricMuscle said:


> I'm sure the grills are not helping the situation but this thread was about the benefits of mounting your drivers on-axis and the problems that arise when they are mounted off-axis. How and why those who compete do what they do and what they have found to compensate for issues caused by early reflections. The many issues mounting a small mid or tweeter on the sail panel or A-pillar can create and why the kick panel location is better in most cases.
> 
> .....but then, even after all of this cutting edge discussion, Hanatsu posts that he is still gonna mount his stuff on the sail panel and just dismiss all of this brilliant brainstorming we have had from all over the world so, I don't really know what to tell you, I'm feeling kinda broken, like all of my efforts to eradicate early reflections and create superior SQ have fallen on deaf ears, possibly from too much high SPL.


LOL... Eradicate early reflections??? Good luck with that. Not going to happen (at least not in any possible practical manner below 1kHz).


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## 14642

Well, if you're using a 3-way and using a small midrange AND a tweeter, then the three drivers (with the exception of the tweeter) will probably e playing within their piston range, where dispersion is pretty much hemispherical or wider. 

That means that on-axis and off-axis are the same. Sound will radiate in essentially all directions from each of the speakers. I think the best thing to do is to move them AWAY from the windshield. Tweeters in the sail panels and the midrange in the top of the door. All open-back speakers, even little ones, require some specific enclosure volume at a minimum to provide flat response. I just don't see a little pod for a 4" in the sail panel being enough volume. 

Making a tiny box around the basket of a 6" speaker and putting it in the A-Pillar is REALLY not a good idea. Why stick a 6" up there and then restrict the low frequencies with a tiny box? I see it all the time...


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## cajunner

two things:

1.) Windshields can work in or out of your favor. 

the angle of the windshield, the distance from the glass, the mounting scheme of the speaker and it's size, even the type can make big differences in what you end up with.

using lycan's theory of virtual drivers, the sound from the speaker and the sound from the reflection off the glass will be off by a small amount which is going to be part ambience, part out of focus imaging. It also moves the axis or focal point of your image into a combing pattern. This is not necessarily that bad, if you can get the drivers to go low enough into the mid bass to anchor the image. I'll take a slightly comby, slightly out of focus image for spatial coherence and uniformity in the width, and with the increased depth of the staging.

if there's full range speakers in the dash the sound doesn't have to go through a crossover and all those extra added ripples in the pond to deal with, which can be difficult to process, the crossover anomalies. And choosing the wrong complement of drivers by their slope behavior is likely. Having to deal with equalization for boosting the higher frequencies from a wide-bander approach is not that big of a deal in comparison. And a super tweeter is always an option, as the sparkle way up top, as long as it's level matched, and not too far off FR between the left and right, is easy enough to do.

One thing I've noticed is it's rare for a dash-only front stage to sound as good as when you add in some rear-fill. It's just too far forward, and doesn't sound right.

I prefer the doors myself but there have been dash mounted mid installs I've come to enjoy for various reasons. No problems with a full cab of people, the stage doesn't rainbow, and the size of the acoustic space seems larger.


----------



## 14642

cajunner said:


> two things:
> 
> 1.)
> using lycan's theory of virtual drivers, the sound from the speaker and the sound from the reflection off the glass will be off by a small amount which is going to be part ambience, part out of focus imaging. It also moves the axis or focal point of your image into a combing pattern. This is not necessarily that bad, if you can get the drivers to go low enough into the mid bass to anchor the image. I'll take a slightly comby, slightly out of focus image for spatial coherence and uniformity in the width, and with the increased depth of the staging.
> 
> if there's full range speakers in the dash the sound doesn't have to go through a crossover and all those extra added ripples in the pond to deal with, which can be difficult to process, the crossover anomalies. And choosing the wrong complement of drivers by their slope behavior is likely. Having to deal with equalization for boosting the higher frequencies from a wide-bander approach is not that big of a deal in comparison. And a super tweeter is always an option, as the sparkle way up top, as long as it's level matched, and not too far off FR between the left and right, is easy enough to do.


I just don't agree with any of this. Those reflections off the windshield are simply too short to be perceived as ambience. They simply spread the image. The comb filtering that happens as a result of the reflections can be a big equalization nightmare. It also causes the image to drift differently at different frequencies. All it does is unfocuses the image and creates a jagged frequency response. 

I don't have any idea what "It also moves the axis or focal point of your image into a combing pattern" means.


----------



## MetricMuscle

Andy Wehmeyer said:


> I just don't agree with any of this. Those reflections off the windshield are simply too short to be perceived as ambience.


I must concur with the gentleman from Kalifornia.



cajunner said:


> two things:
> 
> 1.) Windshields can work in or out of your favor.
> 
> the angle of the windshield, the distance from the glass, the mounting scheme of the speaker and it's size, even the type can make big differences in what you end up with.
> 
> *I suppose this is theoretically possible if everything was reflected correctly but I can't say I've seen any discussion which would support the actual ability to control this and the end result be positive.*
> 
> using lycan's theory of virtual drivers, the sound from the speaker and the sound from the reflection off the glass will be off by a small amount which is going to be part ambience, part out of focus imaging. It also moves the axis or focal point of your image into a combing pattern. This is not necessarily that bad, if you can get the drivers to go low enough into the mid bass to anchor the image. I'll take a slightly comby, slightly out of focus image for spatial coherence and uniformity in the width, and with the increased depth of the staging.
> 
> *I've been reading his thread on mid-bass arrays and the creation of virtual drivers but it was clear in that thread the frequencies involved were limited to mid-bass, 80Hz to 330Hz IIRC. The cone of confusion the real drivers must be mounted on took this into account.*
> 
> if there's full range speakers in the dash the sound doesn't have to go through a crossover and all those extra added ripples in the pond to deal with, which can be difficult to process, the crossover anomalies. And choosing the wrong complement of drivers by their slope behavior is likely. Having to deal with equalization for boosting the higher frequencies from a wide-bander approach is not that big of a deal in comparison. And a super tweeter is always an option, as the sparkle way up top, as long as it's level matched, and not too far off FR between the left and right, is easy enough to do.
> 
> One thing I've noticed is it's rare for a dash-only front stage to sound as good as when you add in some rear-fill. It's just too far forward, and doesn't sound right.
> 
> I prefer the doors myself but there have been dash mounted mid installs I've come to enjoy for various reasons. No problems with a full cab of people, the stage doesn't rainbow, and the size of the acoustic space seems larger.


----------



## MetricMuscle

Also it was pretty clear to me that early reflections cause fatigue and aggravation, later reflections can provide some ambiance, a fuller more surround sound effect. Reflections cannot be eliminated, rather managed. Focus on preventing the early ones and don't worry about the later ones. Ways to accomplish this are:

- On-Axis driver placement with narrow dispersion.
- Driver placement away from reflective surfaces.
- Treatment of surfaces to make them less reflective.

To make this sound less impossible I just worry about the path from the driver to the listener, accomplish the above just for this first leg of the sound path. Once the sound has reached the listener it will continue on to either be absorbed or reflected, possibly even be reflected multiple times before reaching the listener again or being absorbed or losing its amplitude. If it takes long enough for it to re-reach the listener then it has become ambiance, less in amplitude and later enough to not be fatiguing. 
A good example of something to consider "after" the listener would be a glass sunroof. Close above the listener's head to quickly reflect sound right back. Luckily my car has a soft cushy panel I can pull forward to cover it.


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## 14642

There is a huge misunderstanding here about on and off axis. For speakers used within their piston range, on axis and off axis produce the same response. For example, below 300Hz for a 6" midbass, there is no real difference between the on axis and the off axis response between 0 and 90 degrees. The same is true for a 3" midrange below 3kHz. Those are pretty standard crossover points. We use the tweeter all the way up to 20k, so we are forced to use it in a range where its dispersion narrows. 

What this means is that AIMING IS UNNECESSARY IF YOU CHOOSE CROSSOVER POINTS IN RANGES WHERE THE SPEAKER'S DISPERSION IS WIDE. Aiming of the tweeter may be helpful. 

