Bizarre recording issue

Hi everyone and hope you are well.

I have been using Audacity to record my vinyl DJ mixes for some years now - a brilliant piece of software which I absolutely love!

Unfortunately I have encountered a recent issue which I just can’t get my head around, a sporadic sound disruption to my recordings which you can clearly hear at the following short example link:

Just to be clear, this sound is not coming through my main speakers when making the recording, it is only apparent on playback in Audacity. It comes and goes, at times the recording is fine and then suddenly it creeps in.

I run Audacity 2.1.3 through my Macbook Pro OS X El Capitan - I use an RCA cable plugged from my DJ mixer into the headphone jack on my laptop to make the recordings.

This is driving me mad, can anybody provide a solution?!


What else is the machine doing? Many apps all open at once? Apps napping in the Dock?

Laptop? Do you ever get the spinning beachball?

Shut down the WiFi with the fan symbol upper right. Apple (upper left) > Shut Down…

Watch for a tiny spinning daisy and see how long it stays on the screen. That’s the Mac struggling to shut everything down. It should not need to struggle very long.

Start and wait for it to settle down. Go make tea. Do Not start anything. Do you get complaints about not being able to reach the internet?

Launch Audacity. Still do it?


Hi Koz and thanks so much for the response :smiley:

Yes this MacBook is definitely very slow in all respects - it is an old computer (2011) and I only use it for Audacity recordings now.

It is slow to shut down and takes around 5 minutes to reboot up, I often get the spinning beachball when using it.

I have followed your instruction and will give it another go now to see if the issue is still there.

Failing this … I do have a newer 2016 MacBook Pro but it runs OS Catalina - I am aware that you need a Terminal workaround for this (which I have successfully implemented ) but my RCA cable will not allow a recording via the headphone input on this computer as the sound option only has ‘internal microphone’ and so this has me stumped too!

Best Regards,

my RCA cable will not allow a recording via the headphone input on this computer

Actually, if you have an old enough Mac, it has an actual Stereo Line-In. Circle with two black arrows.

If it’s a smaller Mac (13" ??) you have one hole and you have to switch it between Stereo Line-In and Stereo Line-Out. One service at a time. All perfectly valid.

Does the new machine have USB ports?

If it does, then the Behringer UCA-202 is for you. It’s a bi-directional stereo adapter with headphone monitoring. That’s my sound mixer on the right.

There is a new version of Audacity on the way shortly that will be Catalina Compliant.

On the older machine, run Activity Monitor. Desktop > Go > Utilities > Activity Monitor. I keep a copy of that ready in my Dock. See if there isn’t one thing, application, or service hogging the machine. Do you use Adobe products? Their various license servers can be a chore to deal with.

But I do expect the older machine to work. I used to regularly get one of the department managers out of trouble by actually closing all the apps he had “napping” in the dock. Application with a little light under it? Right-Click or Control-Tap > Quit.

Browsers can leave trash lying around. Safari > History > Clear History. Be careful with this one because your auto-logins may vanish and you’ll need to know all your passwords and login info. You should have that written down anyway.

Do you have a jammed desktop? I know how tempting that is, but you shouldn’t be storing many more than about 5-7 things on your desktop at a time. The machine has to take the time to actively manage each and every “thing” on your desktop. I have a folder called “Desktops.” Every so often, I gather everything up, dump it in a folder, date it, and move it to Desktops. Use ISO dates. If 20200502 bothers you, put the dashes in. 2020-05-02.

Screen Shot 2020-05-02 at 7.17.46.png
Use Spotlight (upper right search tool) to find things. Pause on a Spotlight entry and it will open a preview panel. If you press and hold Command while Spotlight is active, it will cycle through name and location.


Thanks again for the info Koz, I have cleaned up my old Mac to include running some malware apps and it seems to be shutting down quicker now. Activity monitor all seems ok, nothing looks suspicious in the CPU tab that I can see. I’m going to try to make a recording today and will see how that goes.

My newer Mac does not have a USB but I do have an adapter that acts as a workaround solution and so I think it could be used with the UCA 202 as an alternative option.


Hi Koz,

Just wanted to say a huge thanks as got this sorted! Your kind support helped me diagnose that it was a slow MacBook causing the issue - a good clean up and running some free Malware software sorted things out.

I recorded a little Vinyl Afterhours mix, linked below if you would like to listen and thanks again for all the great support you give on the forum.