Help with re-tubing an ARC VT100 MkII


It's now time for me to retube my Audio Research VT100 MkII. It appears that it's no big deal, if I only want to retube the power tubes. However, I think its time to retube the input tubes as well.

Can anyone offer any advise as to:
1) Should I just spend the reported $700-$800 (seems expensive to me) and send it to ARC?
2) Can anyone offer an alternative to No.1 (I don't know anyone here in Memphis, TN that could do it)
3) Any suggestions as to what brands/types of tubes to replace the old ones?

In advance, thank you!

Louis
louisl

Showing 2 responses by gmorris

Jea48

I retubed my VT100 MKII using the instructions above from Collins. A matched octet(8) from Upscale audio will cost about $240. A set of 8 low noise input tubes 6H23 (6922) will cost about $200. Total $420 plus shipping. You may want to speak to kevin Deal at Upscale. You must use input tubes with close tolerances.
Louis:

The biasing of the input tubes is very tedious and requires several iterations to obtain the optimal settings. It is easier if you have two digital voltmeters and several clip-on cables for the test points. You must bias the input tubes first.

For the output tubes use a rough setting prior to burn-in. There will be some drift of the bias as the tubes burn-in. You need to repeat the final bias after the tubes are sufficiently burned in.