Marshall JMP Super Bass 1992 100w Hand-Wired Head 1972, Black

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Specs


Instrument	Amplifiers
Brand	Marshall
Model	Super Bass 1992
Finish	Black
SKU	AP4079-A
Made In Year	1972
Preamp	12AX7 (x3)
Power	EL34 (x4)
Rectifier	SS
Wattage	100w
Circuit	1992 Super Bass
Transformers	Original Dagnall
PT	T2562
OT	C1998
Choke	C1999
Notes	Buyer should note internal and external pictures before buying, as they are included as part of the description.

Description

The highly revered 1992 Super Bass circuit is the more mellow-voiced counterpart to the 1959 Super Lead. Over the years, many players have grown fond of the Super Bass for its smoother top end and slightly reduced gain, thanks to the shared V1 cathode, and different tone stack values. This particular amp was built in 1972, which marked the final year of Marshall’s hand-wired heads before the transition to PCB construction.

This amp has a few minor changes but remains original where it matters most. All of the original Dagnall transformers are intact, contributing to the commanding sonic presence that defines the Marshall sound. Internally, the filter caps, bias caps, and power cord have been replaced. One of the power tube screen grid resistors has been swapped, with the others remaining original. There was a half power switch added to the back of the amp, which looks surprisingly close to factory work, with screen printing added to the back panel for "Half/Full" power.

The following components have been replaced with modern equivalents: the phase inverter coupling caps, tone stack slope resistor, and treble cap. These were likely swapped during a temporary mod to Super Lead specs and later returned to the original Super Bass configuration, which now aligns with the 1992 schematic. Please refer to the circuit photos for further details.