The second big misunderstanding here is the idea that there are early and late reflections in the car. While reflections from the dash and windshield are shorter than reflections from the back of the car, they are ALL too short to be perceived as stage and room. Think about it. IF you go to a concert at a venue like radio city music hall, the ENTIRE car could be parked on the stage. While the early and late reflections from the concert space might be included in the recording, they CANNOT BE REPRODUCED realistically by two speakers mounted in the car. If they are included in the recording, it's like the entire space has been reduced to the space inside the car. If you want to attempt to reproduce the larger space, you have to have a way to create the late reflections and the early reflections of the larger space. Since some of them come from the back, you need rear speakers with lots of delay that reproduce ONLY that ambient information. Adding more speakers with appropriate delay and steering of the ambient information contained in the recording can create a better reproduction of the original space, but only if the ambient information is included in the recording. 

A room synthesis algorithm adds an arbitrary space to the sound of the recording--like changing the size of the car to the size of some other listening room in which the two stereo loudspeakers are placed.


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## MetricMuscle

I had to re-read this a couple more times. I have focused more on how reflections could damage the sound and how to go about minimizing this situation. So,

- No point in aiming any driver on-axis unless it is being played out of it's range, this is a problem most likely for tweeters as they are asked to cover too wide of a range typically.

- To lessen the damaging reflections found in an automotive environment we can keep drivers away from any hard surface like glass, plastic, metal etc. We can use soft acoustically absorbent material where this situation does exist like mats, carpet, etc.


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## sqnut

In a nutshell, it's a car and you're going to have reflections no matter what you do. Trying to tame reflections is limited really to the top end frequencies via stuff like a dash mat etc. However to really appreciate that difference, the arrival times and response have to be corrected first. You'll get much bigger returns using TA and the eq rather than trying to manage reflections.


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## slugman2894

I think the most important part personally is choosing drivers for the locations of the speakers in the particular vehicle, that's the case for me anyway. I choose my tweeters because I was using the stock location. 


Sent from my iPhone using Tapatalk


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## canuck

Most drivers play well at 30 degrees off axis. Pointing the driver a little off may assist in reducing reflection. 
Going on axis for me made the sound too localized. Going off made it easier to time align. 
Crossover point helps the sweet spot of the driver . 
Equalizing helps with reflection.

If reflection reduction is the goal then the driver side glass is your biggest issue. To match the passenger side the only choice is to go 30 degrees off similar to how the passenger side driver is positioned. 
For me this was the best compromise running a tweet and mid off the Apillar.


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## 14642

sigh...


----------



## subwoofery

Andy Wehmeyer said:


> sigh...


(where's the like button when you need it)  

Kelvin


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## acidbass303

Andy Wehmeyer said:


> sigh...


LOL

sail panels and door panels FTW!


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## canuck

After reading all the posts I checked out show off your a pillars and found maybe one in ten were on axis.

I guess sigh is a nice way to say I dont get it. Everyone I know that competes goes off axis. I will stop posting


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## thehatedguy

The pillars are just bad spots for mids, especially if you have them built out in any manor. Not much if any baffle there for them...and it is a physically narrow spot to put them...near the most reflective area in the car...

But it doesn't stop people from putting them there.


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## subwoofery

And you can't EQ reflections - only attenuate peaks you get from those reflections. 

If you know how to EQ reflections, I'm all ears 

Kelvin


----------



## AAAAAAA

Many manufacturers upgraded car systems have speakers in the corner dash...it's obviously a good place for midrange and is close to a pillars but maybe the end results isn't close... I wonder if they need to be in the dash where the windshield acts as a waveguide... or maybe it's that they are midrange only. I am not sure.


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## subwoofery

They might think that it gives a good sense of 3D rendering coz sounds come from all over the place - unfortunately, it is not what a good system should sound like. 

In most cars, speakers are wired in absolute polarity instead of the correct acoustic one. Good system are already coming but you have to pay a premium fee in order to have a better system than average (Meridian, B&O, etc...) 

What sounds good to somebody might not sound good to another person... 

Kelvin


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## Niebur3

thehatedguy said:


> The pillars are just bad spots for mids, especially if you have them built out in any manor. Not much if any baffle there for them...and it is a physically narrow spot to put them...near the most reflective area in the car...
> 
> But it doesn't stop people from putting them there.


I agree. It seems that many people (even professionals) seem to mount the speakers in what has been proven to be some of the worst mounting locations in cars. I believe aesthetics play a large roll in this, but so does ignorance. I can't say I haven't in the past or won't in the future, but more and more builds seem to have terrible speaker locations, although using top notch expensive drivers that supposedly defy the laws of physics and are immune to reflective surfaces!


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## MetricMuscle

...and we're back!

I just re-read most of this thread after not really thinking too much about it for a month or so.
In another thread someone mentioned when using the MS-8 to mount the center channel in the center of the dash facing up towards the windshield. Same for rear speakers which are better mounted on the rear deck than on the rear doors.

I have options to mount my center channel in the dash but facing rearward, not up towards the windshield.
I could also do this on the rear deck, aimed forward and not directly at the back glass.

Is sub-woofer frequency bad to have reflected off of the back glass?
Mine will sorta use the back glass as a horn, mounted below the rear deck. 
Maybe this isn't considered reflection since it is part of the initial path and all of the sound is following the same reflected/directed path.
Doesn't a waveguide direct and reflect the sound in an organized direction?
Soft absorbent material like carpet and mats only absorb higher frequencies down to what frequency? 1KHz?
Anything below 1KHz is gonna reflect no matter what we do?

Also, I've come to the conclusion that there will be reflections no matter where a driver is mounted so.......


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## quietfly

MetricMuscle said:


> ...and we're back!
> 
> I just re-read most of this thread after not really thinking too much about it for a month or so.
> In another thread someone mentioned when using the MS-8 to mount the center channel in the center of the dash facing up towards the windshield. Same for rear speakers which are better mounted on the rear deck than on the rear doors.
> 
> I have options to mount my center channel in the dash but facing rearward, not up towards the windshield.
> I could also do this on the rear deck, aimed forward and not directly at the back glass.
> 
> Is sub-woofer frequency bad to have reflected off of the back glass?
> The frequency subs play are too long really to "reflect" in that way, instead they kind of ENVELOPE your car. Mine will sorta use the back glass as a horn, mounted below the rear deck.
> Maybe this isn't considered reflection since it is part of the initial path and all of the sound is following the same reflected/directed path.
> At higher frequencies, reflections are much more obvious. and while you can EQ for the original signal, that's not an option for the reflection
> 
> Doesn't a waveguide direct and reflect the sound in an organized direction?
> usually they control the dispersion pattern, which is slightly different from just a reflection. it's more like focusing the output of the speaker
> Soft absorbent material like carpet and mats only absorb higher frequencies down to what frequency? 1KHz?
> an old bikinipunk thread seemed to say that frequencies under 10k don't seem to be effect without significant amounts of material. Others seem to swear by them....
> Anything below 1KHz is gonna reflect no matter what we do?
> It's all about managing the CHAOS
> Also, I've come to the conclusion that there will be reflections no matter where a driver is mounted so.......


It's all about managing the CHAOS


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## MetricMuscle

quietfly said:


> It's all about managing the CHAOS


Under 10KHz or under 1Khz ?


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## quietfly

check out the Thread HERE
although most of the pics are gone. i believe the end up was very little if any measurable result over 5k and the only solid results were with 2 inches of ensolite and above 10k. 

