This amplifier is replica of Gakuoh amplifier based on the schematic in 90 years of Gakuoh I, using 300B tube in pushpull mode. Prestage, driver stage are 5687 tube. Rectifier tube is GZ34.

All transformer are vintage HIrata TANGO, there is only one version because it is impossible to get the same transformers.

Price for order made the same one with the same grade of transformer is 4350USD. Tubes are not included.

Input stage is plate follower and direct connection cathode follower by 5687. Classic type phase inverter circuit is chosen for good balance of naturalness. 300B power tubes are fully driven with low impedance by 5687 in parallel configuration.

Only very low -3db NFB to make the low frequency more stabilize. You can remove NFB if you dont like.

Because the quality of transformer, the max output per channel is 25W, it can drive almost speaker without problem.

Response frequency : 16Hz - 80KHz(-1db)
Hum level : 0.3mV
THD: 3% @ 25W/channel

You can order copper plate for top plate or iron chassis instead of wooden chassis