Hey guys, i'm half way to getting a new car for sq purposes and it will be pretty full on and I have been doing some research on a setup.

What do you think about stereo subs in a car. I know your ears cant directionalize sub bass but some home audio guys still do use 2 subs in stereo with their floorstandings or whatever. Just wondering if anyone has done any testing or research into having 2 subs in stereo up front with their 2 or 3 way front stage in a car? Using time alignment etc to add to the stage and depth.

Thoughts anyone?

Antony

i think if the subs are upfront, then there may be advantages in having stereo subs - in helping to create a balanced soundstage

Thats what i was thinking, and hopefully will be testing in this new car. Has anyone tried this yet?

I haven't tried it upfront, but rear stereo subs caused confusion and didn't work too well.

Running stereo subs should work fine if they're going to be up front. How on earth do you intend to get the proper sealed enclosure size though???

Dont you worry about that. Just something i'm cooking up now that the torana's nearly finished and there are no comps to go to in nsw with the ute. Will hopefully debut it at nationals if marc lets it compete.

Anyone else used or heard stereo subs?

Ant

Yeah only if they are upfront, all these people running rear stereo subs imo aren't doing themselves any favours. If it's up front you want it to stage, if its in the back its the last thing you want.

Im running 9's in my doors and whilst most music has sub bass panned central, it's more noticeable on the lower midbass area.

Needs to be sound deadened though otherwise you'll be hearing stereo resonance/rattles

Ask yourself what 'stereo' actually is, and ignore the fact that you cannot achieve it in the car.

Its an effect causes by the phase changes of an incoming audio wave as it moves around your head. Basically, the effect pulls the soundstage outwards and around. Its image specific, and therefore is only applicable at frequencies that contribute to image or stage.

Frequencies reproduced by subwoofers (excluding distortion harmonics) dont contribute to this because their wavelengths are too long. UP front, at the back, in the sides, whereever. Therefore, there cannot be any such effect like 'stereo' subbass (ignoring the fact that most CD's these days write the subbass as a monoaural effect..).

Therefore having two subwoofers will give you two subwoofers, not a stereo effect.

i was reading a discussion the other day about stereo subs and if it is possible to achieve stereo.

someone said that in blumleins original patent, that he had made a decision to go with stereo crosstalk because it actually gave lower frequencies (sub 270Hz) a 'stereo effect'.

now it was also said that he had the choice of going with stereo crosstalk to give a stereo effect in the sub 270Hz region, or go with no crosstalk and achieve stereo effects above 1500Hz. i think that, if blumlein knew what we now know about the pinnae, he may have gone with no crosstalk.

dont ask me how u can achieve stereo just with crosstalk, but apparently it does contribute significantly to a 'stereo effect' for the sub 270Hz region.

i was gonna read through blumleins patent this afternoon, but i decided to play with my sub instead

EDIT: bah, cant find the thread

There might be a benefit to be had if you use some of the 9-10" "basswoofers" (couldn't think of a better name for them) that scanspeak do. These things are not subwoofers per se, but they can work as the bottom end of a nice 3 way setup. For example, if you can get mids that play down to 200/300 hz, these woofers can fill in everything between that point and the 20hz bottom end. Don't know if anyone's ever tried using these in a car without subs, there might be problems fighting off engine/road noise below 80hz that subs are much better balanced for. Having said that, careful selection of power to each of the drivers (and maybe some dedicated eq to the woofers) should yield some fantastic results, and make it worthwhile running the woofers in stereo. Just something to consider.

I am looking at installing a pair of stereo Utopia 5 WS (5 3/8" ) mini-subs in to the rear passenger doors of my Camry wagon, to complement the front stage.

(That's in addition to the Utopia 27 WX 11" sub in the rear cargo space.)

I am hoping that this will add a little more low end extension and 'punchiness' to the bass upfront.

However, I think it's equally likely that this move could -

a. Add nothing to the sound stage

b. Muddy up the SQ/sound stage

This is especially true considering that my planned system has no active signal processing, although I will be able to low-pass the signal to the Utopia 5 WS subs using the built-in amp filter.

