Tubes Asylum: RE: 300b amps by baileyler Questions about tubes and gear that glows. FAQ

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Posted by baileyler (A ) on November 24, 2021 at 08:00:36

In Reply to: 300b amps posted by stator_99@yahoo.com on November 22, 2021 at 18:19:07:

I have a Ming Da MC805-AA which is 805 driven by 6L6.

300B driver is more common in these types of amps, however, in my opinion a 300B driver is just for show and a waste of this tube.

BTW, I love my MC805-AA, but I would not recommend it (or a similar 845 or 211 amp) for the inexperienced. There is a lot of voltage and heat, and in some cases sloppy construction.

The other thing to take care of is that most (but not all) of these amps seem to be Chinese made. Power transformers on a lot of these (and other Chinese amps) is typically made for 110/220V and not 120/240V. Unless you run it at 110/220V (I do) or the amp has internal voltage regulation (highly unlikely), you have the possibility to run the tubes out of spec (increasing the likelihood of early or even catastrophic failure).

For example, when I run my unit at 120V, the filament voltage on the input tubes (12AX7, 12AU7) is over 7V. When I drop the input voltage to 110V, the filament voltage drops to a perfect 6.3V.

I have more than one Chinese amp that does the same thing at 120V.

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