I've deadened my doors with dynamat extreme and during normal listening there is minimal resonance but at higher volume I can feel vibrations when I lightly touch the door trims.

I thought that wasn't a bad result because I'm running 8s in the doors.

I was listening to the sine sweep on Highway One today and at two points during the low frequencies there was a distinct vibration of a higher pitch than the tone maybe at about 100hz and 200hz.

This is more noticeable in the driver's door and I think this is because the resonance causes the door mounted power window console to vibrate at a higher frequency.

How effective is adding a second layer of dynamat to the inside doorskin?

What is the best product to apply to the inside if the door trims to reduce the resonance?

The trims are made of compressed fibres similar to mdf.
I've been told dynamat doesn't stick to this stuff so well.

Would Sound-off be the best stuff?

I'm a bit doubtful because it is light weight.
I've always thought adding weight was an important factor for deadening.

making the trim fit snugly against the door will reduce rattles.

foam, or similar is good for this, it can be attached to the trim with contact adhesive, and then squashed against the door with good mounting (anchors or trim screws)

The door trims in my car are heavily moulded with intergrated hollow armrests.

The trims don't rattle as such but the armrest area resonates the most seemingly because of the cavity behind them.

Would it help to fill them with expanding foam?

Obviously the trims resonate due to energy transfered from the doors so would another layer of dynamat be worthwhile?

Don't know if this helps at all, as my door cards are plastic but below are the photos of how I stopped something similar in my car. Some careful dynamat placement and some open cell foam to stop the card hitting the inner door. Once I get time in the future I was thinking a nice layer of "Sound Off" over the entire panel to tie it all together if you get what I mean.




The cards are very tight to put back on but it stopped 99% of the noise they added.

Jono

Paint on deadener?

i've got this issue atm, in my last setup I used foam with tape as above? but had a hard time putting the door cards on

Simply raise or lower the resonant frequency above/below the passband of the driver.

Stiffen the resonating device will raise. Unfortunately, your drivers distortion artifacts (and the higher frequencies) can excite these new frequencies. Depends on how well you stiffen it.

Adding mass will lower the resonant frequency of the 'enclosure'. Real mass, not dynamat (too expensive to get a lot of mass from). Lead, steel, other heavy stuff.

As Simon mentioned, isolate contacts that 'ring' with foam. If the actual trim stills resonants (which it sounds like it does), get cracking on what I mentioned above!!

build sealed box for the midbass in the door. NO more rattles and better more controlled midbass. This also means lots of custom work but its the best way to isolate the 8inch driver from the door cavity. If your electric actuator is internally vibrating and this can not be stopped this IS the ONLY answer. I just hope your midbass likes small sealed enclosures.

they sell memory foam with self adheasive backing thats really good for this application, it comes in varied thicknesses, from 5mm up to about 50mm, i used it on mine for the same reason your trying to fix, i also trimmed all the backs of my plastic trim peices with seat insert material to help with road noise and plastic on metal buzz..works great around the kick panels and works exremely well to hush the drone from the transmission hump if you do the back of the centre console peice...(its worse on some cars then others) ...give it a try, youll be happier..

also, just an option to using dynamatt, as it was said its too expensive to get a decent amount of mass from but you can try flash tac, from bunnings, its in the roofing isle, its about 30bux or so for a 10mtr roll thats 100mm wide...heres a pic of it, it varies from 30mm wide up to 250mm wide, try reece plumbing aswell or any hardware shop...

An enclosure would have to be in a massive buildout as I can't use the space inside the door because the power window mechanism is in the way.

Click to view attachment

In the pic you can just see the quadrant gear in the upper right corner of the speaker hole.

It actually intrudes between the spokes of the speaker basket so that when the speaker is held in it's hole with the screws out, the speaker can't be rotated.

If I ever build a full on sq car I'll probably weld midbass enclosures into the firewall in front of the footwells.

Actually I don't think the problem is that drastic because I listened to music for half an hour and didn't hear any resonsnce until I ran the sine sweep at high volume.
The noise seemed to come from the power window control panel in the armrest although I felt some resonance in the doortrim.

I'll add another layer of dynamat to the door and spray the inside of the trim with deadener then stuff foam inside the armrest.
I might also use some of that black putty they hold speaker grilles in with to stop the pw control panel rattling.

If that doesn't fix it I'll lose the sine sweep cd down the back of the seat.

if its only when you do the sine sweep cd thing then i wouldnt worry too much, if you cant hear it at half volume id say its not worth worrying about,

Where can you get the memory foam stuff in Brisbane?

Does this stuff actually work?

Yes, but not as well as dynamat by report. Most people who have tried both will tell you to save your money and do it properly.

id try spotlight or any type of hobby place, clark rubber would be another good place to try.. or you can try bunnings aswell, they should have it, i get mine off my sister thru "tiemans" but i dont think they sell direct to the public,



well, the opinions vary, i found it good, as long as you heat and press it on right to the edges, and youve cleaned the surface well, ive used stinger road kill, and the normal dynamatt, not the extreme stuff...
but my oppinion, i repeat my oppinion of it is, its a not bad option for a daily driver with an average system...if you want perfect results pay perfect dollars, but you can get 288mm wide roll for $120, thats pretty cheap, my cars done all over and hasnt come off anywhere, even the roof, if its coming off, theres another reason, then it isn no good..

what would it cost to do your whole car in dynamatt or stinger road kill, 2 layers on doors, 1 on outer and 1 on the inner panel..???

this is just my oppinion guys, i dont care what people use, i dont sell it, but my experiences with it have been good or i wouldnt say to use it...