Marshall JMP Model 1992 Super Bass 100 Watt Tube Full Stack Amplifier (1971), ser. #4642C.

Marshall JMP Model 1992 Super Bass 100 Watt Model Tube Full Stack Amplifier (1971), made in London, England, serial # 4642C, red tolex covering finish.

This could get loud! Marshall amps are certifiably rock legend, with a sound that has defined entire styles and eras of music. This 1971 100 watt Super Bass full-stack with its matching 1960 and 1960B model 4x12" cabinets in red covering is a real monster, majestic in both in volume and tone. Marshall amps owe their humble beginnings to the Fender Bassman 5F6-A, the original subject re-interpreted using English components and originally sold exclusively through Jim Marshall's London shop. Both the circuit design and sound soon evolved from the Fender paradigm into something entirely their own.

Early Marshalls powered the sound of the Who, Cream, Hendrix and beyond, de rigeur among top UK groups by 1969. Although the dedicated bass models were popular with many A-list bassists (arguably more so than the original Bassman) many notable guitarists have also chosen the Super Bass model over the Super Lead; Jimi Hendrix, Jimmy Page, and Eric Johnson, to name a few. Consequently, the Super Bass has developed something of a cult following, but the differences between Super Lead and Super Bass amount to little more than a handful of components; one circuit can fairly easily be modified into the other.

Similar to the Bassman, Marshall's Super Bass features four inputs and two channels, often jumpered with a short lead for more preamp gain, along with controls for each channel: volume, treble, middle, bass and presence controls. The head sports a quad of EL34 power tubes, putting out a whopping 100-watts into the iconic stack of two closed-back cabinets, each loaded with four 12" Celestion speakers; another Marshall innovation that owed much to The Who's John Entwistle, ever on the lookout for ways to make his bass louder and an early and eager advocate of this full-stack design.

These amps came of age in the later 1960s, an era when bands routinely played large stadiums and festivals, often without PA sound reinforcement for the guitars. At the height of the rock n' roll-era, amplifiers with this sort of power were a necessity rather than a luxury, and the tone became the new rock standard. These days, we also have the luxury of attenuators to tame these beasts somewhat and protect our ears!

This gleaming red Super Bass is a relatively early example of the revered 'Plexi-era' full stack, though featuring an aluminum control panel plate. The serial number ends with the date code "C", indicating assembly in 1971, affirmed by the test date on the chassis label of October 8th, 1971. The angled top cabinet bears the serial number 28008 and the bottom 20186.

Height is 72 in. (182.9 cm.), 29 in. (73.7 cm.) width, and 14 in. (35.6 cm.) deep.

Cosmetically, this magnificent red full stack is in wonderful condition overall. The red Tolex is an older recover, including the cabinet grille cloth coverings. Judging by the later speakers dating to '87/'89, it was likely done around that time. The red Tolex covering shows some very minor scuffing but is generally in fabulous shape. The control panels are in similar condition with all knobs present and nicely intact. The logo and gold piping on the head appear older and likely original, and on the cabinets they look newer, though with the recover likely being just a decade or two younger, it's hard to say for sure! Handles and associated hardware appear original. Both cabinets retain original casters. One of the jack cups shows glue repair often seen on these all-plastic recessed parts. The full stack comes with matching black slip covers bearing the Marshall logo.

Electrically, this amp is nearly all-original, save for the speakers, which are Celestion G12T-75s. The four in the angled cabinet all date to July 3rd of 1987, and the four in the bottom cabinet date to October 6th of 1989. The 'laydown' power and output transformers and choke all appear original to the amp. All pots appear original, retaining undisturbed red-colored solder joints. The amp has otherwise seen our typical maintenance and servicing, including replacement of all electrolytic capacitors, install of a new grounded 3-prong power cord, all sockets, pots and jacks cleaned and power section biased to spec.

The impedance selector on the amplifier is currently set to 8 ohms for use with both cabinets and should be switched to 16 ohms when used with only one.

This magnificent monster is a welcome rarity for our showroom, a gleaming red beast that is, as they used to say, "Ready To Rock"! Excellent - Condition.