Adescendant of the legendary “Bluesbreaker” combo that helped launch the cranked-Marshall sound into the annals of rock, the 2100 combo is also one of the rarest post-plexi models – and a fast-track to classic British tone.

It’s often said that “the Marshall sound” was officially launched in April of 1966, when Eric Clapton cranked up his Model 1962 2×12″ at Decca Studios, warned the engineer he was going to play loud, and proceeded to set down the seminal overdriven guitar sounds on John Mayall’s The Blues Breakers with Eric Clapton. The plexi “stack” might be the image of Marshall tone today, but EC’s combo worked in an age when engineers were hesitant to record loud guitars – and thereby disseminated that sound to the masses.

Marshall’s first combos arrived in late 1964 or early ’65, following the success of JTM45 heads and 4×12″ cabs. Jim Marshall designed the larger 2×12 Lead & Bass (essentially a JTM45 chassis in a combo cab) specifically for Eric Clapton, saying the guitarist requested an amp “powerful enough to play on stage but small enough to fit into the boot of a car.” Other accounts indicate Clapton encountered the Model 1962 after it had come into existence, and perhaps his praise stuck with Jim Marshall. In any case, it launched a legend, and its appeal remains to this day (and it’s worth remembering that many Marshall model numbers look like years, though they have nothing to do with the year they were released).

The so-called Bluesbreaker evolved through the late/mid ’60s, along with Marshall’s move from JTM to JMP (a.k.a. “plexi”) specifications, picking up EL34 output tubes and circuit changes along the way. The replacement of plexiglas control panels with metal in ’69 represented another stage in development, and the next big step came in ’73, when the maker changed from hand-wired turret-board circuits to printed circuit boards (PCBs). Loaded with many of the same desirable components and hand-soldered to the traces, most players agree the early PCB models don’t suffer noticeably for the change. That year also saw the arrival of the Model 2100 Lead & Bass combo, somewhat under the radar.

Manufactured from ’73 to ’76, the 2100 Lead & Bass was, oddly, only available by mail order, and only in the U.K., so examples are thin today as a result. It seems a surprising marketing move, considering it’s a real meat-and-potatoes design in the classic Marshall mold rather than something packed with esoteric quirks or oddities. But its rarity makes it all the more interesting.

The 2100 combo and its sibling Model 1964 head are often described as combining one channel of Marshall’s Model 1987 Lead circuit with one of its 1986 Bass circuits to create the duality. And apparently the amp’s roaring, crunched-up performance has rarely dissuaded owners from this belief, though the truth is the preamp circuit is far simpler. A look at the schematic indicates the 2100/1964 is, in fact, more closely allied to the 1986 Bass. That circuit already had a 500-picofarad capacitor (often referred to as a “bright cap”) and 470k-ohm resistor bypassing the input and wiper of the Volume 1 control, and this same network creates the so-called Lead channel in the 2100, too.

Regarding the rest of the essential gain/voicing circuitry, the 2100/1964 still has the 1986 Bass circuit’s joined cathodes at the first preamp tube, which is biased with an 820-ohm resistor and a 320-microfarad bypass cap. Interestingly, though, a look inside the chassis shows that the PCB – adaptable to use with other models – has empty slots for the big .68-microfarad bypass cap and 2.7k-ohm cathode bias resistor of the Lead circuit proper, meaning these could be added easily and the cathode’s made independent to create two genuine Lead & Bass channels (as determined by circuit topology, rather than the mere act of naming).

Regardless of the arguable misnomer, the 2100/1964 remains a sought-after amp, and few owners have found anything lacking in their performance. Indeed, many appreciate the trenchant, dynamic sonic glories found in playing a six-string guitar through Marshall’s Bass circuit, which can yield a fatter, richer, warmer tone with less fizz in the distortion when it starts to break up. It did the trick for Gary Moore, who occasionally used a 2100 combo, and the famously discerning Paul Weller has used one since moving on from the AC30s of his days with The Jam. Earlier iterations of the Bass circuit in other forms were often favored by Jimi Hendrix, Duane Allman, both Angus and Malcolm Young on occasion, and many others, so it’s a well-established route to tonal bliss for a six-string.

The circuit also shows how much of the hallowed pre-PCB goodness remains; the board is packed with the desirable pale-yellow Mullard “mustard caps” that grace the most collectible JTM45s and plexi variations of several years before, along with the fat reddish-brown carbon-composition resistors of the day. Otherwise, it’s pretty much classic, near-golden-age Marshall goodness through and thπrough.

“I became aware of the Lead & Bass 50 via Paul Weller, who has exclusively used one live for more than 30 years,” says VG reader Collin Whitley, owner of this combo. “It took some time to track down an early example in the U.K., and I was not disappointed. It’s an unusual combo because of its versatility – something Marshall is not particularly known for. The 2100 model has a surprisingly warm clean tone at low volume but delivers Marshall’s famous saturated plexi sound when turned up. It goes from AC30 to AC/DC at the turn of the Volume knob. When jumping channels, it can snarl in all the best ways, and it’s deafeningly loud.”

Loud and heavy, today, a big 50-watt 2×12″ combo isn’t considered a “portable” option the way it might have been back when Clapton slung one into his boot.

This article originally appeared in VG’s June 2023 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.