home audio compared to car audio technology?

[Francious70]

HAHA... that's Dave's car... that's exactly who i was talking about!!!

Honestly, I kinda figured you were. All the clues where there, minus the name.

Paul

 

[WmAx]

Put the speakers in kick pannel pods aimed directly at your head and you'll only get the direct (beamed) sound, the reflections will go elsewhere. And if RTA's to a flat frequency response (it is possible, and not to terribly difficult) then what you have is a perfect reproduction of the recording.

What you propose is not possible under practical circumstances. In order to have a broadband, direct beam of souind, the surface area of the effective radiation area of the driver must be approaching 1 wavelength and longer of the frequency in question. Thus, it's not possible to have 'directive' sound from the surface area availabe on a kickpanel with a direct radiator under the treble band. The most plausible method would be use of a horn, but has some unusual size/installation problems in that mounting location(kick pods). If you did manage(would be one very large set of kickpods to effect midrange directivity down to about 300-400hz(this assumes you have nearby midbasses in the doorpanels to blend usefully!), note that horns have audible resonances/reflections of themselves, products of the mouth area internal reflections. The best execution would involve the ultrasonic devices I mentioned eariler, that are able to produe a true broadband directive signal dispersion.

Sadly, you can't produce a symetrical soundfield for driver and passenger side, just one or the other.

Please tell me, how do you effect a symmetrical soundfiedl? Remember, the soundfieled must have identical reflection time direct vs. reflect, and equal amplitude vs. frequency, at the ear positions. The mere fact of beaming sound to the left side of head(if in left seat), would mean audible reflections/resonances between the head and left window glass due to the close proximity(12-14 inches?). If you equalized the frequency response here using head mounted stereo binaural microphones(you'de have to E.Q. each channel assymetrically on L vs. R, due to the very different angles to ear pinnae of each channel in this seating position), it would not do anything for the destructive reflection times of left soundfield. Again, on top of this and mentioned earlier, you don't really have a practical way to have true directional sound in the first place.

In a home environment, you can effect directive(down through most of the midrange) speakers using direct radiators due to it being practical to have large size speakers in this environment. But, since the direct vs. reflected pathlengths are long enough from speaker to walls, etc.; the reflections(as long as they are roughly equivalent in frequency spectrum distribution vs. direct sound) can be beneficial in this environment, since they would be interpretted as ambience, not interference, at time differences of approx. >5ms, <20ms. A symmetrical soundfield for L and R channels, including reflection times and frequency vs. amplitude response are not a problem either. The only advantage car audio has(it is poorer in all other regards of acoustics) is in the bass band. The car has a small enough cabin to be able to avoid the modal resonances created in a room.

-Chris

 

[Francious70]

Honestly Chris, I have no idea what you just said. I'm gonna say that I've hit the limits of my knowledge, but I'm gonna try to find someone who knows a bit more than me.

Paul

 

[shokhead]

Hows this,HT sounds better then Car Audio and if your car audio sounds better, then its time to work on your HT.

 

[Robsarve]

What you propose is not possible under practical circumstances.

In a car, proper sound quality is NOT a function of getting "unaffected" direct sound with the right blend of "live end-dead end". Instead it is created by cearfully balancing much larger degree of reflections. Successful results can actually be accived with a full non-directional setup thanks to the reflective character of the veheicles interior.

This is why so much work and experience has to go inte proper planning, design and installation of the components.

The only advantage car audio has(it is poorer in all other regards of acoustics) is in the bass band. The car has a small enough cabin to be able to avoid the modal resonances created in a room.
-Chris

Absolutely true, but that does not mean that a car cannot sound seriously good. It just takes a little while longer since it´s quite a bit more to it then just buying the stuff and working on toe-in angles. There are cars out there that has the ability to rival a seriously good home system, no doubt. But building such a a car takes a LOT of skill and several months work.
Plus the use all the toys that IMHO makes Car Audio more advanced then HT: individual 31-band eq´s for every cannel, fully flexible crossovers and time alignment in 0,05 ms steps of the drivers.

I have a faily nice HT with 4 kW of IcePower amplification at home. And it sounds a lot better then any of my car stereos, but that doesn´t mean I don´t enjoy the music wile driving.

 

[WmAx]

In a car, proper sound quality is NOT a function of getting "unaffected" direct sound with the right blend of "live end-dead end". Instead it is created by cearfully balancing much larger degree of reflections. Successful results can actually be accived with a full non-directional setup thanks to the reflective character of the veheicles interior.

