I have this weird problem that when I play my electric bass (Fender PB), the sound gets quiet after a couple of seconds of playing (drops from about -12db to -36db). If I pause for a second and start playing again, it starts out normally and drops quiet again if I play, say, eighth notes at 140bpm.
I have my bass plugged into my Macbook Pro via an iRig2 and I tested in both Audacity and Logic Pro and got the same result. It’s as if a long release limiter or compressor was in play…
Do you have an amp? Or can go to a shop to try? You need to test straight into an amp. This will tell you if it is the bass or not. And try a different cord when you do that just in case.
Tempted to blame the iRig so yeah I would say take it out of the equation - either an amp or an audio interface (a real, powered one with preamps.)
You can also buy cables that are a 1/4" instrument → Mic In for use with laptops and mobile devices - kind of like the iRig but simpler. They are substandard for recording but work fine for things like tuners, and would allow you to test this as well. Petersen (the strobe tuner company) sells one for about $15USD.
Solved: MacOS has a “Use ambient noise reduction” feature in System Preferences under Sound. This is turned on by default in MacOS Catalina (which I had) and couldn’t be turned off. This was the culprit. I upgraded to MacOS Big Sur and now the toggle is back in System Prefs under Sound/Input and the sound is now good after turning it off. Phew.
