I sent Wayne an updated Merlin schematic, along with the TX coupled unity gain linestage. Hopefully, he'll be able to post them soon.I am waiting for my modified Peerless S265's to arrive from Heyboer. I figure some time soon...:) Still trying to find a matched pair of plate Iron for the new amp. I need 1k2-1k3 VCT at 300 mA or so, plus filter chokes.
On the new Merlin schematic, I forgot the Zener clamps for the gate-source voltage protection. 18V Zeners. Cathode( the banded end ) to the gate, anode to the source of the IRF820. I also left out the CCS details. They can be brought forward from the original.
I investigated some 500 mW types from Mouser. Wide variation in impedance, and leakage. I went for a low Z, low leakage type BZX55C18, when BZX79C18 was not available. Small diff between them, but a large diff from the 1N**** type. Lots less leakage, and impedance. It does pay to read the data sheets carefully.
Anyway, lots of cool stuff to play with, and I am getting good sound.
cheers,
Douglas