I've already covered all of this in past posts within this thread.

but that does not mean that a car cannot sound seriously good.

I never said it could not. In a past post within this thread, I specifically stated I did not doubt it could sound very good.

The discussion that ensued was not in relation to whether a car audio system could sound good -- it was in relation to being able to create an effective diffuse sound field that was realistic(perceptual realism), for example to reproduce the sound perceptually of real space of concert hall, for example. I pointed out at least one theoretical method that would work in a car(though impractical) to achieve this effect. I can think of others, but none are practical -- they would require a very large dash and extensive modifciations involving large structures protruding from the dash(totally impractical). At this point, the thread has become confused, or so it would seem.

-Chris

 

[WmAx]

Honestly Chris, I have no idea what you just said. I'm gonna say that I've hit the limits of my knowledge, but I'm gonna try to find someone who knows a bit more than me.

Paul

I will explain specific issues that are not clear. Just point out these specific statements.

-Chris

 

[Francious70]

Thanks for your understanding Chris. Starting with this, I have no clue what your saying.

In order to have a broadband, direct beam of souind, the surface area of the effective radiation area of the driver must be approaching 1 wavelength and longer of the frequency in question. Thus, it's not possible to have 'directive' sound from the surface area availabe on a kickpanel with a direct radiator under the treble band. The best execution would involve the ultrasonic devices I mentioned eariler, that are able to produe a true broadband directive signal dispersion.

Remember, the soundfieled must have identical reflection time direct vs. reflect, and equal amplitude vs. frequency, at the ear positions. The mere fact of beaming sound to the left side of head(if in left seat), would mean audible reflections/resonances between the head and left window glass due to the close proximity(12-14 inches?). If you equalized the frequency response here using head mounted stereo binaural microphones(you'de have to E.Q. each channel assymetrically on L vs. R, due to the very different angles to ear pinnae of each channel in this seating position), it would not do anything for the destructive reflection times of left soundfield.

In a home environment, you can effect directive(down through most of the midrange) speakers using direct radiators due to it being practical to have large size speakers in this environment. But, since the direct vs. reflected pathlengths are long enough from speaker to walls, etc.; the reflections(as long as they are roughly equivalent in frequency spectrum distribution vs. direct sound) can be beneficial in this environment, since they would be interpretted as ambience, not interference, at time differences of approx. >5ms, <20ms. A symmetrical soundfield for L and R channels, including reflection times and frequency vs. amplitude response are not a problem either.

I bolded what's German to me.

Paul

 

[Errin@PG]

Thanks to Francious70 I have found an intelligent forum, with my type of discussion.

I love my HT do not get me wrong, but I have to take the stance that car audio is more advanced than home I know from reading along a little that the technology standpoint has moved primarily toward the acoustic side and that "youth" is in defense of car where "age and wisdom" is in defense of home, I feel that I'm a good cross point of both. I am also into Sound Quality not Sound Quantity.

Here is my ground for in car being more advanced than in home

1. They both started with the same technology.
2. Car has a serious set of restrictions compared to home.
3. In car offers anything that in home offers, just on a scaled down version, including - internet, fully tracking sattelite TV (not offered in home), streaming A/V.
4. In Car has advanced further due to restrictions, D & T class amps would never have been invented if not for car.
5. Interconnectability and communication was developed for car and is being used in home now (controlling multiple items from one point).

Acoustically speaking they're both on the same plain, though you need a competent installer to work on your car where in home you just pull it out of the box and connect it and make minor adjustments. In car you need to know all about the random acoustics and how to deal with them, you need to know how to work with the existing systems, in general you need to be mechanically orientated, but most importantly you need to be creative.

 

[annunaki]

4. In Car has advanced further due to restrictions, D & T class amps would never have been invented if not for car.

Not necessarily. Space and heat have become bigger concerns recently. Efficency is always a priority. There is no T class amplifier realistically. There is however, full range class D. "Class T" was coined by Tripath Technologies, who marketed the first full range class D amplifier through the use of a variable switching frequecy amp design which utilizes a low pass filter that keeps any noise out of the audible frequency band. I belive that amplifier classes run from A-I, and S. http://www.rane.com/par-a.html#amplifier_classes

 

[guess88]

Wm... what i think Franc's talking about more is putting words in laymen's terms. There no sense in using big words if most of your audience has difficulty understanding them. Maybe that's how you talk though, personally, i leave that speak for my term papers.

