Jadis Orchestra Reference bias adjustment?


I would be very grateful, if someone could explain me (in easy terms),
How to check and adjust the bias setting on my JOR with KT-90 tubes.
maresmares
Trelja what label 88 are you usig? I bought a quad of Electro Harmonix 88 (EH88) and sounded like c**p. Seems not all tubes are the same. I may try the JJ77's I've heard good things. Or JJ88's, or both. Keep one sell the other.
Robert, I sent you a few photos, illustrating the respective resistor. Let me know if it's not obvious. You just do this for each tube... Once you get the hang of it, you can almost do it in your sleep. In fact, I had my daughter do it for the pictures - she was 12 years old at the time.

110 mV is applicable for whatever output tube you are using in the JOR. Please note, you cannot use 6L6 (5881/KT66) variants. If you can (or, Pierre), please let us know if your experience in rolling the 12AX7/5751 drivers impacts the bias settings ala the differences in gain from manufacturer to manufacturer. Unfortunately, your dealer in Thailand is incorrect in his assertion that the amplifier is autobias. It is not fixed bias, either. As you know, the bias is set using the potentiometers...

Paul, I'm using JJ KT88. This is the KT88 that Jadis sources as well. I believe they say they are special issue for Jadis, but I'm not willing to spend that kind of price premium. The EL34 tubes I use are also JJ. I'm not a fan of Russian tubes in most instances. The Chinese Shuguang/Valve Art/Penta KT88 have a lot of fans right now, and Kevin Hayes is even using them as the OEM tubes in the VAC equipment, which says a lot to anyone who is lucky enough to know Kevin. The KT77 would appeal to someone trying to split the KT88/E34L line, though in the JOR they may give up some power to the KT88 - I don't have a JOR around these days to find out.

Interestingly enough, we had a 12AX7 tube shootout at my home on Saturday morning, and the Chinese Shuguang 12AX7 came in third place out of a pretty impressive lot of six variants. I know that Pierre really hates the Shuguang 12AX7, but Jadis France and I are pretty high on it. At any rate, it's nice to see a $6 new production tube fare better than some of the most vaunted NOS 12AX7 varieties.
Thanks a lot. I really appreciate all the help. With the pictures and descriptions, it should be easy now.

ItÂ’s great to get all the support here at Audiogon
It is obvious that Joe (Trelja) has no limits to the generosity of his time and expertise. When I bought his JOR, he compiled an entire color manual of bias instructions for me. We all appreciate your helpfulness, Joe.
Though I must thank Denis for his unbridled kindness, the document I put together when I sold him my JOR was flawed.

It seemed there must have been some confusion in the translation of the biasing instructions into English, and that is what I used to bias the amp. There are 4 potentiometers in the JOR, one for each tube. The instructions I received stated setting one pot of each channel to 110 mV, the other to 0.0 mV. After having this pointed out to me, it was obvious that ALL FOUR tubes should be running at 110 mV.

I'll take full responsibility for the previous errors of my ways. I should have followed up with a confirmation of the instructions with Jadis - France, but I did not. My fault...