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Marshall JFX1

Digital Effects Unit By Paul White
Published September 1996

Axe devotees may be surprised to learn that Marshall released this little‑known digital effects processor last year. Paul White gets in his annual half‑hour's guitar practice, and finds an overlooked unit worthy of some consideration...

Marshall took their time getting into the digital effects market, but it's nevertheless a brave move considering that, to the best of my knowledge, no other British company has succeeded in building digital effects for the MI and project studio markets. A first glimpse at the JFX1 might lead you to believe that it is a rather tame affair — it offers reverb, chorus, delay, or a multi‑effects combination of all three, but no pitch‑shifting, Leslie effects, autopanning, enhancement, or any of the other esoterica that we've come to expect from the latest generation of studio effects units. Even so, to dismiss the JFX1 as being too little, too late would be to completely miss the point. The JFX1 is primarily designed to sound good and be easy to use — an important point if you happen to be a guitarist whose only previous experience has been with effects pedals. The included effects have been carefully chosen to work well with the guitar, although they are equally applicable to general studio use; for the more adventurous, up to four parameters per patch can be assigned to MIDI control.

Guitarists tend to be very fussy creatures, and the problem with most guitar amps is that the effects loop works more like an insert point, meaning that both your clean and effected signals go through the external unit. It would be unthinkable to send the dry part of a carefully‑nurtured analogue guitar sound through a set of digital converters for no good reason, so Marshall have taken the wise step of keeping the dry signal path analogue and using a high‑quality VCA to handle any necessary gain changes. The 'dry signal path' problem doesn't usually arise in the studio, where you're using aux sends, because the dry sound is invariably turned off, but if you have to use the same effects box both on the road and in the studio, this could be an important consideration.

A Bit Of Background

The JFX1 is a mono‑in, stereo‑out processor using a 16‑bit, 64 times oversampling conversion system in conjunction with 24‑bit internal processing. This translates to a 20Hz to 20kHz frequency response with a dynamic range of 94dB, which compares favourably with the better studio units around. There's a total of 127 patches to choose from, and the first 50 are preprogrammed with factory settings. These may be overwritten, but there is a routine that allows them to be restored without affecting the remaining user patches. One particularly useful feature as far as guitar players are concerned is the Remote jack, which can be used to channel‑switch a conventional guitar amp; furthermore, the Remote status may be programmed as part of a patch.

The styling of this 1U processor is unmistakably Marshall, with traditional gold anodising and distinctive logo, though I'm afraid they have succumbed to the temptation to use an external power supply. Unusually for a digital processor, the JFX1 has almost as many knobs as buttons — and from a simplicity point of view, there are refreshingly few of either. A 2‑line, 16‑character LCD window shows both patch names and edit data, and by pressing the nearby toggle switch, you can get a numerical display of the dry and effect output levels to quickly set up your dry/effect balance. The input level is set using a single rotary control, and a lone Peak LED flashes to tell you not to turn up any further! Three data knobs are used to interact with the displayed parameters, and in Meter mode, two of these are assigned to the direct and effect output levels. In Patch Edit mode, these three knobs allow the direct adjustment of three displayed parameters, but in normal Performance mode, they are disengaged.

The combination effects can get very close to an idealised tape echo, complete with spring reverb and analogue chorus...

No multi‑effects unit would be complete without Up/Down buttons, but these are provided merely to help you scroll through the patches in Play mode, or to navigate various parameter options in Edit mode. The actual parameter tweaking is done using familiar knobs. To edit a patch, you simply hit Edit, and to get back to the patch you originally left, you push Quit. Where there's more than one page of parameters, pressing Edit again will step you through them.

The System key gives you access to the system parameters, such as the various MIDI options, remote jack operation, and so on, while Store allows you store an edited patch to a selected location. There's little more to the operation than that, and for anyone who has used any form of digital effects unit before, the JFX1 will hold no mysteries.

The Effects

The effects on offer are Chorus/Flange, Delay, and Reverb, or Multi‑Effects. The last of these allows you to combine the previous three effects, albeit with fewer options.

    This actually comprises five different modes, which give mono or stereo chorus or flanging, plus a rich 6‑voice chorus which works using six slightly different delay times. Subjectively, the chorus and flange effects work very well, and manage to remain rich and musical rather than simply overpowering you.
    Multi‑Tap mode combines a 6‑point multi‑tapped delay with chorus, and here you can adjust each delay tap individually up to a maximum of 730ms, then set how much chorus you'd like applied to each tap. You can also alter the stereo pan position of each tap, and there's separate control of overall feedback from the left and right outputs back to the input, to create decaying repeats. This is probably the most time‑consuming effect to set up, but you can get some very warm and dynamic sounds out of it.