 

[Errin@PG]

There is no T class amplifier realistically. There is however, full range class D. "Class T" was coined by Tripath Technologies, who marketed the first full range class D amplifier

If I can make a slight correction T-class amplifiers do exist even if they "coined" the phrase, think about it this way If you locate a previously never before seen star in the sky you have the right to name it, or if you design a new technology you can call it whatever you feel like.

Class D by nature can not run full range it is virtually an extremely rapid switching B class amp (I know there's more to it) and the switching in turn causes audible high frequency atifacts heard through the out put. D class also utilizes PWM technology which is the primary characteristic of D class and T-class uses no such thing http://www.tripath.com/downloads/an1.pdf.

Back to car you said that heat a space are now becoming a concern for home if I understood correctly, whereas it has always been a concern in car plus many other aspects not really worried about in home (most commonly efficiency until recently)

 

[WmAx]

Thanks for your understanding Chris. Starting with this, I have no clue what your saying.

Originally Posted by WmAx
In order to have a broadband, direct beam of sound, the surface area of the effective radiation area of the driver must be approaching 1 wavelength and longer of the frequency in question. Thus, it's not possible to have 'directive' sound from the surface area available on a kickpanel with a direct radiator under the treble band. The best execution would involve the ultrasonic devices I mentioned earlier, that are able to produce a true broadband directive signal dispersion.

In order to have a directive beam of sound emanating from a direct radiator, the effective surface area which emits, must be large, relative the specific frequency desired to be directed/focused. The energy is dispersed across the diaphragm from an essentially infinite number of points, that are all in-phase at a given moment in time. If you move off of the direct axis to a point at which a vector path can be drawn, and the difference is significant in relation the wavelength of a given frequency, eventually at a certain point the emitted energy from multiple points will meet where it is out of phase with each other(identical signals, different path lengths combining = the relative phase rotation of two compared signals must differ for the majority of times of occurance), thus cancelling/interfering. Therefor, in this circumstance, it can said to be taking on directive characteristics. This is still a relative situation, and the degree of directivity depends on how much larger the radiation area is compared to the emitted frequency. But the wavelengths in even the upper midrange, are considerable in size, relative to the drivers used in car audio for that purpose. Marginal(near useless) directivity could be achieved in the upper midrange band, at best; with none at lower frequencies. The ultrasonic transducers I mentioned, because the actual emmited frequencies are very high in frequency(ultra-sonic), they are easily controllable in direction with relatively small panel sizes. The ultra-sonic frequencies are combined at the termination point(ear, microphone, whatever is within the path) to create the audible content.

Originally Posted by WmAx
Remember, the soundfield must have identical reflection time direct vs. reflect, and equal amplitude vs. frequency, at the ear positions.

You have:
-direct sound emitted by transducer(s)
-reflected sound(s) from surface(s)
-reflection time(s) associated with the reflected sound(s)

The reflected properties of L vs. R channels will be considerably different, even IF you managed to achieve identical on axis sound. The reflections, especially, on the L channel(if you are in driver seat) will be considerably negative in attribute. The L channel in particular will suffer from having a strong direct sound arriving at ear, and that sound bouncing off the side of head, to the window from 1' give or take a little, then bouncing back to your head again. Because of the relative short pathlength, this will be relatively high in amplitude. The R channel will not have this very close reflected panel(window) to cause this effect.

Originally Posted by WmAx
If you equalized the frequency response here using head mounted stereo binaural microphones(you'd have to E.Q. each channel assymetrically on L vs. R, due to the very different angles to ear pinna of each channel in this seating position), it would not do anything for the destructive reflection times of left soundfield.

A binaural microphone is one that mounts just inside the ear canal. This is required for your application of assisting in ideal response, because the ear structure is a dynamic filtering device(this is part of how it senses direction, etc.). The ear will modify high frequency response transfer function relative to the angle of direct sound arrival. Since the L channel will be almost directly in front of you, and R channel will to the distant right at a significant angle, then the only way to accurately compensate for this difference would be making measurements using binaural microphones and adjusting E.Q. to compensate to achieve a symmetrical response curve to each side of the head. This will not compensate for the reflected time difference.

Originally Posted by WmAx
In a home environment, you can effect directive(down through most of the midrange) speakers using direct radiators due to it being practical to have large size speakers in this environment.

