How do you measure distortion?

[icor1031]

With mics like these? Or some other tool entirely?

And, What software?

Thanks!

http://parts.digikey.com/1/parts/853-microphone-cartridge-6mm-omni-wm-61a.html

[Face]

Re: How do you measure distortion?

OmniMic.

[relder]

Re: How do you measure distortion?

For distortion I've had the best results with SoundEasy. I wasn't as successful with HOLM with the same hardware.

Did that with a Behringer ECM8000 and either a UB802 preamp or M-audio USB sound card, can't remember which.

[icor1031]

Re: How do you measure distortion?

Yikes, that's some major $$.

I'll just rely on other's measurements.

[Face]

Re: How do you measure distortion?

You can also use Arta and a calibrated mic.

[icor1031]

Re: How do you measure distortion?

Hey mate.

Is it possible to get the mics I bought, calibrated?

You can also use Arta and a calibrated mic.

[donradick]

Re: How do you measure distortion?

Hey mate.

Is it possible to get the mics I bought, calibrated?

AFAIK, calibration costs about $40.
A new Dayton mike (Behringer EMM-6) from PE with calibration costs $40.

[icor1031]

Re: How do you measure distortion?

Three questions..

Where would I get it calibrated?
Can I have all 10 mics done for $40, or is it *gasp* $40 each?
Can I buy tools to calibrate myself, or is that expensive? $$

Thanks!

AFAIK, calibration costs about $40.
A new Dayton mike (Behringer EMM-6) from PE with calibration costs $40.

[relder]

Re: How do you measure distortion?

Three questions..

Where would I get it calibrated?
Can I have all 10 mics done for $40, or is it *gasp* $40 each?
Can I buy tools to calibrate myself, or is that expensive? $$

Thanks!

To calibrate a mic you minimally need a calibrated mic. Chicken/egg.

I got mine calibrated by Kim Girardin (PM me for email) in MN for $40 (including return shipment.) I'm not sure if he does volume discount, but the need for more than one calibrated mic is minimal.

[icor1031]

Re: How do you measure distortion?

Okay.. So, I buy one already calibrated mic for $40.
What software do I use, to apply that to the other mic?

Thanks!

To calibrate a mic you minimally need a calibrated mic. Chicken/egg.

I got mine calibrated by Kim Girardin (PM me for email) in MN for $40 (including return shipment.) I'm not sure if he does volume discount, but the need for more than one calibrated mic is minimal.

[charlielaub]

Re: How do you measure distortion?

1. Make a measurement with a source (like a speaker) using the calibrated mic. This is the "reference" measurement.
2. Make a careful measurement of the position in space of the reference mic.
3. Remove the reference mic.
4. Place another mic at the exact same position in space and do the exact same measurement with the "unknown".
5. Subtract the response of the reference from the response of the unknown - this is the frequency response difference.
6. Add the FR difference to the calibrated microphone's reference calibration (supplied by the manufacturer or the place that calibrated it) to generate a new reference curve for the unknown mic.

Repeat for the rest of your mics.

By the way, this has nothing to do with distortion measurements. Distortion is always cited in reference to the fundamental, so minor deviations are inconsequential. The main reason to calibrate a mic is to make possible accurate frequency response measurements.

-Charlie

[greywarden]

Re: How do you measure distortion?

I just bought one from Cross Spectrum... but the calibration file is waaaay different from a FRD file, so I'm just using a normal mic right now :rolleyes:

I'll put some effort into it this weekend.

[charlielaub]

Re: How do you measure distortion?

I use ARTA (STEPS) to measure driver distortion. ARTA is available in a free demo version that lets you do everything. It's not the creme de la creme as far as distortion measurements go, but its pretty darn good.

You can do a quickie distortion by processing an impulse (similar to what you would do when obtaining frequency response) or you can use the STEPS companion program to measure up to 5th order (IIRC) distortion.

-Charlie

[charlielaub]

Re: How do you measure distortion?

I just bought one from Cross Spectrum... but the calibration file is waaaay different from a FRD file, so I'm just using a normal mic right now :rolleyes:

I'll put some effort into it this weekend.

Open your .mic file in a text editor - you'll see that it is just a tabulation of frequency and deviation (deviation of the SPL from "flat" as measured by the mic). You can easily get this same info from FRD files by throwing away the phase information. The problem will be getting a sufficiently wide band source to get 20-20k (or wider) frequency response to compare to the reference. Might need to make multiple measurements in low and high parts of the spectrum.

-Charlie

[icor1031]

Re: How do you measure distortion?

..With what software?

1. Make a measurement with a source (like a speaker) using the calibrated mic. This is the "reference" measurement.
2. Make a careful measurement of the position in space of the reference mic.
3. Remove the reference mic.
4. Place another mic at the exact same position in space and do the exact same measurement with the "unknown".
5. Subtract the response of the reference from the response of the unknown - this is the frequency response difference.
6. Add the FR difference to the calibrated microphone's reference calibration (supplied by the manufacturer or the place that calibrated it) to generate a new reference curve for the unknown mic.

Repeat for the rest of your mics.