If your interested, the Roughneck is a Fender 5F1 champ (Geralds favourite Champ, mentioned in his first book) with these mods: 

1.The cathode bias cap is increased to 100uF@100v 

2.The feedback resistor is increased in value to 56K, instead of 22K. 

3.The first 12AX7 stage has the cathode resistor bypassed by a 25uF@25v cap. 

4.Gerald doesn't use a 12AX7, he uses a 5751 tube instead. 

5.The input stage doesn't consist of a 1Meg resistor and two 68K resistors going to the grid of the first tube.

  The 1Meg resistor is removed, the 68K resistors are replaced with 470K resistors, one of these 470K resistors has a 250pF silver mica cap across it. 

   The shorting terminal on the input jacks,are connected to earth so that when one user is using the amp the first stage always sees a 470K grid leak resistor. 

   From the guitar output you get a 470K resistor in series followed by a 470K resistor to earth (grid leak). So the 250pF cap provides trble boost or shunt. 


6. Gerald also recommends a silver mica cap across the volume control (100pf to 250pF) for those who require more brightness. 

More notes:

Regarding construction, the amp uses all 1/4 watt carbon comp resistors, the filter caps are Sprague Atoms, the two decoupling caps are Orange drops (forgot to check which series). 

Here are relevant voltages; 

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Amp using stock 6L6 and GZ34 tube. 

mains voltage at the time of testing; 245Vac. 

rail to O/P txer; 404Vdc 

rail to O/P valve screen grid; 361Vdc 

rail to preamp; 306Vdc. 

AC voltage across mains TX secondary; 667Vac. 

voltage on preamp plates; 187Vdc. 

voltage on preamp cathodes; 1.82Vdc. 

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Voltages using 5Y3 rect and 6L6 tubes. 

rail to O/P tx; 368Vdc. 

rail to screen grid; 325Vdc. 

rail to preamp tubes; 279Vdc. 


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Voltages using 5Y3 rect and 6V6 tubes. 

rail to O/P tx; 382Vdc. 

rail to screen grid; 332Vdc. 

rail to preamp tubes; 283Vdc.