Biasing a Hoffman Princeton Reverb

[Jerome]

I dont like guess poking around in live amp so can someone tell me where to check bias on a Hoffman Princeton reverb and what range should I put these 6V6s. This is my first 6v6 amp I have always had EL84s. This amp sounds super great! I just want to make sure its set right. Thanks!

[sluckey]

Initially adjust the bias pot for -36VDC as measured on pin 5 of BOTH 6V6s. (Higher voltage equals cooler running tubes, lower voltage equals hotter running tubes.) To facilitate bias fine tuning, Hoffman installed two 1Ω resistors on the board. These resistors connect to pin 8 of each 6V6. You will monitor the millivolt reading on pin 8 of each 6V6 while setting the bias.

Now read this page for details...

     http://www.duncanamps.com/technical/lvbias.html

[Jerome]

Sweet! All good there. Ok only issue I am having is when I turn the volume up past 6 it makes a shrill sound and cuts every thing out. This is were I should be breaking up and getting gritty but very unpleasant. Under 6 it sounds amazing! Tremolo is also a bit week.

[sluckey]

when I turn the volume up past 6 it makes a shrill sound and cuts every thing out.

Reverse the OT plate leads. Does that help?

Tremolo needs a STRONG 12AX7, so swap some tubes first. Tremolo strength is also affected by adjusting the bias. Sometimes you need to compromise between optimum bias setting and strong tremolo.