Sonic Farm Pro Audio Xcalibur JC

There is a shielded power supply and voltage regulator board-all DC voltages, even the tubes' filaments supply, are regulated. There are inputs for balanced microphone, line level, and a front panel ¼-inch jack with 2.2 meg-ohm impedance for unbalanced keyboard instruments or guitars and bass. The summing/mixer/output stage in the JC has a variable Output level control and uses a TI OPA2604AP op-amp chip for summing and mixing. In the OT mode (Output Transformer), the chip drives the i:i primary of the output transformer that adds no gain. Because of a compact iU front panel with not enough space to spell out the controls' full names, I quickly learned the abbreviations and the signal chain order.