Ampeg Reverbrocket 2 GS-12R
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CJ
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CJ
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CJ
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here is where things get interesting, this is the schematic from the back panel,
notice that the tubes listed at the bottom do not match the tubes on the schematic,
according to Ken Fisher of Trainwreck fame, who worked at Ampeg during the 60's, there were so many changes made to the amps that the drafting dept could not keep up, so there are miles of files that never saw daylight, indeed, this schematic is not to be found anywhere, either in Pitman's book of online, note that one section of the 6U10 Compactgron being used as the inverter, which is rare. Other changes are the 1 M resistor across the lamp in the LDR box no longer there, and the Intensity control wired different.
this amp sounds awesome, nice clean sound with an EL84 chime to it, then after 1 oclock on the vol, it starts to break up like an overdriven Fender, then past that, an overdriven Marshall. One of those amps that you do not want to unplug.
notice that the tubes listed at the bottom do not match the tubes on the schematic,
according to Ken Fisher of Trainwreck fame, who worked at Ampeg during the 60's, there were so many changes made to the amps that the drafting dept could not keep up, so there are miles of files that never saw daylight, indeed, this schematic is not to be found anywhere, either in Pitman's book of online, note that one section of the 6U10 Compactgron being used as the inverter, which is rare. Other changes are the 1 M resistor across the lamp in the LDR box no longer there, and the Intensity control wired different.
this amp sounds awesome, nice clean sound with an EL84 chime to it, then after 1 oclock on the vol, it starts to break up like an overdriven Fender, then past that, an overdriven Marshall. One of those amps that you do not want to unplug.
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CJ
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6U10 Pin 10 -- resistor is likely 56K (not 5-point-6-K) to match the one at pin 4.
6U10 pin 9 -- I wonder at 1.5Meg:1.3Meg. A 4:1 ratio would be dart-board. The DC voltages suggest 4.8:1 voltage ratio, 3.8:1 resistor ratio. 4.7Meg:1.2Meg?? 1.5Meg:390K?
"Pilot" is drawn as curly-filament but is surely a neon (two spaced rods) (cheaper!); no sin there.
The LDR light is probably also a neon.
> 1 M resistor across the lamp in the LDR box no longer there
LDRs and neons vary a lot, especially when working in the slot between on and off. They may have got a new batch and had to fiddle other parts to get acceptable action.
6U10 pin 9 -- I wonder at 1.5Meg:1.3Meg. A 4:1 ratio would be dart-board. The DC voltages suggest 4.8:1 voltage ratio, 3.8:1 resistor ratio. 4.7Meg:1.2Meg?? 1.5Meg:390K?
"Pilot" is drawn as curly-filament but is surely a neon (two spaced rods) (cheaper!); no sin there.
The LDR light is probably also a neon.
> 1 M resistor across the lamp in the LDR box no longer there
LDRs and neons vary a lot, especially when working in the slot between on and off. They may have got a new batch and had to fiddle other parts to get acceptable action.
CJ
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