[Darkstar860]

Hey there folks !

I was curious what is the difference (if there is any) of a grey plate RCA 12ax7 and a black plate 12ax7 ?

-Walt B

I found two (grey plate) 12ax7's. They work and sound great, but im not sure how much life they have left in them. So i was looking at getting some and cant figure out if Grey plate or Black plate would sound better in the SMS. Or if there is even a difference.

[Chocol8]

I think the short black plate ones tend to be more resistant to microphonics which is extra important in the first position for each channel.

I wouldn't be in a rush to replace them if nothing is wrong. A good pre-amp tube should outlive most of us. Power tubes do wear out over time but after far more hours than many on the internet would have you believe.

[Darkstar860]

I have long and short plate GE and RCA tubes. 12AX7. I was wondering if anyone mixes long and short plate and if so where in the amp do you have the longs as oppose to the short ?

In my SMS CTP ive been messing around and I have a short plate in V1 and a long plate in V2. Sounds amazing. But wasnt sure if anyone thinks maybe a short in V2 and a long in V1 etc.

Just curious what everyones thoughts were. Been finding good deals on NOS and high tested RCA and GE tubes lately. Crazy. Trying to stock up on GE and RCA preamp tubes. Next ill stock back up on 6L6 and 6V6 and EL84's. My fav tubes are these. But ive been using JJ's forever and they are great tubes so im not talking smack about them. Just love the vintage tubes, call me crazy.

[SpringheelJak]

The grey plate has a lower noise floor, and is recommended for cleans over the black plate. Apparently the grey plate 7025 RCA were stock tubes for fender blackface/twin amps since the 60’s!

Edit: Up until about the 70’s.

https://fuzzaudio.com/best-tubes-for-fender-amps