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

OP please just stop and maybe offer something worth even thinking about.  bump  

So the tiny little gray or blue "triangle" corner traps (popular a while ago) always made me chuckle.

Those were not intended for and were never promoted to be bass traps

and I’m not promoting these nor commenting on their effectiveness, and you may well be correct,  but comments like below with nothing to back them up are basically worthless conjecture

And those tiny little "acoustic resonators" (often sold at very high price) are unlikely to do anything but placebo.

Last I heard, you all occupy a single listening position.. you are not some omnipresent being who float around in space.. listening from every inch of the room.

Standing waves occur between 2 parallel walls. Hence, look at the wall spots straight in front of you, behind you, to either side and above you.

Dennis Foley's mention of full wall coverage of ACDA, etc could come in handy with multiple listening positions (hometheater, for example). It has some other benefits as well, but, will consume significant real estate in smaller rooms. ACDA is huge and can give you a hernia if you try to move it around too much.

Very few panels out there will do anything under a 100 Hz. His ACDA will get much lower. But, the correct thing to do is to "cancel out" modes in the subwoofer range with strategic placement of subs, phase correction, etc. Use the panels for ranges above the sub crossover.

For SBIR, you can use panels right behind the speaker woofers or pull the speakers out enough so the SBIR frequencies get pushed into the subwoofer range.

Unless you are an omnipresent being with telescopic ears listening in every corner, your corner traps don't mean much. 

Stop looking at what some flat earth audiophile did as gospel and get a measurement mic. Thereafter, download a free measurement software known as REW.

God bless.

🍿🍿 🍿 

I have GIK corner bass traps. They are very effective in the corners behind my speakers. They didn’t do much in the corners behind my listening position...so I stack two of them in corners behind my speakers.

apparently the bass pressure was greatest in the corners behind my speakers...which makes sense due to closer proximity to speakers than corners behind me.

i would say they are pretty effective down to 60hz...going off memory they start rolling off at 80hz. They have scatter plates attached as i didn’t want to risk having a dead room.

There is also an option to add a range limiter plate, which focuses on absorbing more bass and less mids and highs....which is what you want because due to lengths of wavelengths, there will be a surplus of longer waves (bass) and a shortage of shorter waves (treble).

To answer the question of whether or not bass traps are needed I think it's a function of room size (close reflections vs longer reflections). If you have a 20x30 room bass traps are more of a nice to do but will definitely help. If you have a 12X16 room, bass traps are going to have obvious improvements if you buy the right traps and put them in the right places.