What are the best Room Accustic Treaments members have found?


I  am looking into adding some room acoustic treatments to my room.  I am just looking for advice on some simple room treatments that fellow members found worthy of purchase. 
128x128davidrolson
I have just been through finding the right treatments. I've been in touch with Jim Smith (GetBetterSound.com) and I have been following his lead on the issue. He's got nearly 40 years experience in voicing systems of all sizes and types for people like us, manufacturers and dealers.
I've used HFTs. They do what has been said. But they are High Frequency Transducers. What about low frequency, nodes and booming? HFTs won't touch the low frequency.

In my small room(11'X12'X8') the HFTs worked very well but I still had booming bass and nodes. I had to use absorption for that. As my research began the consulting from GiK I received was way off base and I live in Atlanta and went to their plant. One guy sold me 2" panels when I needed 4", the next guy wanted me to buy about $2000 worth of additional panels after I already purchased six. He had them hanging from the ceiling and everywhere else. If I'd have done what he recommended my room would be dead! And he didn't address the trihedral corners! ,GIK is much more pricey than say ATS. Same stuff, way better prices but no consulting.

I always agree with what @millercarbon says, but in this case I take exception to his statements about the HFTs. They are not a be all, end all.
I checked out ASC on Jim Smiths recommendation. Truly phenomenal products. In my room I need two 16" tube traps. No problem, $2500 plus $250 shipping, great consulting though.
I did put a 4" panel in the front corners and some huge foam traps in the front upper trihedral corners. That tamed things down quite a bit. I have 2" panels at the early reflection point on the sides and directly behind the listening position. It sounds right. My speakers are at near field (64" away and 54" apart) The sound stage is stable, wide and deep. I'm still dealing with a node that occurs only occasionally now.
The sum of all this. If your room is too bright the HFTs will tame it nicely. If you have booming bass you'll have to absorb it.
Rollin (formerly Rollintubes)
“I know HFTs are high frequency transducers but what about transducers for low frequencies?” - That’s gold, Jerry, gold! 

High frequency transducers affect low frequencies of the acoustic waves as well as higher up the frequency range. That’s because - as first reported by Stereo Times for the Franck Tchang tiny little bowl acoustic resonators - small aperture bowls act to “equalize” sound pressure in the room, so all acoustic frequencies are affected. In fact everyone was quite surprised to hear the bass improved so much.
Sometimes simple is amazingly effective.   When I placed a pair of ficus trees (artificial) behind my 6 ft Maggies, the change from the diffusion was a huge improvement at a minimal cost.

Nothing against all the other suggestions, just that one need not spend the earth to achieve significant improvement.
I've used HFTs. They DO NOT help the bass. I had three levels of HFT and one level of HFT 2.0. Still had bass booming and nodes.

@lemonhaze is dead on. Read the information out there.
Rollin (formerly Rollintubes)
OMG 😳 Did I just see lemon head mention Ethan Winer? Now, I’m sure I must be right. Read the information out there.