Hi, I hope it's ok to open a thread here to cover more basic issues. As I'm used to building speakers for hifi use (and taking the room into consideration!), I'm constantly feeling a bit, let's call it, "philosophically alienated" when entering the car audio world. Perhaps someone with a similar background can help me increase my understanding...? In general, yes I know and have experienced myself that car systems can sound decent. So there must be reasons why that is in spite of the issues I have in my mind, and guess it might actually be useful to find some answers as to what these reasons are. Those issues would be:
a) everything is off-axis, the individual chassis are far removed from each other, the listeners are sitting very close to the speakers (extreme near-field), and basically always outside of the stereo listening triangle. How does one come up with a proper sound setting for that, which works well and creates a stereo illusion for all occupant numbers, and also not a noticable change in response from different passenger heights/positions? I can only guess, does one routinely use speakers that have basically non-linear frequency responses on-axis (rising treble), to have a linear response at the off-axis listener position?
b) is a point source characteristic, and with that, stereo imaging and "virtual stage size" even a consideration? apart from coax speakers, which rarely are positioned anywhere near to creating an acoustic stage (in front of the listeners), I'd say there are very few system configurations that would allow for a classical point source (generous rule of thumb: distance between speaker centers less than the wavelength at crossover frequency - meaning about 17cm between tweeter and mid/woofer at 2kHz)?
c) since there are no regularly shaped acoustic baffles, various predetermined speaker positions, and a lot of hard, acoustically reflective surfaces including glass of varying curvature, which are pretty much acoustic mirrors for any mid-high frequency waves and therefore highly influential - how (apart from creating complex 3d models including the acoustic properties of seats and dashboard lining) does one even have a concept of a plan to find out how a given system might sound when installed in a different car? I guess that will also be the reason why just about no manufacturers publish any sort of frequency response charts for their systems, right?
a) everything is off-axis, the individual chassis are far removed from each other, the listeners are sitting very close to the speakers (extreme near-field), and basically always outside of the stereo listening triangle. How does one come up with a proper sound setting for that, which works well and creates a stereo illusion for all occupant numbers, and also not a noticable change in response from different passenger heights/positions? I can only guess, does one routinely use speakers that have basically non-linear frequency responses on-axis (rising treble), to have a linear response at the off-axis listener position?
b) is a point source characteristic, and with that, stereo imaging and "virtual stage size" even a consideration? apart from coax speakers, which rarely are positioned anywhere near to creating an acoustic stage (in front of the listeners), I'd say there are very few system configurations that would allow for a classical point source (generous rule of thumb: distance between speaker centers less than the wavelength at crossover frequency - meaning about 17cm between tweeter and mid/woofer at 2kHz)?
c) since there are no regularly shaped acoustic baffles, various predetermined speaker positions, and a lot of hard, acoustically reflective surfaces including glass of varying curvature, which are pretty much acoustic mirrors for any mid-high frequency waves and therefore highly influential - how (apart from creating complex 3d models including the acoustic properties of seats and dashboard lining) does one even have a concept of a plan to find out how a given system might sound when installed in a different car? I guess that will also be the reason why just about no manufacturers publish any sort of frequency response charts for their systems, right?
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I have used the windshield to a benefit by carefully aiming the dash mounted midrange/tweeter.
Many use dsp with varying signal delay for the different speaker positions to help it all work as well.
Many use dsp with varying signal delay for the different speaker positions to help it all work as well.
I have struggled also with sound in car.
Most problems are from car as bad sound environment, too small room with lot of early reflections and just reflections.
Here are impulse response measurement of little treated room with red line and car with blue.
Most problems are from car as bad sound environment, too small room with lot of early reflections and just reflections.
Here are impulse response measurement of little treated room with red line and car with blue.
Car audio is one huge trade-off/compromise after another.
At one time, placing the mid/high frequency drivers in the outer footwells/kickpanels was popular, installing a center and/or outer dash speakers to raise the stage. This isn't really practical with smaller right-hand drive vehicles.
