Audio Research vt100mkll question

I am currently using an ARC VT100 mkII in my system. The 6H30 tubes are used in the VT100 mkIII amp. As mentioned previously, you need a set (8) 6922 tubes. Upscale audio sells the 6H23 (NOS 6922) with the required tolerance/balance that are necessary for the VT100 MKII. Poorly selected input tubes will cause your 6550C output tubes to arc and take out the bias resistor.

The above article by Collins is excellent in providing guidance in setting the bias of your amp correctly.

Myron: Please tell us. What did Leonard say?

Hi Guys,
I managed to talk to Leonard who advised that there could be some perminant damage due to the use of the wrong valves, so weeping, with a screwdriver in hand I took the cover off the VT100 and found that the valves were in-fact 6922's not the 6h30's as i'd been advised by the previous owner. So kind of good news there. I suspect that the valves in situ are the original factory supplied valves and hence 5 years or so old and that the previous owner was trying to "up sell" this amp by claiming a recent upgrade etc.(not so good).

I've just bought a matched octet of jj electronics ECC88 so I'm going to replace these and bias up the amp this weekend. Looking forward to it.

After that I'm going to replace the 6550's with a matched octet of jj electronic KT88's which leonard has confirmed will work fine.

I'll let you know how I go.

i really like this amp and have heard it sound great in a well balanced system...

btw, you might find the jj e88's a little lacking in resolution....

Borg

I think it is important to note again that the VT100 MKII requires input tubes with closely matched tolerances. You may encounter problems with arcing of the output tubes with a loss of the bias resistors if the tubes are not properly pre-selected.