YMMV


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## Hanatsu

Absorption rate of an absorbing material is higher as you higher in frequency, on the other hand, dispersion goes down when you go higher in frequency so not much of the sound power gets reflected into areas where haven't aimed the driver. Absorbing sound in a car is one of those "good luck with that" things. Well, unless you don't care about driving the car xD


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## quietfly

Hanatsu said:


> Absorption rate of an absorbing material is higher as you higher in frequency, on the other hand, dispersion goes down when you go higher in frequency so not much of the sound power gets reflected into areas where haven't aimed the driver. Absorbing sound in a car is one of those "good luck with that" things. Well, unless you don't care about driving the car xD



the Magic Bus apparently does it pretty well however that seems to be the exception rather than the rule


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## Viperoni

Andy Wehmeyer said:


> There is a huge misunderstanding here about on and off axis. For speakers used within their piston range, on axis and off axis produce the same response. For example, below 300Hz for a 6" midbass, there is no real difference between the on axis and the off axis response between 0 and 90 degrees. The same is true for a 3" midrange below 3kHz. Those are pretty standard crossover points. We use the tweeter all the way up to 20k, so we are forced to use it in a range where its dispersion narrows.
> 
> What this means is that AIMING IS UNNECESSARY IF YOU CHOOSE CROSSOVER POINTS IN RANGES WHERE THE SPEAKER'S DISPERSION IS WIDE. Aiming of the tweeter may be helpful.



In terms of managing a tweeter's reflections while it's in its pistonic range, how about using a horn tweeter with rather narrow dispersion?

At 45 degrees, this B&C tweeter is down around 6db at 5khz and 12db @ 10khz:
http://www.parts-express.com/pedocs/specs/294-580-bc-speakers-de35-specifications-45777.pdf


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## WinWiz

Looking at frequency response graphs of my dyn. 17w75 the off axis response looks identical to the on axis response up to about 3Khz. Does this mean that on or off axis placement doesn't really matter if I cross steep below 3Khz?


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## Hanatsu

Yeah if you got EQ 

Tapaaatalk!!


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## MetricMuscle

Viperoni said:


> In terms of managing a tweeter's reflections while it's in its pistonic range, how about using a horn tweeter with rather narrow dispersion?
> 
> At 45 degrees, this B&C tweeter is down around 6db at 5khz and 12db @ 10khz:
> http://www.parts-express.com/pedocs/specs/294-580-bc-speakers-de35-specifications-45777.pdf


So, are there tweeters designed to have narrow dispersion?
- It's easier to aim a tweeter On-Axis.
- A bigger issue will now be reflections.
- Aimed On-Axis, narrow dispersion would be a good thing, no?

This would probably not be a Home Audio type tweeter since this is not an issue nor something anyone is attempting to achieve. Home audio has less reflective surfaces and it is likely the listener won't stay seated in the exact same spot. Drivers will be farther away from the listener than in CarAudio. Making them gigantic is also an option for Home Audio.

Domes and Ring Radiator tweeters usually list wide dispersion as one of their many attributes. That B&C is a Pro Audio tweeter and they are usually designed to be farther away from the listener so it's dispersion is probably correct for that application. 108db efficient as well, yowzers!


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## mojozoom

I've been comtemplating this very same thing for a while now.

Reflections from A-pillar mounted tweets are going to be picked up by the opposite ear and summed with the direct sounds. We can compensate focr that by altering eq until we still get a centered image, but as freq changes so does the polar response of the tweet so we'd need to eq like crazy to keep it even close to centered. Then what we end up with though (especially when the sound pans left or right) is poor tonality.

Right now if I open my front windows the image gets way more focused.

If we could minimize the reflections by either a more directional tweet or by applying absorbing materials around the tweet to block omni style behavior then we'd gain some ground on the whole issue.

I've been contemplating some sort of large foam block at the A-pillar with the tweet mounted down a tunnel and aimed dead on axis for the driver. All covered with speaker grill cloth of course.

As a starting point I'm thinking aiming the tweets a little more behind my head than directly on axis might be a step in the right direction. That way more of the energy will be directed to the back of the car where it can bounce around a bit and have less impact on the front stage, and the headrest will suck some up as well. The right tweet would end up aimed probably toward the drivers side back seat headrest, and the left pretty much at the top of my shoulder.


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## Viperoni

MetricMuscle said:


> So, are there tweeters designed to have narrow dispersion?
> - It's easier to aim a tweeter On-Axis.
> - A bigger issue will now be reflections.
> - Aimed On-Axis, narrow dispersion would be a good thing, no?


Faceplates & horns can help control directivity, which seems like it will help our situation, based on what Andy is saying.



MetricMuscle said:


> This would probably not be a Home Audio type tweeter since this is not an issue nor something anyone is attempting to achieve. Home audio has less reflective surfaces and it is likely the listener won't stay seated in the exact same spot. Drivers will be farther away from the listener than in CarAudio. Making them gigantic is also an option for Home Audio.


I'm not sure that's true, as reflections are an issue in a home environment as well. The THX spec, for example, has directivity specs for the front speakers, which a horn tweeter *can* lend a hand in.



MetricMuscle said:


> Domes and Ring Radiator tweeters usually list wide dispersion as one of their many attributes. That B&C is a Pro Audio tweeter and they are usually designed to be farther away from the listener so it's dispersion is probably correct for that application. 108db efficient as well, yowzers!


Correct - home *music* applications tend to like wide dispersion tweeters - the opposite of the home theater situation I mentioned above.
Exactly, besides having the driver being further away from the listener, requiring the "throw", I imagine reflections are an even bigger issue in concert type situations. Also, horns help efficiency (as you mentioned), which Pro Audio DEFINITELY needs.

I'd love to hear some input from Andy on using a narrow dispersion horn near the windshield/A-pillar/dash junction.


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## MetricMuscle

Good points!
Home Theater is more of a captive audience, seated closer to the source. Room reflections are more of the later reflections which don't actually occur in an automotive environment due to the small size. Later reflections are not as undesirable as early.

Is there now a Home Theater style/type driver? 
The Horizontal MTM or Line Array has really no other purpose except for a center channel under a screen in Home Theater. These still use non-specific home audio style drivers.

I would also think a highly efficient tweeter aimed directly at the listener would/should/could also not need as much power nor be as loud which minimizes the energy available to be reflected in the first place.


----------



## mojozoom

mojozoom said:


> The right tweet would end up aimed probably toward the drivers side back seat headrest, and the left pretty much at the top of my shoulder.


I measured the L/R separation of five different aimings of the left side tweeter last night using REW. It lines up as one would expect; on-axis aiming allows alot of information to reach the right ear, whereas aiming the tweeter along a path parallel to the drivers door window glass provided the best separation.

The worst result came from aiming the tweeter at the rear-view mirror. This was a recommendation in a published car audio book that I thought I'd try out. From 4k-6k it provided high separation, but above and below that it was the worst of the tests, showing negative separation (the right ear was picking up more sound level from the left speaker than the left ear was).

I'll do a complete battery of tests for multiple aimings of each side and post the results shortly.


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## Hanatsu

Got the measurements of that? Interested 

Tapaaatalk!!


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## 14642

This idea that the correct polarity is the one that sounds good is a little silly. If reversing the polarity sounds better, then I think more investigation is required. If it's an out of phase issue between left and right due to a distance in difference that you're correcting with a polarity change, then delay is a better fix. Reversing the polarity just exchanges one problem for another. Swapping the polarity of BOTH right and left due to crossover phase shift (i.e. 12dB/octave butterworth filters or distance between mids and tweeters) is a completely different exercise.

When I hear things like "you have to experiment to find out what works best", I cringe. When I hear, "you gotta play with the settings", i throw up in my mouth a little bit.


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## mojozoom

Here's the separation data for on-axis aiming compared to aiming parallel to the drivers door glass. Keep in mind this is for the left side which is pretty sensitive:











Here's the data for on-axis compared to aiming at the rear view. 










These tweeters show no drop in output at 45 degrees off-axis until you get out past about 5k hz, so that may explain a little of what we see in the first graph.

I think this process should be a little cleaner on the left side tweeter and give more distinct results.


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## subwoofery

Andy Wehmeyer said:


> This idea that the correct polarity is the one that sounds good is a little silly. If reversing the polarity sounds better, then I think more investigation is required. If it's an out of phase issue between left and right due to a distance in difference that you're correcting with a polarity change, then delay is a better fix. Reversing the polarity just exchanges one problem for another. Swapping the polarity of BOTH right and left due to crossover phase shift (i.e. 12dB/octave butterworth filters or distance between mids and tweeters) is a completely different exercise.
> 
> When I hear things like "you have to experiment to find out what works best", I cringe. When I hear, "you gotta play with the settings", i throw up in my mouth a little bit.


