[audiochef]

I was told that using egg crate pattern foam in conjunction with whatever damping material you use in the cabinet increases performance.

I got some of this acoustic foam from Parts Express.
I first  added a 5inch square to the chamber of the mid in my tower 2s. I noticed improved clarity.from the driver. I then added about 1 square foot to each side of the upper woofer. It became less muddy sounding, cleaner mids and increased output. I had to retune the speaker.

Before posting this, I wanted to experiment with the 40s. I only had 1 piece of foam so instead of ordering more ,I happened to have something very similar , but softer. That yellow convoluted matress foam from Target, about $14.00. I added about 1.5 square feet to each side down from the upper woofer. The difference is not subtle. Same results as above , but even more. The bass growls and is tight as a nut. That elusive mid bass is increased. Big big diference.

I don't Know what's going on other than having something to do with standing waves that long cabinets are prone to have.

And I suppose this is all tuneable with the amount you add.

By the way, be sure the foam is lined along the cabinet.

[Florian]

That sounds pretty cool. Thanks for sharing !
I still have tons of that stuff laying around and i will give it a try too.
Big B what do you think?

-Flo

[John Casler]

On an associated note, I have been prodding B, to "experiment" with both "Black Hole 5" and the "Sonic Barrier" offered by Parts Express.

I am not a speaker designer as you all know, but I am a tweaker and I think the smaller thicknesses could be used both to line the inside and outside of the neopanel enclosure.  The 1 1/4" thickness then could line the inside of the cabinet walls themselves.

I predict another level of detail clairity, not only in the bass, but also in the upper/mid frequencies as well.

If It works as well as I think, we may add it to the menu of upgrades, or owners can simply DIY.  I will go as far as to predict that it will be a "must have" or "must do" option/tweak

It "should thoretically" work through reducing several areas of potentially harmful resonances.

[audiochef]

I've obviously been listening to recordings with good amounts of bass and this is definately the best bass I've  heard in this room.

It goes as deep as I remember the Rm2s and T2s did in here, but is positively now more taught and articulate now.

I'm looking forward for somebody else out there to experiment with different amounts and or Sonic Barrier and report back here.

[LAL]

When I made my RM40 cabinets  I placed a 9.5 inch x 9.5 inch piece of Blackhole #5 on the rear panel directly behind the midwoofer. Seems to work well, but I then have nothing to compare it with. This would be an easy tweak to experiment with.

[inRMsway]

    I just now tried it too! And it works exactly as described. I removed all the fiberglass, stuck a square of Black Hole behind the Midwoofer and lined everything with eggcrate mattress topper with triple folded pieces between the midrange box to cabinet outer edges. No stuffing at all and attached with double sticking carpet tape. Then for the mid boxes, I lined those with the same and then stuffed with Acousta-stuf rather than lambswool (which I bought also but didn't like as well when I talked into the box as a test).
    In addition, I wanted to properly seal the neos to the cabinet as they have gaps where the wiring area is. Maybe at those frequencies it doesn't matter but I used thicker weatherstripping around the outer edge starting and ending at the bulge where the wiring area is. I stuffed some of the previous thin weatherstripping under the gaps on each side of wiring zone and then used a thick piece to bridge the gap. A couple of thin pieces on the bulges and I think we have a 99% seal now. And......I think it extends the upper bass/lower mids of the Neos and adds impact. The lining/acoustuff may play a role as well, but I also feel a closer more direct sound much like it's coming right off the mikes. These speakers are tweekelicious!  JAY