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

I spent 4+ years personally building my own dedicated listening room. The room is 13.5’ x 15.5’ x 9’. (I consider this a small room.) The room was originally our separate dining room. I closed it off and stripped down to studs on front and rear wall. All walls and ceiling are acoustically treated. Based on Dennis Foley’s acoustic product design principles, I spent 100s of hours designing and building my own absorption panels/ boxes and diffusers of various types, sizes and weight. It took numerous trials and errors to determine the best way to design and implement acoustic treatment within my room. I watched all of Dennis Foley’s videos as well as read/ watched as many other acoustic treatment related online videos, articles, books and photos, as I possibly could. I’ve learned a lot about room acoustic treatment and design. I’m just a typical audiophile who wants the best sound possible from my room. I agree (somewhat) with Dennis that corner bass traps are not always required. Depending on your specific room size/ shape, speaker placement..etc, sound pressure build-up can be more pronounced in other areas besides the corners. Address those areas first. If the corners end up being the biggest issue, then corner bass traps are likely needed. More often than not, corner bass traps alone don’t entirely fix low frequency issues. I don’t have corner bass traps. My room has a 5/6db variance between 30hz to 14khz - in a small room. I’m very happy. 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 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. 

@seanheis1 The front wall, front wall sides and ceiling above front wall required a lot of low frequency management.  To control 125hrz to 250hrz issue, ceiling required proper treatment. 
 

https://www.audiogon.com/systems/8747

Thank you seanheis1 & ozzy62.

Everything you see in the room was designed, hand built and installed by me. Crazy amount of work! Well worth it! Total weight of all the material close to 3000lbs. Mass/ weight, proper design and placement all play a role in low frequency management. This allowed me to avoid using corner bass traps - not needed. For other rooms, bass traps might be beneficial, but not mine.