Best way to tame room modes?

[Markus_Menasci]

I have a huge boom at 40hz and a dip at 50 and 70hz.
I found the corner with the 40hz boom. I tried placing around 20 pillows there and no change. So I just used the parametric eq to tame it. Is this the best way?

[Suedkiez (Just a fellow user like you)]

Measure the room and use DSP in Roon. Taming room modes this low with passive means is impossible because the wave lengths are just too long, you would need huge traps.

You can use parametric EQ or a convolution filter.

Quick, cheap and simple way to get good results already:

Room correction using your iPhone and HouseCurve

I would like to share an app note on room correction for Roon using HouseCurve, an audio analysis app for your iPhone/iPad. Full disclosure, I’m the author of HouseCurve. I wrote this app note a few months ago and it has been getting a lot of interest. I’m sharing it here on the Roon community forum so I can answer questions for Roon users. One of the most common questions is about the quality of iPhone microphones. The sort answer is “actually, pretty good, especially when you don’t have…

Or invest a bit more and get your filters tailormade:

HAF - Home Audio Fidelity (Room Correction / convolution filter creation)

Hi All, I would like to share with you a young company providing with high quality room audio correction available on Roon. This is HomeAudioFidelity: https://www.homeaudiofidelity.com/ You will find more details about the technology embedded in this solution. From my point of view, this is the best solution I have implemented so far. Previously I was doing my own corrections using Rew and Rephase but with this solution the results are far more efficient with a very nice soundstage, deep, la…

There is also other software. Lots of other info here:

A guide how to do room correction and use it in Roon

I have experimented with REW (Room EQ Wizard) and room correction, and how to apply it in Roon, and decided to write a guide about it. This is what produced best result for me (I sit in a small room with concrete walls), but the way I did it should work well in bigger rooms and for different walls as well. This guide assumes you have a 2.0 or 2.1 system, and works best if you have a specific listening position and you sit in the middle of the sound, with an equal distance to left and right speak…

Otherwise the only options are tuned diaphragm traps like

Tuned Membrane Bass Traps Archives - Gik Acoustics

Or active traps like

PSI Audio AVAA C20 - Active Bass Trap

[Boris_Molodyi]

If this is room modes and interference, DSP won’t help that much. A second sub would be a better option. Or, well, active traps.

[Suedkiez (Just a fellow user like you)]

@Boris_Molodyi

If this is room modes and interference, DSP won’t help that much.

Not to fill in very deep dips, but he says he has big booms, which can be reduced

[Boris_Molodyi]

Well, yes, but wouldn’t it reduce 40Hz even more everywhere else?

[Suedkiez (Just a fellow user like you)]

How so? A PEQ at the right place, or IMHO better a convolution filter, would only affect the specific frequency

[Boris_Molodyi]

But if it is that frequency that adds, due to room reflections, to a big peak in a specific location, all you can do with PEQ is lower it enough that it is reasonable in that spot. So there will be a dip at 40Hz elsewhere no? If the goal is to fix up a sound one spot that will do, but if the goal is to even out response across the entire room, you really need multiple sources for big wavelengths.

[Suedkiez (Just a fellow user like you)]

Yeah, though you can average it out good enough for the whole couch or something like that. Sure, in other parts of the room there will still be peaks and dips in this case. May or may not be a problem in a particular case. If it sounds great in the listening position, it’s all many people care about. I accept that there’s a corner in the open kitchen with a bass boom Though even that got better with DSP.

(Edit: And if you care for multiple positions, though not simultaneously, measure them separately and switch DSP as needed)

But even if you have multiple sources you may still have a peak at the listening position as that’s a question of room measurements and position, and will still occur even if there are sources in different places. Eventually, only a very large room helps that pushes resonances into inaudible depths.

[Boris_Molodyi]

40Hz is 8.5 meters wavelength , it might work. Depending on goals, ,room layout, and placement options, might be also easier to just move the sub

[Markus_Menasci]

i have 2 subs

[Boris_Molodyi]

Have you tried moving them around so it does not add quite as much at the main listening position?

[Marin_Weigel (Bram Stoker's Cappuccino)]

@Markus_Menasci

… I found the corner with the 40hz boom. I tried placing around 20 pillows there and no change …

Actually no wonder, since a pressure node is a particle displacement antinode.
You need to put the absorber where there’s an audible null at that frequency, to be most effective!
From http://www.sengpielaudio.com/RoomModes.htm
Left: sound pressure for a room mode
Right: air molecule displacement for a room mode

[Markus_Menasci]

Actually, even if I disable the subs the towers have the same issue

[Arjan_H]

That is why foam corner traps don’t work for bass.
If you would have 8 subs and a rectangular room you can try the Double Bass Array.
Otherwise build diaphragmatic traps. I made two “small” ones to take care of a nasty 71 Hz problem and they do work! The 71 Hz is still there but gone is the decay.
I built the acoustic fields ones. They really work. But you need space against the wall for them.

[Boris_Molodyi]

Other than mentioned traps, and I assume moving towers isn’t practical, moving subs might help, if you can get them to cancel / add elsewhere.

[Markus_Menasci]

Funny, if I set the left sub out of phase it evens the bass notes quite a bit. But now there is a big boost at 60 lol.

[Suedkiez (Just a fellow user like you)]

If you have an iPhone or iPad (or can borrow one), 7 euros, and 10-30 minutes, you could try if HouseCurve solves the basic problem for you (and then could potentially build on that with more sophisticated filters)

[Markus_Menasci]

I will thanks

[Boris_Molodyi]

Makes sense…

Are subs running stereo or both on the mono sub output? Something that can do phase as well as frequency adjustment might be able to work it out. Not sure, but Housecurve likely can do it at least to some degree ,so try that…

[Markus_Menasci]

dual RELs off of a Parasound P5