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In Reply to: RE: 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.
Edits: 11/24/21Follow Ups:
Filament voltage is important also... :) Not sure what I'd sacrifice first, and in truth it has never come up. My first DH amp happened to get a TX that worked out OK. The second got a small variac on the filament Iron.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
That's correct. It's also a problem with Chinese step up transformers. They will all give you 245 V instead of 220-230V.
Driver tube is a very important element in any tube amp. To say 300B driver there is just for show is simply not true. To realize a potential of a SET amp one needs a high efficiency speakers. There is no exception of this rule and it is what it is.
Edits: 11/25/21
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