For people that don't have access to T/A, what would you suggest then? 

Have access to a L/R EQ? Install drivers so that PLD is as small as possible? Swap polarity of 1 mid anyway? 

Kelvin


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## sqnut

L/R response is not going to sort out a timing issue. In a car ideally TA should be a must. You can play with install to reduce PLD but it is still going to be a major issue.


----------



## subwoofery

sqnut said:


> L/R response is not going to sort out a timing issue. In a car ideally TA should be a must. You can play with install to reduce PLD but it is still going to be a major issue.


That's the thing, I've heard that one competitor (won't say his name coz I'm not sure if it's him) used to win with no T/A at all and still be undefeated in his class (Pro or something). 
Ok he did use some phase manipulation, allpass filters and install his drivers way forward but he did not use T/A - and no he did not compete in 1990  more like 2010+

Kelvin


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## sqnut

subwoofery said:


> That's the thing, I've heard that one competitor (won't say his name coz I'm not sure if it's him) used to win with no T/A at all and still be undefeated in his class (Pro or something).
> Ok he did use some phase manipulation, allpass filters and install his drivers way forward but he did not use T/A - and no he did not compete in 1990  more like 2010+
> 
> Kelvin


It's easier and probably cheaper in the long run to just get TA and use it. Doesn't sound like a MECA competitor.


----------



## cajunner

subwoofery said:


> That's the thing, I've heard that one competitor (won't say his name coz I'm not sure if it's him) used to win with no T/A at all and still be undefeated in his class (Pro or something).
> Ok he did use some phase manipulation, allpass filters and install his drivers way forward but he did not use T/A - and no he did not compete in 1990  more like 2010+
> 
> Kelvin


so what you're saying is someone familiar with electronic circuits was able to bread-board a solution for his particular car and install, that kicked butt without using a digital delay of any kind?

I can believe that.

that's the premise behind the Linkwitz Pluto and it's response shaping, what you essentially get is time alignment without using a digital conversion, analog all the way.

I would think that if you could avoid the D/A, A/D thing altogether, and the jitter and clock crap, and whatever else buggers the signal you could have a more true, approach.

whether that's audible or not, or just an idea that keeps people up at night, I couldn't say, but that kind of mastery of time and space is worth seeking out.

maybe approach audio with a "nuclear bomb resistant" angle, where all circuits that can be fried on a PCB are swapped out for glass tubes, and everything is in the technological chasm of the 1950's.

How neat would that be?


----------



## mojozoom

Hanatsu, here's the curve for the Hertz ET20 tweeter I'm using so you can see the response at 45 degrees:










I think a tweet that dropped off earlier off-axis would help.


----------



## subwoofery

Looks like there would be some massive ringing around 10kHz - freq response isn't very flat either... 

Kelvin


----------



## quietfly

cajunner said:


> so what you're saying is someone familiar with electronic circuits was able to bread-board a solution for his particular car and install, that kicked butt without using a digital delay of any kind?
> 
> I can believe that.
> 
> that's the premise behind the Linkwitz Pluto and it's response shaping, what you essentially get is time alignment without using a digital conversion, analog all the way.
> 
> I would think that if you could avoid the D/A, A/D thing altogether, and the jitter and clock crap, and whatever else buggers the signal you could have a more true, approach.
> 
> whether that's audible or not, or just an idea that keeps people up at night, I couldn't say, but that kind of mastery of time and space is worth seeking out.
> 
> maybe approach audio with a "nuclear bomb resistant" angle, where all circuits that can be fried on a PCB are swapped out for glass tubes, and everything is in the technological chasm of the 1950's.
> 
> How neat would that be?


STEAMPUNK DIYMA....... that would atleast look cool....


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## MetricMuscle

PLD left to right will cause a time alignment issue left to right.
PLD mid to tweeter will cause a phase issue which will cause a time alignment issue between the two drivers and the frequencies they are playing.
Reversing the wiring will change the phase and may or may not help with time alignment.
Locating drivers the proper distance away from the listener will prevent some need for time alignment.

Will a DSP like MS-8 delay the entire frequency range of each channel the same or will it delay differently across the frequency range depending on how it reaches the listener?
If it delays differently across the range, multiple drivers could be on each channel as long as they covered different frequencies, like a passive component system.
If not, more than one driver on each channel will have to have each located correctly to keep phase and PLD correct to the listener. This would not work well with passive component systems.


----------



## cajunner

quietfly said:


> STEAMPUNK DIYMA....... that would atleast look cool....


had to look that up, haha..

but it wouldn't be steampunk, it would be the actual, the original, the analog without the digitized skin..

of course, you'd have to have analog masters, playback source to go along with it.

maybe that's out of the question, but in an off-axis thread, it's all out of the question, haha..


----------



## thehatedguy

If they were using all pass filters then they were using a proaudio processor.


----------



## Hanatsu

mojozoom said:


> Here's the separation data for on-axis aiming compared to aiming parallel to the drivers door glass. Keep in mind this is for the left side which is pretty sensitive:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here's the data for on-axis compared to aiming at the rear view.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> These tweeters show no drop in output at 45 degrees off-axis until you get out past about 5k hz, so that may explain a little of what we see in the first graph.
> 
> I think this process should be a little cleaner on the left side tweeter and give more distinct results.


Interesting... About 10dB separation at the optimal spot. We should perceive that as a half the volume or so. I'll run some tests in my cars when I got the systems running.


----------



## cajunner

thehatedguy said:


> If they were using all pass filters then they were using a proaudio processor.


Linkwitz has links on his site to the schematics to build your own all pass filter, and it's not a pro audio processor that you are working with?

He builds one into the Pluto's electronic crossover to delay the Whisper's output to the acoustic center of the omni driver, while putting the physical position of the Whisper at the edge of the omni's surround, reducing diffractive distortion.

If I was up to the task I'd make the calculations in a car, then build an all pass filter using the same techniques to delay the tweeter to meet with a door woofer's longer path length.

but alas, I'm not up to that task, and anything requiring large scale changes may be out of the all pass's ability in an analog circuit, to make that adjustment.

Or, in the crossing range of the Pluto, using an all pass to delay everything above 1Khz is practical but trying to do the same thing with mid bass transition, or large path length differences of 10" or more, may not be realistic or practical.


----------



## thehatedguy

I really doubt anyone out there in the competition scene is building analog filters. But the proaudio processors like the Rane and Behringer do have all pass networks. I know who Kelvin is talking about, and he was using a Rane.


----------



## subwoofery

Would really like to know what Andy thinks could be our options if we don't plan to have T/A available in the system building... 

Could be an interesting read. 

I'm all for T/A since I managed to create a wonderful soundstage with rear OEM speakers without having to lower the level + create a golf ball center in my girlfriend's car using horns. 

Kelvin


----------



## MetricMuscle

thehatedguy said:


> If they were using all pass filters then they were using a proaudio processor.


This gets discussed some over on diyaudio.com. An All-Pass can just be a HP or LP out of the frequency range you are listening to. Like a HP @10Hz or a LP @ 40KHz. It won't cut anything you actually hear but the design will still have the phase effect. 1st order, 6db slope, 90 degree phase shift. This is usually done on Home Audio to get the mid/tweeter aligned, not L to R.


----------



## cajunner

one of the car audio companies has a left/right image shifter that uses an all-pass analog delay, a little box, knob, whatever... who was it, Focal?

and I remember something about a chip, an analog, perhaps Texas Instruments? That was supposed to make adjustments in analog and had great potential, sort of the Raspberry Pi but audio oriented?

anyways, just rambling about, I feel like the complicated method of creating filters for a specific application and putting that into a car's audio, is just like hammering a screw into the wood, when a digital screwdriver gets it done with much less effort and drama.


----------



## Viperoni

MetricMuscle said:


> Good points!
> Home Theater is more of a captive audience, seated closer to the source. Room reflections are more of the later reflections which don't actually occur in an automotive environment due to the small size. Later reflections are not as undesirable as early.


