Measuring EQ Response of Console

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man-bot

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Dec 20, 2008
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I wanted to start digging into my console a bit more to see if it is really responding the way it is supposed to.  Ultimately its going 40 years and I imagine some components have drifted significantly - so what may be labelled as a fixed frequency (lets say 300hz) on the EQ is really boosting / cutting at something else.

Is there software available that I could use to properly analyze and measure the EQ performance on my desk?

Mike
 
ruffrecords recently posted a link to a free software called ´ roomeqwizard´, which in spite of it´s name also seems to do what you want...
(and that I will also look into as soon as I updated my OS).
Are you talking about your seriesII, which I admired on homerecording-forum,  :p
 
man-bot said:
I wanted to start digging into my console a bit more to see if it is really responding the way it is supposed to.  Ultimately its going 40 years and I imagine some components have drifted significantly - so what may be labelled as a fixed frequency (lets say 300hz) on the EQ is really boosting / cutting at something else.

Is there software available that I could use to properly analyze and measure the EQ performance on my desk?

Mike
You should be able to confirm center frequency empirically pretty easily by commanding full boost and looking for the the frequency peak with a swept oscillator input.  Somewhat less easy with shelving EQ.

Another parameter not widely measured or investigated is Q or bandwidth of peaking EQ sections... There is not even agreement about how to specify that Q so good luck measuring it...

In a console you have the luxury of multiple channels so you can measure them all and look for outliers as evidence of faulty operation.

JR
 
OK - I'll give it a shot and see what I can do.

How do you typically set it up?  I have looked at it before but if I recall I had a hard time getting it set up correctly.

Mike
 
Assuming you have a half-decent audio interface (with proper ASIO) drivers, it's real easy.

The basic idea is, you have an (analog) loop-back connection, from an output back into an input - that's to have a reference by which to compensate for whatever non-linearities the analog circuitry, the ADC and the DAC might impose. And then you have your "test signal output", and your "device-under-test input". All those are selectable in the REW settings.

PS: Google is your friend ;)
https://www.roomeqwizard.com/help/help_en-GB/html/gettingstarted.html#top
 
Another free option is Arta

http://www.artalabs.hr/

it has a real time frequency sweep. twist an eq knob and watch the sweep line move with it. Pretty cool. Sound card in and out. Takes a second to figure it out but worth it.

 
A ghetto quick way i do is feed it white noise then check result with a spectrum analyser plugin.

Another very usefull tool that i use to "see" an analog eq response in action is a plugin by Waves called Q-clone. It is basicaly an impulse response plugin made to "clone" your analog eq settings.  You set "q-capture" on a track looped through your hardware and then you can visualy see the effect of your knob twisting on the eq.  Very usefull to see eq curves.
 
diggy fresh said:
A ghetto quick way i do is feed it white noise then check result with a spectrum analyser plugin.
Which is exactly what I do with REW. It has a sig gen that can generate white noise and a built in real time analyser so you basically get the frequency response plotted on the screen. You can watch it change as you alter the EQ, gain etc.

Cheers

Ian
 
Ok - got REW going... wow!  Pretty awesome tool!  Looks like (from the little I have measured) some channels are bang on still - but finding some wonky EQ curves already...

Thanks for the help!  Pretty happy!
 
man-bot said:
Ok - got REW going... wow!  Pretty awesome tool!  Looks like (from the little I have measured) some channels are bang on still - but finding some wonky EQ curves already...

Thanks for the help!  Pretty happy!

Excellent. It is also good for measuring noise and finding spurious mains hum spikes.

Cheers

Ian
 
Hi Guys,
Can i use REW for Capsule Frequency Response measurements?
Sorry if this is a bit off topic but i would really like to learn this.

Best Regards,
Iwan
 
Up to a point, sure, but it WOULD really help if you had a flat (ie. calibrated, measurement) mic as a "reference" (which would show you the response of the speaker itself), to compare your mic-under-test with.
 
Thanks Khron,

At the moment i'am looking for a affordable measurement mic (analog or usb?), any suggestions are welcome.
 

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