Strange HF Sine Wave in Recording

Thanks Svart. I'll see if I can isolate it to the MicPre...it's definitely some sort of slow ultra-sonic oscillation.

I learned another thing about recording too: When doing quiet intricate agtr strums/plucks etc, have the artist take off their watch

Hours in RX6 removing watch ticks....

I had a particular reverb plugin (Reflect) that did that if more than two instances were used. Virsyn said they fixed it, but it still happened. It was some super high frequencies that I couldn't hear but it was there and the mastering engineer found it and requested a remix.
A very frustrating thing. As others said, I'd swap out the chain one piece at a time till it goes away so you can trace down which piece is the culprit.

Quartz watches put out about 32kHz - Along with 1Hz if analog. Automatics & winders put out 21-28kbph (6-8Hz) along with what I'm sure is a glorious song of sweeping high frequencies due to several wound metal springs under tension.

Next time I crack one open (I do that occasionally), maybe I'll mic it up and see what it's doing...

I tried to replicate this yesterday in my home studio/OD/mixroom. I could not with the same setup...output viewed in RX6 was clean as a whistle.

The problem tracks were cut in a very remote location, close to a ski resort...and I wonder if the power was super dirty from the lifts running. I am running a Furman Balanced Power unit that weighs like 100lbs (no joke) so that should have cleaned that up I think.

I do remember that I had a microphonic/failing tube in my Retro 2A3 EQ that I recently had replaced under warranty by bowie so I wonder if that funky tube could have caused it.

Since I do a lot of remotes, maybe I’ll start making a test recording of my crucial channels and inspecting them in RX6 before committing to tracking.

I usually don't see anything that uniform and high frequency with tubes but the interesting thing with tube microphonics is the way they interact with the chassis and the vibrations of the power transformer. Tubes can sometimes be dead-quiet in most gear but if they are in a chassis that resonates at the resonant frequency of the tube's glass envelope, you can get awful microphonics. The vibration of the PT can sometimes contribute to this.  I can't get that particular tube to exhibit that behavior in any of my gear, but that's not to say there wasn't a "perfect storm" going on that affected it in the Fearn.

Is it possible that a client that day/week had an electronic device that could have introduced the noise? With all the high-gain noise testing I do, I sometimes discover problems when I bring in new devices, particularly those running on wi-fi.