Most effective Room Treatment for slap echo, etc

I hung a woolen tapestry on the offending wall. The tapestry is no larger than about 3 feet on a side, and is spaced a couple inches from the wall.

The effect was dramatic and immediate. The room was harsh before but is now fairly good.

I'd like to replace the tapestry with a large, dense rug...maybe 6'x8' and put the tapestry behind/between my panels.

jdombrow has a good idea. DIY is easy and 'fun'. OC703 is one of the materials of choice. I'd secure the right fabric first, however, since most fabric stores do not carry sound-transparent cloth. You can buy '6-packs' of 1" or even 2" thickness in 2x4 sheets.

I went the auralex route and was not overly impressed by it. While it did produce results, you really needed a lot to equal some of the other items available (or even DIY). I did not glue mine to the wall, I glues a small strip of thin wood to the back of the auralex and hung them from this strip, which better allowed for playing around with placement.

Kal (above) thanks for those links.

I have had very good results with GIK Acoustic products, which are reasonably priced. They also have great customer service. The GIK products have made a HUGE improvement in the sound of my system.

I thought about the DIY route, but it is hard to build for much less than GIK prices. If you do go the DIY route, you may want to check out gearslutz.com and look under studio construction and acoustics forum and the sub-forum for bass traps, acoustic panels, etc., which has a lot of DIY info.

I use Ready Acoustics. Some come with a frame that you can just lean against the wall. I use 2 like this at the first reflection points of my speakers as well as wall mounted ones. I think they also have stand mounted ones.

Just a follow-up to Magfan's comments: Most fabric stores will carry burlap in a number of colors. Burlap is one of the most widely used fabrics for acoustic treatments because of it's open weave. And it's inexpensive.