I have owned this tube amp for over 4 years now, with the tubes still going strong despite putting about 15 hours/week on them.
Still, I don't doubt this is perhaps the most difficult tube amp to bias out there. And, while most people consider my AtmaSpheres hard, I find them a walk in the park. Autobias wouldn't be a bad thing...
Below are the instructions, minus the big warning about high voltages - you shouldn't try this at home, and an illustration that I obviously can't show in my post. Enjoy!
===========================================================
1) See accompanying diagram representing only one channel.
2) Using a digital voltmeter measure the voltage closest to the resistor(5U62, found on the route between the tube and the output transformers, you're going to measure the voltage across the resistor - TRELJA) until the meter reads between 95mV and 120mV(preferably 110mV) as you adjust the 22KOhm pot(outside the 2 tubes - TRELJA).
3) Using another Digital, connect the leads to pin 3(yellow wire) on the output tubes of the same channel. Adjust the second 22KOhm pot(between the 2 tubes - TRELJA) until the reading is close to 0.0mV. This adjustment may change the first reading, so adjust both pots until the readings are correct.
4) Do the same for each channel.
5) Very important. Please note that changing the tubes on any Orchestra unit requires very fine adjustment in order to prevent any damage to the amplifier and to insure continued excellent musical reproduction.
===========================================================
Still, I don't doubt this is perhaps the most difficult tube amp to bias out there. And, while most people consider my AtmaSpheres hard, I find them a walk in the park. Autobias wouldn't be a bad thing...
Below are the instructions, minus the big warning about high voltages - you shouldn't try this at home, and an illustration that I obviously can't show in my post. Enjoy!
===========================================================
1) See accompanying diagram representing only one channel.
2) Using a digital voltmeter measure the voltage closest to the resistor(5U62, found on the route between the tube and the output transformers, you're going to measure the voltage across the resistor - TRELJA) until the meter reads between 95mV and 120mV(preferably 110mV) as you adjust the 22KOhm pot(outside the 2 tubes - TRELJA).
3) Using another Digital, connect the leads to pin 3(yellow wire) on the output tubes of the same channel. Adjust the second 22KOhm pot(between the 2 tubes - TRELJA) until the reading is close to 0.0mV. This adjustment may change the first reading, so adjust both pots until the readings are correct.
4) Do the same for each channel.
5) Very important. Please note that changing the tubes on any Orchestra unit requires very fine adjustment in order to prevent any damage to the amplifier and to insure continued excellent musical reproduction.
===========================================================