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LT1084 / LT1033, but they are limited to 3A. Alternative solution can be a simple Cap Multiplier using
Sanken 2SD2390 / 2SB1560 Darlington’s. The base should be driven by an On-Semi TL431 or Vbe-
multiplier configured for 26.2V, resulting in 25V rails. This should be fed by a J113 degenerated as a
5mA CCS.
The schematics below is borrowed and adapted from Geoff Moss’s excellent JLH Class A site. If you
intend to use the M2 OPS mostly in Class A/B, then a much larger C5,6 will help to reduce rail sagging
during high-current transients.
Power WHAMMY ?
Can I use this in combination with a simple frontend VAS ? How about a WHAMMY Power Amp ?
This is easy to do. All you need is to find a JFET input opamp (e.g. the beloved OPA552) that can take
say +/-30V rails. And then replace the WHAMMY output stage with this.
But how about distortion ? The input impedance of the M2 OPS is about 25k, so any opamp should
have no problem driving that. But the OPA552 has an open loop bandwidth of 10Hz. Thus, distortion
increases with frequency. With a gain of 14, distortion at 2.8Vrms, 1kHz is about 0.005% for the
opamp on its own. Still not bad.