Introduced in 2018, Marshall’s Studio Series amps are U.K.-made, compact, low-wattage renditions of past classics. They’re smart designs in light of the market’s turn to quieter, smaller amps, and they’ve earned Marshall kudos. Earlier Studio Series amps, like the SV20C and ST20C, were 20-watt mini versions of the original late-’60s Plexi and JTM45 models, respectively. Marshall also built Studio versions of the JCM800 and Silver Jubilee. Now, the JCM 900 Studio head and 1x12 combo captures the essence of the company’s high-gain sound of the ’90s.
Replicating the experience and sound of the 900s—the 50- and 100-watt, trouser-leg-flapping monsters from the golden age of grunge and metal—with a 20-watt output stage isn’t easy. As with the previous Studio models, one key to success is the use of large 5881 tubes, but in a cathode-biased output stage driven by lower plate voltages than in the big-bottle amps of old. Along with the ability to retain the beefy, full-throated sound of the originals, this approach yields longer life from tubes that are built to withstand much harder use. And, since the output stage is cathode-biased, a tube change means simply popping in a new pair of 5881s and off you go, with no re-biasing necessary.
Marshall aficionados will note that the JCM900 series amps were originally made with EL34 output tubes, and later 6L6s (which are direct substitutions for the 5881s used here). It was also fixed-bias rather than cathode-biased in both cases. In a circuit like this, though, the high-gain tone is driven much more by the preamp circuit, which is built around two 12AX7 tubes (plus another in the phase inverter). The Studio version also uses diode clipping to increase saturation levels in the style of the high-gain stage in the original 900 Series.
Ground Control
The JCM 900 Studio’s control layout follows a basic footswitchable two-channel topology with a shared EQ stage. Channel A is rhythm and channel B is lead. The knobs are for gain (the channel A preamp), lead gain (the channel B preamp), treble, middle, bass, presence, master reverb, plus master reverb and volume for channel A and master reverb and volume for channel B. There’s a push-button switch to engage the lead channel, but the included 2-button footswitch delivers that function plus reverb on/off. As part of Marshall’s mid-priced PCB-built range, the Studio Series might not fly with the top-shelf, hand-wired crowd, but inside, the construction is good-quality stuff.
The robustly built combo cabinet measures 21"x18"x10" and weighs 39.5 pounds and is dressed up in recognizably ’90s-era Marshall styling. The Celestion G12T-75 speaker within is shrouded by a ported back that’s much more closed than open, which should boost low-end girth relative to a more open-backed design. In addition to the 3-way output level switch, the rear panel includes two line outs (one standard, one recording compensated) with level control, effects loop send and return, one 16-ohm output for the onboard speaker, and outs for either 1x4-ohm, 2x8-ohm, 1x8-ohm, or 2x16-ohm speaker configurations.
Expansively English
Tested with a Gibson ES-355 and a Fender Telecaster, the JCM 900 Studio worked in perfect time-capsule-authentic ’90s fashion. Some players denigrate original 900 models for the fizz and sizzle that the solid-state, diode clipping adds to the lead tone. But 900s were used to make plenty of great heavy rock, grunge, and metal for decades, and by now, they are regarded as modern classics, especially for a certain set of ’90s-era tones. If you want those sounds, the JCM 900 Studio does the job very, very well. In fact, apart from the lower output making it less ideal for super-loud bands on big stages, it’s hard to hear how this new, smaller rendition suffers alongside an actual Model 4100.
“The Studio 900 is a petite, 20-watt Marshall that punches like its ’90s heavyweight inspiration, the JCM900.”
Channel A’s clean tones are useful, if not particularly characterful until you push the gain to edge-of-breakup territory. But it’s pedal-to-the-metal, guitar-god glory from the moment you stomp on the channel B switch. The key elements of 900 sounds—searing high-end bite, aggressive midrange, and low-end wallop— are all there in abundance. The dual master setup, lacking on much of the channel-switching competition, is a real bonus here, too. It enables you to rein in the rhythm channel independently to set up a broad spectrum of channel-to-channel dichotomies from smooth to jarring.
Channel switching makes the JCM 900 a surprisingly versatile amp, and the three output levels (20 watts, 5 watts, and 1 watt) selectable from the back panel make it even more so. No, the 1-watt setting won’t sound exactly like the 20-watt mode with the masters maxed, because 1 watt of output power simply doesn’t push the speaker or fill a room with sound in the same way. But with so much of this circuit’s tone coming from the preamp anyway, it will churn out surprisingly heavy doom riffs at bedroom volumes. The inclusion of reverb was also a standard feature of the original 900 Series amps, and while it is generally unacclaimed in those amps, the effect acquits itself quite well in the Studio 900. And between the reverb and the effects loop, the Studio 900 is a handy little package for adding atmospherics to clean or heavy tones.
The Verdict
As a real Marshall doing real ’90s-era tones in a compact, lower-output package, the JCM 900 Studio is a total success. For players keen to explore the widest range of sounds, I’d argue it’s more versatile than the Studio Jubilee, and it’s an interesting alternative to the JCM800-style Studio Classic. But used as a vehicle for strictly ’90s heaviness, it checks all the boxes at a fair and accessible price—especially when you consider the quality and extra versatility it delivers. . For players keen to explore the widest range of sounds, I’d argue it’s more versatile than the Studio Jubilee, and it’s an interesting alternative to the JCM800-style Studio Classic. But used as a vehicle for strictly ’90s heaviness, it checks all the boxes at a fair and accessible price—especially when you consider the quality and extra versatility it delivers.
