Search for 6AS7 and/or 6080 - a couple threads with builds and ideas on these.
The low plate resistance allows one to use main toroidal trafos as OPTs (but balance the current) and due to the lower voltage in such an amplifier (Shoog likes to run these valves at 100V/100mA) more conventional power supply parts can be used (like some salvaged SS main trafo in a voltage doubler)
What are your ideas?
The low plate resistance allows one to use main toroidal trafos as OPTs (but balance the current) and due to the lower voltage in such an amplifier (Shoog likes to run these valves at 100V/100mA) more conventional power supply parts can be used (like some salvaged SS main trafo in a voltage doubler)
What are your ideas?
Due to its low gain, the driver session will probably need a (separate) higher B+ supply. IIRC Shoog did an amplifier with a PT with 110V+110V to generate about +130VDC for the output tubes (at 100V/100mA) and an addition -130VDC, so the driver could operate with a total supply of 260VDC.
one could also use some SS to do the driver, and use the same B+. Or an interstage, but than it aint a bargain anymore
one could also use some SS to do the driver, and use the same B+. Or an interstage, but than it aint a bargain anymore
100v/100mA with about 1200-2000R plate to plate is my favorite spot to run them, as they are more linear and easier to bias at this point. 165v supply, and garter bias with stacked 330R (30-32 volts bias or so) 10W resistors is my pet circuit with them, driven by my usual 6SL7 concertina. 7-8 watts easy, and very nice. Higher voltage is required for the driver section, but that's so trivial to set up that it's a non-issue. They are fairly easy to drive, so even the 6SL7 or 12AX7, or 6N2P can push them fine in this setup.
Don't do fixed bias. Very inconsistent. The trick with these is to match the idle current, garter bias or a CCS is a good start.
They have a certain "mojo" that's hard to beat, as is my experience with most low plate-resistance tubes.
Don't do fixed bias. Very inconsistent. The trick with these is to match the idle current, garter bias or a CCS is a good start.
They have a certain "mojo" that's hard to beat, as is my experience with most low plate-resistance tubes.
I've been running fixed bias with them without any issues, see the previous post for the schematic
Also you could use an AB-4 or AB-Q from Pavel at audioamp.eu
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