Review: Marshall Custom JTM1 Offset


Marshall Custom Offset – teaser

Last year Marshall celebrated their 50th anniversary by releasing a whole range of limited-edition one-watt combos and half-stacks.

Now we’re in for a cool reprise, as Marshall announced a limited edition of 1,111 of a Custom Offset half-stack in Frankfurt earlier this year. The Custom Offset is based on their JTM1 50th Anniversary amp.

A couple of these rare amps even made it to Finland. managed to get hold of one half-stack for a quick review.


Marshall Offset – full front

The Marshall Custom JTM1 Offset (price in Finland approx 1,000 €) takes the JTM1 as its starting point, but takes the concept even further down the vintage road to give the Custom Offset the look the company’s first batch of JTM45 models. There’s the famous light grey/beige grille cloth, and the offset control panel, which has given this amp its name.

Marshall Offset – full back

As can be expected at this price point, the overall workmanship is of a very high standard, indeed.

Marshall Offset – front panel

The head’s gleaming, chrome-plated front panel, as well as the two black metal control knobs, are clear hints at this amp’s exalted limited edition status.

Marshall Offset – back panel

On the chromed back panel you will find the same Power-switch as on last year’s anniversary models. It drops the amp’s output from one Watt down to one-tenth of a Watt.

The Custom JTM1 Offset’s matching cabinet has an impedance of 16 Ohms, but you can also connect 8 Ohm speaker loads via the second output jack.

Marshall Offset – valves

The Custom head is build around the same valve types as the JTM1 head – we find two ECC83/12AX7-valves, as well as a model ECC82/12AU7.

Marshall Offset – cabinet

The closed-type Marshall cab holds a single Celestion G10F-15 10-inch speaker.


Marshall Offset – head and cab

What kinds of sounds do we usually associate with a vintage-style Marshall? Probably clean tones with a dry character and not very much headroom. On the overdriven and distorted side of things we’d definitely look for creamy compression with a good sprinkling of mid-range grunt and presence bite .

…and these are exactly the types of tones the Marshallin Offset dishes out in a very tasty manner!

A vintage-reissue Fender Telecaster stays fairly clean at the beginning of the Custom Offset’s gain range, but the British type of dryness is clearly present:

The higher output of my Gibson Les Paul Junior’s P-90 clearly drives the preamp more, which results in a nice bit of added graininess at the same settings, especially in the attack phase of each note:

A double-humbucker’d Hamer USA Studio Custom finally pushes this Marshall into real break-up territory – fantastic for old-school Blues. For completely clean tones with humbuckers you will have to turn down your guitar’s volume control:


Turning up the Marshall’s Loudness-control adds more gain to preceedings, but also raises volume levels considerably. The Custom JTM1 Offset is quite a belter for a one-watter, meaning it’s too loud to be played at full-tilt in most apartment buildings.

Luckily for us, there’s the nifty Power-switch on the back panel, which drops the volume down to neighbour-friendly levels. A nice side effect of going oh-point-one Watts is that it also adds another wallop of overdrive into the mix, which is why you can even get some decent Hard ’n’ Heavy-tones out of this tiny rig.

Here’s a taste of what I got at 0.1 Watts and Loudness turned all the way up.

First the Tele…

…next up the Junior…

…and last, but not least, the Hamer:


Marshall Offset – front angle

In my view the Marshall Custom JTM1 Offset is a great-sounding little bugger of a half-stack, giving you most of the classic Marshall tones.

Yes, I know that 1,000 euros is a lot of money for such a tiny amp. If you’re purely on the look-out for a very small valve amp for your living-room or project studio, you will probably get more features (and Watts) for your money from other makes or models.

But the Custom Offset clearly isn’t only about being a small amp; instead there’s a great deal of added prestige in such a well-made, limited edition amp build in England by a company of such standing. The Marshall Custom JTM1 Offset is a boutique-class amp for collectors and purists, and seen in this light the price seems rather fair.

If you’re interested I’d recommend speedy action, though, because the availability is, indeed, very limited!


Marshall Custom JTM1 Offset

Finnish distributor: EM Nordic

Thanks to DLX Music Helsinki for the loan of the review sample!



+ quality of workmanship

+ sound

+ Power-switch

+ small size

+ collectability 


Marshall Offset – badge

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