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Room correction - Linux

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Lilith

Lilith

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I think I'm comparing apples and oranges. At the moment I try to plot the IR from REW next to the Filter, but what is described in the DRC manual is the uncorrected IR from REW vs some corrected IR. (?)
 

digitalfrost

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Why don't you just drag the files into REW?

1653849247215.png


Red measurement,
Green correction,
blue both.
 
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Lilith

Lilith

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Why don't you just drag the files into REW?

View attachment 209693

Red measurement,
Green correction,
blue both.
Oh man.... I tried loading the pcm file, but this looks strange. The wav file that I use for the convolver looks like this. The resolution is much higher in your plot.

1VNRs0U.png

Left and right channel. Did you cut it below 20 Hz or is just not shown?
 
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Lilith

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and with the measurements:

LNQ10fg.png
 

digitalfrost

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Our Limits are different. Press the Limits button. Mine are:

1653852644561.png


Or simply choose Fit to data. As for smoothing, I chose Var smoothing. Press control in the All SPL tab and you can change the smoothing for all graphs at the same time. There you can also align SPL to get them to overlap.
 
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Lilith

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The filter is not smoothed in my case. Your green curve (which is also the filter) is much higher resolved. Is there a setting in Drc to increase the resolution?

I think it's cause I used the ERB scale.
 
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Lilith

Lilith

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I tried also the minimal, normal and insane filter. Green is the psychoacoustic filter (erb), red is normal and blue is insane, orange is minimal. minimal seems to be a good compromise by eye.

YbNvNbd.png
 
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Lilith

Lilith

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Is it possbile to restrict the correction to let's say < 300 Hz only?
 
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Lilith

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Both the configurations files and the target curves affect how it will sound in the end. It's definitely worth it to tune both. I would start with the target curve because it is much easier.
Note that due to frequency dependend windowing the correction strength is also related to the window length so it makes little sense to compare target curves without knowing the other parameters. Still I will attach mine so you can try it.

The easiest way remove content below a certain frequency is with the target curve. Here you can see I've set a subsonic filter at 30hz.

Code:
0 -40.0
28 -20.0
29 2.49
35 2.49
41 2.47
47 2.46
53 2.43
59 2.4
64 2.35
70 2.29
76 2.23
82 2.14
88 2.05
94 1.95
100 1.84
105 1.72
111 1.6
117 1.48
123 1.37
129 1.25
135 1.14
141 1.04
147 0.94
152 0.85
158 0.77
164 0.69
170 0.63
176 0.56
182 0.51
188 0.46
193 0.42
199 0.38
205 0.34
211 0.31
217 0.28
223 0.26
229 0.23
234 0.21
240 0.19
480 0.0
20000 -7.5
22000 -40.0
24000 -100.0

This is for 48khz, adjust accordingly. Also, take a look at the peak limiting settings especially PLStartFreq and and PLMaxGain to influence how much boost you will get in the bass.

The simplest way to make a target curve yourself is to start thinking in db/oct and adjusting the tilt in 0.1db increments - this is easily audible over the whole frequency range. I would wager you will end up with a tilt between 0.67-1.1db/oct.
My curve is a bit more elaborate with a configurable bass boost and as you can see I use a knee at 480hz for the high frequency tilt.

If you want less correction for the high frequencies, instead of simply making a hard cut by changing the *EndFreq parameters, you can make MPUpperWindow and RTUpperWindow smaller. Be aware that you might have to turn down EPUpperWindow as well. I like to use much less excess phase correction than the rest because too much will collapse the soundstage depth (I use 5 cycles).
Or you can play with the window exponents as layed out in the manual.

View attachment 180138
Doesn't this sound muffled?
 

ernestcarl

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I do not use DRC, but I agree that less correction should be applied to monitors the higher in frequency one goes — esp. if they already are calibrated and designed to be “flat”. I am wary of the idea of having to compensate for those comb filter like waviness above 1 kHz, for example — both magnitude and phase. In Genelec’s room calibration guides, they also do not recommend detailed “room correction” higher up (including the midrange — a little bit is fine, sure, but the expectation is very limited correction should be applied to their “flat” studio monitors). Rather adjustments should be more generally about tone control.
 

digitalfrost

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Doesn't this sound muffled?
Not for me. Note that this is not a steady state curve, but it has to be taken into account together with the settings and you can see from my measurements that the corrected curve in the high frequencies is nowhere near -7dB.

