How to measure driver distortion?

[goldyrathore]

Hi,

I would like to know whether it is possible to measure driver distortion using a mic and a PC? If yes, can anyone suggest me some freeware tools? I intend to measure distortion for some woofers and midranges.

Thanks in advance,
Goldy

[MarkMcK]

CY referenced this software in another thread. If I could remember the thread I would just send you to it, but since I can't here is the URL:

http://audio.rightmark.org/download.shtml

You can measure distortion using a microphone with less distortion than the device you are testing. You can measure distortion without destroying the device you are testing if you are careful.

The software is the easy part. Setting references, calibrating the test set up, and protecting your ears from the SPL are all the difficult parts.

Best to have a very good reason for measuring distortion before going to all the work to be able to measure distortion accurately.

Good designing and good building,

Mark

[JMB]

Hi all,

I may be wrong but unless they updated this software since last year, you can't yet measure driver distortion with this. I think it is currently only capable of measuring sound cards. It may be a future goal for the authors as some of the options suggest it.

Jay

[scott wurcer]

Originally posted by goldyrathore
Hi,

I would like to know whether it is possible to measure driver distortion using a mic and a PC? If yes, can anyone suggest me some freeware tools? I intend to measure distortion for some woofers and midranges.

Thanks in advance,
Goldy

Actually you could probably do alright with something like Cooledit and one of those cheap Panasonic capsules. Those mics are actually pretty good, but if you think about it you can get yourself in the far field in a big space where the mic (and your ears) only see a lower level. A simple frequency sweep could be used to roughly calibrate. There are still several sources of error but at highish levels you are looking at percents of distortion from most drivers.

Thought number two, has anyone ever tried this? Put the driver under test several feet away. Right next to the mic put a small good driver and adjust the amplitude and phase of the same frequency to null the fundamental. Now the mic sees no sound pressure at the fundamental and only the harmonics from the DUT are picked up.