Look closely at this internal view of #6406 and you’ll see that the 1959T has an extra ECC83/12AX7 tube for the tremolo circuit. To the left is the tremolo circuit board, with the main circuit board in the center and the power board at the right. This early version uses a bridge rectifier with the robust Radiospares military/industrial power transformer. When most recently acquired, this amplifier was missing some original parts, but was restored using the most accurate possible replacements. Photo by Michael Brown.

In November 1965 the Marshall team completed several of the new 100-watt amplifiers ordered by the Who. The band dispatched their roadie to retrieve their new gear. He proceeded to throw each amplifier into his truck one after the other, just like firewood. “I can’t believe he just did that!” Jim Marshall would later recall thinking.

Townshend’s 8x12 and the Birth of the Stack
At the same time that Townshend demanded Marshall build him 100-watt “weapons,”, he also asked for 8x12 speaker cabinets. Jim later shared what Townshend said when he warned him that they’d be nearly impossible to move. “I told Pete, ‘no problem, I’ll make a 4x12 with a straight front and then put an angled one on top.’ He shook his head and said, ‘No, I don’t want that, Jim, I want all eight speakers in one cabinet.’ I told him that it was going to be too heavy and that his roadies were going to complain like mad. His reply was, ‘Never mind them, they get paid,’ and off he went!” Townshend ordered four of the behemoths fitted with Celestion T652 12" speakers, which are similar to 15-watt Celestion Blue Alnico 12" speakers. The bottom half of the cabinet was closed, while the top half was partially opened.

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In this clip of the Who performing at London’s Fifth National Jazz & Blues Festival on August 6, 1965, you can tell that the bass and guitar sounds aren’t great, which could explain why Pete Townshend and John Entwistle don’t look very happy. At the 2:05 mark, a frustrated Townshend fiddles with switches on his Vox amps before taking off his Rickenbacker guitar and launching it over them. This was around the time he ordered 100-watt Marshalls for the Who.

At this gig in France, Townshend and Entwistle each use one 100-watt stack. Townshend’s Fender Telecaster allows you to really hear the Marshall head’s dynamics and how its GEC KT66 output tubes work in concert with the T652 alnico speakers in the 8x12 cabinet. The tremolo model’s two additional knobs and longer control panel distinguish it from the bass model.

At the historic Pier Pavilion (it’s misidentified as “Pear Pavilion” in the video’s opening screen) in Suffolk county, UK, Pete Townshend and the Who blaze through “I’m a Boy,” “Substitute,” and “My Generation” before trashing the stage. Notice the battle-scarred 8x12 cabinets. Townshend and Entwistle each play through two full stacks, and the tone is wonderful.

Marshall presumably tested the first 8x12 cabinet using one or more of the 12 original, dual-output amplifiers. Though Marshall can’t corroborate which exact amp was used, an old masking-tape diagram on the back panel of #6406 shows where the output jacks were located and how each half of the 8x12 cabinet was 16 ohms, for a total load of 8 ohms.

The 8x12 idea didn’t last long for Townshend, though. As Marshall recounted, “A couple of weeks later, he came back and said, ‘you were absolutely right, Jim, they are way too heavy, my roadies are furious!’ He wanted me to just cut the 8x12s in half but that wasn’t possible because of the way they were made—we weren’t using fingerlocked joints in those early days, so the cabs were butt-jointed. So I told him, ‘Look, Pete, I can’t do that because the whole thing will fall apart if I do! Just leave it with me and I’ll get it sorted out.’ So I ended up doing what I wanted to do in the first place—a straight-fronted cab with an angled one sitting on top.” Jim concluded, “the stack was a combination of design ideas from Pete and myself. I don’t mind admitting that we initially built the stack with looks very much in mind, because a wall of them does make a fantastic backdrop on any stage.”

A 2005 40th Anniversary JTM45/100 (left) head cabinet and chassis, complete with dual Drake transformers. The late Jim Marshall (right) with the first JTM45 head in 2011. Photos by Matt York.

40 Years Later
In 2005 Marshall celebrated the 40th anniversary of the 100-watt stack with a limited run of 250 full-stack replicas of the original amplifier and speaker cabinets. Finally, more guitarists could gain access to the dynamic tones of a dual 50-watt output stage. The 40th anniversary cabinets recreate the 8x12 look and sound via two 4x12 cabinets loaded with Celestion T652 alnico speakers.