Exactly



MetricMuscle said:


> Is there now a Home Theater style/type driver?


Not sure what you mean by this?



MetricMuscle said:


> The Horizontal MTM or Line Array has really no other purpose except for a center channel under a screen in Home Theater. These still use non-specific home audio style drivers.


A horizontal MTM is a bad choice as a CC in a HT because it promotes vertical dispersion while limiting horizontal dispersion. They're just used for aesthetic reasons.




MetricMuscle said:


> I would also think a highly efficient tweeter aimed directly at the listener would/should/could also not need as much power nor be as loud which minimizes the energy available to be reflected in the first place.


I would think so as well, but according to mojozoom's graphs, it seems like aiming the left tweeter parallel to the drivers door is the way to go. Which isn't that bad, but may cause a minor issue with narrow directivity horn tweeter we're talking about.

Kind of combining the two thoughts we have going on here, in an attempt to limit horizontal dispersion, how about a horizontal MTM on the dash?
You've got limited horizontal dispersion (good), pretty much the same vertical dispersion as a horizontal MT (ok), and better efficiency (good).
The only downside is packaging - most people won't be able to fit 5-1/4" drivers. However, an MTM with Aura NS3's and a 1" smaller faceplate tweeter should fit fine....


----------



## Viperoni

mojozoom said:


> Here's the separation data for on-axis aiming compared to aiming parallel to the drivers door glass. Keep in mind this is for the left side which is pretty sensitive:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here's the data for on-axis compared to aiming at the rear view.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> These tweeters show no drop in output at 45 degrees off-axis until you get out past about 5k hz, so that may explain a little of what we see in the first graph.
> 
> I think this process should be a little cleaner on the left side tweeter and give more distinct results.


Sorry if I'm a bit behind the times on this one, but are you only using the left tweeter as your source, with L and R microphones?


----------



## RocketBoots

Andy Wehmeyer said:


> There is a huge misunderstanding here about on and off axis. For speakers used within their piston range, on axis and off axis produce the same response. For example, below 300Hz for a 6" midbass, there is no real difference between the on axis and the off axis response between 0 and 90 degrees. The same is true for a 3" midrange below 3kHz. Those are pretty standard crossover points. We use the tweeter all the way up to 20k, so we are forced to use it in a range where its dispersion narrows.
> 
> What this means is that AIMING IS UNNECESSARY IF YOU CHOOSE CROSSOVER POINTS IN RANGES WHERE THE SPEAKER'S DISPERSION IS WIDE. Aiming of the tweeter may be helpful.
> 
> The second big misunderstanding here is the idea that there are early and late reflections in the car. While reflections from the dash and windshield are shorter than reflections from the back of the car, they are ALL too short to be perceived as stage and room. Think about it. IF you go to a concert at a venue like radio city music hall, the ENTIRE car could be parked on the stage. While the early and late reflections from the concert space might be included in the recording, they CANNOT BE REPRODUCED realistically by two speakers mounted in the car. If they are included in the recording, it's like the entire space has been reduced to the space inside the car. If you want to attempt to reproduce the larger space, you have to have a way to create the late reflections and the early reflections of the larger space. Since some of them come from the back, you need rear speakers with lots of delay that reproduce ONLY that ambient information. Adding more speakers with appropriate delay and steering of the ambient information contained in the recording can create a better reproduction of the original space, but only if the ambient information is included in the recording.
> 
> A room synthesis algorithm adds an arbitrary space to the sound of the recording--like changing the size of the car to the size of some other listening room in which the two stereo loudspeakers are placed.


So if we were to apply this to an example from an earlier post about the BMW with the woofer under the seat, if it's crossed below 300Hz, aside from the fact that there is a big physical obstruction (your ass) on top of the driver, would/could it sound and blend as good with the 3" mid high on the door and tweet in the sail compared to a woofer that was, say, on the bottom of the door panel?

There is so much blah blah blah; the theoretical and real world are so different sometimes. It's hard to sort out, and prioritize factors for installs.



Andy Wehmeyer said:


> sigh...


LOL; just beat your head against a wall. Less frustrating sometimes.


----------



## subwoofery

Andy Wehmeyer said:


> This idea that the correct polarity is the one that sounds good is a little silly. If reversing the polarity sounds better, then I think more investigation is required. If it's an out of phase issue between left and right due to a distance in difference that you're correcting with a polarity change, then delay is a better fix. Reversing the polarity just exchanges one problem for another. Swapping the polarity of BOTH right and left due to crossover phase shift (i.e. 12dB/octave butterworth filters or distance between mids and tweeters) is a completely different exercise.
> 
> When I hear things like "you have to experiment to find out what works best", I cringe. When I hear, "you gotta play with the settings", i throw up in my mouth a little bit.


Would like to ask again: 



> For people that don't have access to T/A, what would you suggest then?
> 
> Have access to a L/R EQ? Install drivers so that PLD is as small as possible? Swap polarity of 1 mid anyway?
> 
> Kelvin


Andy? Care to help me?  

Thanks, 
Kelvin


----------



## 14642

Well, if you don't have access to TA, then choosing speaker locations that minimize the need for TA is the next best thing. A center channel and an upmixer are also helpful and minimize the need for TA, since the center image doesn't depend on a perfect acoustic sum from right and left. 

IN reading this thread, I noticed some blowback about tweeter response. When you measure a tweeter, the baffle is a big deal. The height of the dome creates a dip in the response. If you're mounting the tweeter in a box or on a flat baffle, you'll see that dip. In an A-pillar or sail panel, the dip will go away or at least be very different. To get an idea of what the response of the tweeter is, measure it without a baffle. A simple ground plane measurement from 2M is similar enough to anechoic that you'll at least be able to see what's up before bashing speaker manufaturers. In the graph of the Hertz tweeter above, those two peaks are probably the result of a little ringing, and a highQ alignment and ALSO that dip.


----------



## subwoofery

Andy Wehmeyer said:


> Well, if you don't have access to TA, then choosing speaker locations that minimize the need for TA is the next best thing. A center channel and an upmixer are also helpful and minimize the need for TA, since the center image doesn't depend on a perfect acoustic sum from right and left.
> 
> IN reading this thread, I noticed some blowback about tweeter response. When you measure a tweeter, the baffle is a big deal. The height of the dome creates a dip in the response. If you're mounting the tweeter in a box or on a flat baffle, you'll see that dip. In an A-pillar or sail panel, the dip will go away or at least be very different. To get an idea of what the response of the tweeter is, measure it without a baffle. A simple ground plane measurement from 2M is similar enough to anechoic that you'll at least be able to see what's up before bashing speaker manufaturers. In the graph of the Hertz tweeter above, those two peaks are probably the result of a little ringing, and a highQ alignment and ALSO that dip.


Thanks Andy for the reply - not what I was expecting though 

Kelvin


----------



## 14642

Hmmm...what were you expecting? A diatribe on all pass filters? Those are a bit more difficult to do than even a simple delay, which is more effective. You can do an all pass filter as an active circuit--just sum a 12dB/oct HPF and a 12dB/oct LPF.


----------



## subwoofery

Andy Wehmeyer said:


> Hmmm...what were you expecting? A diatribe on all pass filters? Those are a bit more difficult to do than even a simple delay, which is more effective. You can do an all pass filter as an active circuit--just sum a 12dB/oct HPF and a 12dB/oct LPF.


Yeah something fancy that only you have the secret for  

So doing an all-pass filter adds enough ms to one driver that it can put every frequencies timing back in phase? 
How difficult would it be to implement time delay in passive Xover with today's technology? Even in home audio, they are still doing it mechanically. 

I know RF has a remote for their passive Xover that can switch phase 180° on MIDs and TWs. But reading your post, it's not nearly the same thing as adding a delay. 

Kelvin


----------



## Lord Raven

This is exactly what I have been preaching and someone, today, called my ears to be iron ears cause I am listening to Focal on axis. I think, in short, you're saying, it is almost impossible to have a perfect sound in a car environment. Loud, yes, you can go loud as you can but cannot achieve the perfect sound.


