FS are a pair of NOS finished calibrated and tested Jean Hiraga 20 W class A amps. Good way to try out the amp without the hassle of building it and optimizing it. Price $140 for the pair. Two more pairs are available. These were only used during dial in which required mounting them on the heatsink and connecting them.
Modern Toshiba and Sanken (genuine) semiconductors were used. A high precision trimpot was introduced for fine tuning. This is a plug and play board and gives a few mV DC offset on the output. The PCB was redesigned for short signal path and large vias with custom C-channel heatsinks for excellent thermal stability. The +/- supply, ouptut and ground are designed to be screwed on the wire crimped loop terminals. The inputs are solder on.
All that is needed is a CRC-type power supply and a good enclosure with plenty of heatsink. They were setup to match the original Hiraga 20W bias numbers, approx +/-20 V rails and 1A bias. The components are barely breaking a sweat.
input pairs: toshiba 2sa1016/2sc2362
drivers: toshiba 2sc4793/2sa1837
output: sanken 2sc2922/2sa1216
Modern Toshiba and Sanken (genuine) semiconductors were used. A high precision trimpot was introduced for fine tuning. This is a plug and play board and gives a few mV DC offset on the output. The PCB was redesigned for short signal path and large vias with custom C-channel heatsinks for excellent thermal stability. The +/- supply, ouptut and ground are designed to be screwed on the wire crimped loop terminals. The inputs are solder on.
All that is needed is a CRC-type power supply and a good enclosure with plenty of heatsink. They were setup to match the original Hiraga 20W bias numbers, approx +/-20 V rails and 1A bias. The components are barely breaking a sweat.
input pairs: toshiba 2sa1016/2sc2362
drivers: toshiba 2sc4793/2sa1837
output: sanken 2sc2922/2sa1216
