so bass traps in corners do nothing, it seems we have been fooled. or are being fooled.

Bass trap works if you know where to put them.i used to own Martin Logan request. And I saw Gale Sander and Bruce Brissom if Iam right? They put the bass trap near the side of both the SL3 Martin Logan . Yes indeed I works. When I applied my DIY bass traps.To do tweaks you have to have an open mind, listening to other people experience is not as good as doing it yourself. 

Dennis means well. Whether or not you agree with him, he’s working hard to bring better sound to this hobby that we all care so much about.

I diy’d all diffusion panels (the formula, home depot lumber, saw, glue, nails, stain, no other magic required)...His ACDA panels are quite unique though, I have never heard definition and resolution to the current level in my room until those came in. He has some theories on the ’rate of absorption’ of a panel (which nobody looks into), effect on the ear and i am starting to believe him. Guy spent years dev’ing those.

P..S if a guy has a tiny room and speakers sitting 6 inches from a corner (bad location to begin with)...yeah, a corner trap will do something for sbir if it’s sitting directly behind the woofers..

A Umik cal’d mic is 70 bucks....you’d be surprised how many guys around here don’t have one (facepalm). They’ll do everything 300 hz and under by ear is the claim.. I highly doubt it.

As another person posted, they mostly treat upper bass, lower mids. Lowest bass registers extremely long wave length, hard to trap. At one point I had 2 21"tube traps stacked in both front corners, single 16" in back corners, These were fairly effective in getting rid of upper, maybe a bit of mid bass resonance that was masking mid range. Mismatch between speakers, amps was cause of much of this resonance. Now that I have effective control of bass with proper amp/speaker interface I no longer have any bass issues, and even with somewhat recent addition of two Rel subs. Not a single bass trap in room, diffusion with just a bit of absorption does it for me. Not having a square room is big help as well.

 Guys, I feel it would be remiss of me not to warn you about Dennis Fooley. Apart from him frequently offering dubious information he has spent time in prison. Best to steer clear.

To those who think that bass traps do not belong in corners here is a simple test. Play something with a prominent beat and then walk around your room, you'll find plenty of bass in the corners and this is where you want to place bass traps. Bass builds up in places other than the corners just not as much and you would not want a large bass trap/s sitting in the middle of your room. Corners are easier to accommodate and more effective.

Multi-subs properly set up will help tame the peaks and nulls and really improve your sound but benefit from some absorption to reduce long delay in decay.

If going to subs to improve your acoustics, which I strongly advise, choose sealed rather than ported and it's essential that they have continuously variable phase.

I can’t help but chime in. I’ll steer clear of speaking about Dennis specifically. I have spoken to him on the phone and met him in person at an audio show. I have my opinions but no need to elaborate. 
 

It seems we have moved from corner bass traps to bass traps in general. My experience suggests that corner bass traps if designed correctly and implemented when needed can help mitigate low frequency issues (below 250hz). The hard part is knowing what type of bass trap design is right for your room and then implementing it correctly. I’v used, designed and built many different types of bass traps. Membrane and diagrammatic work the best. Using multiple subwoofers set up correctly throughout the room can also provide benefits. I have room measurements to prove it. The thing is, there are so many variables that contribute to low frequency room modes, one strategy alone may not be enough. It’s really hard to design and build a corner bass trap (triangle shaped) that has the mass/ Q factor or membrane structure to effectively manage bass below 250hz. The good news is that Bass issues below 250hz can be controlled or mostly eliminated even in smaller rooms, but it takes a lot of work and understanding.