Well, I cut the lands and soldered in the orange jumpers and resistors. The rest of the wiring is original. I don't have a bias probe so the 1 Ω resistors will have to stay. I did also cut the land between pin 3 and pin 8. This necessitated another jumper betwee pin 3 only and B+. And I changed the screen resistors to 1k 5w.
Update- the operation was a success. I can't say there's a HUGE difference in sound at low volume, but I can only go be memory. Thanks for your help.
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Peavey VTM Conversion to EL34 & 1 ohm resistors
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Yikes this looks a bit sloppy, remember we are dealing with potentially deadly high voltage here!
(outside the bias circuit)
You could just use a bias probe to set the bias and not have to add the 1 ohm resistors onto the board. As per the other thread the JSX has a switchable voltage divider to allow both types of tubes to be used, and Eurotubes advocates making hybrid versions that run 2x EL34 and 2x 6L6s with separate bias circuits for each.
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Originally posted by g1 View PostYes you would have to make another cut to isolate the 2 pin 8's. But please explain what you mean about pin3, that is the plate?
Peavy_vtm_120.pdf
Edit:
I see we have been here before - Peavey VTM - from 6L6 to EL34Last edited by Dave H; 05-26-2019, 11:38 AM.
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Yes you would have to make another cut to isolate the 2 pin 8's. But please explain what you mean about pin3, that is the plate?
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Peavey VTM Conversion to EL34 & 1 ohm resistors
I've cut the land between pins 1 & 3 and tied pin 1 to pin 8. I now need to insert the 1 Ω resistiors to ground. But since the PC board has pin 8's tied to each other as well as ground, Do i need to make another cut to isolate them and have the 1 Ω resistors be the only path to ground? This seems correct. I guess I just need some confidence here.
I've also made a bias adjust ckt with a 3.3k resistor in series with a 50k pot (R8 & R9 respectively on the Peavey PSU board).
I believe this is all there is to it although, when I try to trace the bias ckt on the VTM schematic, I get lost. I'm comfortable with Marshall's way of doing it but the Peavey schematic loses me.
Thanks!Tags: None
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