This is modification from my 6C19P DC power amp. Reference is 6C33C-B power IVC amp written as an article in MJ Audio Technology, 2016 Jun. The circuit uses only 3 tubes; one WE418A and pair of 6C33C-B.
I use a WE404A and quad of 6C19P. The schematic is as shown below.
The circuit was checked with LT Spice simulation. WE404A is substituted by ECC88(6DJ8).
The drive circuit with offset control is mead on universal PCB.
Below is schematic of power supply unit. I use 'R-core Transformer (RA series)' made by Phoenix Co. (Japan based, looks very small company, but they take any order of small lot, even only one. They will make it as per purchaser's specification(primary/secondary voltage and rating) , and deliver it in around 10 days. Excellent company!)
Below is power regulators for drive circuit. The regulators start operating when timer counts up (approx. 30sec.) Rohm's MOS-FET used for regulator output control gives good performance even for such high voltage regulation. The regulators are now significant part of the amplifier circuit.
The other MOS-FETs (2SK851) on +/- 160V are just for switching power to 6C19P, which is activated by timer relay (hard timer) with 120 sec. setting, and cut off the power when amplifier output offset detection is activated.
Below is inside power supply unit.
The 6C19Ps with OTL configuration drive the loud speaker very powerful. Low tone sound is precise and rigid, and this is one of the hallmark of the series of DC power amplifiers. I feel beauty in the quality of the sound. The music from this instrument is vivid and real as if the player performs here. This is the best amplifier I have ever made. It is also interesting that combination of technologies from USA (WE404A), Russia (6C19P), and Japan (Rohm's MOS-FET) integrates hear.
(End)
