2. amps-preamps
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Is your tube amp really a tube amp?

I use and love the older ARC D70Mk2 tube amp. To many people, this design is a true tube amp...however, ARC uses a LOT of transistors in the circuit. In the "day" a transistor was considered a ss device. Anyone know of a tube amp that uses NO transistors in the circuit...only tubes. I suspect that in my amp, the audio signal passes only through the tubes and not through the "ss" devices ( don't know this for sure)...Therefore, what is a TRUE tube amp...how many of us are actually using such a device ( no transistors or other ss devices whatsoever in the amp), vs. a hybrid...what's the definition of that term in regards to tube gear?
128x128daveyf
ebm
9,311 posts
 
Is this thread really 2.
bill_k
912 posts
 
FYI - A tube rectifier is the tube equivalent of a diode, rectifying the AC into DC.
noromance's avatar
noromance
9,771 posts
 
yes... but you'd need a massive dropper resistor to get the voltage down to heater voltage levels.
atmasphere's avatar
atmasphere
11,807 posts
 
There are no tube rectifiers that can handle filament currents.

So if one is to use DC filaments the most often used technique is to use some sort of semiconductor. This is still considered a tube amp/tube preamp. In the old days (1950s) selenium rectifiers were used, for example in the Dynaco ST-70 and PAS-3. Those are tube products and are not considered hybrids.
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