Testing DIY Eq's

I know this is a simple question. Can you describe your method of testing the DIY eq's you build. To tests how they perform. What equipment is used and how to compare to what is expected of the unit.

Thanks in advance,

Bonsaimaster

There are plenty of software where you can measure things like frequency response (and curves), THD, SNR, etc…

And your ears of course 

I generally first measure the frequency response with the controls set to flat to make sure the response if flat under these conditions. Then I measure the response at each boost and cut frequency with maximum boost and also with maximum cut to make sure the boost/cut frequencies are correct and the the actual amount of boost/cut is correct. If all these are correct then the EQ is basically correct. I use a Lindos  Minisonic MS10 audio test set for the measurements:

http://www.lindos.co.uk/test_and_measurement

Cheers

Ian

I like using Room EQ Wizard as a free option to use with your Audio Interface for frequency measurements.

Humner said:

I like using Room EQ Wizard as a free option to use with your Audio Interface for frequency measurements.

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Do you use the pink noise source for that?

Cheers

Ian

ruffrecords said:

Do you use the pink noise source for that?

Cheers

Ian

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REW has sinewaves. Using pink for filters and EQ's gives wrong results.

I'm using my Reaper (DAW).It has FFT signal generator(Flat response 20Hz to 20kHz).Then adding insert point to add hardware eq to DAW.And then adding analyzer plugin.It's working for me.Not best way maybe but best for me.

ForthMonkey said:

I'm using my Reaper (DAW).It has FFT signal generator(Flat response 20Hz to 20kHz).Then adding insert point to add hardware eq to DAW.And then adding analyzer plugin.It's working for me.Not best way maybe but best for me.

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FFT is good enough for displaying basic "what goes on", but is generally not as accurate as using sine sweep. Now FFT allows (almost) real-time analysis of any signal.

abbey road d enfer said:

FFT is good enough for displaying basic "what goes on", but is generally not as accurate as using sine sweep. Now FFT allows (almost) real-time analysis of any signal.

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Yes,FFT easy to use for real time.I'm not master about analyzing.Best and easy way is this for me.I've built API 550,Harrison 32C and Pultec eqs and tried this method.No issue.Even i'm using this method to measure my new summing mixer and mic preamps.

abbey road d enfer said:

REW has sinewaves. Using pink for filters and EQ's gives wrong results.

Click to expand...

Quite right -I forgot about it's frequency response function.

Cheers

Ian

ForthMonkey said:

Yes,FFT easy to use for real time.I'm not master about analyzing.

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For someone like me, who was born before FFT was available practically, that is a quite disturbing affirmation. FFT is a trapped course. It is very easy to get erroneous results, particularly when it comes to spectral analysis (filter response or noise).

Best and easy way is this for me.I've built API 550,Harrison 32C and Pultec eqs and tried this method.No issue.Even i'm using this method to measure my new summing mixer and mic preamps.

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No big issue as long as you don't have to document precisely your performance measurements. Also if you want to fine-tune a circuit, wrong windowing can result in over optimistic results, or, on the contrary induce you to believe you have failed.

<Also if you want to fine-tune a circuit, wrong windowing can result in over optimistic results, or, on the contrary induce you to believe you have failed.>

That is a very interesting observation. Makes me interested in buying an analog distortion analyzer.

I use visual analyzer, free software, I can use noise for quick test or  a sweep for more precise curves.

FuzzMeasure (Mac only)

http://supermegaultragroovy.com/products/fuzzmeasure/

Fun and easy to use! Make sure you use a decent audio interface