Technics SU-8080

Technics' heyday, contemporary of the RS-7500 or RS-9900US mammoths and companion of the equally mid-end ST-8080.

The SU-8080, or 80A by its traditional Panasonic nickname, holds a first stage differential amplifier, a purely resistive loaded voltage amplifier, an emitter-follower and a two-stage Darlington-connected fully complementary output.
There isn't a single coupling capacitor anywhere.

The main source for the entire planet, then, was long-play records and the related input stage was designed with care so as to lower inherent noise and allow a wide dynamic range : ± 1% tolerance metalized film resistors and ± 2% polypropylene capacitors only, surrounding a pair of M47L transistors in differential amp structure with a current mirror load.

The line level stages consist of a first stage differential amplifier with current mirror loading and "Technics' unique dual packaged transistors which are well matched for thermal stability".

The power-supply is 1976 healthy with two transformers, four 80V / 10,000µF caps and two separate rectifier circuits.
There seems however to have been three types of transformers used, perhaps to cater for differing local electric standards ; the all have the same size (visually at least) but their respective top cases look quite different...

High level inputs can be routed directly to the power amplifier section without going through any other circuits.
The attenuator uses "1% tolerance metal film resistors in the NFB loop of each channel's amplifier and maintains gain difference within 0,5dB."

Also cared for was the muting circuit : it is here accomplished by altering the final stage's NFB by 14dB, instead of adding resistance after the attenuator. The result is that dynamic range isn't lowered by the use of the muting switch.
This allows an extended and more progressive attenuation range when the input source has a very high output level - wish I had that in my current Wega 42P powerhouse !

Output transistors are Toshiba's 2SD427 / 2SB557, one pair per channel, mounted on sizeable heatsinks.

Relays however still had to kick in to shorten signal paths and New Class A and exotic capacitors and copper shielded R-Core transformers and... etc.
But the 80A already was (is) a strong mid-end performer, very good looking (when in good shape) and quite fair sounding, too, when brought back to spec.

Available in Europe until 1980, by which time the 80A was, in Japan, an old thing from the past.



Lots of nudies here.