Marshall JTM45/100 Super Bass 100w Head RARE 1967, Black

This example features rare and unique transition-era aesthetics, with a JTM45/MKII front panel paired with the Super Bass 100 rear panel, typically found on the Black Flag JTM models introduced later in 1967. The beginning of the serial number has worn away, but it is most likely "10016." This would align closely with another documented near-identical 100-watt Super Bass, serial number 10019:

The front Marshall logo and handle are a later replacement, and the white plaque on the rear panel is missing. While it is impossible to say with certainty whether the head shell is original, it is unquestionably period-correct and remains in excellent condition, as does the rest of the amp. The backplate shows light wear and includes a small notation indicating 8/16-ohm operation. Another interesting feature of these transition-era amps is the reinforced aluminum block mounted to the chassis, intended to help support the substantial weight of the transformers.

Internally, this amp boasts the impressive feat of retaining its original Radio Spares filter capacitors! They have been carefully reformed on a Variac, though their long-term lifespan is impossible to predict—in other words, enjoy them while you can. Due to the way they were originally mounted, they are somewhat sensitive to vibration, so a previous technician secured them with hot glue. Perhaps not elegant, but certainly effective. Additionally, 100k series resistors were added to the power supply to properly distribute the voltage divider.

On the preamp side, an additional Radio Spares capacitor and resistor were later added to split the preamp supply nodes, another feature shared with the later Black Flag JTM100 amps and also documented in the aforementioned serial number 10019. Judging sound-wise, there was no reason to alter this arrangement.

The V1 preamp's 250uf bypass capacitor has been replaced with an earlier period-appropriate type. One screen grid resistor was also replaced with a modern cement resistor. In the bias circuit, two resistors were changed and a trim pot was added for easier adjustment, with the assembly secured using hot glue. All of the potentiometers date to early 1967.

Aside from these minor changes, the remainder of the circuit has stayed original. Please see the circuit photos for additional details. The amp was set up "Jimi Style" with US made Sylvania 7581's, which are the closest American equivalent to British KT66's. It is also configured for 220V operation, which helps tame the substantial plate voltage this amp runs at.

The end result is a sound that can only be described as legendary. Anyone brave enough to unleash all 120 watts of output power will undoubtedly be grinning from ear to ear—and perhaps earn the right to call themselves "experienced," in the words of James Marshall Hendrix himself. It also comes with an original cover.