An electrostatic loudspeaker has a very large size diaphragm. As I detailed earlier about how this basicly works to direct soundwaves, I don’t need to explain that part again. Obviously, it is not a problem to have a 16” wide(or larger) ESL panel in a home audio environment.

Originally Posted by WmAx
But, since the direct vs. reflected pathlengths are long enough from speaker to walls, etc.; the reflections(as long as they are roughly equivalent in frequency spectrum distribution vs. direct sound) can be beneficial in this environment, since they would be interpreted as ambience, not interference, at time differences of approx. >5ms, <20ms. A symmetrical soundfield for L and R channels, including reflection times and frequency vs. amplitude response are not a problem either.

The human ear roughly begins to sense a direct vs. reflected sound signal(of the same original signal) as ambience effect when it is equal to or greater than about 5ms(roughly 5’ in distance), but not to approach or exceed 20ms. Significantly less time difference than 5ms is interpreted as negative -- a muddy type effect that hurts sound quality. The proper proportion of sufficiently delayed signals reflected from the wall(s) act like phantom sound sources. This contributes to a perceived diffused soundfield, so far as the human hearing mechanism is concerned.

The bottom line is that the car interior is inferior in comparison to a home environment, acoustically.

-Chris

 

[WmAx]

Acoustically speaking they're both on the same plain,

If by this, you mean they are equal in standpoint of acoustics, then it would appear you skipped over or ignored some posts, particularly ones from me. If you don't mean this, please accept my pre-emptive apology for misunderstanding your statement.

-Chris

 

[shokhead]

Originally Posted by WmAx
In order to have a broadband, direct beam of sound, the surface area of the effective radiation area of the driver must be approaching 1 wavelength and longer of the frequency in question. Thus, it's not possible to have 'directive' sound from the surface area available on a kickpanel with a direct radiator under the treble band. The best execution would involve the ultrasonic devices I mentioned earlier, that are able to produce a true broadband directive signal dispersion.

In order to have a directive beam of sound emanating from a direct radiator, the effective surface area which emits, must be large, relative the specific frequency desired to be directed/focused. The energy is dispersed across the diaphragm from an essentially infinite number of points, essentially in-phase. If you move off the direct axis to a point at which a vector path can be drawn, and the difference is significant in relation the wavelength of a given frequency, eventually at a point the emitted energy will meet a points where it is out of phase with each other, thus cancelling itself effectively. Therefor in that case, it can said to be directive. But the wavelengths in even the upper midrange, are considerable in size, relative to the drivers used in car audio for that purpose. The ultrasonic transducers I mentioned, because the actual emmited frequencies are very high in frequency(ultra-sonic), they are easily controllable in direction with relatively small panel sizes. The ultra-sonic frequencies are combined at the termination point(ear, microphone, whatever is within the path) to create the audible content.

Originally Posted by WmAx
Remember, the soundfield must have identical reflection time direct vs. reflect, and equal amplitude vs. frequency, at the ear positions.

You have:
-direct sound emitted by transducer(s)
-reflected sound(s) from surface(s)
-reflection time(s) associated with the reflected sound(s)

The reflected properties of L vs. R channels will be considerably different, even IF you managed to achieve identical on axis sound. The reflections, especially, on the L channel(if you are in driver seat) will be considerably negative in attribute. The L channel in particular will suffer from having a strong direct sound arriving at ear, and that sound bouncing off the window from 1” give or take a little, then bouncing back to your ear again. Because of the relative short pathlength, this will be relatively high in amplitude. The R channel will not have this very close reflected panel(window) to cause this effect.

Originally Posted by WmAx
If you equalized the frequency response here using head mounted stereo binaural microphones(you'd have to E.Q. each channel assymetrically on L vs. R, due to the very different angles to ear pinna of each channel in this seating position), it would not do anything for the destructive reflection times of left soundfield.

A binaural microphone is one that mounts just inside the ear canal. This is required for your application of assisting in ideal response, because the ear structure is a dynamic filtering device(this is part of how it senses direction, etc.). The ear will modify high frequency response transfer function relative to the angle of direct sound arrival. Since the L channel will be almost directly in front of you, and R channel will to the distant right at a significant angle, then the only way to accurately compensate for this difference would be making measurements using binaural microphones and adjusting E.Q. to compensate to achieve a symmetrical response curve to each side of the head. This will not compensate for the reflected time difference.

Originally Posted by WmAx
In a home environment, you can effect directive(down through most of the midrange) speakers using direct radiators due to it being practical to have large size speakers in this environment.

