Question (bouncing sound off the glass) - Chevy Impala SS Forum
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post #1 of 12 (permalink) Old 11-07-2003, 02:45 PM
Crispix396
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I was looking at doing an install using 3way components, midbass in door, but with a 3.5 and a tweet in the dash next to the A-pillars. would be really gawdy to mount them upright, so my next idea would be to flush mount them inthe dash, and reflect off the windshield.

we all do it in the rear window (well not in a wagon ) what are the cons to doing it this way?

In the past i have put tweets in the rear, and positioned them to reflect off the glass in places that would still aim them at me.. (not int he wagon of course...
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post #2 of 12 (permalink) Old 11-08-2003, 10:30 AM
sydneyssnowflake
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Since you would be reflecting your front stage - as opposed to just rear fill or bass - would you possibly have to worry about it distorting the sound waves? I don't know much at all about car stereo, just a thought I had.
post #3 of 12 (permalink) Old 11-12-2003, 01:13 PM
HEADSICK
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You be better off getting angled tweeters, and mounting them in the door panels. Mounting them in the dash would be some serious work, and with the contours of the caprice/ss dashes, would be very hard to make look decent. IF I get a chance, I'll snap some pics tonight, so you can see what I mean.
 
post #4 of 12 (permalink) Old 11-12-2003, 01:48 PM
Crispix396
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well i am doing a 3 way system... and i am trying to broaden my 'stage' out some. I looked into ounting them flat int he dash facing up into the glass for reflective angeling purposes, but now am leaning toward cutting out some of the dash, and then mounting them in the dash facing toward the riders...
post #5 of 12 (permalink) Old 11-12-2003, 04:31 PM
HEADSICK
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Here's the pics of my tweeter set-up.

post #6 of 12 (permalink) Old 11-13-2003, 03:46 PM
azroadmonster
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Crispix, which mids are you using? Are the cone or dome? I have a 3-way setup in my car, but I actually molded the mids/tweeters into the A-pillar. The mids I used are Macrom silk-domes, so there isn't that much depth to contend with. It sounds fantastic and really opens up the midrange vs. having a 2 way setup.
post #7 of 12 (permalink) Old 11-13-2003, 04:58 PM
Crispix396
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do you ahve any photo of how you modded them into the a pillar... that is my next step is to try that. I think i can pull it off, but i will still have to cut some of the dash away...
post #8 of 12 (permalink) Old 11-13-2003, 07:09 PM
azroadmonster
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Here's a couple pics of the finished product:

right pillar

left pillar

and for the hell of it, my radio install/swap:

radio
post #9 of 12 (permalink) Old 11-15-2003, 06:30 PM
ophidia31
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you definitly dont want your highs bouncing off of the front windshield. it will break up the pattern and make your highs sound harsh. high frequencies are more directional than lower mids-bass frequencies. so for highs you want them as close to relation as possible. there are cars where they calculate the angle that the sound would reflect off the angle of the windshield but that is in major competition cars and dont think you have the time or patience to want to do something like that. the midrange in the dash would be just fine to put there....when you find the depth and room. unless you use a horn driver for the mid and mount it under each side of the dash. I just finished my front stage with a 2inch center channel in the defroster grill, 6 1/2 components in the doors and and 8in sub in the middle underdash to take up depth that the 61/2s cant reproduce to well. there is pics of all of them on my page except for the 8. soon to be posted when i find my camera.
post #10 of 12 (permalink) Old 11-19-2003, 06:55 AM
kdrolt
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Quote:
Originally posted by ophidia31:
you definitly dont want your highs bouncing off of the front windshield. it will break up the pattern and make your highs sound harsh. high frequencies are more directional than lower mids-bass frequencies. ...
So long as the glass is locally flat, it won't break up the (beam) pattern -- the pattern will be completely maintained. Locally flat means, for example, you can see the optical reflection of the tweeter in the glass and it's an undistorted image of the tweeter.

Quote:
... so for highs you want them as close to relation as possible.
Well, close isn't really relevant inside a car. You'll always be closer to the speaker(s) in a car than in a living room. What's more important is that the tweeters are pointing more-or-less at the heads (or ears) of the riders starting with the driver.

Quote:
there are cars where they calculate the angle that the sound would reflect off the angle of the windshield but that is in major competition cars and dont think you have the time or patience to want to do something like that. ...


Instead of calculating it, just use optics..... that is, use the optical reflection of the glass to help pre-position the tweeter before you finish the install.

If there is any downside to using tweeters that reflect off the windshield it is that you could actually have two sound sources there: one for the tweeter, and the other from the sound reflection of the tweeter. This always happens btw, but it's not a problem if the tweeter is directional enough (large enough in diameter compared to the lowest wavelength it radiates) so that you don't get interference between the real sound source (the tweeter) and the image source (reflection of the tweeter). A tweeter will be directional enough if the crossover network is set to a high enough frequency. I know that's vague, but it is true.

If you got significant interference, then you would hear a fluttering of sound amplitude at high frequencies as you move you head laterally within the car. To show this in more detail requires math, and this isn't the place for that. So it's a lot easier to place them (temporarily) and test/listen.

In some sense, car audio is driven by the locations where the speakers can be placed, rather than placing them where they ought to go. A car interior is a very lousy listening room because it's so small and there is so much glass (which reflects but doesn't significantly absorb), so quality car audio is much more of a business of compromises than it is in home audio. High SPL car audio is a different animal with completely different goals.

Door placement of a tweeter would seemingly eliminate the reflection source (giving you only the direct source from the tweeter itself), but you still get reflections from the tweeter at longer delays from the other hard surfaces in the car. In underwater sound and in auditorium acoustics, this would be called reverberation. In a Grand Canyon sense, it's just called an echo. It still affects the quality of the sound, sometimes it can be helpful (if cleverly done) or it can be a nuisance (if not done smartly).

Your ears can be very useful tools to decide if it sounds good or not. So I suggest you try the tweeter placement using double-sided sticky tape as a temporary measure and see how you like it. HTH. - Ken
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