Hi,
That picture appears in Mo Foster's Excellent book Seventeen Watts, it's a
much clearer copy, the caption says it was in 1960, no date.
Logically it makes sense to use lower power amps in recording studios but as has
been said many times, and AC30/4 makes the same noise as the AC15 because it uses
the same front end as the AC15, with a few minor component differences.
Hopefully I'll get up close and personal with Phil Kelly's TV front AC30 Twin tomorrow!
Amanda