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Marshall ST20C Studio JTM 1 x 12-inch 20-/5-watt Tube Combo Amplifier

20/5W, 2-ch 1x12" Tube Guitar Combo Amplifier with Celestion G12M-65 Creamback, 3-band EQ, Presence, DI Out, and FX Loop
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Item ID: ST20C
Marshall ST20C Studio JTM 1 x 12-inch 20-/5-watt Tube Combo Amplifier
Price:$1,599 and 99 cents
Special Financing - Ends Aug 2, 2026. $45/month with 36 month financing*

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Marshall ST20C Studio JTM 1 x 12-inch 20-/5-watt Tube Combo Amplifier
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Price:$1,599 and 99 cents
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A Return to Marshall’s JTM Roots

Marshall’s Studio series has long served as a Sweetwater favorite, as it perfectly packs many of the company’s iconic amplifier models down into compact, gig-and-studio-ready combos and heads. From the Super Lead to the Silver Jubilee, the Studio series encompasses almost the entirety of Marshall’s long history — with the ST20C Studio JTM, it reaches all the way back to the beginning. This 20-watt, 1 x 12-inch combo amplifier precisely replicates the creamy highs, loose lows, and smoky overdriven tone of the original Marshall 2245 — the platform that arguably defined the biting sound of British blues rock, while also setting the stage for Marshall’s later amplifier creations. Plus, while it’s certainly a vintage throwback, the ST20C Studio JTM comes equipped with all the Studio series’ usual bells and whistles, including a 5-watt power scaling mode, FX loop, and speaker-emulated DI output. Vintage-inspired from the metal “coffin”-style logo to the levant front covering, the UK-built ST20C Studio JTM is a top-tier tonal tribute to the model that began the Marshall legend.

A tonal tribute to Marshall’s famed 2245/JTM 45

More than just an aesthetic tribute to Marshall’s early days, the ST20C Studio JTM’s dual 5881 power tubes and trio of ECC83 preamp and phase inverter tubes match the original 2245. In comparison to the later EL34-equipped Marshall models that would define hard rock in the 1970s, the ST20C Studio JTM’s tone harkens back to the birth of British blues-rock, perfectly capturing the loose bass, rounder response, and compelling natural compression of its JTM inspiration. Overall, the ST20C Studio JTM supplies an extraordinarily versatile tube tone that can take you from stadium-ready power-chord rhythms to dark, moody blues lines without breaking a sweat. And if you’re after just a touch more control, Sweetwater guitarists recommend trying out the time-tested trick of patching both channels together and blending their tones!

Vintage-inspired Celestion G12M-65 Creamback speaker

Originally released amid rock’s mid-1960s revolution, the Celestion G12M Creamback found in many a vintage Marshall amplifier helped define the sound of the burgeoning blues-rock scene. It’s arguably Celestion’s most iconic ceramic magnet speaker, gracing the records of countless all-time greats, including Jimi Hendrix, Eric Clapton, Jimmy Page, and Jeff Beck. The Marshall ST20C Studio JTM combo’s G12M-65 retains the same vocal-like midrange, creamy highs, and aggressive overdriven tone of the original, only with a significantly higher power rating and a slightly improved low-end response to better suit the modern guitarist. For players who clamor for the raw and organic dirty tones that set the stage for Marshall’s dominance of the classic rock era, Sweetwater guitarists agree: the Celestion G12M-65 speaker is tough to top.

Loaded with all the player-friendly features you need

Consider yourself lucky, because the Marshall ST20C Studio JTM sports plenty of onboard features not found on the original 2245. An onboard FX loop makes integrating your pedals and external processors a breeze. Attaining cranked tones at listenable volumes is a breeze thanks to a power reduction circuit. You also get a speaker-emulated DI output for easy recording or routing to a PA. You’ll value the ST20C Studio JTM modern flexibility almost as much as you appreciate its classic tone.

Early-era Marshall aesthetics

Far from the later plexi-equipped, script logo Marshalls that we all know and love, the Studio JTM series reaches back to an earlier time in the Marshall legend — when Marshall amps still wore their American influence on their sleeve. This amp’s levant front covering, gold piping/beading, and handsome metal Marshall “coffin” logo look as though they rolled right out of Jim Marshall’s workshop, beaming with early 1960s style. And perhaps best of all, the ST20C Studio JTM boasts a high-end enclosure crafted from finger-jointed plywood for a lighter weight and superior sound.

Marshall ST20C Studio JTM 1 x 12-inch 20-watt Tube Combo Amp Features:

  • 2-channel, 20-watt tube combo amplifier inspired by Marshall’s early 2245 model
  • Dual 5881 power tubes, 2 ECC83 preamp tubes, and an ECC83 phase splitter capture the creamy highs, loose lows, and exceptionally dynamic overdrive of the original JTM
  • Celestion G12M-65 Creamback speaker offers a slightly higher power rating and enhanced bass response over the original Creamback found in early Marshall amps
  • High Treble and Normal channels can be patched together for endless tonal experimentation
  • Treble, Middle, Bass, and Presence knobs to dial in your sound to perfection
  • Speaker-emulated DI output for easy recording and straight-to-PA gigging
  • FX loop makes it a breeze to integrate your favorite time-based and modulation pedals
  • JTM-inspired aesthetics, including levant front covering, metal “coffin” logo, gold piping, and fawn fret
  • Premium finger-jointed plywood enclosure
  • Handbuilt in the UK Marshall factory

