# Reflecting off windshield



## Jimi77 (Jul 4, 2005)

I tried searching but didn't find much useful info. I remember way back when Werewolf started a good thread on ECA about using windshield reflections, but that's been lost. 

Anyway, I have a dash that I think would be a good candidate (90 Pontiac Grand Am). The stock locations were ~4" firing up into the windshield and I used them temporarily and it wasn't bad. I'm willing to do some modification to the dash if necessary.

Does anybody have some good threads on reflections bookmarked or other good info on using windshield reflections? Is there a set of "rules" to follow for this type of install? FYI, this would be a 3-way front stage, midbass in the kick, midrange & tweeter would be in the dash and/or a-pillar.


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## Mic10is (Aug 20, 2007)

recess the speaker enough so you donot get any direct energy off the speaker, only the reflected energy and you should be fine


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## Oliver (Jun 25, 2007)

I've seen tweeters mounted on the doors bouncing off the windshield, ( search Joe Black on the internet ). http://pages.suddenlink.net/black743/ page 2



> The doors were completely reconstructed and molded to house a 1 inch titanium tweeter. However, this tweeter is firing at a very sharp forward angle toward the front windshield, 85 degrees off axis of the door so that no direct sound is heard from the door. In fact, this location works so well, there is a path length from the tweeter of over 8 feet to the listener. Pro Tech compression drivers were mounted in the familiar under-dash location and 5 inch Focal Pro Audio drivers were mounted in custom fiberglass enclosures in the floor of the car, with a path length difference of only one-inch.


I'd be hesitant to bounce the midrange, just me, I guess.

G'Luck


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## michaelsil1 (May 24, 2007)

I've heard a couple of cars that have done this and the results were very good.


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## left channel (Jul 9, 2008)

This was a pretty good thread...

http://www.diymobileaudio.com/forum...iring-off-glass-what-overcome.html#post795744


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## Jimi77 (Jul 4, 2005)

Mic10is said:


> recess the speaker enough so you donot get any direct energy off the speaker, only the reflected energy and you should be fine


Any advice on how much is "enough.?" 

I can't really recess the speaker because there is duct work directly under where it would go, but I would be willing to build up the dash ~1/2 - 1" and the speaker is already recessed ~1/2".

FWIW, output isn't a really big concern.... I'm getting old.


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## Mic10is (Aug 20, 2007)

issue is if you can hear direct sound, then when it combines with reflected sound= comb filtering.
so recessing it below the level of the dash, so it isnt visible at all would be your best option or angling it some to fire directly at the windshield and away from the listener


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## left channel (Jul 9, 2008)

A speaker that has poor off axis response will have a similar effect as recessing it.


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## Jimi77 (Jul 4, 2005)

Mic10is said:


> issue is if you can hear direct sound, then when it combines with reflected sound= comb filtering.
> so recessing it below the level of the dash, so it isnt visible at all would be your best option or angling it some to fire directly at the windshield and away from the listener


Cool. I think I can accomplish both. Still might go with pods on-axis instead, but I think reflecting will expand the soundstage a little for me.


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## thehatedguy (May 4, 2007)

What Jeff (werewolf) orignially had said was that you could put domes up in the corners of the dash and use the reflection as virtual speaker/speaker locations. The closer the speaker is to the glass, the higher in frequencies the resulting comb filtering will be. You can probably push most of the combs up high enough so that they will be in the tweeter's passband so they won't become much of an issue. And the reflected sound will arrive close enough to the direct sound that they will add together in our aural processing.


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## thehatedguy (May 4, 2007)

The original thread on ECA was about domes.

http://web.archive.org/web/20060319...itecaraudio.com/showthread.php?threadid=96808

I built a car using the domes up in the corners of the dash and it won SBN the same year the thread was made.


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## Jimi77 (Jul 4, 2005)

thehatedguy said:


> The original thread on ECA was about domes.
> 
> Elite Car Audio : Car Audio Forum - Dashboard Domes & Reflection Combs
> 
> I built a car using the domes up in the corners of the dash and it won SBN the same year the thread was made.


Awesome. Thanks a bunch - I liked referring to some of Steve Head's tutorials from time to time.


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## 14642 (May 19, 2008)

Recessing the speakers into the dash to eliminate direct sound won't work, unless you use a really high high pass filter--and in that case, you'd have a 4" tweeter.


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## thehatedguy (May 4, 2007)

That's where Steve got it from. He tuned the car that I was refering to before he did that tutorial.

And recessing like Andy said wouldn't do anything because the speaker will radiate 180 degrees below beaming and will narrow as you get to beaming. The baffle is essentially a 180 degree waveguide down low.


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