Taming room modes - 50, 144, 249, 468Hz room mode?

[jmdesignz2]

Hi all-

I finally got a minidsp Umik-1 calibrated USB mic and got some measurements

 

I find I have what look to be room modes that need to be tamed

at 50, 144, 249, 468Hz

 

Here is the chart - showing a left and right channels and both summed

 

[jmdesignz2]

I did not calibrate the "sound card" of my macbook pro. Would that make much difference here?

[wgscott]

You might want to play with the free trial of Dirac (and buy it if you like what it does).

 

What you are starting with doesn't look that bad to me.

[Ralf11]

not that bad really - is the room rectangular? anything in the corners right now?

[jmdesignz2]

The response was visually smoothed with REW's psychoacoustic setting

 

The room is a rectangle- 11.5 ft x 21.67 feet x 8 feet tall - it's not full enclosed -

 

hallway on the right of the right speaker

 

rear of room opens up on the right to dining area. House is fully carpeted in berber.

 

Thick drapes along 40% of the left wall.

[jmdesignz2]

not that bad really - is the room rectangular? anything in the corners right now?

 

nothing in the corners as far as "room treatment"

 

but left rear of room has large couch and armchair that are thick and stuffed. Two subs- one about mid-way on the left wall.

The other sub is directly behind the right speaker.

[wgscott]

It looks pretty flat. Do you hear any anomalies?

 

I'd try Dirac. If you don't get an audible improvement, just declare victory and move on to the next problem. Many people would be happy to have something that looked like that after doing a bunch of room treatments.

[jmdesignz2]

del

[jmdesignz2]

It looks pretty flat. Do you hear any anomalies?

 

I'd try Dirac. If you don't get an audible improvement, just declare victory and move on to the next problem. Many people would be happy to have something that looked like that after doing a bunch of room treatments.

 

hmmm - I can't seem to get Dirac to work. Went through the calibration and using the filter created - Dirac is selected as output device in sound control panel. Filter is ON and Dirac says streaming. But - only sound is coming out of the left speaker.

 

Any clues?

 

Using Decibel player

[ecwl]

I agree with wgscott, the measurement looks pretty smooth. I suspect the only room mode that significantly affects your sound quality is probably the 50Hz one. OP should be able to get REW to recommend a parametric EQ setting to tune out that mode. It would also be interesting to see what the histogram/waterfall plot looks like to see if there are other bad resonances that didn't show up on the frequency response. If I were OP, I'd only touch the 50Hz wide peak and enjoy the music.

 

 

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[ecwl]

As to OP's Dirac question, I've only used it a few times. If I recall correctly, you can measure a filter for both speakers or for each individual speaker. When you're done, you have to program Dirac to take the left channel input, apply the correct filter, and send tip to the left channel output and then you have to do the same for the right channel. No sound coming out of the right channel, may be because you only programmed the left channel but not the right. But like I said, I've only played with Dirac a few times so my memory is foggy.

 

 

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[Ralf11]

beyond the bass...

 

maybe the room is too dead?

 

it sounds asymmetrical so that could be the most difficult issue

 

what have you done for the 1st reflection points?

 

and... any parallel surfaces that are bare?

[Fitzcaraldo215]

As to OP's Dirac question, I've only used it a few times. If I recall correctly, you can measure a filter for both speakers or for each individual speaker. When you're done, you have to program Dirac to take the left channel input, apply the correct filter, and send tip to the left channel output and then you have to do the same for the right channel. No sound coming out of the right channel, may be because you only programmed the left channel but not the right. But like I said, I've only played with Dirac a few times so my memory is foggy.

 

 

Sent from my iPad using Computer Audiophile

 

That is not a correct or helpful description of how Dirac works. You define your speaker layout - 2.0, 5.1, etc. Then it sends the test tone from each and successively every channel you defined for each mike position before you move the mike to the next position, and so on. The filters are calculated discretely for each and every defined channel in one simple operation after the mike test tone sweep is done at the multiple mike positions. You can verify in DLCT via its graphic display the measured and spatially averaged response separately for each channel, as well as the target curve and predicted response by channel, after the filter calculation.

 

It is hard to envision a problem during calibration as the culprit here, provided DLCT gave no error messages and all the steps were followed per the instructions. More likely, there is some error interfacing the source to DAP to the DAC.

[ecwl]

That is not a correct or helpful description of how Dirac works. You define your speaker layout - 2.0, 5.1, etc. Then it sends the test tone from each and successively every channel you defined for each mike position before you move the mike to the next position, and so on. The filters are calculated discretely for each and every defined channel in one simple operation after the mike test tone sweep is done at the multiple mike positions. You can verify in DLCT via its graphic display the measured and spatially averaged response separately for each channel, as well as the target curve and predicted response by channel, after the filter calculation.

