Adding an adjustable fixed bias to a fixed bias fender amp?

[catnine]

 There is a range resister and the other resister on a fixed bias amp . I saw on the hoffman site a way to add a 50k lin pot in series with a 10k ohm resister . Doing it his way still creates a voltage divider is that right? It offers you from 10k to 60k ohms so you will not have to change the range resister. I have two questions , lets say you dial in the full 60k ohms will this cause the power tube to idle colder? The other question is I read of a way to sort of safe guard the negetive voltage applied in case the wiper or the pots carbon path breaks for some odd reason. so this is what I came up with , let me know if this will at least do the job to a point. I said voltage divider , I meant variable resister just to clarify. Since my PT has a 50 volt bias tap and looking at other schems with this tap and 6V6's I figure the range resister can be 1k ohm and perhaps the 50 k lin pot and a 27 k resister to ground and if 27k is to much then I will go with the 10k resister to ground.

[sluckey]

This is covered very well in the Tube Amp library of information. Take a look.

[catnine]

This is covered very well in the Tube Amp library of information. Take a look.

Yes I know , that's where I found it , the idea of it in the library of info . I did the same thing except I used a heavy duty pot that I could access under the chassis since my chassis would need to be removed . The other thing I did was use the right leg of the pot and tied it to the wiper leg just in case the wiper did not make contact for any reason that the pots 50k carbon strip would still be connected to the say 10 k ohm resister to ground.