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

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. 

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.

Wow, aren’t you something special? So, a guy who spent some time in the big house for a drug conviction or whatever can’t lead a normal life, run a legitimate business, thereafter?

Plenty of white collar crooks in this country (who do way worse) never make it to the big house because they paid a handsome sum to a gang of lawyers. Move on!

@deep_333 - so.... you are a judge of First Amendment here? Supreme Ruler of Truth? Yeah, people post relevant information. So yeah, move on.