Preamp tubes: three ECC83.
Output tubes: four 6550.
Controls: Pre-Amp Volume, Master Volume, Treble, Middle, Bass, Presence.
Speakers: four Celestion G12T-75 12″ speakers per cab.
Output: approximately 100 watts RMS.
Late-’60s plexis might catch the majority of the raves, but the amp many music fans hear in their mind’s ear when they think “cranked Marshall” is actually a JCM800. By comparison, amps from the ’60s and early ’70s are likely to sound rather tame, verging on clean, unless they really are pushed hard; at which point they can sound glorious, sure, but at volume levels that not many gigs can handle.
Even so, back in 1981, when the series first hit the market, the JCM800 represented, for many Marshall fans, the departure of the old way of doing things – the end of an era, essentially. In truth, it was a natural evolution. As good as the amps that descended from the classic plexi template already sounded, plenty of players were looking for a hotter front end from them, and some control over the output level, too. The new line quickly proved perfect for the mega-crunch stadium rock of the era, and became a near-instant classic in the process.
For all the JCM800s out there still doing great service in their various guises, this 1984 2203 Lead Series 100-watter in red stands as a worthy ambassador, and a good representative of the development of the big-boy lead model. “The JCM800” wasn’t just one model, but a range of lead and bass amps, Marshall’s central and flagship lineup for the ’80s (replaced by the JCM900 in the ’90s). The long-running 50-watt model 1957 and 100-watt model 1959 brought all the way forward from the plexi era were still available in the JCM800 guise, but as the ’80s arrived, everyone wanted a Master Volume control on their amp, and the 50-watt 2204 and 100-watt 2203 had it (as they had since the mid ’70s), and, as a result, outsold the non-master amps by a large margin.
Along with the JCM800 designation came a new and somewhat more contemporary look. Instead of sitting in a cutout in the fascia, as on the older amps, the control panel ran the full width of the head, and the fascia itself was covered in grillecloth rather than the same vinyl as the rest of the head shell. However much many guitarists still enjoyed the classic non-Master-Volume topology of the 1957 and 1959 models, the 2203 and 2204 and their respective combos really couldn’t live without this additional knob; rather than sporting the old-school Marshall’s dual Normal and High Treble channels, the JCM800 2203 used that first ECC83 preamp tube to cascade two gain stages in the preamp, and the resultant maelstrom needed some reining-in.
The amp’s two inputs tapped different stages of a single channel, essentially, and were arguably mislabeled: rather than “Low Sensitivity” and High Sensitivity,” which most standard paired inputs deliver, they actually access low- and high-gain points within the preamp circuit. Plug into Low, and your guitar signal runs straight to the so-called Pre-Amp Volume control via a simple network of capacitors and resistors, then into the second half of the preamp tube. Jack into High, on the other hand, and you go straight into the first half of that same ECC83, and are then routed via a switch in the Low input jack which, when nothing is plugged into it, shunts the signal onward for the journey described in the low-gain path, via the second gain stage and so on. In other words, High stacks an additional gain stage in front of the Low (a.k.a. “clean”) input’s gain stage – not unlike the preamp found in the original Mark I configuration of the Mesa/Boogie, as it happens – making it all hot and sizzly in short order, and necessitating that Master Volume that follows the Pre-Amp Volume on the panel. Despite its positioning, however, this level control doesn’t enter the 2203 circuit until after the tone stack, which itself is a traditional Marshall three-knob, cathode-follower affair driven by a second ECC83. The Low Sensitivity input yields a slightly anemic tone, in fact, and isn’t quite the pathway to pre-Master-Volume plexi-style voices that all this might imply. The gain stage brought in via the High Sensitivity input, on the other hand, reintroduced much of the classic Marshall preamp topology, just more of it, with the big .68uF cathode bypass cap that gave the High Treble channels of yore their crispy-crunchy character.
In latter years, some players poo-pooed the configuration of the JCM800’s Master Volume, declaring that placing such controls after the phase inverter yields more sonically transparent results. But it’s hard to argue with the unholy fury of these amps when cranked up, and with at least some volume pumping through a pair of matching 4×12 cabs. This is the sound of Slash, Billy Duffy of The Cult, Steve Stevens with Billy Idol, even AC/DC at times, and countless others, from the ’80s right up to today. Whatever the purists like to grumble about (and there’s always something), the hit-making potential of the JCM800 2203 is hard to dispute. Another oft-grumbled-about feature of these amps as distributed in North America at this time is their use of 6550 output tubes rather than EL34s. The EL34 has simply become associated so inseparably with “Marshall tone” in the minds of many players that using anything else seems an abomination. Preconceptions aside, these amps can sound great with 6550s, and many significant guitarists even prefer them that way. Otherwise, the conversion to EL34s mainly requires a modification to the bias supply and sometimes a slight change in the way the negative feedback loop is connected, and is a simple and cheap bit of work.
Our featured amp, owned by Chip Coleman, shows the configuration of the 2203 Lead Series just after it was changed from two vertical inputs to two horizontal inputs, circa 1984. The shift helped Marshall streamline production slightly by connecting the two inputs directly to the circuit board – since they were then on the same plane as the control knobs – rather than having to use flying leads from board to jacks. The speaker cabs partnered with JCM800s of this era were Marshall’s straight bottom and half-slanted top cabs loaded with four Celestion G12T-75 speakers. Though they haven’t received quite the kudos of the G12-65 of the late ’70s and early ’80s, these were a distinct upgrade on Marshall’s rather flat-sounding G12-70 speakers with which the earliest JCM800s debuted.
So, screaming classic-rock tones, a solid Marshall pedigree, surprising versatility, and all at what remains a very accessible price on the vintage market. Hard not to add a smokin’ JCM800 to the arsenal, eh?
This article originally appeared in VG August 2014 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.