ShinyFalcon

All the inputs are balanced. I left the inputs floating when I tested, potentiometer was already installed, but I haven't tested since then. I used O+ and GND, but all combinations of GND from star to earth ground didn't change the noise much, and sometimes louder on one side depending if headphone return floats or not. When I tested unbalanced phones the transformer was chirping occasionally, so maybe some instability.

The board is the revision with the gate resistors. Removing the current limit transistors helped. The transistors did check out OK though, so I don't know. Shortly after installing the opamp I had to remove the positive rail transistors as well. Anyways, amp is making music and sounds great! Can unbalanced headphones be made to work on fully balanced amplifiers? I get lots of noise when I try on the balanced Dynahi, which I assume is due to the servo.

I'm having a similar problem with jwzhan, the negative rail is ~0V and the positive rail is +30V with the Dynahi as load, negative LED slightly brighter than positive LED, both dim. On first power-up, no load, the 1N4007 diode on the negative rail was incorrectly soldered (- end on -30V, + end on gnd), so negative rail went to 0V. I swapped that diode against the silkscreen (+ end on -30V, - end on gnd) in agreement with the schematics on the first page, and voltage is +/-30V. Also, if I install the 20k dual tracking resistor, negative rail goes to -40V. Maybe something blew in the process. I have another PSU that wasn't turned on before the diode swap, but waiting for some 10V references to come in. I'll assume that the outermost trimpots are the ones in parallel with the 500 ohm resistors. Both of these reach max resistance of 1.3kohm (measuring outer pins) when both turned completely counterclockwise, and decreases when trimpot is turned clockwise. I can't measure the resistance of the middle trimpots, it reads a constant 0.8 kohm, so I just set them middle of the range. PCB revision is 0.2 for the PSU, and 1.0 for the Dynahi.