So with the 6CY7 V2.0 Zebrawood amp finished and my 6L6UL project on the back burner, I’ve been working on a new SET amplifier. I have been thinking about an amp somewhere between my small SETs and the big 6336 SET amp. But I’ve run into a hiccough.
When I first started working on the 6336 SET I was looking for an answer to the very low sensitivity of the big power triodes. My solution for that amp was the cascaded driver documented here and here. Well, that solution worked out so well in the 6336 SET that I decided to use it in my new amp as well. And this is where the trouble started.
I settled on the 6AS7/6080 as the power tube for the new amp. This is a dual triode pass tube like the 6336 but it is a much simpler tube with which to work. The power levels in the filament and plate dissipations are not nearly so extreme so it runs significantly cooler. It also doesn’t require the kind of warmup time that the 6336 does. And best of all, it has the same pinout as the 6336.
So at first I decided to simply use the same basic layout for the amplifier top plate as the 6336 amp. I took the same 12 1/2" by 9 1/2" layout used for the 6336 and modified it for different transformers and choke. And at first I was happy with my design. But there were a few issues with the wiring layout that I had not worked out. So I put it aside for a while.
When I came back to it after a couple of weeks, I had a mental shift and decided that what I really needed was a more simple layout like the Marblewood. So I spent yesterday coming up with an entirely new layout based on the more open Marblewood design with the primary filter choke below the plate. And when I finished the internal layout and worked out all the problems, I didn’t like it.
And now I’m at an impasse. I have two separate layouts for this new amp, with neither am I particularly happy, and I need to decide how to get myself out of this particular dilemma. I have an idea on which way to go based on the iron I already have on hand, but I’m not completely sure yet.
So what do other people do when they run into this kind of design impasse? I had to order a couple of 2.5kΩ output transformers from Edcor for the new design, so I have about six weeks to come up with a layout solution and choose some hardwood for a chassis.
I’m interested in what other people have to say. Any suggestions on what path I should take? And why?