 

It is hard to envision a problem during calibration as the culprit here, provided DLCT gave no error messages and all the steps were followed per the instructions. More likely, there is some error interfacing the source to DAP to the DAC.

 

Sure. I was programming a miniDSP device with Dirac software and ran into the same problem OP did when I had no sound from one channel. It was the very last step where we have already saved the correct filters for the left and then the right channel independently and we had to program which filter to use for which channel. But that's a miniDSP device. I presume the Dirac software is now more user-friendly or works differently for non-miniDSP devices. It'll be interesting to see what the actual problem was for OP in the end.

 

 

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[wgscott]

Any clues?

 

No. But ecwl had a better suggestion -- just play with the parametric equalizer.

[jmdesignz2]

I agree with wgscott, the measurement looks pretty smooth. I suspect the only room mode that significantly affects your sound quality is probably the 50Hz one. OP should be able to get REW to recommend a parametric EQ setting to tune out that mode. It would also be interesting to see what the histogram/waterfall plot looks like to see if there are other bad resonances that didn't show up on the frequency response. If I were OP, I'd only touch the 50Hz wide peak and enjoy the music.

 

 

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@ecwl - here is the waterfall - what do you think?

 

[ecwl]

So like I said before, I think you need to tune out the 50Hz peak. Your speakers probably are not that loud for 20-30Hz but the room resonance boosts the dB which is why you get a reasonably flat frequency response. Sometimes, the resonance here can make music sound muddy. I suspect it doesn't in your room and your main problem is from the broad 50Hz peak. But the 20-30Hz may be an area worth tweaking if fixing the 50Hz doesn't get you to where you want to be. REW usually gives a recommendation of what to put in for parametric EQ for the 50Hz peak

 

 

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[jmdesignz2]

So like I said before, I think you need to tune out the 50Hz peak. Your speakers probably are not that loud for 20-30Hz but the room resonance boosts the dB which is why you get a reasonably flat frequency response. Sometimes, the resonance here can make music sound muddy. I suspect it doesn't in your room and your main problem is from the broad 50Hz peak. But the 20-30Hz may be an area worth tweaking if fixing the 50Hz doesn't get you to where you want to be. REW usually gives a recommendation of what to put in for parametric EQ for the 50Hz peak

 

 

Sent from my iPhone using Computer Audiophile

 

I am waiting to hear back from GIK about some corner bass traps for 50Hz absorption.

Seems a pretty tall order to absorb almost 9dB at 50Hz?

 

My listening room is L shaped.

I only have two left corners I can use bass traps in due to the open corner top right doorway/hall and dining room bottom right.

[Ralf11]

does anyone have comments on the decay times in his waterfall plot?

[Kal Rubinson]

I am waiting to hear back from GIK about some corner bass traps for 50Hz absorption.

Seems a pretty tall order to absorb almost 9dB at 50Hz?

But it is a piece of cake for a PEQ.

[jmdesignz2]

But it is a piece of cake for a PEQ.

 

but I thought it was better to correct the room modes as much as possible first?

[wgscott]

but I thought it was better to correct the room modes as much as possible first?

 

Do what works. Try the parametric EQ and if it improves things, either be happy or see if you can reproduce the same thing with a stuffed grizzly bear mounted in the corner.

 

This is computer audio! Tune your system with equalization and room correction software without apology. It makes far more sense than tuning it with designer USB cables. Room treatments are great if you have a near-ideal room to begin with and no spouse or children or TV or windows or L-shaped spaces or ... a life.

[jmdesignz2]

Do what works. Try the parametric EQ and if it improves things, either be happy or see if you can reproduce the same thing with a stuffed grizzly bear mounted in the corner.

 

This is computer audio! Tune your system with equalization and room correction software without apology. It makes far more sense than tuning it with designer USB cables. Room treatments are great if you have a near-ideal room to begin with and no spouse or children or TV or windows or L-shaped spaces or ... a life.

 

I would but just cannot seem to get Dirac filter to work...sound only coming from one channel - left speaker

[wgscott]

I think this is the source of the problem:

 

[ATTACH=CONFIG]31111[/ATTACH]

 

For some reason what got installed as a kernel extension has one channel. Try re-installing it, or get Dirac to tell you how to fix it.

[Kal Rubinson]

but I thought it was better to correct the room modes as much as possible first?

 

So, is a physical correction of -9dB at 50Hz (and of appropriate Q) possible in your room?