# Quick Q - Large bodies how wide...



## roduk (Sep 19, 2008)

In relation to seating position and edge of car? 

I am redoing the mounting of my horns to try and get the last little bit of performance out of them... They were tilted up a little bit - in fact quite a lot, so I will get them level again, but width wise where _exactly_ is best?

As far out as possible?
Inside of outer horn mouth lined up with ear?
Inside of outer horn mouth lined up with something else?

Thanks - I'm back out after dinner to see what I can do, so any help would be hugely appreciated.

Porsche 914, ID Large Bodies, B&C DE250 drivers.


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## minbari (Mar 3, 2011)

from what I understand of it, you want the outermost edge of the mouth to be lined up with your ear. I am sure there is some wiggle room.


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## roduk (Sep 19, 2008)

Thats what I thought - atm they are wider than that, what would be the advantage of going wider than the ear?


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## Mic10is (Aug 20, 2007)

mounted as wide and deep as possible
mine physically say wider then the apillar and door panel.


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## Patrick Bateman (Sep 11, 2006)

roduk said:


> In relation to seating position and edge of car?
> 
> I am redoing the mounting of my horns to try and get the last little bit of performance out of them... They were tilted up a little bit - in fact quite a lot, so I will get them level again, but width wise where _exactly_ is best?
> 
> ...


For the first five or ten years that I did audio, I spent a lot of time messing with loudspeaker locations, trying to get a soundstage that's wide and deep. With a lot of experience under my belt, I've found there are a lot of things that you can do to fake it


just a handful of things, off the top of my head:

#1 - use a roundover on the mouth of the horn bodies. (See my Homster thread on diyaudio). Besides improving the off-axis response, the roundover blurs the transition from the horn body to the interior of the car. This makes the horns sound 'bigger' and it's less apparent where they're located. Anything you can do to reduce diffraction will make the apparent source of the sound more nebulous, and this fixes one of the problems with horns, which is that they have a tendency to sound 'anchored' to the speaker.

#2 - Pay close attention to the transition from the horn body to the vehicle. If there's a gap, fill it. You want a smooth gradual transition from horn to car.


One of the members on here has a BMW with ID horns that executed these concepts really well. If you dig around here you'll see pics. His horns blend really seamlessly into the interior. This isn't just good cosmetics - it has a huge and audible effect.


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## roduk (Sep 19, 2008)

Thanks for that, I am building a new lower dash to meet the horns, so will build it smooth and uniform all the way across from one side of the car to the other. 

One further question - this new panel, what should I cover it in? Currently it is vinyl, but would alcantara make any sonic improvements? (it's the whole lower panel, from clocks down..) as I am going to get it pro trimmed, it could be covered in anything now..

So I went back out and moved the horns into a more favourable location, they have moved back about three inches, and are out as wide as possible, the outer horn mouth is about 3-4 inches further out than my ear. They were at the width before, but I'm delighted to get that extra depth as I know it will make a difference as the horns are pretty nearfield.


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## Mic10is (Aug 20, 2007)

roduk said:


> Thanks for that, I am building a new lower dash to meet the horns, so will build it smooth and uniform all the way across from one side of the car to the other.
> 
> One further question - this new panel, what should I cover it in? Currently it is vinyl, but would alcantara make any sonic improvements? (it's the whole lower panel, from clocks down..) as I am going to get it pro trimmed, it could be covered anything now..
> 
> So I went back out and moved the horns into a more favourable location, they have moved back about three inches, and are out as wide as possible, the outer horn mouth is about 3-4 inches further out than my ear. They were at the width before, but I'm delighted together that extra depth as I know it will make a difference..


nothing to thick otherwise it will absorb high freq content.


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## roduk (Sep 19, 2008)

So would reflective material be better (vinyl) as opposed to alcantara which may absorb? I wouldn't do vinyl, I'd probably do leather tbh. 

So the options are black smooth leather, or black alcantara.. Any other opinions??


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## Patrick Bateman (Sep 11, 2006)

roduk said:


> Thanks for that, I am building a new lower dash to meet the horns, so will build it smooth and uniform all the way across from one side of the car to the other.
> 
> One further question - this new panel, what should I cover it in? Currently it is vinyl, but would alcantara make any sonic improvements? (it's the whole lower panel, from clocks down..) as I am going to get it pro trimmed, it could be covered in anything now..
> 
> So I went back out and moved the horns into a more favourable location, they have moved back about three inches, and are out as wide as possible, the outer horn mouth is about 3-4 inches further out than my ear. They were at the width before, but I'm delighted to get that extra depth as I know it will make a difference as the horns are pretty nearfield.



Not to get too crazy and complex, but high frequency localization is totally different than low frequency localization.

*Taken to the extreme, I can put a tweeter 60cm from your head and trick you into thinking it's 200cm away*

It's not as simple as locating the horns wide and deep; you have to juggle a lot of variables.

Just a handful, off the top of my head:

#1 - if at all possible, try to create an unobstructed line from the mouth of the horn to the listener's ear. This means that it's arguably better to have the horns closer to the dash than pushed back against the firewall. *Basically the problem you run into when you push the horns back is that the height of the soundstage will get compressed, because the dash will constrain the vertical beamwidth of the horn.

#2 - reflections SUCK. Do everything you can possibly do to eliminate them. Just take a look near the horn mouth and make sure there's no obstructions.



As far as the alcantra goes, think about it this way:

Anything that diffuses the sound from the tweeters will reduce the 'signature' of the car.

Does that make sense?

Picture a pair of horns playing in a room that's made of concrete. You know how terrible this will sound; you've probably been to a nightclub or two that was built like that, and the sound is atrocious.

Now picture a pair of horns playing in a room that's covered in carpet. The carpet will diffuse the reflections and the room will tend to 'disappear.'

Check out what Mark Eldridge did with his 4-Runner. He used these concepts extensively; he literally aimed the output of the horns at a spot in the car that was designed to absorb their output.


YES this concept will lower your total SPL, but we have SPL TO BURN with compression drivers. So who cares if you lose a couple dB?

The key to all of this sound absorbtion stuff is that you have to 'add' back the high frequency energy that you lose.

Ask me questions about this if it doesn't make sense; this is fairly advanced stuff.

Basically we play the music with the horns, then absorb as much of the reflections as possible with treatment, then measure the result and use equalization to come up with an overall response that's pleasant. The room treatment will radically alter the frequency response, so don't even try this if you don't have an EQ and a way to measure things. But even a plain ol' iphone RTA will do the trick.*


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## roduk (Sep 19, 2008)

Ok, so alcantara may be an improvement then.. The whole interior is vinyl, I need to get door cards retrimmed and this lower panel, so I'll do both in alcantara, I'll also put a layer of foam on the door cards under it to try and absorb reflections from the horns bouncing off the door panels. 

Interesting about line of sight... Now I can 'see' both horns from the drivers seat, before I could see down the throat right to the back and the CD, now, I can see the mouth and about 1/2 of the depth of the horn itself. They are a LOT more level now, the weight of the driver must have bent my brackets a bit as they were firing up quite a bit, whereas now they are level with the road again..

Please don't be frightened about getting technical re this, I can handle it, and it's my favourite part of car audio, so crack on.

I have an Audiocontrol rta, and also the REW room analyser to hand. (Dab hand with an rta, not yet used the REW yet, I got it as I am starting to think that the rta was/is a bit of a blunt tool that can only chop the tree down, not carve it into a beautiful form.


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