Recording volume level slider adjusting by itself

Hi, I’m new to this board but not new to Audacity having used it many times before on Windows computers but I am now using it on an old iMac (Mid 2010 on High Sierra) for the first time. I have a dedicated Cassette Deck directly connected from it’s stereo L-R Line Out to the sound input (next to headphone) socket on the iMac using a 2RCA splitter cable with 3.5mm jack and I am selecting Built-in input (rather than Built-in microphone) and (Stereo) Recording and Built-in Output in Audacity.

I have come across an issue in the last couple of days that is really frustrating me and is giving me doubts as to whether I can trust using Audacity for a project to digitise 500+ cassettes. I just happened to be monitoring a test recording and suddenly noticed the recording volume slider was moving of it’s own accord. I thought I was seeing things but now since watching closely during several more test recordings I am seeing the same thing happen. Additionally even if I move the slider back to the recording level where I want it to be it will then start moving again of it’s own accord.

I have been looking through this forum and searched other websites and can see various references to this happening on Windows PCs but not for Mac, and the Windows issues seemed to mainly be attributed to a Skype setting which I don’t have installed. I assume something else is taking control of the recording level but so far I have been unable to find it and have tried various adjustments to the microphone and have turned off Siri. I can’t see anything else installed such as Zoom that would take control but I am still getting the same issue on recordings today.

Has anyone else come across this issue as I am not going to make any further recordings with Audacity until I can find out what’s causing this and hopefully a resolution. Many thanks.

Which Audacity?

Audacity > About Audacity.


Sorry, Audacity 2.3.3

I’ve seen this kind of behaviour with Skype and other voip type applications.
It won’t be Audacity doing it because Audacity has no code to do that.

You could try looking in the “Activity Monitor” to see what is running (