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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
jea48
2,944 posts
 
I just went through Collins site.... I am sure glad I bought the VT50.

I can not speak for the VT100, but for the VT50 for about the first 10 to 50 hours of tube burn in, for the EH6550 power tubes, I reset the bias trim pots about 6 times , a pain in the butt. I did not notice if Collins mentioned anything about readjusting bias pots after burn-in of the new tubes.

Maybe others who have posted can respond on readjusting bias after burn-in.

You may want to check with ARC. Is ARC pre-burning in the tubes....

Jim
gmorris
351 posts
 
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.
audphile1's avatar
audphile1
1,368 posts
 
Another advantage of getting tubes from upscale is that they run the tubes in for 72 hours before doing any matching. At least they do that when you get their platinum grade. So I think you can expect the tubes to be stabilized by the time you receive them. I don't know if Research runs the tubes in before doing adjustments, but I would think that they do. At least this would be logical to do on their part. ARC should tell you though. Good luck.
jea48
2,944 posts
 
>>"Another advantage of getting tubes from upscale is that they run the tubes in for 72 hours before doing any matching."<< [Audphile1]

My Son bought me a new set of EH tubes from "The Tube Store" for my VT50 last Christmas. Obviously they did not pre burn-in the tubes before they tested them.
I will try upscale the next time.
audphile1's avatar
audphile1
1,368 posts
 
Jea48, Upscale's a little bit more money, but I think it's worth it for what you get from them.
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