Leave tubes in phono section if not using it?


Hi,

I just bought a mid 1980's Moscode Minuet preamp (not Minuet in A) on AudioGon. I haven't received it yet, but I think it uses 4 12AX7's (2 in phono section, 2 in line stage).

I don't plan on using the phono stage. I was thinking of just pulling the tubes in the phono section with the hopes of reducing noise/hum and saving myself two tubes. But, I know I could use shorting plugs on the phono imput jacks to possibly eliminate some noise that way.

My question: Is it possible that pulling the tubes can upset some critical design parameter and create a detrimental situation, or even do some damage?

I will not have a manual or schematic for this unit.

Any thoughts would be much appreciated.

Thanks,

Rich
richgib
Leave the tubes in. If you operate this preamp without tubes in place, it will "un-load" the regulators. Voltages in some places will rise, and may rise above the rating of some components. The repair bill will most likely be higher than the cost of a couple of cheap tubes.
Gentlemen I need your knowledge
hello possesses a minuet moscode (not in A) and I read that it had four 12AX7 but I have two 12AX7 and two 12AU7
precisions would you please?
so what tubes is dedicated for phono and which are dedicated to the preamp section?
do you know a way to know and tell me how I could understand?
it is a very very good preamp and I love it like working with my MOSCODE 300!
I search the shema of minuet and 300
thank you for your help because I never found anything on this subject and I despair
(anyone know what it is dedicated tube in the minuet in A? this is the same?)
thank you very much
Bob (France)
The Minuet will be fine if you pull the 2 phono pre tubes out. They are the ones on the left looking at it from the front.
My VAC Sig MKIIa has a pair of 12au7 for tape and a pair 6922 for linestage. I don't use tape but found the 12au7 position very sensitive to tube rolling. All VAC owners that roll 12au7 had similar results.

Listen before removing or replacing with inexpensive tubes.