In short, the 2A3 cathode bypass cap (C4)is has been lifted off ground and repositioned in the conventional ultrapath configuration. One note: C4 is now a slightly higher value with increased power rating. I wanted to share that this works extremely well, and truly does sound more detailed, present, immediate, etc., etc. I have always wanted to experiment with some interstage coupling, and this may be the perfect opportunity, as well.
Also, the 125K ohm attenuators I put on the amps have their respective input and wiper lugs bypassed with 47pfd. silver mica caps. I have been doing some research on guitar amp. mods, and found that this indeed assists the 'passing' (as in a high pass filter)of high frequency information and transients at lower volume levels. This is done effectively without compromising (in my opinion)the overall frequency balance of the amplifier. This is just sort of tuning an amplifier to one's personal taste -- like seasoning food to taste, as it were.
I'm planning on building the original DRD amps sometime when I can afford the transformers, 'specially those OPTs with silver secondary windings.
C5 (input stage cathode bypass cap)has also been removed, despite warnings against it. I have found no loss in gain, but greater detail once again. The frequency balance is not over-etched as I anticipated, and I even use inexpensive $35. mylar coupling capacitors. I have used Hovlands and Solens and other much more costly, and honestly prefer the cheapo mylars.
I've also completely redone the grounding scheme on the amplifiers, but that might be another story some other time -- maybe not.
Have fun, I look forward to hearing what builders say about the new DRD amps. The wiring dress on the DRD circuit shown is very nice.
Erik
