Re: Deadening dash speakers
Yes I always stuff the dash with melamine foam underneath the speaker. Also look for ways to blcok the sound wave from just coming out the bottom of the dashboard for example my car has some factory flexible sound panels that snap on the bottom of the dash. Just be creative if you find any ways to attenuate the back wave. I can't say this is critical though its just something to keep in mind.
More importantly look for flex in the dash itself. In my car the dash was not supported in the outer corner, no problem at all for OEM but if you pushed it down with your fingers you could get it to move 1/2". I managed to wedge a small block of wood (finger size) between the unsupported corner of the dash and the firewall to rigidify this.
Then I put 2 layers of dynamat all around on the top of the dash - I could do this because I am using a dashpad that covers everything. Dash pads used to be more populate in car audio until someone pointed out the math that a 1/4" dashpad only absorbs frequncies above 15kHz or something, but I still just feel that the more soft, absorbent surfaces the better.
If you're not running a dash pad then I doubt you will want to put dynamat on top of your dash, but I'm just pointing it out. These two changes made a noticeable difference in the quality of my mid-range. When Peter @ PSSounds does a dash build he pulls the whole dash out and covers the bottom of the speaker mounting with a bondo/fiberglass milkshake.
So yeah bottom line anything you can do to stiffen the dash surface and structure and attenuate the back wave will be good.
Re: Deadening dash speakers
I once purchased a whole bag of Polyfill, with the intention of putting it behind my dash wideband speakers somehow. However, when I started researching it, I found that most people only recommended using something like Polyfill for dash speakers if they are in an enclosure. If used in an "Infinite Baffle" setup, it seemed that most said that you *want* the speakers to use the open area under the dash to help "do their thing". It seemed that it was more important to make sure that you used a good-sealing speaker baffle to help keep the speakers front wave separate from the back wave.
In my case, I never used the Polyfill after I did the research on it. From what I remember, it's something that you'd normally use with speakers that are in enclosures - not "infinite baffle" installations like these dash speakers.
Curious to hear what others say.
@preston - I can't believe that you actually put CLD *on top* of your dashboard!! That is definitely the first time that I've heard of that! I mean how many problems can small dash speakers really cause in terms of "vibrations" being that they only play mid/high freqs? I use widebands crossed at 500hz and the speaker cones themselves barely even move, even at higher volumes, let alone cause the rest of the dashboard to vibrate. :-)
Re: Deadening dash speakers
You want to make sure the sound coming from the back of the speaker has no way of interfering with what's coming from the front of the speaker. Just dropping the speakers into the dash locations can have really bad results. I've used 2" PVC endcaps in all 3 of my Rams (09, 11, and 16) and they seem to work OK. I make sure to open up the back of them enough for the speaker to basically be IB and stuff open cell foam in them. The backwave is attenuated enough to not cause any issues. I secure a mounting ring to them with epoxy. Not saying my way is best but it's a really simple method that works for me.
Re: Deadening dash speakers
I wish I saved the threads from when I was researching this. You'd have to do some searching to see what others have done (unless we get more people posting responses here).
For example, this is the first one I saw when I did a search. These folks seem to believe that you don't need enclosures/polyfill for dash speakers:
https://www.diymobileaudio.com/threa...eakers.431302/
But like mentioned above, a lot of probably just depends on your car. In my car, I don't think the sound from the backwave could make it out of my dash with any real intensity if it's life depended on it (if it had a life!), but I've seen pictures of others where you could look through the dash speaker hole and see right down to the floor. So I guess it just all depends on the specific car.
Re: Deadening dash speakers
Quote:
I found that most people only recommended using something like Polyfill for dash speakers if they are in an enclosure. If used in an "Infinite Baffle" setup, it seemed that most said that you *want* the speakers to use the open area under the dash to help "do their thing". It seemed that it was more important to make sure that you used a good-sealing speaker baffle to help keep the speakers front wave separate from the back wave.
My thinking is that an enclosure is a sealed air space that is a totall different animal. No matter how much stuffing you put behind the speaker its not going to act like an air spring/suspension in the way that an enclosure does. No way will stuffing the dash change the q of the speaker for example. Now, you don't want to choke off the speaker, it would be possible to stuff so much crap in there that it will interfere with the sound, but we're not talking stuffing it like a teddy bear, just filling in the empty space and blocking the direct under dash path to the cabin. And with no science at all, I just feel that poly fill would be much less effective at this than a closed cell foam like melamine (while we're on the subject).
Then again, what with the popularity of dipole speakers in the home, who's to say it might not sound better with some attenuated backwave coming into the cabin ? I realize its not hte same thing, just speculating that maybe the attenuation of hte back wave isn't overly important. I tend to think that adding more absorption and "soft surfaces" is a good thing in and of itself regardless of the backwave.
Quote:
@preston - I can't believe that you actually put CLD *on top* of your dashboard!!
Yeah, I definitely felt like I needed to damp the dashboard, and I really didn't feel like pulling it out (although I was tempted so I could open up the holes and properly mount a baffle and try my 5.5" Satori drivers).
I've always used dash pads and I'd noticed previously that a dash pad allowed me to cover up quite a bit of baffle butchery and still have things look nice. so I thought, why not ?
Between wedging the wood block in to stiffen the dash corners and the 2 layers of CLD, it made a noticeable difference in some upper mid-range ringing/resonance. I don't want to overstate it we are talking about tiny little things that only audiofools notice, but I was pleased with the improvement.
Re: Deadening dash speakers
Quote:
Originally Posted by
jtrosky
I wish I saved the threads from when I was researching this. You'd have to do some searching to see what others have done (unless we get more people posting responses here).
For example, this is the first one I saw when I did a search. These folks seem to believe that you don't need enclosures/polyfill for dash speakers:
https://www.diymobileaudio.com/threa...eakers.431302/
But like mentioned above, a lot of probably just depends on your car. In my car, I don't think the sound from the backwave could make it out of my dash with any real intensity if it's life depended on it (if it had a life!), but I've seen pictures of others where you could look through the dash speaker hole and see right down to the floor. So I guess it just all depends on the specific car.
Yeah, in my Ram it's a straight unobstructed shot down to the floor from the dash opening on the drivers side. Passenger side the hvac fan housing is in the way but still open air down even though it's a PITA to get wire to the floor on that side if you don't hold your mouth just right. So yeah, I guess I agree that "it depends" and one size will never fit all for all vehicles.
