I picked up a couple of valve PA heads on the cheap, without valves, so jotting down a few notes for later. I believe that this is almost the same as a Philips 982, based on early observations.
The preamp was converted to something very similar to the Marshall 18w, with two inputs, volume, tone and a master volume (which I usually leave wide open, but it’s nice to have). The two input channels each go to a side of the 12AX7 preamp, with one input running both in parallel. The output section is now running 2 x 6L6 instead of EL34s and the transformer was rewired to provide a 4 and 8 ohm output at close to 6.6k P-P. The 4 ohm is 7.1k and the 8 ohm is 6.4k.
STEANE’S SOUND SYSTEMS MODEL S 311 VALVE PA AMPLIFIER
VALVE LINE-UP
INPUTS / OUTPUTS / CONTROLS
TRANSFORMERS
More wax paper coupling caps – at least the rest looks clean and there’s a decent amount of space to work in the chassis. Despite the pots looking very corroded, they still very smooth to turn.
Ducon electrolytic caps seem to be common in a lot of Australian amps. In my limited experience, they seem to be OK after they have a chance to reform. Fingers crossed that these will be the same.
UNDER THE HOOD
