Very bad room acoustics (40hz resonance, bad reverbation time), what would you recommend?

[Eckerslad]

I have a 4.5 metre deep room with about a 14dB peak at about 40Hz. Years ago I purchased 4 GIK Monsters, which had no effect on the modal peaks. They’re just not physically deep enough. DSP was the answer - in my case a Trinnov Nova.

Have you tried positioning the speakers further away from the corners? Closer together will lose the equilateral triangle, but may reduce (but not completely solve) the problem. Moving the couch forward, further away from the rear wall will help too.

 

[Titurel]

I have a 4.5 metre deep room with about a 14dB peak at about 40Hz. Years ago I purchased 4 GIK Monsters, which had no effect on the modal peaks. They’re just not physically deep enough. DSP was the answer - in my case a Trinnov Nova.

Have you tried positioning the speakers further away from the corners? Closer together will lose the equilateral triangle, but may reduce (but not completely solve) the problem. Moving the couch forward, further away from the rear wall will help too.

Nothing especially wrong with the Monster Traps except most people won't (or can't) put them where they'd be most effective for low bass. They are velocity absorbers, thus not very effective where air velocity is lowest, like near a surface. You touch on this when you say they're not deep enough, but deep in this context is not so much physical depth (the thickness of the rock wool) as it is the distance of the rock wool from the reflecting surfaces, sometimes described as the airspace behind the resistance material. To deal with room modes, that distance is 1/4 of the offending wave length, or way the hell out into the room. Thicker baffles are generally more effective, but placement is really king.

As a general rule, if you're hunting boomy bass you're best off using pressure (resonant) traps or e-traps (active traps, effectively anti-woofers), which work best in close proximity to walls, not out in your living room.

 

[Eckerslad]

Nothing especially wrong with the Monster Traps except most people won't (or can't) put them where they'd be most effective for low bass. They are velocity absorbers, thus not very effective where air velocity is lowest, like near a surface. You touch on this when you say they're not deep enough, but deep in this context is not so much physical depth (the thickness of the rock wool) as it is the distance of the rock wool from the reflecting surfaces, sometimes described as the airspace behind the resistance material. To deal with room modes, that distance is 1/4 of the offending wave length, or way the hell out into the room. Thicker baffles are generally more effective, but placement is really king.

As a general rule, if you're hunting boomy bass you're best off using pressure (resonant) traps or e-traps (active traps, effectively anti-woofers), which work best in close proximity to walls, not out in your living room.

The trouble is a quarter wavelength is the centre of the room for a standing wave! I’d expect pressure traps (like GIK’s Scopus 40) would work better, but you would need lots of them and I suspect you’d still need DSP to finish the job.

If you look at the data from the PSI AVAA active traps they certainly work, but don’t completely remove the bass buildups.

I still use the Monster traps, they are a good product, but my room modes are controlled with DSP, which I have come to believe is the only practical solution in a 4.5 metre room.