#1
I ordered a matched quad of JJ E34L's (EL34) from The TubeStore, and the stickers on the top of them all say 36. Does this mean they should be biased to 36mA? Because Eurotubes guy says about 38-44mA.

And also, I ordered a new Reverb tank, so would it be ok to run the amp without a tank in for the moment?
Last edited by CallmeTravis at Feb 21, 2008,
#6
er i dont really know much about this but black is usually the ground color on most electronic stuff i know off.
Schecter C-1 classic
Takamine GS330S
Roland microcube FTW!
#10
I have instructions on a "permenant" biasprobe. This is what I used to do with my amps.

To mod the amp, you will need to get some 1 Ohm, 1 Watt(or bigger) precision resistors(as many as you have output tubes). Precision resistors are accurate to 1% of stated value. If your electronic parts store won't let you measure before you buy or doesn't have 1%'ers, buy a bunch and measure them. You need exactly 1 Ohm.

1. Remove the wire or solder joints between the cathode and ground on all output tubes. (Pin 8 on 6L6, 6550,EL34... pin 3 on EL84/6BQ.

2. Solder a 1 Ohm resistor between the cathode and ground. Ohm's Law states, I=E/R (current= voltage/resistance). If a resistance is 1 Ohm, then I=E, because any number divided by 1 equals that number.

3. Plug in the guitar and speaker, Connect one of your meter leads to the chassis side and the other lead to the tube side of the 1 Ohm resistor. Use biasprobe charts to determine the approximate proper current draw for your amp.
#11
Quote by The Real Ming
I have instructions on a "permenant" biasprobe. This is what I used to do with my amps.

To mod the amp, you will need to get some 1 Ohm, 1 Watt(or bigger) precision resistors(as many as you have output tubes). Precision resistors are accurate to 1% of stated value. If your electronic parts store won't let you measure before you buy or doesn't have 1%'ers, buy a bunch and measure them. You need exactly 1 Ohm.

1. Remove the wire or solder joints between the cathode and ground on all output tubes. (Pin 8 on 6L6, 6550,EL34... pin 3 on EL84/6BQ.

2. Solder a 1 Ohm resistor between the cathode and ground. Ohm's Law states, I=E/R (current= voltage/resistance). If a resistance is 1 Ohm, then I=E, because any number divided by 1 equals that number.

3. Plug in the guitar and speaker, Connect one of your meter leads to the chassis side and the other lead to the tube side of the 1 Ohm resistor. Use biasprobe charts to determine the approximate proper current draw for your amp.

No no no no no no no. I'm not doing that lol. I am prepared to buy a bias probe, but how would I do it without one?
#12
That way or build one.


If you are unsure of these two easy methods, then just buy a bias probe.

Or you could do the oscilloscope/signal generator method, I'm guessing this way is beyond your grasp? If not let me know.
Last edited by The Real Ming at Feb 22, 2008,
#13
id get the bias probe like The Real Ming said, and dont forget to have your multimeter on the right setting before you try and take the plate voltage, i had mines on the wrong one and blew the multimeter