Just to give a little more point to a peculiarity of AC30/6 chassis produced in late 1961 and early 1962. Some, if not all, have a "phantom" hole for the rectifier valve, wrongly positioned. A blank disk of metal was welded in to seal it up. The two extraneous screw holes for the valve base surround were left unfilled. AC30/4 chassis do not seem to have this peculiarity.

In terms of serial numbers, the span is from AC30/6 number 4763 (black panel) to number 5156 (copper panel).

Whether every amp in this range has or had the phantom hole is not known at present. A run of 300 of more would be fair number to get wrong. That the mistake - made by a new "chassis bender" / assistant (?) - coincides fairly closely with discontinuation of the AC30/4 certainly suggests there is a story to be told.

Serial number 4763.

Serial number 5002.

On to AC30s with serial numbers in the 6000s .

Back to AC30/6s with serial numbers in the 4000s (black control panels).