Egg crate foam vs. Zaph recommendations?

[ro9397]

Zaph audio's pages are filled with great information. From his Design Mantra page: "...For damping vented enclosures, I use Whispermat, Sonic Barrier or 1/2" carpet padding doubled up. Whispermat is the best value. Sonic Barrier is expensive but occasionally handy since it comes with adhesive and is sold in small (but expensive) quantities. Carpet padding is surprisingly effective and cheap but it varies in performance. I never use egg crate foam because it just plain does not perform well..."

Can anyone confirm or contradict John's results re. egg crate foam vs. the three alternatives he prefers above? System is reflex 160 mm Dynaudio Esotec midbass, .35 cf, 2nd order acoustic filter @ 2.2 kHz.

TIA!

[bear]

so called egg crate foam is awful stuff both from the point of view of it's inevitable disintegration and outgassing and pretty limited effectiveness as an absorber of sound.

Not sure what the term "damping" of enclosures refers to - internal reflected radiation, or control of cabinet walls?

Egg crate foam is not good for either.

I use something else other than the suggested products... fwiw.

_-_-bea

[wintermute]

I did some tests with various types of foam about 5 - 6 years ago. egg-crate foam was pretty ordinary, but not useless. see post below for a comparison

http://www.diyaudio.com/forums/multi...ml#post2012367

also this one (but only showing the effectiveness of the soundsorber barrier. Speaker Dampening Materials. What do people use?

Tony.

[Ron E]

The question is - which eggcrate foam?
Mattress foam? Polyurethane or latex?
Packing foam?
Acoustic foam?
Open cell or closed cell?

All will absorb sound, they aren't useless, but are they better than dacron or fiberglass? I just use pillow stuffing (chopped polyfill) in most boxes. I used some cheap (free) white 3/4" thick packing foam in some vented boxes recently - it was much better than nothing.

[chops]

I've never had any experience with the materials mentioned by the OP, but have always used to great success both poly-fill and/or fiberglass. They both seem to do what I need them to do. Plus they are both cheap and readily available nearly everywhere.

[bear]

better than nothing may or may not be good...

and it may not solve the intended problem...

_-_-bear

[ro9397]

A big thank you to all replies!

bear,
The cabinet is only .35cf internal made of the following panel materials:

Sides/top/base 1.25" laminate total, 5/8" BB ply over 5/8" particle board, my favorite general panel material
Baffle/rear 1" laminated MDF, 2x 1/2"

It's about 25 lbs empty, pretty solid, a 3-materials blend for superb spread of resonance and constrained layer damping properties. No bracing. Strictly by ear three persons (one a woman with extensive audio/music experience and much better ears than mine, the other a lifelong pro percussionist) compared above to a heavier cabinet, same internal volume, with sides/top/base comprising solid 1.25" Ovangkol (gorgeous finger joints) and baffle/rear made of the same 1" laminate MDF. Tossup, maybe the laminate was preferred (I expected the opposite). In the proverbial knuckle tap test both cabinets seemed well damped, only the briefest ring, the Ovangkol resonating about 1/2 octave higher than the laminate. The cabinets seem great overall, especially for livable thickness resulting in ideal, classic proportions.

So...the primary function of internal damping in this application appears to be minimizing internal reflected radiation with some but less concern for minimizing panel resonance.

I'd sure love to hear any of Krutke's better designs properly implemented, especially smaller limited range speakers (exotic 5-piece sub employed).

[ro9397]

Originally Posted by Ron E

The question is - which eggcrate foam?
Mattress foam? Polyurethane or latex?
Packing foam?
Acoustic foam?
Open cell or closed cell?

All will absorb sound, they aren't useless, but are they better than dacron or fiberglass? I just use pillow stuffing (chopped polyfill) in most boxes. I used some cheap (free) white 3/4" thick packing foam in some vented boxes recently - it was much better than nothing.

My apology...I'm open to any suggestions, especially the money-saving variety. The cabinets are small but there are six total: 2 per 3 Trinaural channels...2 monitors per channel following Dr. Floyd Toole's latest recommendations for ambiance radiation...one monitor is above the other, the lower monitor swivels 65-degrees outward toward the nearby side wall (L/R channels) and with 7ms delay via vertical offset...for the center I fire the lower monitor downward 65-degrees reflecting off a pedestal wood base. I'll post images after the cabinet and stand remake is done. I've been listening to it for about 9 mos and it flat out works like nothing I've ever heard before.

The system already performed admirably with 1.5" egg crate foam...appears to be open cell. I can't remember the source. No idea about any of the qualifiers mentioned above, sorry.

It occurs to me, based on past performance, maybe I should leave well enough alone. OTOH I could compare two otherwise identical cabinets (using the Trinaural center channel) and decide thereafter.

[Ron E]

Originally Posted by ro9397

My apology...I'm open to any suggestions, especially the money-saving variety.

I was merely hinting (perhaps it was too subtle...) that a blanket (ha!) statement (even by a respected designer) is useless. There are many types of egg-crate foam. Which did he mean?

Use your ears, and apparently those of your musical friends, and judge for yourself....

[Brett]

Fibreglass insulation and poly pillow stuffing both work very well and are very cheap.