Audio Research VT200 Biasing Schematic ETC.

Re VT-100 mkl and mkll. I prefer to use 2 volt meters. Still kind of a pain. I suggest people get some grabber test leads as it's safer rather then just using probes.

Biasing the small signal tubes is not as bad as it seems. The process is a bit finaky until you get comfortable with it, but I can do mine in about 15 mins with a single digital volt meter. The trick is to check the 60v rail voltages, and switch 2 tubes around at a time to get them as close as possible. This will make the lower mAmp adjustments easier whilst keeping the 60v rails even on the upper and lower traces. Albert does a good job of describing the process on the link. The ouptut tube bias is really easy, but keep in mind there is over 400v at this resistor!

Dischief,

Not sure about the VT200 but the biasing of a VT100 mark 1&2 can be a bear if changing the small signal tubes along with the power tubes.If done improperly the new tubes and or the amp could be damaged.

My understanding changing the power tubes only is some what simple....

You might want to give ARC a call and find out if the VT200 bias like the VT100 mark 1&2.

http://mycollins.net/audio/artube1.html
http://mycollins.net/audio/artube1.html
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Kentaja gives good advice. If you think the VT series is hard to bias you should try one of their older amps.

Biasing any of the VT series amps is a snap. The instructions clearly state the procedure and the resistors, 2 per channel as I recall, where the readings are made are on the top of the PCB right under the top cover. No need to dig around inside to find the resistors. The resistors/test points are clearly identified on the board. Can't get much easier than that.

I understand the caution and concern but no need to make a simple procedure difficult.