ab763

[selloutrr]

I used a compubias to set the bias it's 8-13w resting when played signal applied it's closer to 27 watts per tube

http://www.compu-bias.com/docs/Compubia ... ternet.pdf

If you click on the manual you can see a picture of the face that has the wattage chart for each tube.

[selloutrr]

I'm not a fan of the scope and signal bias method it's never sounded any better then using a bias probe and takes a lot longer. I like the transformer shunt method, but it can be time consuming, and the compubias the best.
I use two Compubias so I can meter up to 4 tubes in real time. and see exactly how they react and pick a happy medium if tubes aren't exactly matched. I've biased over 100 amps each way and the compubias is the fastest, safest and just as accurate as the transformer shunt since you can set the wattage.

[passfan]

I used a compubias to set the bias it's 8-13w resting when played signal applied it's closer to 27 watts per tube

http://www.compu-bias.com/docs/Compubia ... ternet.pdf

If you click on the manual you can see a picture of the face that has the wattage chart for each tube.

Well previously in this post you stated you were using Tesla's, 6L6GC and your compubias chart gives the 6L6GC for class AB1 as 15 watts to 21 watts not 8 watts to 13 watts. Somethings wrong here, check your info.

[Andy Le Blanc]

yep ... 11 what? static dissipation is not the same as a dynamic measurement.
It doesn't matter where in the circuit you get the number, your right on about the scope method.
You need a hard number from a repeatable measurement to do the math...
shunt or a known resistance is much more better, but 11W static is a bit goofy.
I go for at least 19W per tube, max plate for old 6l6 types....

if it was cathode I go balls to the wall for the tube type, 6l6gc is 35 w
the 70% figure is 24w... max for old 6l6 is 21.5w by rca data .. 11 is still cold
looking at it for older types at least 15W... most older players I know prefer it hotter any way..

I'd take another look at your approach.
Can anybody make a good argument the other way in support of a really cold bias?

[Phil_S]

I used a compubias to set the bias it's 8-13w resting when played signal applied it's closer to 27 watts per tube

http://www.compu-bias.com/docs/Compubia ... ternet.pdf

If you click on the manual you can see a picture of the face that has the wattage chart for each tube.

Please look at page 13. 6L6GC power = 30W, 70% = 21W. IMO, like everyone else says, you've got it set way cold.

[selloutrr]

My bad! I'll fix it next month when it comes back. The owner is out of town on vacation.

Though He did like the tone, cold I agree now that I looked at page 13, but still a very nice tone! It was very smooth for classical and jazz guitar since he likes a darker tone.

Thanks for pointing it out!

[Phil_S]

Ehh....in this day and age, even old farts like me have given up on actually reading the directions. We have grown used to plug n play. This is a reminder to all of us that the old tried and true technology of the printed word retains its value!

[selloutrr]

and not to hurry!!!

I was rushed with the ... "Hey buddy my amp is acting up and has a wicked ground noise can you fix it... by the way I'm leaving on vacation and wont be back for a month, can you get it back to me before I go? I leave tomorrow afternoon. "

So.. yeah.. rushed and overlooked, Thanks again for pointing it out!

I still really like the compubias! works great for house calls!