The more basic delay effects offer the familiar mono, stereo and ping‑pong modes, where the maximum delay time is 1660ms in mono or 830ms in either of the stereo configurations. Setting these up is fairly simple, and really only involves choosing a delay type, dialling in a delay time and then setting up the necessary amount of feedback to give the right number of decaying repeats.

    Here, the traditional categories of Plate, Room, Hall and Large Hall are combined with the terms Dark, Warm, Standard and Bright to provide a good range of starting points. Once selected, you can alter the reverb decay and the HF decay characteristics, but there's no pre‑delay, or any of the other fancy parameters you often find in modern studio reverb units. In spite of its apparent simplicity, the reverb section sounds very good, and works especially well with guitars.
    Good though the individual effects are, the most fun to be had is with the Multi‑Effects, where chorus, reverb and delay are combined in parallel and summed to a stereo output. In this mode, the delay is also followed by a ducker circuit, which is very effective if you want the delay level to swell only during breaks in your playing. There are four ducker settings to choose from.
Considering that Marshall set out to build a great‑sounding, accessible effects box specifically intended for the guitar market, I can only conclude that they succeeded.

Some of the effects in this mode are pared down a little to share out the processing power and memory, but you still get a choice of four chorus types, the most complex of which has four taps rather than the six available in the main Chorus mode. The maximum delay time is now 739ms (still sufficiently long for most tasks), and you get to choose from three basic delay characters: Clean, Warm or Dark, which apply to both mono and stereo delays. Clean is basically a straight delay, while Warm includes some HF damping. Dark offers more damping to really soften the sound of the delays, but an unexpected bonus is that you can also select from four types of compression, which squeeze the delayed signal in a way that makes it sound very much like a vintage tape echo. Now, why aren't these options available in the main Delay algorithm?

The Reverb section suffers the most simplification in Multi‑Effect mode, leaving you only with control over the decay time. What the maximum reverb decay time is isn't entirely clear, but it is adjustable up to several seconds. The relative levels of the chorus, reverb and delay contributions can be adjusted independently, and a finished patch can be given a name up to 12 characters in length.

Marshalling The Thoughts

Admittedly, the effects options available on the JFX1 aren't as comprehensive as you'd find on a typical studio processor (even one costing less) but despite this, the quality of the effects provided is surprisingly good, both artistically and technically. The main advantage of this unit is that it's very quick and easy to programme, largely because all irrelevant parameters have been omitted, and those remaining have been rationalised where possible. Perhaps the most successful effects are the multi‑tapped chorus and the combination effects that can get very close to sounding like an idealised tape echo, complete with spring reverb and analogue chorus — but even the basic 'bread and butter' effects are clean, vice‑free, and very musical. The inclusion of both a ducker and optional compression in the Multi‑Effect delay algorithm is a big bonus in recreating classic sounds easily, and for guitarists using dual‑channel amps, the ability to include channel switching as part of a patch is only to be welcomed.

No unit is perfect, and I can't help wondering why the ducker, delay filtering and compression aren't available in the delay‑only mode; and when it comes to reverb, why no pre‑delay or reverse/gated algorithms? I would also have liked to see better input metering, and knowing what kind of peak signals guitars can generate when pushed hard, some kind of analogue limiter on the input stage might also have been a good idea. Having made that point, the JFX1 seems less prone to overload than many of the digital effects units I've tried — so maybe they've slipped something in and just not told us about it!

In the studio, the JFX1 is perfectly competent, but offers less scope in terms of the range of effects it can create than something like the Alesis Midiverb 4. Because of this, I wouldn't recommend the JFX1 as a first choice for exclusive studio use, but if you're a guitar player who wants something to use on gigs that's also up to scratch for studio use in terms of sound quality, the JFX1 starts to look like a much better proposition, and its supreme ease of use means that even total novices won't be intimidated by it. Considering that Marshall set out to build a great‑sounding, accessible effects box specifically intended for the guitar market, I can only conclude that they succeeded.

MIDI & Patches

Patches may be called up using MIDI Program Change messages, and as seems to be standard practice, you can create an assignment table to map specific patches to specific Program Change numbers if you need to. Though the MIDI side of the operation is fairly simple, you can still opt to work on any MIDI channel or in Omni mode, and up to four parameters per patch can be selected from a list to be assigned to real‑time MIDI control. Any MIDI Controller number between 0 and 121 can be assigned to these parameters, and the setup can be different for each patch.

Patches may be dumped or loaded via SysEx, and one sensible feature is that the Utility pages allow you to monitor the condition of the internal battery, which is necessary to retain the patch information when the unit is switched off.


  • Clean, musical effects.
  • Extremely easy to use.
  • Good at recreating vintage tape delay effects.


  • Competing units offer more flexibility for the same price or less.
  • No reverse or gated reverb algorithms.


A good choice for the musician who both gigs and records, especially the guitar player. More difficult to justify the cost for studio use only, unless you really need the vintage tape delay sounds.