2204 to 1959 questions

[Just Mike]

I built a 2204 and I'm starting to tweak it. I decided to go plexi with it and I'm a little befuddled with what to do with the 2nd half of v1. With nothing tied to it, won't it create hum? I guess I need to somehow "disengage" it. Pointers please..
Thanks.

[neikeel]

V1a is the normal channel, with a 250uF capacitor and 820R resistor, it has 100k plate resistor and 0.022uF output coupler and goes to a 1 Meg volume pot (lug nearest inputs). The middle lug (wiper is hooked up to a 470k resistor on the board - the one that is not bypassed with a 500pF cap.
V1b is the bright or lead channel with a 0.68uF capacitor and either 820R(early) or 2k7(post 68) resistor. 100k plate resistor, 0.0022uF output coupler tied to the first lug of the 1 meg volume pot which has a 5000pF ceramic disc capacitor across that lug and the middle lug, the middle lug is then connected to the 470k resistor on the board which has the 500pF bypass cap across it.
That is stock 1959. Are you trying to do something different?

[Just Mike]

WHat should I do if I'm not going to use the normal channel? I just want a bright channel input.

[neikeel]

If you are just using the normal channel I suggest you simply ground the V1a coupling wire (the one that would go to the pot first lug on a 1959.
I recommend the preamp section of this to you:http://home.comcast.net/%7Ejbjdav26/Nei ... 202in1.pdf