MC 30 and 12AU7

Seamaster

Active Member
Need some help here about MC30's phase inverter tube, those 12AU7.

Well, I am not really a 12AU7 fan, I have quite a collection of tubes of other types. So, in this position, do MC30 have 6 volt or 12 volt power supply to the heater? I am hoping is 6V, therefore, I can use other types of tubes with adapters. Thanks!
 
I prefer 6CG7 silver plate with shield, 6sn7, CV181, or 6f8g with round plate


BTW, i don't have much experiences on 12V tubes on how they sound other than 12AX7 and 12AT7
 
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Need some help here about MC30's phase inverter tube, those 12AU7.

Well, I am not really a 12AU7 fan, I have quite a collection of tubes of other types. So, in this position, do MC30 have 6 volt or 12 volt power supply to the heater? I am hoping is 6V, therefore, I can use other types of tubes with adapters. Thanks!
Afaik, all vintage Mac amps are 6.3VAC heater bus, and most 12V series dual triodes are also usable on 6 volts with the socket appropriately wired as with these Mac amps.
I'd be loathe to second guess the designer on the choice of tube types for circuit design parameters.
 
the guys over on vintage asylum suggest to rewire the socket for a 6gc7. two wires only change.
 
Buy yourself an adapter and try a 6cg7. You may like it so you mod your amp to take this tube instead.
 
Thanks guys for the kind replies. And thank god the MC30 is on 6.3v bus! Now, with 6.3v on the heater, that opens up a lots of options. I am aware that people mod their MC30 to take 6CG7, but at this moment, my amps are done deal that will come with 12au7. I mean I bought them from /www.vintagevacuumaudio.com, the work already been done. I had amps that take 6SN7; therefore, I did very intensive test with other tube types using adapters. By the end of the day, yeah, 6CG7 was the winner but 6F8G was not far behind. 6CG7s were very clean, clear, great separation, fast, and most importantly (too me), they have awesome bass line, great timing, impactful, and with good texture.
 
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