TC Electronic Ampworx JIMS 45 Preamp

The TC Electronic Ampworx JIMS 45 is a preamp pedal from TC Electronic that packs a digital model of a 1965 Marshall JTM45 tube amplifier into a stompbox. It is part of TC Electronic's Ampworx series of preamp pedals, built on the company's AMPWORX modeling technology, and it is designed to do the amp's job on a pedalboard: feed it into a power amp, a flat amplifier, or a recording interface and it supplies the preamp character, EQ, and cabinet sound of the original¹².

Guitar World's reviewer Trevor Curwen describes the pedal as "modeled on a Marshall JTM45," noting the name is presumably a nod to Jim Marshall himself¹. Pedal of the Day goes further, calling it "the best and most precise digital amp modeling of this famous amp you have ever run your guitar through"².

A digital model of the Marshall JTM 45

The JIMS 45 is a digital simulation, not an analog circuit. Pedal of the Day describes it as "a true-to-life digital simulation of a 1965 Marshall JTM 45 tube amplifier," created using TC Electronic's AMPWORX modeling technology². For a player, that means the pedal is reproducing the behavior of the original amp's circuit in software rather than clipping a signal with diodes or transistors, the way an analog overdrive or distortion pedal would.

The original JTM45, the amp being modeled, is the Marshall design the pedal takes its name from. Guitar World notes the JIMS 45 is "affectionately named, we assume, after Jim Marshall"¹.

Channels and controls

The pedal gives you seven parameters to shape the sound, laid out much like the front panel of the amp it models².

The Normal and High knobs mirror the two inputs of a JTM45: Normal controls the gain of the Normal signal path and High controls the gain of the Bright signal path, so you can lean on the brighter voicing or blend toward the darker one by how you set each¹².

Green and Red channels

The two footswitchable channels are two takes on the same amp²:

• Green channel: the original amp's circuit with a "master volume" set at 50% added after the tonestack. This lets you push the preamp into breakup while holding the overall level down, something the original amp could not do.
• Red channel: the original amp's stock circuit, which did not have a master volume control. Here the pedal behaves like the real thing: turn up the gain and everything gets louder with it.

Boost

On top of the amp model there is up to +18dB of on-board boost, and the Pre/Post switch decides where it sits in the chain. Set Pre-Amp, it drives the modeled circuit harder; set Post-Amp, it raises the output level after the amp model, more like a clean boost pedal².

Cabinet emulation and D.I. use

The JIMS 45's D.I. options integrate the official Celestion Digital impulse response of a 4x12 cabinet loaded with G12M Creamback speakers²¹. Guitar World's reviewer confirms the speaker emulation is Celestion G12M Creambacks in a 4x12 cabinet configuration with the JIMS 45¹. That means the direct output carries the modeled cabinet's frequency response, so you can record or run straight to a PA without a real cab, while the sound still reflects the speakers the original design is associated with.

How it differs from the JIMS 800

The JIMS 45 sits alongside the Ampworx JIMS 800 in the same series, and the two cover different ends of the Marshall story²¹³.

Both pedals use the same AMPWORX modeling technology and are preamp pedals in the same series²³. The practical difference for a player is gain character and era: the JIMS 45 models the lower-gain, mid-1960s JTM45 design, while the JIMS 800 models the higher-gain JCM800 and adds a Resonance control for shaping the low end²³. Pedal of the Day describes the JIMS 800 as one that "pays gorgeous tribute to classic, guitar-driven rock"³.

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