Switching power tube type
- Thread starter Willis
- Start date
Curly
Moe's Bluesman
Re: Switching power tube type
you need to be a little more specific - from what to what, in which amp?
the change in power tubes alone doesn't require a change in bias method, but you do need to consider the wiring of the socket. for instance, a common switch is from 6L6 to EL-34, and that requires rewiring the sockets, since the pin assignments are different for those tubes. It may also require adding a resistor if the current draw is different.
however, this shouldn't be a difficult job for a good tech
you need to be a little more specific - from what to what, in which amp?
the change in power tubes alone doesn't require a change in bias method, but you do need to consider the wiring of the socket. for instance, a common switch is from 6L6 to EL-34, and that requires rewiring the sockets, since the pin assignments are different for those tubes. It may also require adding a resistor if the current draw is different.
however, this shouldn't be a difficult job for a good tech
mind_transplant
New member
Re: Switching power tube type
Curly is completely right, converting 6L6 to EL34/6CA7/KT77 is fairly simple for a tech or someone experienced with tube amp maintenance, I've done it back and forth a number of times. I too would suggest going to a tech if you're not very comfortable working on tube amps, Ive seen too many Fenders (some vintage pieces too) seriously hurting because someone either just popped in EL-34s or messed up the conversion. :disappoin
The problem (bias notwithstanding) is that on 6L6-style tubes pin 1 is unused and wired as a terminal, while EL34-style tubes' suppressor grid is pin 1. People who just swap tubes (or make a mistake re-wiring) now have the signal and bias (terminal on 6L6) connected to the suppressor grid (should run to ground) and therefore fry their tubes and sometimes more very quickly. :angryfire If you still want to do it yourself, I can suggest some books...
Curly is completely right, converting 6L6 to EL34/6CA7/KT77 is fairly simple for a tech or someone experienced with tube amp maintenance, I've done it back and forth a number of times. I too would suggest going to a tech if you're not very comfortable working on tube amps, Ive seen too many Fenders (some vintage pieces too) seriously hurting because someone either just popped in EL-34s or messed up the conversion. :disappoin
The problem (bias notwithstanding) is that on 6L6-style tubes pin 1 is unused and wired as a terminal, while EL34-style tubes' suppressor grid is pin 1. People who just swap tubes (or make a mistake re-wiring) now have the signal and bias (terminal on 6L6) connected to the suppressor grid (should run to ground) and therefore fry their tubes and sometimes more very quickly. :angryfire If you still want to do it yourself, I can suggest some books...
