I’ve have a collection of old LPs that I’m trying to digitize, and am using an ION turntable with Audacity 2.3.3 on Windows 10. In a considerably older version of Audacity (don’t remember which) I did not have this problem, but now certain recordings, especially from the late 1960s seem to drop a stereo channel. I wind up with a stereo recording, but a known portion is absent altogether or extremely faint. Good example is The Mamas & The Papas–missing voices or instrumental sections. This problem all but vanishes with recordings from the late 1970s onward. I have tried adjusting the recording settings (e.g. input source, or attempting to record in mono) to no avail. Any suggestions?
Sometimes Windows is set-up for mono but Audacity is set-up for stereo.
I can’t give you the exact steps because there’s nothing plugged-into my computer right now, but… Right click on the Windows speaker/volume icon, select Open Sound Settings. Select the USB device as your Input Device, then Manage Sound Devices and dig through the menus and try to find the mono/stereo setting.
but now certain recordings, especially from the late 1960s seem to drop a stereo channel…
…This problem all but vanishes with recordings from the late 1970s onward.
You’re probably not getting proper stereo on the newer recordings either. 
Some early stereo recordings were mixed in an “unnatural” way with the lead vocals or lead instruments panned hard-left & hard-right, sometimes with nothing in the center, so it’s more noticeable.
It might be worthwhile plugging the turntable into your regular stereo and make a note of how the vocals/instruments are panned on one of those records. Then you can use it as a test record in the future.
It worked like a charm, and as a bonus, I am now able to monitor the sound while it’s recording. Thank you so much!
Hi! After a few months of things working just the way I wanted, Windows had to make a major update to my computer. Now I’m back to square one with incorrect stereo reproduction and no sound during recording. I went through the same steps that you provided previously, but this time there is no mono/stereo option anywhere in the control panel. Windows Help is useless so far. Just wondering if this has happened elsewhere and if there is a possible fix? Thank you–and I want to reiterate my appreciation for your help last time.
i figured it out and wrote everything down this time. Thanks!
Cliff - can you share the process you figured out and wrote down? I keep running into this problem as well. Thanks!
Windows Processing and “Enhancements” is provided to improve on-line voice communications. It likes mono (one voice channel) and hates music.
There is a relatively common microphone connection error which makes your voice vanish if you’re listening at the other end in mono. There was a recent real broadcast interview where the host microphone was broken this way. You only heard the guest. I’m not shocked if Windows detected this error and automatically corrected it. This is the same effect that some early recordings used to make music seem “deep” or “fake stereo.”
As you’re finding, sometimes updating your computer isn’t the best thing. Ideally, you have a vinyl transfer computer that doesn’t connect to the internet and doesn’t update, and a second computer which does all your regular jobs and does update.
The audiobook people are running into similar problems. The last thing they want is the computer “helping them” record their voice. The solution in that case is also a divorced computer or stop recording on the computer in favor of a real sound recorder.
Koz