At one time, placing the mid/high frequency drivers in the outer footwells/kickpanels was popular, installing a center and/or outer dash speakers to raise the stage. This isn't really practical with smaller right-hand drive vehicles.
One of the reasons center channels are common in car audio. They fill in the hole in the middle and alleviate bunching at the near speaker that often occur with asymmetric layouts.
Over the right frequency range, many drivers are pretty smooth off-axis. Aiming the front/side speakers toward the center of the car (at the point between the heads of the front listeners) can also help, since both front seat occupants are similarly off-axis for left and right speakers then.
Equalization is very common in car audio, so rarely is anyone using the natural frequency response of the speakers.
Sail panel or A-pillar pods that contain a small midrange and tweeter very near each other are common additions in custom installations. These often handle a few hundred hertz and up, so do a good job of bringing the image height up and forward. Depth in the soundstage is harder to achieve, but processing or delays are sometimes used to enhance that.
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In my opinion, the original mistake is to transport home listening to the car.
It's a mistake because at home listening is the only thing you can concentrate on and fully appreciate.
In the car you have to drive, pay attention to the road and traffic, and identifying the instrumental detail becomes a danger.
Listening in the car is pure fun, i believe that a meticulously reconstructed soundstage is of little use, unless you always listen with the car stationary, but what's the point?
Many enthusiasts use DSP to recreate a home soundstage in the car, but they have never listened at home, they don't know what it is, they are just following a trend.
To date, for me, the best evolution of car audio i have listened to with the Citroen C3 factory system, because it allows the same stage for the driver and the front passenger.
It is not as accurate as listening at home, but it's the same for both.
This has always been my goal.
To get more out of this setup, you just need good amplifiers, good speakers, and a good subwoofer.
It's a mistake because at home listening is the only thing you can concentrate on and fully appreciate.
In the car you have to drive, pay attention to the road and traffic, and identifying the instrumental detail becomes a danger.
Listening in the car is pure fun, i believe that a meticulously reconstructed soundstage is of little use, unless you always listen with the car stationary, but what's the point?
Many enthusiasts use DSP to recreate a home soundstage in the car, but they have never listened at home, they don't know what it is, they are just following a trend.
To date, for me, the best evolution of car audio i have listened to with the Citroen C3 factory system, because it allows the same stage for the driver and the front passenger.
It is not as accurate as listening at home, but it's the same for both.
This has always been my goal.
To get more out of this setup, you just need good amplifiers, good speakers, and a good subwoofer.
I listened to the same multi-amplified solution with two front ways and subwoofer in a friend's car a while ago, and i liked it a lot.
Still similar stage for the two front passengers, like the current Citroen C3 system.
The C3 look pretty cool!
A dash mounted subwoofer is rare. I tried to find a way to do that in my new Corolla.
Have done that before but were aimed downward.
It does help the presentation/illusion for sure.
The frequency charted as shown really tells the story about how cars react with amplified sound.
A dash mounted subwoofer is rare. I tried to find a way to do that in my new Corolla.
Have done that before but were aimed downward.
It does help the presentation/illusion for sure.
The frequency charted as shown really tells the story about how cars react with amplified sound.
