A super cheap way to try if you hear a difference is to simply place pillows on the first reflection points...except ceiling, of course.
I built my DIY traps with fiberglass panels and they work fine for me. Maybe commercial ones would be better, but the physics behind what's going on is pretty basic, especially at the high frequencies these can treat, so I tend to think DIY gets you very close to "there".
Using REW I could not measure any impact on low frequencies by using these or DIY tube traps (ok, a marginal improvement with the latter that was not worth the looks), but did notice a clear impact from using a Helmholtz resonator (at the design frequency, of course).
I built my DIY traps with fiberglass panels and they work fine for me. Maybe commercial ones would be better, but the physics behind what's going on is pretty basic, especially at the high frequencies these can treat, so I tend to think DIY gets you very close to "there".
Using REW I could not measure any impact on low frequencies by using these or DIY tube traps (ok, a marginal improvement with the latter that was not worth the looks), but did notice a clear impact from using a Helmholtz resonator (at the design frequency, of course).