Biasing 6V6's

[ibenhad]

So I finally got my plate voltages (395-400) and replaced the 6L6's in my amp back to 6V6's that it was originally built for. I can't get the bias (using a bias probe) above 11.5 ma across both tubes. Any ideas?

[GearHeadFred]

Whoever installed the 6L6s probably changed a resistor in the bias circuit to be in the proper range for 6L6s.. What type of amp are you working with?

[ibenhad]

Thats the problem, it's a kit amp??? I am not sure. What resistor would I change?

This shows the bias circuit I hope:
http://i247.photobucket.com/albums/gg155/ibenhad/board2.jpg

[WaltC]

your amp has individual adj. pots for each tube and you'll probably need to adjust the value of the two 47K resistors at the top of the board (one for each tube). It's easiest using a decade resistor box, but you can get there using trial and error.

[ibenhad]

WaltC (http://www.thegearpage.net/board/member.php?u=11108) thanks for the help. I wish they were individual adj. pots but one is a bias balance control for matching tubes I believe. What exactly is a decade resistor box? Yes I will google it but if others are reading this post they may be too lazy and it is good to know. What value would you replace them with?

[skipm45]

Here's one. It's pretty cheap and has a wide range
http://www.allspectrum.com/store/product_info.php?products_id=390&osCsid=a7eb50d69aee5881dda99533f6f24e1b&sdesc=Resistor+Substitution+%2F+Decade+Box%2C+1%25 +1W+Model+%23+RS-500



HTH

Skip
www.skipzcircuits.com (http://www.skipzcircuits.com)

[GearHeadFred]

Obvious question... but do you have a schematic?

[ibenhad]

This was a kit amp that someone built. Not even sure what kind. Was told it was a Trinity by the seller but I don't think it is. So no I don't.