# Alternative horn placement...



## GavGT (Sep 5, 2011)

Hi guys, DIYMA newbie here....

Been thinking about switching to horns for SQ for a short while now, and i see most people put them under the dash. Has anyone ever installed them firing up through the dash at the screen, so effectively you are hearing the reflection? I see alot of European cars are using full range drivers in this manner and doing very well in competion, s was wondering if it would work. Car is a BMW E34 btw.

If it has been used to good effect, what body/driver was being used?

Thanks


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## Horsemanwill (Jun 1, 2008)

it's been done but with few good things coming out of it.


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## GavGT (Sep 5, 2011)

Horsemanwill said:


> it's been done but with few good things coming out of it.


Ok, any details or links? Did it cause imaging issues etc?

I have a PG eq232 in case there are any drastic RTA issues

Cheers


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## Horsemanwill (Jun 1, 2008)

loading it off the glass causes the wavelengths to go crazy if i remeber right. you've got no control of what it does off the glass.


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## TokoSpeaker (Nov 12, 2010)

From my opinion as newbie too, you can add a pair of super tweeter such as Mundorf AMT or RAAL for up the dash.

But for HLCD, it is still better under dash.

Thank you.


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## minbari (Mar 3, 2011)

not having done alot with these, but from what I read. bad idea. the way these disperse sound, you will get alot of direct and reflected sound at the same time. I cant image that sounding good.


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## Eric Stevens (Dec 29, 2007)

For a single seat system you can get reasonable results with drivers up on the dash horns or direct radiator setup. This relies heavily on signal delays to make things work. I still like the results I have achieved with the reduced path length difference of underdash mounting. Now if you can get wide mounting with a good PLD measurement with them up high go for it by all means.

For a two seat competition car it will never do well from both seats. Setting up any system to image correctly is about equal time arrival and equal amplitude for both channels. A speaker that is closer arrives sooner and with more volume than a speaker that is farther away.

Only way around this is to do a proper center channel with a L C R system. Even thought the results can be quite good for this type of system its still not as good as a well done 2 channel set up with a good phantom center IMHO.

Eric


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## GavGT (Sep 5, 2011)

Eric Stevens said:


> For a single seat system you can get reasonable results with drivers up on the dash horns or direct radiator setup. This relies heavily on signal delays to make things work. I still like the results I have achieved with the reduced path length difference of underdash mounting. Now if you can get wide mounting with a good PLD measurement with them up high go for it by all means.
> 
> For a two seat competition car it will never do well from both seats. Setting up any system to image correctly is about equal time arrival and equal amplitude for both channels. A speaker that is closer arrives sooner and with more volume than a speaker that is farther away.
> 
> ...


Thanks for that! The E34 does look perfect for them judging by the shape of the underside of the dash. It's ID Pro with full size bodies i'm looking at. How difficult would it be to build a passive crossover for these as i'm running 2 way front end and the moment, and want to keep things simple, especially as my H/U doesn't have any form of DSP. It does have a 13 band eq though, i'm hoping that would be enough to tame them were needed. I have a PG eq232 as well but any form of seperate eq or dsp unit would put me in a higher class in competition so i would like to avoid it if possible.

Gav

PS: Would any crossover have to be bi-amped in order to get as much power as possible to the mid/bass?


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## Eric Stevens (Dec 29, 2007)

GavGT said:


> Thanks for that! The E34 does look perfect for them judging by the shape of the underside of the dash. It's ID Pro with full size bodies i'm looking at. How difficult would it be to build a passive crossover for these as i'm running 2 way front end and the moment, and want to keep things simple, especially as my H/U doesn't have any form of DSP. It does have a 13 band eq though, i'm hoping that would be enough to tame them were needed. I have a PG eq232 as well but any form of seperate eq or dsp unit would put me in a higher class in competition so i would like to avoid it if possible.
> 
> Gav
> 
> PS: Would any crossover have to be bi-amped in order to get as much power as possible to the mid/bass?



It is not easy to do a passive for the horns but its certainly possible.If you are willing and have a way to do frequency response measurements and are willing to work on it realizing it might take several tries then go for it. 

The drivers will need to be level matched which can be done with a l-pad on the horns I recommend a minimum 12dB/oct low pass on the mids and 6 to 12dB/oct high pass on the horn. If you are real daring you could go for 24dB on both.

Eric


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## GavGT (Sep 5, 2011)

Eric Stevens said:


> It is not easy to do a passive for the horns but its certainly possible.If you are willing and have a way to do frequency response measurements and are willing to work on it realizing it might take several tries then go for it.
> 
> The drivers will need to be level matched which can be done with a l-pad on the horns I recommend a minimum 12dB/oct low pass on the mids and 6 to 12dB/oct high pass on the horn. If you are real daring you could go for 24dB on both.
> 
> Eric


Thanks again Eric for replying.

I'm thinking it might be easier to make seperate crossovers for the mids and horns, that way i can swap out parts without affecting the other, and run seperate amps so i can level match easier. Are there any good crossover calculators out there that will take into account horns? Dont mind having a stab at it if so.

unfortunately i have no RTA, any testing would have to be done with test tones and spl meter on a phone app. Far from ideal but better than nothing, especially when i can hear it doesn't sound right but need to pinpoint problems, i'm pretty new to EQ'ing.

Gav


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## TXwrxWagon (Sep 26, 2008)

Gav.... Eric directly and indirectly "learned me" pretty much everything I know and have had the guts to try with horns. With that said.. I have had success with up firing BUT not off the windshield directly.

