HI, I think a lot would depend on the overall circuit, and the parts used. If the circuit is right, most tubes will be pretty linear. If the parts are good quality, the amplifier should be more transparent and control frequencies better. In other words, it may be better to go for the best implementation, rather than go for any particular tube. Just my 2 cents. -akhilesh
Yes, except for grid bias voltage. Also, the 6550s would be more reliable than the EL34s because 6550 screen grids don't draw as much current. Screen overheating is a major cause of EL34 premature death. Ask any guy who plays metal thru a Marshall amp.
It is not a fixed ratio. 6550s need about 20-50% more negative bias voltage than EL34s in the same circuit. Depends on plate voltage, screen voltage and even the brands of tubes involved.
Wayne Parham Messages: 18792 Registered: January 2001
Illuminati (33rd Degree)
Thanks, Eric, that's the kind of information I was looking for. It's enough difference that they definitely shouldn't be considered drop-in replacements. A person could easily modify most circuits, some with as simple a change as a resistor or two. Others might need power supply mods or an entirely new supply. But either way, it isn't something that a tube roller could do without a soldering iron and some understanding of electronics.