Musicians Roadhouse

I'm considering going with greenbacks in my 1960 Vintage cab, but I don't know which greens would sound the best with the LM?

Alright, i had 6100 #1 on the bench because i was losing the bias voltage intermittently. While checking out the board in noticed a few different resistor/cap values than you see on the schematic. The resistors pertain to the feedback loop for the PI.

Schematic
R228 100K R229 470 R210 10k
LM board
R228 1Meg R229 1K R210 15K

The DC coupling/blocking caps on the PI are also not the same as the schematic:

Schematic C219-220 .1uf (100n)
LM .22uF (220N)

This cap change prolly allows for more bass to go forward.

100n at the PI? That can't be right... Could you be looking at a mislabeled 1987X schematic? Are you seeing 100n on the 6100 board, or 22n?

I'm continually blown-away by this amp! I spent several hours with it today using my '02 Gibson Firebird... Amazing tone! The plexi mode sounds every bit as good as any of the vintage ones I've owned. This may be the most underrated amp ever.

My amps have the .22N on the boards. Interestingly enough this "newer " schematic also shows those caps as only "250 volts".
Definitely a typo of some sort.

http://home.myfairpoint.net/vze1u14s/si ... weramp.pdf

This older schematic with the zener in the bias supply has the right parts on it, or i should say what matches the production amps.

http://home.myfairpoint.net/vze1u14s/si ... 0zener.pdf

Yup, these amps are stellar. A little TLC and they will serve you well. Now just do some tube rolling and you will be all set.

In knew i had this somewhere. This is the breakdown of some of the resistor/caps changes i note above. And yup they did use a 100n after the PI on the 6100 non LE/LM.

So, converting a 6100 to alternate specs isn't simply a matter of swapping-out screen and bias resistors after all.

No. Have you seen the factory conversion manual to go from EL34 to 5881/6l6GC for multiple different amp series?
Check this out, there are more than just screen grids that need to be addressed.

http://home.myfairpoint.net/vze1u14s/si ... ersion.pdf

If you look at the4 conversions for the caps that follow the PI it seems 100n is interchanged with the 22nand a 47n depending on model and wattage.

I couldn't imagine ever changing over to EL34's. It was the same with my RK100... It was setup to run EL34 or 6L6 tubes, but no matter what tube brands I tried, or how I biased them, 6L6's always sounded preferable to me. Then again, both of these amps were designed to run optimally with 6L6's. I'd love to try another EL34 6100, one that I know is running properly.