I guess the saving grace will be that I'll be able to fade the little subs out if I find them to be to the detriment of the front stage...

If they're going low in your doors it might be ok if you can get the baffle big enough. Maybe lowpass them lower than 300 though. Your rear doors should also be well sealed and deadened.

I know the paper, read it a few times before. If you have a copy though, shoot it through!!

From what I'm aware of though, if crosstalk is the only thing that they're relying on, you'll need to achieve a certain amount of phase change at the listening position anyway. Not only that, but you'll need to ensure the phase change between the drivers is large enough for the shape of the head to sufficiently 'flip it'. Thats why 'stereo' requires 120 degree azimuth. You'll never get subwoofers on a symmetrical (but polar opposite) plane to create the phase change needed inside a car.

They're either behind you, or if your lucky, in front of you. No stereo triangle. Not even close.

i thought i'd saved a copy of it into my audio archives. but apparently not

my recollection is hazy. i wanted to confirm a few things. apparently blumlein did dedicate a fair wack of his patent in the justification for crosstalk.

but yer, not gonna happen in car. achieving stereo is hard enough!

Hard? Achieving stereo in the car is impossible.

so how u going about it? are u using stereo or something else?

ill shoot u through some pics when i get my dash pulled out again.

i've come up with something a little different. but im using the 'something else' category to!

I'm not bothering to even try, at the moment. Later on, I'll skip stereo and aim for Ambiphonics or Vector Based Amplitude Panning from a carputer. My guess is you're doing the same?

For others think of it this way. What is the stereo effect? Not stereo as in 2 channels of sound, but the ACTUAL effect.

Its an effect that produces a wider and deeper stage then the speakers. It eliminates the speakers from the reproduction (aurally). It achieves this by two ways. One is the individual channels of information sent via the transmission media. The other is by forcibly setting up enough crosstalk to force a phase change as the wave moves around your head.

For a full 180 degree soundstage (real stereo), you need all your speakers in the same field (near/far) and at 120 degree azimuth. This is the only way you'll be able to pull the phase as the wave moves around your head. Given that most cars dont have their speakers at even CLOSE to 120 degrees of azimuth, you'll never get that phase change. And therefore, you'll never get that stereo effect. It takes a LOT of processing, fantastic interior space and a little luck to get even close.

Thats why 'old Abmo keeps referring to Monophonic Panning. This effect is basically having the speakers at the extremes of the stage, and the image spilt open between them (sound familiar, anyone?). There was a fantastic thread on EliteCar a few months ago on it, quite good.

Basically, stereo requires similar reproduction space to the recording space, because it doesn't deal with this (and hence in an environment where the space has a MAJOR effect on the effect, it simply doesnt work). More effective methods, like Ambiphonics and VBAP, actually deal with the reproduction space, and therefore are more effective.

my setup is a bastardised setup using ambiohponic principles. basically, i use the RACE program to eliminate crosstalk, but at the same time dont have the speakers directly ahead. ie, my setup will remove (assuming perfect radiation from the drivers) the crosstalk electronically, but i will have to compromise on the HRTF due to the speakers not being directly ahead.

of course, the image wont sit on the centre of the bonnet, but sit directly ahead of the driver and the driver will be sitting in the very front seat. but at least there will be an image.

i haven't tried this setup in car very much. it seems to work with my $20 computer speakers (i was surprised, as i thought i would be sitting to close), but whether the early reflections and combing will kill it in car, i simply dont know.

I thought so. I'm going to try the Hafler effect in car (done it in home) to give me a boost first, and see how far I can get with that. Then the next step will be the Carputer....

Definitely let us know how you go!!

lots and lots of pics!

im still not convinced it will work. it all sounds good in theory, but i think im going to be sitting to close and that the RACE program wont be able to cancel out enough crosstalk.

on the other hand, sitting so close to the speakers will also negate a lot of the early relfection issues as well. its gunna be a case of suck it and see

ill be interested to hear ur results with the hafler effect in car. now THAT would be interesting

Most of your music recorded and mastered to conventional methods have all the bass information summed to mono, coming from the way that vinyl worked; the practice is still used today in a lot of recordings.