Sound City 50+ help

[WORMDIRT]

I dunno if this is in the right spot. fuggit
Ok, I have a sound city 50 plus, mark 4
2 things
1) What do I need to change to get the bias to go lower, the lowest setting on the pots is 49ma
2) What is the third potentiometer for? 2 are for each individual power tube's bias, and the third??
ok, 3 things.. Can this thing run 6550's?

Schems

http://soundcitysite.com/sc_lb50plus_schemo_left.jpg
http://soundcitysite.com/sc_lb50plus_schemo_right.jpg

[Faldoe]

ask here:

http://music-electronics-forum.com/forum.php

[Phosphene Audio]

I had one of these that an old timer repair man gave me that was pretty knackered.

Honestly, I hemmed and hawed about restoring it, but I think I made the best choice when I just took the Partridge transformers out, put them in a new chassis and started over.


The amp I built with the xfmrs is more or less a 4 hole marshall, but with only one input jack that permanently feeds both channels, as well as a master volume. I used it on every track here:

http://kdhx.org/music/live-performances ... es-4-18-14