7581A Tubes in Super Reverb

[ckpop]

Need a some help with my bias math using a JAN 7581A in a super reverb amp. Plate voltage 468v, Current draw 40ma for around 18watts.
Looking for the formula for to figure out what percent of where I am at of the 70% of class AB1. The 7581A is a 35watt tube.
Need to brush up on my formulas. Thanks

[Rob Livesey]

Hi,

I picked up a handy spreadsheet from somewhere years ago.

Just edit the info and it gives you a nice graphic for percentage dissipation.

http://www.roblivesey.com/download/load.xls

Rob.

[JazzGuitarGimp]

Hi Ckpop,

Presently, you are at 18.72 watts (468 x 0.040). If you divide the measured dissipation (18.72) by the tubes' max power (35 watts) , that will give you the percentage of power dissipation, so:

18.72
-------- = 53.9%
35

Cheers,
Lou