Cabinet Damping

[pjpoes]

I recently decided to do some upgrades to my speakers and thought that a simple and relativly inexpensive upgrade might be further cabinent dampening. Previously I was using industrial felt, I believe its called, which was simply cut to shape and placed in the cabinet. Its a ported enclosure, and no further fillers of any sort was used.

I purchased the dampening material from Parts express which looks to me much like the BlackHole Dampening material. Again, I cut it to shape so that every surface, including the slot port's outer surfaces, could be covered with a piece, in order to reduce resonance. I did one speaker at a time so that I could compare.

Once the adhesive had dried somewhat and I had put the speakers all back together, I began a basic knuckle rap test. This displayed a clear difference between the speaker with just felt and with this new stuff. The speaker is now much deader. I thought, ok but does it have an affect on sound.

I thought previously that the speaker had bass which was a little wooly at times, maybe not the tightest around. I wracked it up to Focal drivers and ported enclosures maybe. Though I had always read nothing but great things about the Focal W cone speakers I used, especially for detail, resolution, and tightness in the bass range. Well with the cabinet now firmed up I think the bass sounds better. I can't say its a drastic difference akin to changing the enclosure Q or drasticly better drivers, but its much better. I also think the midrange improved some, which I think is because the foam is doing a better job of absorbing midrange inside the cabinet. I noticed this when I was sticking my head near the speaker openings, comparing the felt to the foam, the foam had more of a "Black Hole" effect, though both seemed quite dead. The port also seems to have less midrange coming out of it now. Anyway, I recomend you all try this fine product in your speaker projects. I used it in my subwoofer enclosures as well, but noticed much less of an effect with that one, I think the bass energy is just too much for that pad to have much of an effect, and I simply needed, as I did in my second enclosure, a heavier better braced enclosure.

[kscharf]

The last time I bought speaker fill material from Madisound, it turned out to be a bag of 'teddy bear / pillow' stuffing material for three times the price. I bought a bag of the same stuff from the local fabric shop for use with my current project. (would have been even cheaper at Wal*Mart).

[ruerose]

Anyone used interior wall ROXUL mineral wool batts in a TL? I am wonding if they would perform better or worse than regular fiberglass batts.

[EC8010]

I think you need to distinguish between damping panel resonances and damping airborne standing waves. The two are quite different.

Panel resonances can sometimes be damped by sticking a heavy glutinous material to the panels (although, frankly, it's better to make the panels more rigid in the first place by bracing them and pushing the resonances up to a higher frequency where they're more easily damped).

Airborne standing waves are damped by placing a light fibrous material within the volume of the enclosure. Best damping is obtained where air velocity is at a maximum (the centre). Unfortunately, that interferes with reflex boxes, so you have to place it near the walls, were it doesn't work nearly as well.

Oh, and "dampening" is what happens when things get wet...

[planet10]

I don't really recommend dampening your speaker at all... they tend not to like to get wet

Changing or adding damping can have a profound effect. There are many factors that affect how well the damping material will perform, so one indeed has to play.

dave

[planet10]

Originally posted by EC8010
Panel resonances can sometimes be damped by sticking a heavy glutinous material to the panels (although, frankly, it's better to make the panels more rigid in the first place by bracing them and pushing the resonances up to a higher frequency where they're more easily damped).

Totally agreed on that...

dave

[Cal Weldon]

Originally posted by ruerose
mineral wool batts

I like to use it.

[Geoff H]

I'm glad someone has pointed out the difference between dampening, and damping. I prefer the latter when needed.

Just another question I was too embarrassed to ask!

[Cal Weldon]

Dampening is to moisten.

Damping is that noise in my engine.

[454Casull]

Originally posted by EC8010
Unfortunately, that interferes with reflex boxes, so you have to place it near the walls, were it doesn't work nearly as well.

Oh, and "dampening" is what happens when things get wet...

Dampening is really the same as damping.

http://www.m-w.com/dictionary/dampen

Also, here's an interesting article:

http://sound.westhost.com/articles/boxstuff.htm