----------



## sqnut

Lord Raven said:


> ................ it is almost impossible to have a perfect sound in a car environment. Loud, yes, you can go loud as you can but cannot achieve the perfect sound.


If you don't have incredible sound in a car, most likely its a tuning issue (assuming basics are in place).


----------



## Lord Raven

sqnut said:


> If you don't have incredible sound in a car, most likely its a tuning issue (assuming basics are in place).


With millions of iterations, I've attained the best possible sound with an MS8. Sound is almost perfect but when I compare it with home audio, the road noise and everything above 80kph, you just don't hear the music, maybe 50% is the road noise. Turn it up, will kill your hearing in matter of minutes. So I'm of the opinion, you cannot achieve perfect sound in a car.


----------



## Justin Zazzi

Well if you were to move your refrigerator, microwave oven, food processor, dishwasher, and clothes dryer into your living room and turn them all on, the noise would make your home system sound pretty terrible too right?

Don't blame the car for being too loud when you're driving it. That's like saying it's impossible to play an epic game of Jenga on the deck of a small sailboat when you're sailing it. Neither situation is the ideal environment for the activity, so we shouldn't get mad when it doesn't work perfectly.


----------



## Lord Raven

Jazzi said:


> Well if you were to move your refrigerator, microwave oven, food processor, dishwasher, and clothes dryer into your living room and turn them all on, the noise would make your home system sound pretty terrible too right?
> 
> Don't blame the car for being too loud when you're driving it. That's like saying it's impossible to play an epic game of Jenga on the deck of a small sailboat when you're sailing it. Neither situation is the ideal environment for the activity, so we shouldn't get mad when it doesn't work perfectly.


I did put a lot of sound proofing as well, STP. And then I tried to calculate the noise levels at these 30, 50, 70, 80 kph speeds using a Dayton imm-6 mic. At 80, which is the normal speed here, you hear a lot of noise as well. 

These days, I have a headphone rig, sennheiser HD 600, tube amp, DAC and my PC. Your argument is invalid ? But yes, the sound from heavy outdoor units of ACs which surround you over here, is a killer. Thanks to the walls.


----------



## Hisma

i have a question here. 

I read the earlier posts about how as long as you cross over your speaker before it starts to beam, then on/off axis is not very important. But we also know that we will almost certainly have to run a tweeter past it's beaming point, so therefore we are best off aiming tweeters on axis.

However, I saw a document from focal (I need to find it but can't seem to track it down) where they recommend that you aim their tweeters off axis, and aim them so that they fire directly at each other. The same way your mid woofers are when they are mounted in your door. 

So what I did was use the pods that focal provides (they are meant for dash mounting, so they allow the tweeters to stand straight up when mounted on a dash), and I placed the tweeters above my factory speaker grill.

My factory speaker grill is very close to my windshield, but because I am aiming the tweeters to fire at each other, They are not aimed directly at the glass. See my picture.










I can swivel the tweeters, so I have tried both direct on axis angle, as well as the angle in the picture. The off axis sounds much better, both in sound stage, as well as sound quality. 

This flies in the face of what was stated throughout this thread. 

Can someone give me some insight? Also, would there be value in buying pods for my tweeters and mounting them in my a-pillar above my mids? As I said I think my system already sounds good now, but everything here says to get as far away from the windshield as possible and I am right up against it at the moment.

Thanks!


----------



## gijoe

Hisma said:


> i have a question here.
> 
> I read the earlier posts about how as long as you cross over your speaker before it starts to beam, then on/off axis is not very important. But we also know that we will almost certainly have to run a tweeter past it's beaming point, so therefore we are best off aiming tweeters on axis.
> 
> However, I saw a document from focal (I need to find it but can't seem to track it down) where they recommend that you aim their tweeters off axis, and aim them so that they fire directly at each other. The same way your mid woofers are when they are mounted in your door.
> 
> So what I did was use the pods that focal provides (they are meant for dash mounting, so they allow the tweeters to stand straight up when mounted on a dash), and I placed the tweeters above my factory speaker grill.
> 
> My factory speaker grill is very close to my windshield, but because I am aiming the tweeters to fire at each other, They are not aimed directly at the glass. See my picture.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I can swivel the tweeters, so I have tried both direct on axis angle, as well as the angle in the picture. The off axis sounds much better, both in sound stage, as well as sound quality.
> 
> This flies in the face of what was stated throughout this thread.
> 
> Can someone give me some insight? Also, would there be value in buying pods for my tweeters and mounting them in my a-pillar above my mids? As I said I think my system already sounds good now, but everything here says to get as far away from the windshield as possible and I am right up against it at the moment.
> 
> Thanks!


You have to keep in mind what off axis does to the response at beaming, it attenuates the signal outside of the beam. Some tweeters work well off axis, above beaming because they are "bright" and benefit from some attenuating. Focal in particular has a reputation for having tweeters that benefit from being off axis. With accurate frequency response measurements you can tell if a tweeter can could benefit from being off axis, the thing is, with some decent EQ you can keep them on axis and just lower the top end to keep them from being too "bright."


----------



## Hisma

gijoe said:


> You have to keep in mind what off axis does to the response at beaming, it attenuates the signal outside of the beam. Some tweeters work well off axis, above beaming because they are "bright" and benefit from some attenuating. Focal in particular has a reputation for having tweeters that benefit from being off axis. With accurate frequency response measurements you can tell if a tweeter can could benefit from being off axis, the thing is, with some decent EQ you can keep them on axis and just lower the top end to keep them from being too "bright."


Yeah I understand that focals are considered bright. 

I haven't done any tuning yet, but there is clearly a big bump in the frequency response on-axis in the 13k or so range, according to this chart.










Off axis it is much more subdued. So I get that part. But what about off axis vs on axis for sound stage purposes? I found that on axis, the sound didn't "blend" as well (you can tell i'm a newb here right?). With the tweeters off axis, I can hear vocals centered right in the middle of my dash, and overall just a greater depth on the sound stage. it just sounds much better. 

I don't think it was brought up in here what on axis vs off axis does to sound stage. You seem to have recommended that I try to EQ out the bumps so that I can aim the tweeters on axis, but is it really worth it to go on axis anyway? I have a C-DSP and I am running 3-way active, so while I haven't tuned my system yet, I could definitely tune the tweeters to sound better on axis. But I don't really see the point.


----------



## gijoe

It's really not going to make a difference if you leave them off axis, or put them on axis and EQ the top end down. With regard to staging, I suspect it was at least partially psychological. Had you tried on axis with 13khz and up attenuated, you would likely have gotten the same results as you have off axis.

And, that bump in the frequency response is right where the tweeter would beam. I suspect Focal did this on purpose to give the best FR to the majority of people purchasing the set. Keep in mind, we are the minority here, and the vast majority of people who buy car speakers just put them in factory locations, off axis. They were likely designed to accommodate those people, since they make up the majority of sales.


----------



## Hisma

*Re: Is off-axis better for front stage? - Hybrid Audio*

Makes sense. Thanks for the explanation.


----------



## hunde

This has been a pretty fascinating read. a) because i'm about to do my first pillars, with dyn mids and tweets, in a sprinter. b) i worked in many aspects of home audio over a 20 year period. Never would i say i'm an expert, but learning new tricks like room analysis / correction, so it's very pertinent!

This dash is huge. Upside - so are pillars, much placement room without any visual impediment. I run into plenty as it is...

If you have some thoughts on best starting point, my thread is HERE

Cheers,

Tom


----------



## BMW Alpina

gijoe said:


> It's really not going to make a difference if you leave them off axis, or put them on axis and EQ the top end down. With regard to staging, I suspect it was at least partially psychological. Had you tried on axis with 13khz and up attenuated, you would likely have gotten the same results as you have off axis.
> 
> And, that bump in the frequency response is right where the tweeter would beam. I suspect Focal did this on purpose to give the best FR to the majority of people purchasing the set. Keep in mind, we are the minority here, and the vast majority of people who buy car speakers just put them in factory locations, off axis. They were likely designed to accommodate those people, since they make up the majority of sales.


