Why can’t I find the ACX Check plug-in that will actually download and work?

I just downloaded the most recent version of Audacity and I’m trying to download the ACX check plug-in. I can find it but when I download it for my Mac, I get a 4 kB document that will not open with Audacity. Is this plug-in still supported by audacity? Is there another plug-in that has taken its place? Thanks.

I’m a Windows guy, but -

Installing Plug-ins

Tools-> Nyquist installer. Then you might have to go-to Effect → Plug-in Manager to enable it.

Which you think is…? The forum is rife with people “Using The Latest Version” and it’s not. Worse, there are instances where the version before the latest is the more stable.

You should get a 4K Nyquist Program.

Screen Shot 2024-01-11 at 3.53.19 PM

When you have troubles is a good time to force your machine to read the full filename and not to lop off the filename extension. In the case of a Mac, you can right-click > Get Info and it should give you the full, correct filename.


I tried right-clicking and the filename is the same as your screenshot, but still no love. I’m running version 3.4.2

i downloaded and installed Audacity version 2.4.2 and was able to install the ACX-Check plugin. It will not show up in 3.4.2, nor do you get the correct menu options when you open the Nyquist installer.

A few versions ago, the way to install Nyquist plug-ins changed a little.

Previously (example Audacity 2.4.2), you would use the “Nyquist Plug-in Installer” to copy the “.ny” file to the correct location, then use Audacity’s Plug-in Manager to enable the plug-in.

In recent versions (example Audacity 3.4.2), the term"plug-in" was changed to “plugin”, and you would use the “Nyquist Plugin Installer” to copy the “.ny” file to the correct location, and the restart Audacity. The plugin does not appear in the Plugin Manager until Audacity is restarted. The plugin is enabled automatically when Audacity is restarted.

Thank you!

Is this a good time to mention Audacity Audiobook Mastering? That’s an associated Macro or batch program that can take your finished chapter and force it to meet ACX Peak and RMS (Loudness) standards.

Without that, ACX-Check will just tell you your chapter fails ACX and have a happy day. It dusts off its hands and goes home.

We recently discovered an oddity with the Audacity MP3 Export Tools. If you produce your chapters as mono sound files (one blue wave—recommended) then your File > Export Audio > MP3 should be set to Mono.

If you work in stereo, two blue waves, your left and right channels need to match and your MP3 Export should say Stereo. There is no forcing a Mono MP3 at the export step. That will produce a damaged MP3!


Really? Is that a Windows thing? I am able to export a mono track as a stereo MP3, and I get (as expected) a “dual mono” MP3 file.

Format                                   : MPEG Audio
File size                                : 6.46 KiB
Duration                                 : 1 s 44 ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 47.4 kb/s
Writing library                          : LAME3.100

Format                                   : MPEG Audio
Format version                           : Version 1
Format profile                           : Layer 3
Format settings                          : Joint stereo / MS Stereo
Duration                                 : 1 s 45 ms
Bit rate mode                            : Variable
Bit rate                                 : 47.4 kb/s
Minimum bit rate                         : 32.0 kb/s
Channel(s)                               : 2 channels
Sampling rate                            : 44.1 kHz
Frame rate                               : 38.281 FPS (1152 SPF)
Compression mode                         : Lossy
Stream size                              : 6.05 KiB (94%)
Writing library                          : LAME3.100
Encoding settings                        : -m j -V 2 -q 0 -lowpass 18.5 --vbr-new -b 32

Correct. What you can’t do is start with a matched track, mastered, stereo show and force a mono MP3 that passes ACX.

Screen Shot 2024-01-12 at 8.35.48 PM


Unless there’s already a thread about this, perhaps you should start a new one. On Linux, I don’t see a problem, so perhaps you are observing a bug on macOS (but I don’t really see what you are getting at, as I don’t see a problem here).

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