Auralex acoustic form.

I've had great results with Auralex inclucding the LENRDS. You can see how I used them by looking at the pictures of my system.

Etran - Check my system and the Auralex. Depending on your speaker type and the problems you have you can find interesting ways to use it. Use push pins from Staples and you can reposition endlessly to find what works best for you.
Expensive? Huh? A 2 x 4 sheet of 2 inch is $20 at Guitar Center. Sam Ash has it too if you have one of those nearby.
My experience is that the LERNDS bass traps work quite well. Again, try a number of different positions to see what works best for you - Live wall-dead wall, ceilings, 1st reflection points - it's all good. Plus don't forget to alternate the types you use for an interesting visual effect.
Other sources -
http://www.foambymail.com/soundproofing.html
www.cascadeaudio.com (Suggested by Nsgarch a while ago).
Wow - I guess you're into diffusors eh Sgr?
Have fun.

I have Silverline Audio SR-12/Carver super Jr and want to tame the relection sounds from the side walls and tighten up the bass. I have window with heavy curtain behind the speakers and 6 6'x6" mirror strips on the back wall behind listener. Is it better to remove the mirror strips and put some acoustic foams on ? Thank you all for the great help and info.

BTW I find the prices for Auralex (and good service) to be good at Full Compass http://www.fullcompass.com

$20 is high for the 2" foam IME.

Has any tried the 2'x2' Sonoflat?