Since the power tube plate voltage on the Express is ~400VDC, why can you use 6V6 tubes? None of the data sheets I have read have a maximum plate voltage near that.
I am trying a pair of NOS GE 6V6GTA tubes and they seem to work. They do get some blue (gassy?) around the plates when pushed hard.
I'm confused. Can anybody explain this to me?
thanks
Why can the Express use 6V6 tubes at high plate voltage?
Moderators: pompeiisneaks, Colossal
Re: Why can the Express use 6V6 tubes at high plate voltage?
Most 6V6 data sheets low-ball the plate voltages. Blackface Deluxe Reverbs operate at well over most specified max voltages. That said, some brands of tubes can become snack food in an amp like that. That's why many tube sellers will specifically say something like "can handle high plate voltages in Deluxes."
Don't fret about the blue glow, it's normal. I've got some 1960-vintage West German 6L6s that are worth using just for the glow!
Don't fret about the blue glow, it's normal. I've got some 1960-vintage West German 6L6s that are worth using just for the glow!
Rich Gordon
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
www.myspace.com/bigboyamplifiers
"The takers get the honey, the givers get the blues." --Robin Trower
-
David Root
- Posts: 3540
- Joined: Fri Aug 04, 2006 3:00 pm
- Location: Chilliwack BC
Ultimate 6V6 amp
The ultimate 6V6 amp has to be the famous Jim Kelly FACS (Footswitch Activated Channel Switching) four 6V6 amps of the early '80s, now collectors' pieces. 495V on the plates! A full 60W out of four 6V6s, without exceeding rated dissipation either. There's a schematic on schematicheaven.com if you're interested. Note his back-to-basics PI and probably the first use of diode bounding in a guitar amp design. Kelly was way out front of his time.
The 6V6 was designed for use in early TV circuits on a 15% duty at 1200 V, so 495V at 100% is not that much of a stretch, done right. Having said that, I would only use good NOS, or JJ6V6S or the new Tungsol 6V6 at these voltages though, most of the cheap stuff will vaporize!
The 6V6 was designed for use in early TV circuits on a 15% duty at 1200 V, so 495V at 100% is not that much of a stretch, done right. Having said that, I would only use good NOS, or JJ6V6S or the new Tungsol 6V6 at these voltages though, most of the cheap stuff will vaporize!