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Tech Specs

  • Type: Tube
  • Number of Channels: 2
  • Output Power: 20W (5W)
  • Speaker Size: 1 x 12" Celestion G12M-65 Creamback
  • Preamp Tubes: 2 x 12AX7 (preamp), 1 x 12AX7 (phase)
  • Power Tubes: 2 x 5881
  • EQ: 3-band EQ, Presence Control
  • Inputs: 2 x 1/4" (High Treble), 2 x 1/4" (Normal)
  • Outputs: 5 x 1/4" (4/8/16 ohms), 1 x 1/4" (DI out)
  • Effects Loop: Yes (on/off switch)
  • Power Source: Standard IEC AC cable
  • Height: 18.1"
  • Width: 19.7"
  • Depth: 10.4"
  • Weight: 39.2 lbs.
  • Manufacturer Part Number: ST20C-U

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Reviews

JTM 45 Updated
I play the Studio JTM in tandem with a really great Marshall clone (Germino 45). Make no mistake, let there be no doubt the Germino 45 is the Best JTM on the planet! Both amps are played through a OX box with Genelec Studio monitors and the matching speaker cabs (2-1x12 cabs with cream backs for the JTM studio and a 2x12 with greenbacks for the Germino) for my use, at reasonable volume levels and with use through a attenuator the JTM is really close to the Marshall JTM sounds. Un attenuated and if you can get the volume up the Germino out shines the JTM studio and it should. The JTM studio is a great amp at volume levels that are usable in smaller spaces. The JTM studio 1x12 combo with the additional 1x12 cabinet is very close to a hand wired dead nuts clone running old British made Gelelec KT66 tubes and you can move the smaller combo without needing help. JTM studio is a great amp and with a Wampler Plexi drive it's gets close to Plexi tone. I have had these amps for a while and play them every day. Marshall hit a home run with the JTM studio in my book. Great job Marshall and Sweetwater!
This is THE amp!
This is one of those amps that you can plug your guitar into with all the amp's knobs can be at noon and it will sound glorious. There's no unusable setting, it's never too harsh and remains full regardless of where the eq is set, the amp just doesn't sound bad.

If someone uses this amp and says they are getting a bad sound out of it, I'd wager they most likely don't know what they're doing.

The Celestion Creamback 65 speaker is the best speaker for a Vintage Marshall type amp. It takes the Harsh frequencies and tames then into something musical. I would not like this speaker in a Fender-type amp, but it suits a vintage Marshall amp perfectly.

The cab is wide and thick, there's a depth to that which gives the amp a bigger sound, maybe this influences the amp's feel. It sounds and feels much bigger than it looks, has the feel of a cranked Marshall through a half-stack, I feel.

This amp is for someone who wants the REAL deal. There are tons of clones of this amp, but cannot take the place of it. This is well made, craftsmanship is top-notch, it is every bit of good I hoped for!
Music background: Praise and Worship
Possibly the perfect club amp
I bought my ST20c based on the rave reviews, gorgeous looks, and need to add a Marshall to my family. It's turned out to be an amazing little amp, a nearly perfect club amp.

Tone wise, it's a Marshall, but with heavy doses of Fender Tweed but also a lot of Vox-like chime. Loads of chime, in fact. You really have to work to get a bad sound out of this amp.

While I prefer the bright/normal controls of the Marshall Origin series, the separate bright/ normal channels on this amp, when jumpered, provide plenty of flexibility too. The 5/20 watt selector is super helpful, and it's easy to imagine surviving sans pedal in a pinch, using only the guitar's volume knob to dial in crunch to taste.

Overall, this is a great little amp, priced similarly to the Fender 65RI series.
Clean sounds great
I got his amp because the reviews said it had a "good Marshall clean tone". It does have the best clean tone in any amp I have ever owned. I thought clean tone was only best from a Fender, some are pretty good, but this has the best warm clean tone ever.
It also is a very low noise amp. I had a 5watt Vibro Champ that had noticeable hum when it was mic'ed up.

I recommend this amp for a very clean tone platform that offers very low amp noise/hum.

Also, it has the effects loop, I have the reverb and delay on the input, and I think I prefer that.
Anyway, you have options.

As far as good overdrive when the master volume is cranked, not gonna happen. Get a Gov'nor



My guitars, 2006 les paul studio 498t 490R & an American tele
Buy the head instead!
Buy the head of this amp instead.... This amp has tube rattle badly! My wife has purchased the Combo of this amp for me last year at Christmas. I was thrilled, but after playing it the combo had the worse tube rattle ever on certain frequencies! I expected this maybe was just a one off situation. I had another combo amp sent to my house and returned this one, but the problem was identical. I then went to Guitar Center and demoed a few and they had the same issue. I finally realized I should just get the head and cab version of this. I ended up finally getting my head and cab as Sweetwater was sold out for months and no restock! No issues at all, and it's one of the best sounding amps I have personally heard. I appreciate Sweetwaters service and they did everything they could possibly do to make the situation right! I would totally buy a handwired version of this amp! My only fear is it going out one day and not being able to service it, as it's my favorite amp!

There are countless "British"-style guitar amplifiers out there, but take it from the lifelong guitarists and tone connoisseurs at Sweetwater, when it comes to Marshall tone, there's nothing like the real thing. We've played them all, from vintage JTM45s and the ultra-cool Plexi reissue to modern handmade masterpieces such as the JVM410. There isn't a model among them we can't recommend with total confidence, and that includes their more affordable models too, like MG, DSL, and Code series amps. Thanks to our tight relationship with Marshall, Sweetwater's always on the cutting edge of their latest designs, custom models, and limited-edition gems. If you want iconic tone from across the pond, you want Marshall, and your Sweetwater Sales Engineer will help you find the perfect one.