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Room Measurement Tutorial for Dummies Part 2

Krunok

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Here's a zipped .mdat for REW, JBL LSR 308 (original version) and MartinLogan reQuest electrostats, using minDSP OpenDRC-DI and AcourateDRC.

https://www.dropbox.com/sh/i3poj7mwoi0ezfp/AAD-jejRX1Edz4gwESwY4qxea?dl=0

Measured at 10 feet (listening position), mic aimed at phantom center.

1~6 JBL Left/Right/Both Speakers without DRC, L/R/Both with DRC
7~12 ML L/R/Both without DRC, raw L/R/Both with DRC

The DRC is "flat", which may not be to everyone's taste, and the files are 15 months old.
Good morning and thank you! :)

I'm looking at #11 - would that be right Martin Logan with DRC? What smoothing is used?
It looks excellent except for those few dips at 200, 450 and 1500Hz..
 

RayDunzl

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I'm looking at #11 - would that be right Martin Logan with DRC?
Yes.

What smoothing is used?
None. You choose the average you want to see.

Open the Overlays window and you can apply the same smoothing to all the measurements at once.
 

Krunok

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None. You choose the average you want to see.

Open the Overlays window and you can apply the same smoothing to all the measurements at once.
I remember reading somewhere that applying Var smoothing is recommended in REW before importing data to rePhase. Is that correct?

Btw, when Var smoothing is applied both, JBL and ML, are looking flat as hell! You obviously are not fan of raising the bass and rolling off the HF. :)
Which particular models are your speakers?

Btw, when you measure only one speaker wouldn't it make sense to point mike to that speaker instead to the center point between left and right speaker?

P.S. how comes the #10 and #11 curves are much flatter than #12, which has dip at 45Hz?
 
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RayDunzl

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I remember reading somewhere that applying Var smoothing is recommended in REW before importing data to rePhase. Is that correct?
rePhase is a manual correction tool. You decide what to adjust, and you can decide how to smooth the data you look at prior to wiggling the sliders to make a filter to "correct" it. To some degree, it's like juggling Jello. Fix this area break that other one.

Btw, when Var smoothing is applied both, JBL and ML, are looking flat as hell! You obviously are not fan of raising the bass and rolling off the HF.
My excuse would be that when critically listening, the SPL for the low end is in the "pretty flat" area of Fletcher Munson (80-100dB), so no boost is needed.

1538406636504.png


30 minutes of "normal loud" right now. Piano, electric bass, sax, and trumpet/flugelhorn:

1538411464961.png 1538411447966.png

At lower levels, the bass is still there (enough for my ear), so no boost is needed. I don't play much louder, so no adjustment neede there, either. Music typically already has plenty of roll-off in the highs. Note the slope to -50dB starting around 1kHz, above.

I have, of course, played around with it and tend to prefer no noticeable boost in the bass for well-recorded material. I'm not a headbanger or fan of EDM, I do like to differentiate between string and electric bass and kick drum, want the 5th string of a 5-string bass (31Hz) to be 'right there", and can appreciate the lowest notes of a piano (27.5Hz) presented with appropriate weight.

As for the high end, I'm consciously immune to many of those frequencies, but folks who aren't don't complain when they sit down here and listen. If they are just judging from a distance, then I can get a response like this:

"The house curve is to put back what a normal room will do, you correct to flat which sounds rubbish and then you add in the lf room gain and the hf dropoff ." - Rodney Gold (R.I.P.)

Ok, whatever.

Here's a "corrected" in-room RTA versus the raw left and right channels of a CD. My goal at the time (and still) being "reproduce the recording" (flat response). The black traces are "live" but not well synchronized in the software, so they don't line up (some delay occurs between the three instances of REW), so I mainly pay attention to the peaks (red). Since the in-room is the sum of the L + R, the peaks won't quite line up either, when playing stereo, but can be very close with single speaker or mono (or mono-ized) two-speaker source.

1538406368195.png

Which particular models are your speakers?
JBL LSR 308
Martin Logan reQuest

(more stuff listed in my sig, below)
 
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Krunok

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rePhase is a manual correction tool. You decide what to adjust, and you can decide how to smooth the data you look at prior to wiggling the sliders to make a filter to "correct" it. To some degree, it's like juggling Jello. Fix this area break that other one.



My excuse would be that when critically listening, the SPL for the low end is in the "pretty flat" area of Fletcher Munson (80-100dB), so no boost is needed.

