Introducing our newest design...
MODEL 50A Interstage Transformer driven KT88 Monoblock Power Amplifier
There is a story here, and it goes like this:
In 1954 The Fisher Radio Corporation designed an awkward looking duck, called the Model 50A. It was an amplifier that cut very few corners. It used an interstage transformer to drive a single pair of triode mode power tubes . It got about three times the power normally available from a pair of triode-wired pentode output tubes.
It used dual tube rectifiers and had a choke-input power supply, among other niceties. The net result of all this, was an ultra sweet , dimensional, powerful sounding amplifier that ran the power tubes very conservatively.
I had the good fortune and opportunity to rebuild some original 50A units. The more I listened , the more I came to understand that the sound was special, and the set of design choices made by Fisher in 1954, were still as impeccable as they were 50-plus years ago. The more I thought about it, the more I wanted to build an amp that embodied the essential features of the original 50A, with some taking advantage of modern capacitors and materials.
Design Summary
*40 Watts RMS Output, 4, 8 ohms (16 ohms available).
*Dual tube rectifier, high current power supply, very soft starting
*Choke Input power supply
*Interstage transformer final signal drive
*Triode wired KT88 output stage
*Tube regulated bias power supply
*Onboard bias meter
Preliminary dimensions 16"L x 9" W x 9-1/4" H, Weight 42 lbs.
Tube Complement:
2x KT88 (6550, 6L6, El-34)
3x 6CG7
2x 6CL6
2x 6CK3 (among other similar rectifiers with 9-HP pin basing)
Basic Model US Retail per pair , $7250.
"Special" model with upgrade transformer set , price T.B.A.