# Testing an audio compressor

**URL:** <https://forum.quantasylum.com/t/testing-an-audio-compressor/2231>\
**Category:** Uncategorized\
**Created:** [March 1, 2026, 6:43pm UTC](https://forum.quantasylum.com/t/testing-an-audio-compressor/2231 "2026-03-01T18:43:05Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![skipburrows](https://avatars.discourse-cdn.com/v4/letter/s/8797f3/32.png) [@skipburrows](https://forum.quantasylum.com/u/skipburrows)\
**Post date:** [March 1, 2026, 6:43pm UTC](https://forum.quantasylum.com/t/testing-an-audio-compressor/2231/1 "2026-03-01T18:43:05Z")

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Hey all…

I’m currently in development of a new audio compressor. I’ve been tuning the attack and release time mostly by ear. However now that I think it’s sounding nice I’d really like to dig in and try and get the actual time values of the attack and release times. Not really sure how to approach this using the q403. Any advice would be extremely helpful…..

Cheers to all and thanks..

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**Author:** ![Sven](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@Sven](https://forum.quantasylum.com/u/Sven)\
**Post date:** [March 5, 2026, 4:34pm UTC](https://forum.quantasylum.com/t/testing-an-audio-compressor/2231/2 "2026-03-05T16:34:38Z")

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Interested too at this question and possible answer by Matt. Löng time ago I was also evaluating capacitor values for a vintage compressor regarding dacay time switchable settings. What I used was a soundcard program which could create bursts. The input and output was measured with a storage oscilloscope. This worked suffient.

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**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://forum.quantasylum.com/u/matt)\
**Post date:** [March 5, 2026, 11:46pm UTC](https://forum.quantasylum.com/t/testing-an-audio-compressor/2231/3 "2026-03-05T23:46:05Z")

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Hi @skipburrows and @Sven,

The link below is a good starting point. Some other suggestions from the algorithm as in 2) and 3)

1. [Measuring Compressor Response - #4 by amp-haus](https://forum.quantasylum.com/t/measuring-compressor-response/73/4)

2. [Pulsating oscillator - #18 by matt](https://forum.quantasylum.com/t/pulsating-oscillator/1875/18)

3. [The issues with QA403 and 1.183 in terms of usage - #18 by matt](https://forum.quantasylum.com/t/the-issues-with-qa403-and-1-183-in-terms-of-usage/981/18)

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**Author:** ![daleshirk](https://avatars.discourse-cdn.com/v4/letter/d/e9bcb4/32.png) [@daleshirk](https://forum.quantasylum.com/u/daleshirk)\
**Post date:** [March 7, 2026, 3:33pm UTC](https://forum.quantasylum.com/t/testing-an-audio-compressor/2231/4 "2026-03-07T15:33:12Z")

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Skip,

The tool you want is here:

 ![image](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/2/2624ba425bed66fa6c19abf151e8194c7aded6e8.png)

Set the transition times to zero. I like a half second pre-conditioning at lower level, then maybe a half second at the higher level (+20dB), then a couple seconds back at the lower level again, because release times are always longer than attack times. Make sure each duration is long enough that the gain stabilizes at the final value before the next transition.

“De-skew the input” offsets the time axis in case there is a delay through the processor. It’s common to see a spike in the reported gain right at the transition if the IN/OUT are not exactly synchronized. Gain is only measured once per cycle, so use a high frequency for high time resolution.

As in all things measurement, you have to know ahead of time what the measured result will be to correctly set up your measurement, so expect a series of successive approximations, especially if you want a publishable result.

Dale