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

Showing 1 response by robetozian

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.