There is some debate about how to interpret the production code information on late ‘50s to mid-1967 tube charts and Greg Huntington is still working with those.
Also note the vertical black lines on the control panel (found on earliest silverface amps) and the large ceramic power resistors coming off the power tube sockets which indicates the AB568 circuit. But really, these cabs were large because they were of a “special design” that “greatly improves tone and volume without distortion, and permits optimum performance of the speakers.” At least that’s the reason according to the ’69 catalog.
Also, another thing I’ve never seen before is a what appears to be a shipping tag of some sort (see photo).
These are marked with EIA code “606” which is the company number for Schumacher.
Well, this universal “truth” was debunked when we found a bunch of amps with transformers made by the Better Coil and Transformers company.
Mid-1968 Super Reverb export model modified by Hagstrm for the Swedish market.