I read some thread where the Focal Sales Manager (or something like that) recommend the Focal BE tweeter off axis because they were designed to be put in stock location,
but then again usually someone who is buying tweeter as expensive as Focal BE tweeter most likely do not put their tweeter in stock factory location... I think...


----------



## Elektra

BMW Alpina said:


> I read some thread where the Focal Sales Manager (or something like that) recommend the Focal BE tweeter off axis because they were designed to be put in stock location,
> but then again usually someone who is buying tweeter as expensive as Focal BE tweeter most likely do not put their tweeter in stock factory location... I think...




I have the Kit 7 and I think that tweeter is best suited more on-axis as apposed to off-axis 

I would use a tweeter more off axis if it was an extremely bright tweeter to tame it a bit but the BE tweeter imho is ultra smooth so no need to have it off axis 

If you set the Focal set up correctly it's one of the most natural sets you will hear you could sit and listen for hours on all types of music - set it up wrong and your going to be running out your car after 5mins 


Sent from my iPhone using Tapatalk


----------



## Elektra

Andy Wehmeyer said:


> There are several things that can help to create depth in the stage. First, it's important to separate the stage from the room ambience. The stage is where the musicians are and the room is where you are. Think of an auditorium--the stage dimensions are not the same as the room dimensions. In a bar, it's all one space. This may or may not exist in the recording. If it does, it may be real or fake--doesn't matter so long as it's there.
> 
> To leep it relatively simple, early reflections describe the area around the musicians and late reflections describe the listening space. For studio recordings, these reflections may or may not be added to the mix. IF they're added, then they're often the result of a room synthesis algorithm. many of these are very effective.
> 
> So...first, these reflections have to be included in the recording for you to reproduce them. If you have access to the EMMA disc and the IASCA disc, check out two tracks. Listen to the 7 drum beats track on the IASCA disc and then listen to the track on the EMMA disc where the guy speaks as he walks around the stage. These are good examples of tracks do and don't include these cues. No matter what you do (well, almost--but I'll get to that later), the 7 drum beats will NOT appear far outside the left and right speakers because the recording is simply panned from left to right using simple level controls in the recording.
> 
> The cues do exist in the track on the EMMA disc and they aren't synthesized. With this track it's possible to hear the room larger than the car.
> 
> Then, listen to a third track. Check out "I Will Rise Up" by Lyle Lovett. It's on "It's Not Big, It's Large". I'm not sure whether this is a studio track with room synthesis or recorded live, but it's a good example of a recording that includes a stage and a room. It seems close-miced so it will appeal to those of you who like live recordings and those who don't.
> 
> OK, now think about what you hear when you listen to a concert--choose an auditorium for this mental exercise. The musicians are on stage. You hear the sound directly from the musicians, the sound that's reproduced over the mains (the big speakers on the stage that point AT you) and the sound of those reflected from the side and back walls of the room. You also hear the sound of the musicians and the stage monitors reflected from the surfaces that make up the stage.
> 
> Think about what it would take to ACCURATELY reproduce that even using a recording and speakers placed on the stage if you were in sitting in the auditorium. If you had a speaker located at the position of each of the musicians and those were miced and piped into the house system, that might do it. If you placed two stereo speakers on the stage and piped the output of those through the house system, that would require those speakers to reproduce the space of the stage. Hmmm...
> 
> In both of these scenarios, you'd hear the room. The reflected sound would come from all around you, just as it did in the live recording. You'd probably hear a pretty good approximation of what you heard live.
> 
> Now, take those two speakers and place them in your live-in room. Hmmm...now the reflected sound you hear is defined by the boundaries of the room. Early reflections come from the space around the speakers and late reflections come from the back and side walls. All the sound from the speakers is reflected by those walls--the sound of the room isn't separated from the sound of the musicians. The early and late reflections are all included in the sound from the front speakers. You may sense from the recording that there was a room, but it won't be reproduced AS a room.
> 
> Now, what if we move to a car. The space is tiny. So tiny that there are no late reflections generated by the "room". We hear the car and the speakers as the same event. Acoustic crosstalk makes this worse.
> 
> OK, so what can we do? Eliminating reflections will get us back to the two stereo speakers in a dead room, but it isn't practical because we have to be able to see through the windshield and the windows. Kick panel mounting helps because the speakers are moved away from the glass. That helps, but low frequencies are still reflected--no matter the surface material--carpet doesn't eliminate low frequency or midrange reflections very well. Much of the ambient information is high frequency stuff, though. OK. So that's an improvement. Now we're closer to good 2-channel.
> 
> But what about the room? For recordings that don't include a room, we're now OK. Dry, studio recordings will sound dry. Images will be small and located between the speakers.90% of the cars I listen to and 99% of competition cars I listen to sound like this. When judges and competitors say, "The musicians aren't behind you when they play live", this is what they're after. When they turn their head to determine if something is coming from behind them so they can take points away, this is what they're after. I don't think those guys have ever been to a live show, and if they have, they weren't listening to the room.
> 
> If you want to win competitions, this is the way to do it. Figure out how to generate a bunch of early reflections in your car. Mount the speakers off axis in the kick panels and bounce **** around all over the place. Maybe you'll get lucky. You may have to remove the dash, cut a big hole in it so the sound of the speakers can bounce off the windshield with the longest path length you can pull off. this will increase the sense of "depth". This is a matter of trial and error and will seem like magic when you get to something you like.
> 
> If you use only front speakers and mount the speakers on your a-pillars and point them at the listeners, you'll NEVER get there. Someone will blast me and say that their car does it, but I'd postulate it's because they've never heard a room or never paid any attention to what live music sounds like.
> 
> So, what else can we do to approximate a room? Simple. Use an upmixer and rear speakers. Most of the upmixers (PL2, DTS Neo, Logic7) help this by attempting to remove the ambient sounds and steer those to the rear. You have to have rear speakers and they have to play loudly enough to be heard as real events. Fortunately, gain controls on the amp that drive the rear speakers make this simple. With this method, if the recording includes a room, it will be better approximated in your car. JBL's MS-8 does this. Other processors with PL2 also do this. It's very effective, but there are some artifacts. Get used to it.
> 
> The third way is to use a room synthesis algorithm that GENERATES a fake room. Early reflections can be added to the front speakers and late reflections can be added to the rear speakers. this can make the car sound larger than it is no matter the recording. This is what I used to use in my Volvo. It also works and I managed to win IASCA at SBN with it. Judges said, "I've never heard a car that REPRODUCED the ambience in the recording the way yours does." I didn't tell them that the ambience didn't EXIST in the recording until after I collected my trophy. There are no car audio processors that include this, yet. I did it with a PC and some custom software, courtesy of a Harman colleague.
> 
> So, after all this, my suggestion is--if you want depth, you have to have a system that can either reproduce it or create it. Two speakers on the a-pillars won't do it. You need rear speakers and you need the right information to be played by those rear speakers.




Thanks Andy

Your an absolute abyss of information (hope that came out right ..)

From summing up what you said earlier mids and tweeters are not a great idea on the A-Pillars - due to reflections, and you need to worry about where on the dash to install them...

The question I would like to know is this 

Would I get a better sonic result if I placed a 3" mid say on the top 3rd of the door with the midbass below it in the traditional place and then install the tweeter on axis on the A-pillar?

Regarding the position of the tweeter... to avoid some reflections from the windscreen and side glass - I was thinking installing the tweeter between the sail position and the bottom corner of the actual A-Pillar nearest to the dash... see pic...

With regards to on-axis - if I went 100% on axis to each ear - the angle will be be different on both sides - is that a problem? Aesthetically people like Symmetry for there pods but if I were to have equal on axis positioning then it's all about the end result rather than aesthetics?

Also guys like to find a angle that can suite the passenger as well... in my case I would rather benefit entirely on my listening position rather than giving the passenger a better experience - besides I don't think they would suffer too much in any case....

Thanks for your help...

See pic...











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## robtr8

Put Andy's GB40's in the doors. Absolutely amazing transformation.


