Just put new jj kt88 in the nitro need ADVICE!

[wizardy]

Hey guys.
I've followed fastredponycar Bias DIY tutorial for my new JJ kt88
I've never checked the amp bias before today
I've been running the amp in 50 watts mod the last few months because it blew 2 tubes and I didn't bought new tubes since today.

When I've first checked the bias, it was at 33mA on the voltmeter
Is it normal??
(The tubes are rated at 35 on the retail JJ box)

I've then turned the bias wheel SEVERAL times to get it to 52ma as recommended.

I'd also like to know if I should bias it lower than 52ma in 100 watts mod because if I use it in 50 watts mod, the bias won't be perfect?

Please help me
thanks

[sasquatch]

If you're going to use only two power tubes and play in 1/2 power (50 watt) mode... you should bias it with the amp set up that way.

[splawndude]

+1

was the 52mA rec' from Scott based on only 2 tubes? I run my amp at half power but on EL34s. I made a biasing tutorial that is now in the FAQ that might help. Honesty, you should check the bias and adjust it anytime you change or swap tubes. Running half power and then blowing two tubes is a sign to call Scott. If my amp blew two tubes I would def inspect the sockets and the board itself for damage. Retube and then rebias. Not an amp tech here - just what I would do out of gate.

[banenis]

I don't know if it's important but doesn't the nitro run at 120 watts and 60 in half power if you're using kt88s and 100/50 with el34s? I'm not an tech savvy when it comes power tube tech stuff but I just worry about setting things up assuming I'll be at 100 watts when it's actually 120. I plan on retubing mine after Christmas and I don't know if the wattage is pertinent to proper biasing but this seemed like an appropriate discussion in which to ask.

[splatter]

Nov 28, 2010 12:07:01 GMT -5 banenis said:

I don't know if it's important but doesn't the nitro run at 120 watts and 60 in half power if you're using kt88s and 100/50 with el34s? I'm not an tech savvy when it comes power tube tech stuff but I just worry about setting things up assuming I'll be at 100 watts when it's actually 120. I plan on retubing mine after Christmas and I don't know if the wattage is pertinent to proper biasing but this seemed like an appropriate discussion in which to ask.

the fact that it is 120w instead of 100w has nothing to do with how to bias it . However I do agree that if you are going to run it at 1/2 power all the time you should bias it at 1/2 power . just so you can get a more accurate reading on what the amp is doing .