I am trying to recover (2) hard-drives with pics that will make this easier to understand but I will try to put it into words...

Imagine the top of your E34's dash as just flat... just inside (toward the cabin) of the defrost vents is where the horn's would be firing straight up. In my case a mid-70's Mustang II same layout.

First what I did was tilt the entire horn at an angle aiming more along the angle of the widnshield. So instead of reflecting into/onto the glass it was using it as a plane to travel.

Next, I formed a fiberglass "hood" the followed the windshield and then turned the opening toward the listeners, about 2.5" above the dash top. Just enough not to make a drastic change in flow, but enough to redirect.

I lined the throat of the "hood" with basic dampening materials to keep it non-resonant. Also packed the transition between the removable dash top and the opening of the horns with non-hardening clay to give a solid gasket and base for transfer.

I have always used a "super tweeter" with my horn set ups to add a very low level sparkle the judges like. I usually turn them off for my own listening. 

I would have to look when I get home... I don't remember what exact year, but the car was top 5 at MidWest Showdown in Chicago. A failed subwoofer speaker fuse, kept us out of qualifying for Finals by under 2 points, and we had top 2 Tonality and Image scores. 

Yes, Eric is 210% right, its is nearly impossible to replicate the success of underdash. Without serious work and enthusiasm. It worked for me, but I wasn't willing to say "fail".. 

I own 3 cars with Eric's horns.. only the 1 is not under-dash. Now with the advent of Mini-horns and smaller, high-end Compression Drivers... its silly not to exhaust under-dash options before undertaking wild reconfiguration challenges.

Rob


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## GavGT (Sep 5, 2011)

Thats a very well put and informative reply, thanks alot.

The problem i'm facing is that i want a stealth look, and drastically changing the dash is not really what i'm aiming for. however, if i could have most of the shaping of the transition between horn and dash actually below the level of the top of the dash, and then have the opening covered in grill cloth, it could work. I want the car to sound as good as it possibly can, if that means having them under the dash then so be it. 

How i should run them without an active crossover i think is going to present a far bigger problem i think.

Gav


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## TXwrxWagon (Sep 26, 2008)

Eric & Mic & Horse will handle the passive question better than I.....

I understand about not doing drastic dash mods... Just offering that it CAN be done... but, as Eric said... its nearly impossible...

Rob


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## thehatedguy (May 4, 2007)

No offense, but i dunno about Mic and Will designing passive XOs.

There are a couple good free passive crossover design programs out there, but you will at least need some kind of FR data to use them. Impedance curves would be good to have for zobels and the such. Since published FR data is specific to certain horns, you really need to measure the FR yourself in car to get the best results.

But once you get that data, we can load it into the program and get a crossover knocked out. We can vary the Q of the filters so that you can have 24 dB slopes without 2 caps and 2 coils per XO.

If you have active EQ of some sort it would help getting the FR smooth without a lot of notch filters.


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## Mic10is (Aug 20, 2007)

Sorry I dont do passives and personally wouldnt on horns either


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## Horsemanwill (Jun 1, 2008)

no offense taken here, i wouldn't know where to start when it comes to designing a passive network. i but if Eric or matt designed one and posted it on the old ID board i'd have a copy which i don't lol. good place to go learn on some horns besides here is here

Getting started on installing horns in a car. - BackYard Installers


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## GavGT (Sep 5, 2011)

Thanks guys. It looks like i will either have to change my head unit, for one that has a good EQ and active filtering, or fit my PG EQ232 and go from that to an active crossover. Will most 2 or 3 way crossovers give me a high pass at 800-1500hz?

I didn't want to go down the outboard eq/processor route as it would put me in a higher class of competition, and my install skills aren't up to scratch yet, but i will just have to do what i can to get it sounding immense instead.

How does this sound in thoery?

Head unit Pioneer MEH-9100r with 6 disc changer > Phoenix Gold EQ232 > active crossover > amps (still undecided possibly dls/genesis)
ID CD ultra horns full bodies under dash
tweeters on top of dash/a pillars crossed over very high passively powered by h/u if needed.
Not decided on mid/bass but will go in kick panels (large in the E34 possibly rear vented/sealed depending on midbass used)
Subs - pair of Phoenix Gold XS124 12" firing through ski hatch.

Provided i get the eq'ing spot on, would i really need t/a? Or would i be better off getting one of the top line Pioneer h/u that has active filters/ta/eq built in and forget about the eq 232? Scarily this would put me in a lower class of competition.

Gav


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## Eric Stevens (Dec 29, 2007)

GavGT said:


> Thanks guys. It looks like i will either have to change my head unit, for one that has a good EQ and active filtering, or fit my PG EQ232 and go from that to an active crossover. Will most 2 or 3 way crossovers give me a high pass at 800-1500hz?
> 
> I didn't want to go down the outboard eq/processor route as it would put me in a higher class of competition, and my install skills aren't up to scratch yet, but i will just have to do what i can to get it sounding immense instead.
> 
> ...


I would highly suggest forgetting the old school EQ232 and go for Pioneer P99rs or P01 whatever is in your market. It has everything on board and is very high quality.

Signal delays are not necessary but they are useful.

Eric


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## GavGT (Sep 5, 2011)

Hmmm i suspect you're right, i might set the eq up while I'm still running 2 way comps up front just to see if i can get it sounding better and give me some practise. Plus it will make sure the eq works ready for when i sell it on. I think I'm going to give up on the passives unless i can get hold of the matching ones for the horns.

Gav


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