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## Elektra

robtr8 said:


> Put Andy's GB40's in the doors. Absolutely amazing transformation.




Did you do an enclosure behind it? 


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## JVD240

robtr8 said:


> Put Andy's GB40's in the doors. Absolutely amazing transformation.


Nice! I'm about to get started on my E91. Was curious if the GB40 would fit with the sweet Frog grille.

Oh, and Elektra. Here's the on/off axis response of the GB40 as measured by our very own ErinH. 0, 15, 30 and 60 degrees respectively.










Gives you a good idea of where you can low pass this driver and still have a relatively smooth frequency response.


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## Elektra

JVD240 said:


> Nice! I'm about to get started on my E91. Was curious if the GB40 would fit with the sweet Frog grille.
> 
> 
> 
> Oh, and Elektra. Here's the on/off axis response of the GB40 as measured by our very own ErinH. 0, 15, 30 and 60 degrees respectively.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Gives you a good idea of where you can low pass this driver and still have a relatively smooth frequency response.




So between 2000hz and 3000hz? Where would you cross them at? 


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## JVD240

Yep, somewhere in that range depending on slope.

Keep in mind your driver side mid will be significantly more off axis than your passenger side. Picking a speaker with smooth FR, both on and off axis, will make it easier to achieve a matched L/R frequency response in the car. So basically... use speakers in the proper pass band (before beaming) whenever possible.


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## robtr8

No enclosure, it's pretty dang tight back there.


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## JVD240

robtr8 said:


> No enclosure, it's pretty dang tight back there.


Coupe or sedan?


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## robtr8

Coupe. Supposedly a very tight fit but I was assured by NW Musicar that Andy designed the GB40 FOR BMW's.

I did everything else first, keeping the factory mids for a minute while I waited for the GB40's to show up. Sounded OK. Added the GB40's. Absolutely amazing, midbass and voices just came alive!

On the install, I obviously ditched the ridiculously huge outer bezel, slotted the door card for the chrome inner bezel/grill's tabs, mounted the driver to the inner mount and installed that inside the door card with the inner bezel outside the door card poking through the whole assemble. I think some modification to the door card's mounting holes was necessary. In both cases I used a Milwaukee 12v vibrate saw with a small not terribly aggressive blade. You'll see when you get all the bits laid out.


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## JVD240

robtr8 said:


> Coupe. Supposedly a very tight fit but I was assured by NW Musicar that Andy designed the GB40 FOR BMW's.
> 
> I did everything else first, keeping the factory mids for a minute while I waited for the GB40's to show up. Sounded OK. Added the GB40's, took the high pass all the way down to 250 (as low as the 7800 will let the mids go) and the low pass up to 4k. Absolutely amazing, midbass and voices just came alive!
> 
> On the install, I obviously ditched the ridiculously huge outer bezel, slotted the door card for the chrome inner bezel/grill's tabs, mounted the driver to the inner mount and installed that inside the door card with the inner bezel outside the door card poking through the whole assemble. I think some modification to the door card's mounting holes was necessary. In both cases I used a Milwaukee 12v vibrate saw with a small not terribly aggressive blade. You'll see when you get all the bits laid out.


Awesome, thanks for the info! I believe the Sedans/Wagons (my car) have slightly more depth in the doors.


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## Elektra

JVD240 said:


> Yep, somewhere in that range depending on slope.
> 
> 
> 
> Keep in mind your driver side mid will be significantly more off axis than your passenger side. Picking a speaker with smooth FR, both on and off axis, will make it easier to achieve a matched L/R frequency response in the car. So basically... use speakers in the proper pass band (before beaming) whenever possible.




I suppose ideal is like 2500hz if you want to take into consideration the beaming effect - you would then need a tweeter that is comfortable at 2500hz which should not be too hard to find as most Scan tweeters have a FS of 500hz (for example) 


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## Elektra

robtr8 said:


> No enclosure, it's pretty dang tight back there.




Did you mount over or behind the door panel?


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## robtr8

Behind. Let me know if you see a better way. Not entirely sure I did it as God intended.

I have them high passed at 125 hz and low passed at 6.3 khz. Also turned down 4db.

Rugrat just got home with the e92 from his Organic Chem II class so I played the Lyle Lovett track Andy mentioned in that and then played it in my moose that has the mids and tweets up on the A pillars. No comparison. The GB40 imaging and impact are phenomenal.


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## lyraxx

interesting


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## Niick

Hey folks, I thought this might be a good thread to post this video on. In the video I'm explaining a bit about a little known (in car audio circles) measurement called coherence. 

Coherence can aide in the determination of crossover points based upon the direct to reverberate ratio of sound at the microphone position, or in the case of Smaart 8, at multiple microphone positions. 

The coherence reading will be affected by speaker positioning, aiming, beaming, and the direct to reflected energy ratio on a per frequency basis. 

It can be used especially in aiding tweeter and midrange placement and aiming during installation as well. 

I plan on also doing a video of coherence using ARTA. 

https://youtu.be/N3WcEVtAJM8


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## Swaglife81

Some good info in this thread. I'm kinda torn between better tweeter aiming. To many people generalize the terms with on vs off axis. So many different aiming tactics like one off axis and one on axis. Both aiming towards the center line or both aiming towards the headliner. I see so many different tweeter positions from audiophiles. Seems alot of tweeters benefits from very slight off axis aiming, that 15-20 degree area for bright tweeters. Am I safe to say that even at 30+ degrees that it can be EQ to sound just as good and less EQ with on axis. Meaning if someone wasn't going to install a dsp the benefits of on axis are greater. If someone is going to tune by dsp than a 15-30 degree off axis placement is ok because of tuning capabilities. Either route I see there will be reflection somewhere in the car. Which we all know is a horrible acoustic environment. I expect honestly a true on axis in your face tweeter aiming would need alot more toning down by dsp. A more perfect tweeter install would be more towards both aimed at center line or towards the center headliner area. When listening to opinions alot of people like off axis overall sound. Is this because this tones the high end of the frequencies down and they are using bright tweeters without dsp tuning? 

Just my thoughts, let me know if I'm in the right ballpark with my comments.


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## 156546

Niick said:


> Hey folks, I thought this might be a good thread to post this video on. In the video I'm explaining a bit about a little known (in car audio circles) measurement called coherence.
> 
> Coherence can aide in the determination of crossover points based upon the direct to reverberate ratio of sound at the microphone position, or in the case of Smaart 8, at multiple microphone positions.
> 
> The coherence reading will be affected by speaker positioning, aiming, beaming, and the direct to reflected energy ratio on a per frequency basis.
> 
> It can be used especially in aiding tweeter and midrange placement and aiming during installation as well.
> 
> I plan on also doing a video of coherence using ARTA.
> 
> https://youtu.be/N3WcEVtAJM8


Not understanding this. Beaming is the point at which the on axis response and the off axis response begin (and continue as frequency increases) to diverge. So, at frequencies where the dispersion is narrow, there's LESS contribution from reflecting surfaces.

What are you using for the reference trace and are you using your spatial average as the other trace?


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## soundboy

What best for ribbon tweeter mount, on-axis or off-axis ? (have try to read me up this)

Is pair of Sony XES-H50 , have Frequency range 3,500-40,000Hz from the spec!

Sony recommended crossover frequency 5,000 Hz or above...

I shall mount xes frontspeakers like this (car MB C240-2003 , will not rebuild the dash for 6" this time) :

Ribbon tweeter on dashboard. (not sure of correction right now)

6" speaker in the doors.(XES-F50)


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## CrossFired

lyraxx said:


> interesting


Yes...Very.


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## robtr8

Boy, talk about dragging up an old post. Had to go back and read what the heck this was all about. I don't even have the car anymore. Traded it and a pile of cash for the F Type.


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## MetricMuscle

WOW, THIS IS A GREAT MUST READ THREAD !!!! 

First of all I'd like thank Andy for his patience and understanding with us slow on the uptake learners out there, namely me. In reading this again I'm amazed how hard headed I was, probably in part from carrying around inaccurate information. THANK YOU ANDY!! for putting me on the correct path and taking the time it took.


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