The Stancor original Williamson and Williamson Ultralinear amplifiers were kits marketed by Stancor to showcase the performance of their transformers. They used a separate power supply chassis connected by a 4 conductor cable. A pair of these makes a great sounding stereo power amplifier. The Ultralinear is much preferred because the power output is much greater. 25 watts vs. 8 watts.
I rebuilt a set of these, and can attest to their fine performance.
I cut pieces of circuit board material into the shape of the original capacitor bases, and drilled holes for the new capacitors.
At Right: The new next to the old.
Below: An amplifier chassis with the new capacitors.
One of the originals was a dual capacitor, so my replacement has 2 capacitors, too.
I made covers from sheet steel and attached rubber feet to them
The modern cords and the steel bottom covers make these amplifiers much safer.
Ultra-linear circuits are easy to identify by the number of transformer leads going to the output tubes. Ultra-linear circuits have 2 wires to each tube, while other circuits have just one. If you find a Stancor chassis with the labels missing, this is how you can tell which version you have.
The amplifier has sockets to measure and balance the plate currents on the 807 output tubes. This is important for two reasons. One, balanced current is important to achieve the lowest distortion. Another good reason is to verify that the tubes are not using too much current. This happened to me. C4 was bad. If C4 or C5 are leaky, the grid bias voltage will go positive, and cause the tubes to draw excess current. Drawing only a little too much will cause the plates to glow red to an excessive degree..
The power supply is simple. The supplies are only large enough for a single amplifier, and will overheat if two amps are connected to one power supply.