George,VelvetGeorge wrote:A work in progress.
In order to trace the evolution of the superlead circuit, and to help us communicate about the different eras. I'll try to chronical it here.
I'll update the info as I have it.
'65 the JTM45/100
100 watt version of the JTM 45. Also called "Super Amp". 1202-84 Drake OT (8,16, 100V taps) 4k primary. KT66's. Radio Spares or 1204-43 (3" stack) PT.
Standard JTM 45 circuit. Shared Cathode. 270k mix resistors.
27k NF. .1uf PI caps. 56K/250pf in tone stack.
Non-voltage doubler PT. Bright cap varies by model, but 100pf seems most common.
Late '66 to early '67 Transistion to EL34's, steel chassis and gold rear panel. Earliest JMP's.
Still 2" Drake OT, the 1202-119 (8,16 and 100V taps) or 1202-132 (4,8,16). Both with 1.7k primary. Sometime in '66 the Drake 1203-80 voltage doubler PT came in to use. More research needed on PT's.
Filtering now is 100,100, 32,32, 32 (mounted on chassis), 16,16 (on board).
470k mix resistors. 56k/250pf tone stack. .1uf PI caps.
Mid to late '67 Change to Dagnall 1.5" OT's.
Most other specs the same for a transitional time peroid leading up to the 12000 series.
Very late '67 to early '68. The 12000 series plexis. Named for the serial #'s in the 12xxx range. EVH's famous amp is from this era.
Now we see the first split cathodes using a 820/.68uf combination. Normally with a 820/.68uf in V2 as well. The Tone stack changes to the 33k/500pf arrangement. 47k NF. .022uf PI caps. .0022uf cap in the bright channel V1.
Late '68 to July '69
All filter caps now mounted on top of chassis. The .68uf cap in V2 shows up intermitantly. And the 2.7k replaces the 820 in the split cathode on V1.
47k NF resistor.
Filtering is now all dual 50uf cans.
July '69 The metal panel era begins.
what was the advantage of the filter caps changing from 100,100, 32,32,32/ to 50uf cans?