Some cars are easier than other. If awesome audio is a prerequisite than a vehicle that can support an intricate fit out must be selected first
Speak to an SQ comp winning installer about a PRV or DS18 based fit out for imaging and dynamics. Using custom waveguides just under the dash on each side. Again, these types of projects are based around suitable cars. An older type dash helps greatly. Locally, an older VL Commodore or similar makes for a great SQ car and some on the road flair with Group 1 type body kits and such and a great rear wheel drive system with a v8 or even the models with the 3.0L Nissan straight six. I also once did an EL Falcon for SQ and is another awesome local option for cheap and fun daily driver
My current Subaru XV is right now getting a very high output SQ system with an underrated Taramps 2k@2R mono-bloc for the boot and the existing JL Audio XD400/4 for the fronts
Doors will be getting 6.5” subs in custom BR pods tuned to 47hz and crossing to A pillar sail area tweeter location but using custom pods again that sink into the factory holes. They will have 3” FR drivers facing and staging to the front seat. The FR pods will seat the driver in a waveguide
Speak to an SQ comp winning installer about a PRV or DS18 based fit out for imaging and dynamics. Using custom waveguides just under the dash on each side. Again, these types of projects are based around suitable cars. An older type dash helps greatly. Locally, an older VL Commodore or similar makes for a great SQ car and some on the road flair with Group 1 type body kits and such and a great rear wheel drive system with a v8 or even the models with the 3.0L Nissan straight six. I also once did an EL Falcon for SQ and is another awesome local option for cheap and fun daily driver
My current Subaru XV is right now getting a very high output SQ system with an underrated Taramps 2k@2R mono-bloc for the boot and the existing JL Audio XD400/4 for the fronts
Doors will be getting 6.5” subs in custom BR pods tuned to 47hz and crossing to A pillar sail area tweeter location but using custom pods again that sink into the factory holes. They will have 3” FR drivers facing and staging to the front seat. The FR pods will seat the driver in a waveguide
Thanks for the many interesting replies, everyone! First of all, I have to admit I was previously taking my individual preference as "the general law" - in this case, being unwilling to modify my own vehicle much, cutting apart dashboards or adding custom A-pillar trim etc. - basically I was set on using the existing speaker locations (doorboard 6.5" woofer at lower end of doorboard, 2" capsuled tweeter mounted on top of doorboard close to the door hinge, semi-facing the passengers) - which is probably not the worst setup, but probably not the best either.
Your input made me at least consider installing something like an A-pillar two-way mount for a mid + tweeter or an a-pillar 4/5in coax; that would actually make sense for most of the issues I have regarding stage orientation, point source characteristics etc, if perhaps not solve the room reflection muddiness issues (as impressively shown in kaameelis' plot!) though.
I could imagine a horn/waveguide/controlled directivity device helping with that, but then there are the size constraints: I guess adding 5-10cm of heft around the A-pillars could already be prohibitive, as that might intrude the driver's vision (=problems with local authorities).
Also, there is quite certainly no off-the-shelf a-pillar mount available for my car - a 30 year old Alfa Romeo 164 in quite good interior condition, basically black leather + dark grey plastics plus ~100 neatly arranged, illuminated switches all around; I really love the OEM look of that and can't even stand having a cellphone holder permanently attached, as that looks so out of place, so I'd very much like to have any installation fit that overall look - but I guess that could be overcome with woodwork or 3d printing, and then covering it in (fake?) leather or something that mimics the look of existing surfaces - well, that's the basic problem of speaker building, just something I didn't have to worry about so much yet I guess.
Don't think I'll go for center-channels though any time soon - mostly because I can't think of any good way to install the speakers there, apart from sticking something on top of the dashboard, even though it probably makes sense for providing a good compromise regarding stereo imaging to driver and front passenger. It still got me thinking though, am I correct in assuming this would get used in a regular cinema channel arrangement [L - Center=L+R - R], or (just a quick idea, don't take that too serious) would it make sense to alternate that actual stereo channels as in L - R - L, so that the front passenger might face a reversed stereo image, but both driver and passenger have basically a full stereo triangle available at their position (probably only makes sense with controlled directivity speakers, for which there is no room once more, so I guess strike that thought)?
Your input made me at least consider installing something like an A-pillar two-way mount for a mid + tweeter or an a-pillar 4/5in coax; that would actually make sense for most of the issues I have regarding stage orientation, point source characteristics etc, if perhaps not solve the room reflection muddiness issues (as impressively shown in kaameelis' plot!) though.
I could imagine a horn/waveguide/controlled directivity device helping with that, but then there are the size constraints: I guess adding 5-10cm of heft around the A-pillars could already be prohibitive, as that might intrude the driver's vision (=problems with local authorities).
Also, there is quite certainly no off-the-shelf a-pillar mount available for my car - a 30 year old Alfa Romeo 164 in quite good interior condition, basically black leather + dark grey plastics plus ~100 neatly arranged, illuminated switches all around; I really love the OEM look of that and can't even stand having a cellphone holder permanently attached, as that looks so out of place, so I'd very much like to have any installation fit that overall look - but I guess that could be overcome with woodwork or 3d printing, and then covering it in (fake?) leather or something that mimics the look of existing surfaces - well, that's the basic problem of speaker building, just something I didn't have to worry about so much yet I guess.