I do not use DRC, but I agree that less correction should be applied to monitors the higher in frequency one goes — esp. if they already are calibrated and designed to be “flat”. I am wary of the idea of having to compensate for those comb filter like waviness above 1 kHz, for example — both magnitude and phase. In Genelec’s room calibration guides, they also do not recommend detailed “room correction” higher up (including the midrange — a little bit is fine, sure, but the expectation is very limited correction should be applied to their “flat” studio monitors). Rather adjustments should be more generally about tone control.
DRC is using frequency dependend windowing just like and good room correction.

 
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ernestcarl

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DRC is using frequency dependend windowing just like and good room correction.

While I’m aware of that, even intelligent windowing does nor replace understanding of the actual acoustics reasoning behind the existence of those comb filter like undulations in the graphs and whether they should be even “corrected”.
 
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Lilith

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While I’m aware of that, even intelligent windowing does nor replace understanding of the actual acoustics reasoning behind the existence of those comb filter like undulations in the graphs and whether they should be even “corrected”.
I think it's not possible to only correct up to 1000 Hz, right? I didn't find something in the manual of drc-fir
 

ernestcarl

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I think it's not possible to only correct up to 1000 Hz, right? I didn't find something in the manual of drc-fir

Maybe @fluid can chime in how to do this… there are also a lot more experienced DRC-FIR users over at DIY audio forum so you could try asking there as well.
 

ernestcarl

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Just a little bit of an old example back when I was experimenting with it the "Designer" version of the software:

1654036160073.png


Simple default ERB/psychoacoustic filtering should not replace the understanding of the system calibrator that these monitors essentially anechoically flat esp. for use at ~1m or less in a treated room. While I appreciate the automated phase correction of the xo (using single-point, but filtered/windowed, sweep technique), I would have preferred it completely left everything (minor wavy corrections) above 700 Hz out.

Now, I know the "minimal" profile setting is better in this regard... but I prefer the ability to completely cut off any and all micro-detailed corrections above a certain point. If anyone knows if there's a way to do this manually by adjusting certain the parameters, the information would be appreciated.
 

dasdoing

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the correction windows are totaly editable. So you can define them to go to 1000Hz only by changing the (xx)EndFreq variables. Now the software was not designed for this. you shorten the window it's geometry will be shortened instead of cut off. meaning the software will treat 1000Hz like a treble, and so on. adjusting WindowExponents and UpperWindows will be necessary
 

ernestcarl

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the correction windows are totaly editable. So you can define them to go to 1000Hz only by changing the (xx)EndFreq variables. Now the software was not designed for this. you shorten the window it's geometry will be shortened instead of cut off. meaning the software will treat 1000Hz like a treble, and so on. adjusting WindowExponents and UpperWindows will be necessary

Thank you. Can you just clarify what it would do with the 2 kHz LR4 xo of the monitors if adjusted the way you mentioned? Would it also leave that transition area "un-linearized"?
 

dasdoing

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Thank you. Can you just clarify what it would do with the 2 kHz LR4 xo of the monitors if adjusted the way you mentioned? Would it also leave that transition area "un-linearized"?

If you only make MPEndFreq lower the phase will still be corrected full range in the EP step iianm.
It is also possible to correct phase only by manipulating PLMaxGain, though I am not sure anymore what value that would be. The software is so complex, you don't use it for 6 months you have to realearn it every time lol
 

ernestcarl

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If you only make MPEndFreq lower the phase will still be corrected full range in the EP step iianm.
It is also possible to correct phase only by manipulating PLMaxGain, though I am not sure anymore what value that would be. The software is so complex, you don't use it for 6 months you have to realearn it every time lol

Eh, I think I'd rather just use the Neumann's MA-1 or do manual corrections with rePhase and REW. I can work with scripts, but find it way easier to use (and remember how to use) certain software with more developed GUI.
 

dasdoing

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Eh, I think I'd rather just use the Neumann's MA-1 or do manual corrections with rePhase and REW. I can work with scripts, but find it way easier to use (and remember how to use) certain software with more developed GUI.

yea, it does suck. actually Denis once on the mailing list said that he doesn't want it to be useable to the average user.
Acourate is the best software, as you can do anything DRC (and all others) does easily and much more.
 
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