Hi Jason,

I'm usually shy about posting on the bass list, unless I feel that I have

unique feedback or a topic that hasn't been discussed continuously.

I also consider whether a topic will create excessive emotional reaction.

With the large number of participants I wish the list's S/N was better.

Once, I obtain LAUD I'll be more inclined to post experiments that

hopefully will be of use to other enthusiasts.

Perhaps one improvement that can be made to the page is to title it

Measuring a Miata's transfer function (I assume a Miata) instead of just

'car'. I feel this is important because the TF shown is specific to your

Miata and setup. Another, maybe is to point out that theoretically

cabin/room gain should follow a 12dB per octave rise starting from the

frequency range where the room can no longer support propagation of

1/2 wavelengths and thus becomes a pressure camber.

Though I know real world room/gain rarely follows the smoothness

or the even slope of the theory, Mr William Burton of CSR recently

pointed out to me that I shouldn't state the theory without saying that

it rarely happens that way in real world apps.

My guess to the top two factors affecting real world TF (to what I'm

sure is a very complex phenomenon) are:

cabin seal - I believe this would affect slope

damped very rigid (maybe infinitely rigid?) walls that do not store

energy and re-release it - (affecting smoothness of response)

Oh that's great that you're an electronics design engineer, that

probably would be a job that I would enjoy. Actually, my dad is an

EE, so those kinds of interests must be familial. I may be going

back home for a month in the summer with my Parents, I'll be sure

to ask you where all the (good sounding :-) music venues are.

Yes, car audio seems to vary much more than home systems.

While, mediocre home systems can easily be improved with

maybe a little attention paid to room acoustic interaction, the car

environment seems to have many detrimental constraining factors.

Having listened to about 120 different vehicles both critically

(usually in competitions with strict attention paid to imaging and

other qualities) and casually, only about 3 or 4 ever made me

say a relative 'wow'.

Though natural tonal balance is relatively easy to get right if you

go through the steps of good design and tuning, there are plenty

of cars and listeners that are way off or just don't tune for tonal

balance.

For imaging, even the comparatively 'good' cars have diffuse

images from about center to about 1/2 or 2/3 of the way towards

near side channel. All the images, that exist predominately on

one channel tend to collapse toward it's respective driver.

There sometimes appears to be a tradeoff between sense of

ambiance and imaging accuracy in the setups I've sampled

There are a number of two channels systems that use kick panel

mounted drivers playing almost all of the frequency range that have

a good sense of depth and even height on most of the image, but

If you focus on the images that are predominately in one channel

you can usually hear where the speakers are located.

As a side note, just as people are able to scan their eye's

attention, they can also focus their hearing in different directions.

Systems with center channels can have very good imaging

accuracy in terms getting the center image coming from the

'correct' angle, but can ruin the sense of depth by varying degrees

by drawing you attention to the center channel speaker.

All the systems that I really liked had lots and lots of dynamic

headroom. (ie. lots of power, or more moderate power with high

efficiency drivers).

--

Regards,

Raymund Guerrero

Jason,

> Whoa, just 3? Did they all win

Yes, they did. The fourth was a manufacturer's demo vehicle.

> Though natural tonal balance is relatively easy to get right if you go

> through the steps of good design and tuning, there are plenty of cars

> and listeners that are way off or just don't tune for tonal balance.

>

> What's the methodology for the good ones to tune EQs? Same as in the

> recent article on tuning in one of the car mags? (Can't remember

> which)

If you're speaking of "Tweak Show" by Douglas Winker CSR

Nov/Dec '98 p30-37, yes. That's a very good article and Mr. Winker

definitely knows his stuff (much more than the article shows), has

a good ear and truly loves music. While I can't speak of the actual

methodology for each winning car, I do know that they all used very

skilled tuners and sometimes more than one. One of the useful

techniques discussed in the article refers to playing a series of

1/3 octave tones where two skilled tuners in each seat 'point' to

where the image appears. If both listeners hear the image off

towards the same side, they can try to move the image closer to

center by adjusting the eq for that band.

> There sometimes appears to be a strong connection between

> sense of image depth and imaging accuracy, normally one being

> traded for the other.

>

> This is very interesting. By accuracy, do you mean how well defined

> an image is?

By accuracy, I refer to the 'focus' and correct placement of an image.

It's weak point that the scoring is based on various reference

points of the car, I believe scoring of imaging should only be

referenced to each individual listener. But that's another subject.

In the line: "sense of image depth and imaging accuracy" I meant to

say that ambiance was sometimes being traded for imaging accuracy.

--

Regards,

Raymund Guerrero