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VT100mk2 - Retubing

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Hello everybody. My first post here
So. Having failed to find in my town a technician available or reliable to make the retubing of my ARC VT100mk2 I decided to do it by myself following the instructions on the web: Stereo Setup 2001.

While adjusting the bias on the two quartets of 6550 power is simple, the problem it is rather complicated (for me) for the calibration of the tube bias driver 6922 because you need to adjust the two trimmers for each channel on the points R7-R8 and R 11 R12-so that the difference is not greater than 0.01 mV.
Questions:
- Could i only adjust 6550 quartet and leave unchanged 6922 bias?
- Is it necessary that the 6922 is a matched quartet (hard to find) or two matched pairs are the same for each channel?


Sorry for my bad english
 
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