View attachment 16076

30 minutes of "normal loud" right now. Piano, electric bass, sax, and trumpet/flugelhorn:

View attachment 16080 View attachment 16079

At lower levels, the bass is still there (enough for my ear), so no boost is needed. I don't play much louder, so no adjustment neede there, either. Music typically already has plenty of roll-off in the highs. Note the slope to -50dB starting around 1kHz, above.

I have, of course, played around with it and tend to prefer no noticeable boost in the bass for well-recorded material. I'm not a headbanger or fan of EDM, I do like to differentiate between string and electric bass and kick drum, want the 5th string of a 5-string bass (31Hz) to be 'right there", and can appreciate the lowest notes of a piano (27.5Hz) presented with appropriate weight.

As for the high end, I'm consciously immune to many of those frequencies, but folks who aren't don't complain when they sit down here and listen. If they are just judging from a distance, then I can get a response like this:

"The house curve is to put back what a normal room will do, you correct to flat which sounds rubbish and then you add in the lf room gain and the hf dropoff ." - Rodney Gold (R.I.P.)

Ok, whatever.

Here's a "corrected" in-room RTA versus the raw left and right channels of a CD. My goal at the time (and still) being "reproduce the recording" (flat response). The black traces are "live" but not well synchronized in the software, so they don't line up (some delay occurs between the three instances of REW), so I mainly pay attention to the peaks (red). Since the in-room is the sum of the L + R, the peaks won't quite line up either, when playing stereo, but can be very close with single speaker or mono (or mono-ized) two-speaker source.

View attachment 16075



JBL LSR 308
Martin Logan reQuest

(more stuff listed in my sig, below)
Both of those speakers are very fine products. In my eyes you have chosen them carefully and setup them skilfully - cudos to that.
 

c1ferrari

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I haven't used REW for awhile...is V5.20 Beta 3 pretty stable? I have V5.18 at this time.
 

Manesch

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how would i time align a subwoofer where i use high level in/outs? only by positioning or can i set a delay on lower freq?
 

amirm

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You can just use a tape measure and compare its distance to the distance from your main speakers and dial in the delay that way (about 1 millisecond for every foot). Note that changing the delay will substantially change the room modes in the room so you need to measure the frequency response and see if the correct delay makes things worse or better.
 

Manesch

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You can just use a tape measure and compare its distance to the distance from your main speakers and dial in the delay that way (about 1 millisecond for every foot). Note that changing the delay will substantially change the room modes in the room so you need to measure the frequency response and see if the correct delay makes things worse or better.
Thank you for your answer but my problem is that i use a stereo amp so i go to the "high level" of the sub from the amp and from the "high level" out i go to the mains. Wouldnt setting a delay just delay everything and i would still have the same problem?
 
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how would i time align a subwoofer where i use high level in/outs? only by positioning or can i set a delay on lower freq?
i have kinda the same problem right now i use a Scarlet 2i2 go from it to my Jbl lsr 310s sub and from the sub to the mains and wouldnt setting a delay in example "Equalizer APO" just delay everything so i would have the same outcome?
 
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You can just use a tape measure and compare its distance to the distance from your main speakers and dial in the delay that way (about 1 millisecond for every foot). Note that changing the delay will substantially change the room modes in the room so you need to measure the frequency response and see if the correct delay makes things worse or better.
how would i measure the distance from a down firing sub? normally you would measure from the cone but i dont get it how to do it with a down firing sub
 

Sal1950

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how would i measure the distance from a down firing sub? normally you would measure from the cone but i dont get it how to do it with a down firing sub
I measure mine from the center of the top of the box, don't think the slight additon from the angle is something to worry about.
 

amirm

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I measure mine from the center of the top of the box, don't think the slight additon from the angle is something to worry about.
Correct. The wavelengths here are pretty large so I would not worry about a few inches here and there. You are likely to move your body more than that anyway.
 
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I know you have a lot on your plate, but please add me to the list of folks anxiously awaiting the arrival of the third installment!
 
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I'm sure AP is fantastic, but I much prefer the price of REW!

If Amir has lost interest or hasn't the time to complete part 3, can other members add a tutorial or links about how best to use REW and perhaps suggest target curves for various listening situations?
 

Sal1950

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I did begin to read it, but stopped as the emphasis seemed to be on Windows/HT multi-channel. I'll give it another shot -- Thanks!
 
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