# Advice For Measurements



## Jay Compton (Sep 8, 2016)

I am wanting to start from scratch with measurements so I can use the help. I have a uncalibrated mic but have the downloaded calibration file. I am using the ECM8000 mic with the M Audio pre. I would like some help with how do I measure my room? Both channels together or one at a time? Measure from the listening position with the mic pointed straight up or pointed at the speakers? The mic should be at what height? etc, etc.

Also would like some advice as to the best setup for using the REW program...


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## Wayne A. Pflughaupt (Apr 13, 2006)

Measure one speaker at a time, from the listening position with the mic at ear level. If you downloaded our generic calibration file for the ECM8000, it’s a 0-degree file, so the mic should be pointing at the speaker.

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Ok Wayne thanks brother...


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## Pio2001 (Jul 6, 2016)

Hi,
Perform several measurements from several locations, everywhere your ears are supposed to move around, even if it is 20 cm apart from the central one.

Seeing how different they are will save you the time wasted to accurately correct a 3 dB dip at 128 Hz exactly, while there is a 2 dB peak at that same frequency if you take the same measurement just 40 cm away...


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## Jay Compton (Sep 8, 2016)

Pio2001 said:


> Hi,
> Perform several measurements from several locations, everywhere your ears are supposed to move around, even if it is 20 cm apart from the central one.
> 
> Seeing how different they are will save you the time wasted to accurately correct a 3 dB dip at 128 Hz exactly, while there is a 2 dB peak at that same frequency if you take the same measurement just 40 cm away...


Not real sure what you mean by saving time, I only listen from the listening position. I realize my head will move a little but I usually sit still during a session.


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## Pio2001 (Jul 6, 2016)

I mean that to get a perfectly smooth curve is very difficult and time consuming. And in fact, it is completely unuseful.
Comparing different measurements between them allows to visualize directly what, in the curve, is a characteristic of your listening position, and thus is worth correcting, and what is an accidental artifact of the measurement, thus not worth correcting.


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## Jay Compton (Sep 8, 2016)

Pio2001 said:


> I mean that to get a perfectly smooth curve is very difficult and time consuming. And in fact, it is completely unuseful.
> Comparing different measurements between them allows to visualize directly what, in the curve, is a characteristic of your listening position, and thus is worth correcting, and what is an accidental artifact of the measurement, thus not worth correcting.


Ok the problem I see with that is, I can get the mic to the exact same place every time based in measurements. Doing that in multiple positions will next to impossible and a huge time consuming task!!!


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## Jay Compton (Sep 8, 2016)

Another question, when measuring just the speakers from 1 meter do I measure the 1 meter distance from the driver or the mouth of the horn in my case?


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## Jay Compton (Sep 8, 2016)

Wayne A. Pflughaupt said:


> Measure one speaker at a time, from the listening position with the mic at ear level. If you downloaded our generic calibration file for the ECM8000, it’s a 0-degree file, so the mic should be pointing at the speaker.
> 
> Regards,
> Wayne


Wayne, so I should point the mic at each speaker for this not down the center of the two???


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## Wayne A. Pflughaupt (Apr 13, 2006)

You can do it either way, shouldn’t make any impact on the measurement.

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Wayne A. Pflughaupt said:


> You can do it either way, shouldn’t make any impact on the measurement.
> 
> Regards,
> Wayne


Ok thanks, now about my other question. Should measure the one meter from the driver or mouth of the horn in my case?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Your original post said you wanted a room measurement? That’s done with the mic at the listening position.

Regards,
Wayne A. Pflughaupt


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## Jay Compton (Sep 8, 2016)

Wayne A. Pflughaupt said:


> Your original post said you wanted a room measurement? That’s done with the mic at the listening position.
> 
> Regards,
> Wayne A. Pflughaupt


You are correct Wayne but, shouldn't I want to know what the speakers are doing alone also? Would that help when I eq the room?


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## Wayne A. Pflughaupt (Apr 13, 2006)

If you want to know what the speakers are doing apart from the room, you need to do a gated measurement, or else take measurements outdoors. That may or may not cull information you’d want to use for EQing in-room.

Really, ”room EQ” is a misnomer. We’re more precisely equalizing the effects (changes in frequency response) that the room has inflicted on the speaker. And that’s really only below ~3-500 Hz. Above that point we’re primarily equalizing the response of the speaker itself (at least in a reasonably dampened room).

