Room treatment for bass

[Gordon Palmer]

These are my measurements for my subwoofers,before and after EQ in my untreated room.
My interest is in reducing the ringing..maybe with bass trapping.
My questions are

1. What can I deduce from the graphs? Is my room good,bad or average?
2. I assume there is no practical way to improve at 22Hz?
3. Will targeted (membrane) traps help at the other bad responses?
4. Does sub placement affect ringing (as opposed to freq response)?

Any help appreciated.

 

[DanDan]

Response looks very odd. I am seeing a 30dB rising graph from 100Hz to 20Hz.

 

[Gordon Palmer]

Response looks very odd. I am seeing a 30dB rising graph from 100Hz to 20Hz.

Thanks for responding
Did a bit more measuring and it appears to be a strong room effect on the current sub location
The room has a strong boost at 22HZ measured at MLP.
Measuring the sub at the cone shows an inverse response at around 22hz.
I am less concerned with the frequency response as I have still to try other subwoofer locations and multiple subs.
I am more concerned with the ringing, is it bad compared to the average and how best to mitigate it?
is there a target response to aim for ie -40db @120ms? Currently it varies fro -10 to -30db at 120ms at 30Hz and above.
The ringing is quite audible as boomy at the low end and variable in the mid/high bass with some LFE effects quite good and punchy, and others dull, which I assume is the effect of inconsistent ringing across the bass freq range.
My understanding is that it is impractical to treat the severe 22Hz ringing with room treatment but the 40-90 hz can be mitigated?

 

[DanDan]

There is a 30dB slope in your response. I find it hard to believe. Relatively elevated levels create an impression of longer ringing.
90Hz is pretty accessible, 40 requires massive treatment. 22 fuggedaboudit. This 22 Hz may be your lowest mode, say Length. Just as you have massive peaks at the two generating boundaries, there should be a deep null half way. Can the sub be placed there? This principle applies in all dimensions. One might place a sub half height. Or even under your seat or desk! What type of sub, where in the room, and the rest of the rig, settings?

 

[clubfoot]

If your sub is very heavy like mine place it in your MLP and move the mic around the room instead while taking sweeps. It's a quick and easy way to find a good location. If your room is fairly rectangular try 1/2 and 1/4 room widths first, front and rear walls. Just my .02c.

 

[Gordon Palmer]

If your sub is very heavy like mine place it in your MLP and move the mic around the room instead while taking sweeps. It's a quick and easy way to find a good location. If your room is fairly rectangular try 1/2 and 1/4 room widths first, front and rear walls. Just my .02c.

Thanks.I have done that on a previous setup and it was useful. I intend to do it in this setup but we;re in lockdown here so I'll have to wait to get help moving the sub.
Previously I was only looking at freq response but this time I'm going to focus on the waterfall/spectrogram/decay plots as thats the biggest issue with the bass ringing.

 

[simplex]

These are my measurements for my subwoofers,before and after EQ in my untreated room.

Unfortunately, I can't open these files using REW 5.19.
Error Message: 'File is not in .mdat format.'
Which version did you use?

 

[clubfoot]

No issue opening with 5.20.

 

[pratul]

Thanks.I have done that on a previous setup and it was useful. I intend to do it in this setup but we;re in lockdown here so I'll have to wait to get help moving the sub.
Previously I was only looking at freq response but this time I'm going to focus on the waterfall/spectrogram/decay plots as thats the biggest issue with the bass ringing.

I put my sub onto a moving dolly and moved it around the room to test. It was a lot easier to move. I put the sweep on a loop and monitored the response on REW RTA while rolling the dolly around the room.

 

[DanDan]

Pink Noise would be easier to work with rather than sweeps.

 

[pratul]

Pink Noise would be easier to work with rather than sweeps.

Thanks @DanDan, I'll try that next time.

 

[DanDan]

You are welcome. If I may again repeat a suggestion, a useful 'trick'...... You can place a speaker where the listener will be and move the mic around to find the sweet spot.
This scenario is vice versa, symmetrical, can't think of a better term right now.