Insulation materials

tajanes

I've read, relative to full range driver reflex box designs, that foam is a bass killer as comp'd to fiberglass insulation.  

That got me thinking then that for a three way maybe using foam for the midrange (without or in combo with fiber fill) and fiberglass for the woofer base reflex section may be the way to go...?

Thoughts and experience on insulating materials - thanks

6thplanet

I tend to use rockwool for everything. Roxul brand, fiberglass is my 2nd, then polyfill

jholtz

I've lined the bass portion of all the cabinets I've built with foam for the Statements series, Anthology's and Bordeaux with no bass problems. I use 2" wedge foam. I have no issues with the other methods. Foam is just much easier to work with and is easily available. I do occasionally supplement the foam with polyfill when applicable.

HTH

Jim

PWRRYD

For midrange enclosures I use a combination of damping materials.  I leave some open air space directly behind the mid driver, then a layer of something light like open cell foam, then a layer of something heavy like denim right against the back wall.  Sound waves off the back of the midrange cone have to travel through both damping materials twice before returning to the backside of the cone.  I've never heavily stuffed a mid enclosure with poly or fiberglass.  My gut tells me that would somewhat negate having a very light weight, Mms, cone.

Wolf

Ever do an aperiodically damped sealed mid enclosure? It reduces the Q at resonance, and can do good things. I did this for the Bar-Gain project and was quite impressed. 1:1 volume of total in halves, then I used pegboard atop of open cell foam lightly compressed. Foam line the back volume, and conventional stuff or line the front volume.

You can make a shelf to try with and without if if suits you.

dynamo

I find that too much of any material is a bass killer, and it doesn’t take much. I use mostly fiberglass only because I have it left over from finishing the basement. I just spray glue a little on the walls adjacent to the woofer. I’ve used that cheap foam carpet padding (left over too)  with the same results. It eats the mids but doesn’t affect the bass.

rjj45

I've used a lot of wally mart cheap foam, some expensive foam, Dow703 compressed fiberglass, Duratouch denim and loose polyfill. I will agree with others, if you stuff a midrange enclosure too much, it sort of deadens the sound. OTOH, I've done some MLTL designs, and it's astonishing just how dense 12oz/ft^3 is! But it doesn't seem to affect midrange or bass response. Go figure. 
Probably my favorite for ported boxes is the Dow 703. Really absorptive, and you just cut pieces to size and hot glue them in. Very clean.
BTW, has anyone found an easy way to cut Duratouch?

tajanes

Wolf
"Ever do an aperiodically damped sealed mid enclosure?..."

For one of my biamped two-ways I ran a set of AudioNirvana 6.5s (for above 280Hz), and set the drivers in a quasi tapered / aperiodically damped enclosure.  I'd agree with you in that's a very good way to handle a mid as well.

I'm just revisiting for a new build, and came across the comment re foam vs fiberglass, and thought I'd pass it by this group for comments.

Thanks all, I appreciate your feedback