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Ok hopefully I remembered how to do this? Here are the newish measurements of my room from the LP. So how do they look???


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## Jay Compton (Sep 8, 2016)

Well how do they look???


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## Wayne A. Pflughaupt (Apr 13, 2006)

Sorry ‘bout that, I typically don’t want to take the time to deal with .mdat files. 

They look fine overall, but I’m sure things would sound much better if the broad peak just < 3 kHz were tamed. Bass response < 200 Hz is also pretty poor, but that’s typical for main-channel speakers. That’s why we use subwoofers, optimally placed and properly equalized.

Regards,
Wayne A. Pflughaupt


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## Jay Compton (Sep 8, 2016)

Wayne A. Pflughaupt said:


> Sorry ‘bout that, I typically don’t want to take the time to deal with .mdat files.
> 
> They look fine overall, but I’m sure things would sound much better if the broad peak just < 3 kHz were tamed. Bass response < 200 Hz is also pretty poor, but that’s typical for main-channel speakers. That’s why we use subwoofers, optimally placed and properly equalized.
> 
> ...


Wayne thanks for the imput, now here there are with some eq???


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## Wayne A. Pflughaupt (Apr 13, 2006)

The right channel looks worse after EQ – the broad trough between 300 and 2800 Hz is deeper, which makes the 2800 peak even worse than before. 

The left looks overall about the same. 

However, with both left and right, the bass peak at 40 Hz has been reduced to the point that things probably sound worse, bass-speaking.

Also, with both EQ’d graphs the overall level below 10 kHz dropped as much as 4 dB in places. Wholesale, across-the-board level adjustments shouldn’t happen with proper EQ. Levels should only change in specific places where EQ has been applied

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Ok Wayne,

Made some adjustments and ended up here..


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## Wayne A. Pflughaupt (Apr 13, 2006)

Couldn’t hurt to tame the broad peak at 2.5 kHz some more.

BTW, don’t know if this was mentioned, but above 300 Hz filters for both channels should be matching, not individual.

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Wayne,
I am curious as to why above 300hz both channels should be the same? What if your two channels differ above 300hz would you still use the same adjustments for both?


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## Wayne A. Pflughaupt (Apr 13, 2006)

It’s because it whacks out the imaging. Any equalizer introduces phase changes at the frequencies affected by the filter – that’s how equalization is accomplished. So if you introduce a change in phase in a certain frequency range in one speaker, but the other, you’ll notice that the imaging is affected.

I typically use pink noise in both channels above 300Hz, and EQ both speakers with a single set of filters.

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Ok Wayne,
Thanks that makes perfect sense, I will be going back over the settings this weekend!!!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Probably should have mentioned, you can use the RTA feature with pink noise and adjust the equalizer and see the results instantly on the screen in real time. It’s faster than “measure – EQ – measure – EQ” over and over, but it’s continual noise instead of a quick sweep. So you’ll probably want ear plugs and send the wife to the mall. 

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Wayne,
Are you meaning for above 300hz using the RTA?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Not necessarily above 300 Hz, just an alternative in general to using the sine wave sweep.

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Ok buddy thanks, I will give it a try...


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## Jay Compton (Sep 8, 2016)

Wayne A. Pflughaupt said:


> Not necessarily above 300 Hz, just an alternative in general to using the sine wave sweep.
> 
> Regards,
> Wayne


Wayne,
I did some adjusting today and wanted to ask you, what does it mean when after measuring the left and right channels independently they both line up perfectly on top each other??? From about 100hz to 10,000hz they are one??? Is this correct or even possible???


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## Jay Compton (Sep 8, 2016)

Ok Wayne,
This is where I ended up after making some adjustments today...


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## Wayne A. Pflughaupt (Apr 13, 2006)

Jay Compton said:


> Wayne,
> I did some adjusting today and wanted to ask you, what does it mean when after measuring the left and right channels independently they both line up perfectly on top each other??? From about 100hz to 10,000hz they are one??? Is this correct or even possible???


It would be pretty unusual, but I suppose it’s possible if the room is perfectly symmetrical, and course smoothing was used on the graph (e.g. 1-octave).




Jay Compton said:


> Ok Wayne,
> This is where I ended up after making some adjustments today...


Looks pretty good! :T

Regards, 
Wayne


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## Jay Compton (Sep 8, 2016)

Wayne,
Thanks so much for pointing out that trough, this sounds so much better!!!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Smoothed response usually does. :T

Regards, 
Wayne


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