make a 6505 switchable from el34 and 6l6

[KTB]

Pin 3 is not going to ground. It has a diode between it and ground and diodes block voltage if wired in a certain way which they are. You should be good wiring 1 & 8 together.

[vscrl1]

ok so solder pin 1 to 8 on v8, replace the SGR's, now is my 4.7 resistor going to need to be swapped in the bias circuit?

[KTB]

No ,has nothing to do with bias it's a completely different circuit.

[vscrl1]

I meant for as far as biasing the el34's. Is it the resistor or the pot that needs to be upgraded for the higher sweep for the el34's for them to be biased properly? And just out of curiosity, does the 6505 and 6534+ have the same transformers? I'm really curious as to why peavey didn't just put a switch in the 6505 line like the ultra line for 6l6 and el34 tubes.

[Enzo]

Pin 3 IS'NT shorted to ground, the pin 3 thing is from a different model amp facing this same conversion.

NEVER rely on a blob of solder to connect two points, always use a piece of wire.

I don't know what 4.7 resistor refers to. Just measure the sweep range of your bias control at the tube sockets, without tubes installed. Do whatever is needed to make it go down to maybe 40v and up to 55-60.

The 5150/6505 came out in, what, 1992? Back then it was only basement tweakers who wanted to stuff EL34s into it. Enough market desire in later years caused them to add the switchable feature to basically the same amp.

[vscrl1]

Not sure which amp you are referring to here that is switchable but none of the 6505 line are switchable. 2 come with 6l6's and 1 with el34's. The ultra line are switchable but they are nothing like the 6505 line. The only thing they have in common is the amount of gain. And even then I find that the ultra line amps (xxx and jsx) both have more gain than the 6505 line. Especially the xxx. I had my gain on that thing at like 9 o'clock. And 4.7 refers to the resistor I just installed with the trim pot for the bias mod. The sweep with the 6l6's is about 15ma-57ma.

[Enzo]

You are right, I guess I was thinking of the XXX and JSX for switchable.


Forgive me for being dense, but I don't know what you may have done or used for your bias mod. 4.7 to me means 4.7 ohms, which would have no effect. I assume you might mean 4.7k, but then I don't know where in the circuit you put that resistor, and so couldn't advise as to changing it or anything.

[vscrl1]

Yes 4.7k resistor. It's connected to the bias trim pot I installed. I'll try the other mods first and then I'll see if I can bias it. It might be a bit before I get to it

[KTB]

Did you mean the sweep is -15 volts to -57 volts ? How are you getting ma's ?

[vscrl1]

I'm getting Ma from using a bias probe in the tube sockets