Chris Capel's Dynamic Compressor

I used to work with Chris at his Dad’s company. And I feel compelled to voice that even beyond his technical genius, Chris was one of the kindest, entertaining and complex people I have ever had the privilege of meeting. He was a very gifted individual.

Just started to use this marvelous compressor. I just have one problem, the final word always seems to be louder that the rest of the announcement after I have used the compressor. Has anyone got any ideas? (sends a silent prayer that it is not a blindingly obvious solution).

Using Audacity 2.0.3

Which version of Chris’s compressor are you using?
(if you open the “compress.ny” file in a text editor it should have the version number at around line 30)

Got my attention. I collected the versions before the site when dark, and I’m using 1.2.6 as current. If you have it loaded, it will also announce the version in the Effects list.

I’m using it for the exact reason it was designed, to listen in the car. Or in the truck in my case (Lori, my lorry).

I host a “how-to” podcast about podcasting

Just go back to the head of the web site?


A workaround : Copy a couple of seconds of sound from your track, (a bit with average volume values), then add (paste) it to the start and end of your track, apply Chris’s compressor, then delete the bits you added on.[b]Copy_and_paste_a_section_of_audio[/b]

Thanks, Trebor. Hmm, that page seems to be completely orphaned so is not in the released Manual that we should normally link to in replies. And I see from Bill’s comments that there are issues with the images and explanations. And no explanation of what crossfading is.

Should we tweak that and add it to this Tutorial Audacity Manual ?

Or expand it as a standalone Tutorial to include other methods of repairing takes such as Steve’s EZ-Patch ?

Or a brief FAQ pointing to a Wiki page on repairing takes without re-recording?

Or just add a little to Audacity Manual ? I think that is probably already as long as it can take, actually.


I was just trying to include a link to a page on copying and pasting in Audacity, just in case the OP was a novice.
If there is a more appropriate page on copying and pasting in the Audacity manual feel free to change my link.

Sure. :slight_smile:

As I explained, there isn’t :frowning:

We need to decide what if anything to do about that.


I don’t use Chris’s Compressor, but would adjusting the “Release speed” help?


Toning down the hardness often helps with this.

Version 1.1 doesn’t have a “hardness” setting. Is the “Compress ratio” in 1.1 similar to “hardness” in 1.2.6?


The early versions of Chris’s Compressor had problems with leading and/or trailing words. The “Look-Ahead” system didn’t understand beginnings and endings. He was aware of this problem. I don’t have that problem with 1.2.6 – that I can tell.

Download location for Chris’s compressor version 1.2.6: Compress dynamics 1.2.6.

Thanks for the link theRamenNoodle. I changed your description from “latest version” to “Compress dynamics 1.2.6” because Chris released version 1.2.7.b1 shortly before his death.

Chris’s compressor 1.2.7.b1 is available here Chris’s compressor 1.2.7.b1
This version is open source (MIT license). It includes some new experimental features on top of the previous 1.2.6 code that are not fully developed, so for most users the 1.2.6 version is probably better.

We don’t host the 1.2.6 version as it is not open source and licensed “all rights reserved”*, so if anyone wants to polish up an open source version of Chris’s compressor it should be derived from the 1.2.7.b1 code.

*The license terms of the 1.2.6 version:

;;Authored by Chris Capel (
;;All rights reserved
;;Permission granted for personal use, without redistribution.

I understand that “” (theRamenNoodle) has been granted rights to distribute.

Chris’s father transferred all of Chris’s project, website, and notes to me for hosting on The Audacity to Podcast. So I can also add a link to the beta version and I’ll host any updates that anyone wants to contribute.

So sorry to necro this thread after 3 years, but I didn’t know where else to put this question.

I want to “upgrade” from the standard built-in Audacity compressor to this one but I am having trouble translating the settings.

Most compressors have a ratio of compression, like 1:2, 1:4, etc. This one however has a decimal. .8, .5. etc.

A straight mathematical translation doesn’t seem to make sense to me, as I have seen recommendations for this plugin around .75-.8, but as a ratio that would be LESS than 1:2 (which would be .5) so I’m assuming the two methods can’t be mathematically correlated.

I have seen success using about a 1:4 compression in my work. What would be the equivalent in this plugin?

Finally, a bit off topic, but I want to remove or reduce breathing noises but don’t want something as clumsy as a noise gate. I currently have my noise floor in the regular Audacity compressor to -40. Would setting it to -35 or -30 (in either compressor) improve this without causing undue distortion? What would be the optimal settings for this in Chris’ compressor?

Thank you!

Did you go through the suggestions at

Yes I have. I saw that before coming here. That guy talks about the settings he uses but he doesn’t explain anything from a technical standpoint and doesn’t translate the settings to the standard Audacity compressor, which is the question I was asking.

I don’t think you can get easily from one set of tools to the other. The compressors and limiters started with the code, programming and development and worked down to sound. Chris started with opera in his car and worked up to code. They’re very different tools.

I like to listen to an NPR radio production while hiking and I was fine when I was recording the off-air show from a receiver, but it was noisy with FM Stereo hiss. So now I download the podcast. The two performers have very different vocal styles and one in particular mumbles in his beer on occasion followed by a thermo-nuclear detonation laugh. It’s impossible to listen to, IMHO. The FM radio transmitter compressors took care of that.

Chris to the rescue. His goal was to able to listen to wide volume range opera in the car with minimal distortion or damage, so the tool incorporates all the compressors, limiters and look-ahead processing needed to do that. I use it with the first value, Compression changed from 0.5 to 0.77 and the resulting personal sound player show is indistinguishable from the FM broadcast.

I know of no combination of individual effects tools, processing or settings which will do that. I have never found it desirable to change any of the other settings, but there is one gotcha in 1.2.6. It hates leading digital zero. So when I cut the show down for my iPod, I leave a half-second to one second of interstitial radio network voice messages at the beginning of the show and cut everything else to final. Then Chris Compress with the revised setting and when it’s done, go back and slice off that half-second.

It’s perfectly possible to run Chris with the original 0.5 value. The show will be looser with more expression and volume variation.

This is the original show, default Chris value of 0.5 and the revised setting of 0.77.


I want to remove or reduce breathing noises but don’t want something as clumsy as a noise gate.

Post some of the voice work you think is too gaspy. Twenty seconds WAV mono or ten seconds of WAV Stereo. Scroll down from a forum text window > Upload attachment > Browse.

You can do it in MP3, but we’d rather you didn’t.