Tube Experts -- Help with Retubing AR amp


Although I've owned tube preamps for some time, I'm just getting into tube amps. I recently purchased a VT-100 Mk. II, and need some help.

Audio Research tells me that only they match tubes completely. They claim that their tubes are measured for transconductance and low grid current. They claim many of the large tube dealers don't do this, and that the high percentage of rejects AR sends back to Sovtek (6922) & Svetlana (6550) get sold to these guys.

I don't want to pay AR's outrageous prices, but I want to get some well-tested and matched tubes. Particularly, I want to put KT-88's in. Many guys recommend Svetlanas, although they seem to be twice the price of the Sovtek KT-88s.

Besides some tube recommendations on experience, who will provide closely matched tubes besides Audio Research? l don't believe many suppliers do more than simply do a quick burn and measure, and do not really measure the parameters AR claims to.

AR also stated that the input & driver 6922's they use are closely matched, triode to triode, and that this is necessary for the optimum sound from these sections. When I asked about whether I could replace the 6922's myself, they indicated that they could provide the information on doing this, but said it was quite complicated. Any VT100 owners know about this?

I would greatly appreciate any help you tube maven experts could provide. Thanks! And long live vacuum tubes -- nothing compares.....
kevziek

Showing 1 response by abecollins

I would recommend getting TWO sets of matched quads for the power tubes. I used Svetlana 6550C's in my VT100 MKII. For the driver tubes I chose JAN-Philips 7308 Low Noise. You need 8 driver tubes and I had 12 on hand to get a reasonably good match. Adjusting the power tube bias is very simple but the driver tube adjustments are a bit more involved. I bought all my tubes from http://thetubestore.com and had no issues but you will likely get better match quality from Kevin Deal at http://upscaleaudio.com. You can check out my website with more info and pics.

http://mycollins.net/audio/artube1.html

Good luck!