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Advice For Measurements

5K views 32 replies 3 participants last post by  Wayne A. Pflughaupt 
#1 ·
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...
 
#4 ·
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...
 
#6 ·
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.
 
#14 ·

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

 
#17 ·

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
 
#19 ·

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

 
#23 ·

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

 
#25 ·

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

 
#29 ·
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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