Don't think I'll go for center-channels though any time soon - mostly because I can't think of any good way to install the speakers there, apart from sticking something on top of the dashboard, even though it probably makes sense for providing a good compromise regarding stereo imaging to driver and front passenger. It still got me thinking though, am I correct in assuming this would get used in a regular cinema channel arrangement [L - Center=L+R - R], or (just a quick idea, don't take that too serious) would it make sense to alternate that actual stereo channels as in L - R - L, so that the front passenger might face a reversed stereo image, but both driver and passenger have basically a full stereo triangle available at their position (probably only makes sense with controlled directivity speakers, for which there is no room once more, so I guess strike that thought)?
The pods for the dash/A-pillar locations could be made with fiberglass. You'd heavily mask the area with multiple layers to ensure that no fiberglass could leak through and form it up with... whatever and then fiberglass it. It will conform perfectly and can look OEM if you take your time.
If you don't want to damage the plastic on the A-pillars if you're only going to modify that location, you can buy replacement plastic (not necessarily OEM) for the pillars and you can modify those.
If you don't want to damage the plastic on the A-pillars if you're only going to modify that location, you can buy replacement plastic (not necessarily OEM) for the pillars and you can modify those.
For a hidden center channel installation, another approach I've seen is to put the speaker behind the heating/AC vent. Your Alfa seems to have generous vents in the center of the dash.
The ND64 from Dayton Audio is an interesting driver that can go in a tiny enclosure and perform well down to about 400 Hz. Sensitivity is a bit lacking, but if you are more interested in sound quality, it is typically OK. It does fine in 0.05-0.1 liter, which is basically a cubical box the size of the speaker.
I'm not getting some of what you are trying to say in this paragraph, but there are many ways center can be derived. For modern processors it tends to get complicated. Examples:
https://www.educarmag.com/educar-ma...e-than-one-seat-center-channels-and-upmixing/
https://patents.google.com/patent/US8705769B2/en
"I'm not getting some of what you are trying to say in this paragraph" - I guess I expressed it over-complicated: a regular center channel (as in cinema etc.) takes into account a mixture of both left and right channels - as your links also describe. On the other side, I was having this brainwave that in a car with the specific nearfield arrangement, it might be worthwhile to simply output the unaltered right channel to the center speakers, so that the driver (on LHD cars) sits in a nice stereo triangle between the left and right channels (center position), and the front passenger would be sitting in a inversed-stereo triangle between the center (=right channel) to his left and would have the left channel to his right. Obviously, this could create problems with interference, unless the "spillage" across the outter channels from the other side was limited.
"For a hidden center channel installation, another approach I've seen is to put the speaker behind the heating/AC vent. Your Alfa seems to have generous vents in the center of the dash.
The ND64 from Dayton Audio is an interesting driver that can go in a tiny enclosure and perform well down to about 400 Hz."
That does look like an interesting driver indeed, thanks for the suggestion. In that size, I'd usually pick the cheap+cheerful old Vifa/Peerless TC9FD by default as I've used these about 12 times already and they are really really clean sounding, but the dayton ND64 seems to have way better off-axis behavior...
The ND64 from Dayton Audio is an interesting driver that can go in a tiny enclosure and perform well down to about 400 Hz."
That does look like an interesting driver indeed, thanks for the suggestion. In that size, I'd usually pick the cheap+cheerful old Vifa/Peerless TC9FD by default as I've used these about 12 times already and they are really really clean sounding, but the dayton ND64 seems to have way better off-axis behavior...
I have never tested either speaker, but just looking at how they are built I would definitely go with the Peerless.
Yes, it's like i said.
Finding a correct sound by chasing measurements costs a lot of time and resources, and in the end you will never have the result like at home.
I like the reasonable compromise like yours better.
And i prefer to pay more attention to the quality of the components.