Tethys is an exceptional head phone amp design, capable of being matched up with most head phones available on the market today. Two head phone impedance levels are available, selectable by the user, Hi/600 OHMS and Low/150 OHMS.
The amp circuit is extremely simple, using the 6922/E88CC in a push pull configuration driving the excellent Lundahl LL2765 ouptut transformer.
A CCS, Constant Current Source, is used in the cathodes. There are no coupling capacitors or feedback used in this circuit.
Power Supply:
The all important power supply is the opposite to the 'simple' amp design. This is a MOSFET based regulated B+ power supply with exceptional low noise. The DC filament too is regulated. This results in an ultra quiet power supply that is extremely stable.
AC power is supplied by the excellent Lundahl LL1683 power transformer.
Tethys can be wired for either 120V/60Hz or 220-240VAC/50Hz.
Only high quality components are used in the construction of Tethys. Low-noise Vishay  metal film resistors are used with high quality Panasonic metal oxide resistors in the power supply circuit. WIMA film and Wurth, Nichicon and Panasonic electrolytic capacitors are used throughout the power supply.
The printed circuit board is designed in house and manufactured to FR4-TG standards, and are double-layer with a full top ground plane to ensure complete screening of the circuits.
Tubes are a pair of matched Genalex Gold Lion Gold Pin E88CC's.
General specs:
Amp approximately 100mW
User selectable head phone impedance, 150 OHMS or 600 OHMS
Chassis - 11" x 10.5" x 8"
Chassis weight : 22lb
Warranty: 2 years on the preamp, 6 months for the tubes