An electrostatic loudspeaker has a very large size diaphragm. As I detailed earlier about how this basicly works to direct soundwaves, I don’t need to explain that part again. Obviously, it is not a problem to have a 16” wide(or larger) ESL panel in a home audio environment.

Originally Posted by WmAx
But, since the direct vs. reflected pathlengths are long enough from speaker to walls, etc.; the reflections(as long as they are roughly equivalent in frequency spectrum distribution vs. direct sound) can be beneficial in this environment, since they would be interpreted as ambience, not interference, at time differences of approx. >5ms, <20ms. A symmetrical soundfield for L and R channels, including reflection times and frequency vs. amplitude response are not a problem either.

The human ear roughly begins to sense a direct vs. reflected sound signal(of the same original signal) as ambience effect when it is equal to around 5ms(roughly 4’ in distance). Significantly shorter time difference is interpreted as negative -- a muddy type effect that hurts sound quality. The proper proportion of sufficiently delayed signals reflected from the wall(s) act like phantom sound sources. This contributes to a perceived diffused soundfield, so far as the human hearing mechanism is concerned.

-Chris

I read this twice and i'm not the smartest but it was a great big yawn.

 

[jaxvon]

You must not be an engineer shokhead. I love technical documents. They make my day.

 

[guess88]

bah... i like tech articles too, but generally, i think everything should be put in laymen's terms. All that to explain how much a cars interior sucks for audio... i don't think anyone could argue with that. You could just simply say you're constrained by space, seat position, and just overall environment of the car. There... let that be the cliff notes to us all!!!

BTW - after enjoying a wonderful st patties day night... i came to this conclusion. Audio is like masturbating. You keep developing and setting up more realistic ways to experience sex, but in the end.. you can never beat the real thing.

That might not sound right tommorow, so for now... mind you i've been drinking...

 

[jaxvon]

Indeed guess88. But, regarding the simplification reques, I was the first person to reply to this thread. I posted the following:

Home Audio, by far. The medium simply allows for the most advanced technology to be used. Car audio has too many limitations to be the most advanced. 12V DC Power is the only kind of voltage available. There are never any allowances for driver enclosure, so you get all kinds of bad reflections and such. I could go on and on. That said, there IS some good car audio, but it's still nothing compared to the home realm.

Why it developed into such a big issue is beyond me. I thought that would've been enough detail...

But, then again, the reason this is such a great forum is becuase we have people like WmAx and PLHart onboard who really know their shtuff. I mean, seriously, where else could you post a question about old Infinity speakers, only to the reply: "I was the one who designed those speakers". I mean, seriously, that's awesome.

Back on topic, I appreciate the detail and effort put in my WmAx. I really enjoy reading the technical stuff. But hey, no one can say I didn't try to make it simple and to the point!

 

[guess88]

oh definately... WmAx makes some great points, and he knows his stuff. I just don't like the idea that he doesn't have much experience at all in the car audio field and yet he's judging it. It just goes against my ideologies. Kinda like the corporate office reading how things work and telling people how to do their jobs when they don't have the experience to see what it's all about. Hell... you can even take it to the political level.. damn the man!!! But yeah anyway... most of what he said is right, but you can never properly evaluate anything till it's been experienced. I still take it to a virgin arguing about what sex feels like.

 

[Robsarve]

- it was in relation to being able to create an effective diffuse sound field that was realistic(perceptual realism), for example to reproduce the sound perceptually of real space of concert hall, for example.
I pointed out at least one theoretical method that would work in a car(though impractical) to achieve this effect. I can think of others, but none are practical -- they would require a very large dash and extensive modifciations involving large structures protruding from the dash(totally impractical). At this point, the thread has become confused, or so it would seem.

-Chris

Well I´m a bit confused by default, so that´s not too strange... Honestly I didn´t have the energy to read all these posts in detail, and your posts are VERY detailed.

IF you wanted to simulate a concert hall in car, step one would be to get a 5.1 recording made in a proper way (rear ambience only in the rear channels thank you! -"Hell freezes over" must be one of the worst recordings ever!), then have a system using 5 compact, directed "full range" speakers and suitable electronics.

But that leaves you pretty much fully in the grip of the recording engineer´s vision. And I sense that is not what you wanted?

But you can get surprisingly realistic ambience in car only with a stereo setup up front if you have the right cabin and is prepared to work on the reflective/absorbtional areas behind the listener.

Also I would like to learn more on what the size of the dash has to do with imageing?

//ER