Volume consistency of Twin Reverb in recording environment

[JazzNote]

Yesterday I recorded a track using 3 microphones, two of them in front of my 78 Twin Reverb, the third clipped to the guitar, a few inches away from the top. As it got late I decided to continue the work today, like fixing a few spots and do some punch ins. I left all settings as they were, mics in place, guitar plugged in, but when I continued today I realized that the sound had changed drastically. Hunting for the reason of this change i got to the conclusion that the Twin was producing less volume than yesterday, although the setting had stayed the same. So I turned it up a little (Master from about 4.3 to 5) and got close to yesterday's sound. The Twin is actually in very good shape, serviced a couple of years ago, delivering a minimum of background noise, with high quality preamp tubes, some of them new. I rarely use it, if I do then mainly for recording purposes, most of the time it just stands unused in my studio.

Did anyone else ever experience something similar?

TIA

PS: not sure if I'd better post this in the recording forum.

[bluejaybill]

It can definitely be tricky coming back and punching into an existing guitar track. I usually do as you did, leave everything the same and hope for the best! Often on the next day, my touch is a bit different, harder or softer, that can affect things quite a bit. It can be hard to match the feel as well as the equipment setup.

As to the problem with the Twin, the key could be your later statement about not turning it on very often. Lots of problems can come from non usage. I would wiggle the tubes and twist each know a bunch of times, dirt accumulation can affect those things. Good luck!

[Cunamara]

Changes in wall voltage?

[JazzNote]

Often on the next day, my touch is a bit different, harder or softer, that can affect things quite a bit.
!

This of course was a crucial effect in this situation. The Twin producing less volume made me play harder which also resulted in more volume on the acoustic mic. So simply raising the volume of the recorded amp-mic channels didn't solve the problem. I ended up re-doing all repairs/fixes with raised Twin volume.

[JazzNote]

Changes in wall voltage?

Very unlikely! We are used to having a stable power system here. But of course standards which were normal "yesterday" might not apply anymore in todays world ;-).