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Boss GX700

Guitar Effects Processor/Preamp By Paul White
Published June 1996

Inside the GX700 lies a heart of gold — Roland's innovative physical modelling technology. Paul White straps on his guitar and puts this advanced multi‑effects unit to work.

There's no shortage of guitar effects units on the market, but because guitar sounds are so much a matter of personal taste, you have to try a few out before settling on one that suits your playing style. Some use digital distortion, some have an analogue front end followed by digital effects, and some even include valve preamps teamed with digital effects. For recording, a guitar preamp also needs an amp/speaker simulator, to emulate the tonal changes and filtering caused by a real guitar amp.

The Boss GX700 uses a solid‑state analogue front end to create its distortion and overdrive effects, and this is followed by a powerful multi‑effects unit featuring amp and speaker simulation — which I understand is based on Roland's COSM modelling technology developed for the VG8 guitar system. While COSM may be technically complicated, from the user's point of view, the Boss GX700 is used much like any other effects processor, and most of the effects on offer are quite familiar.

First Impressions

The 1U rack processor is sold under the Boss rather than the Roland name, probably to be more guitarist‑friendly. Apart from the front panel — which looks as though it's been glazed in sweet and sour sauce — the control layout is pretty typical of a well thought‑out effects unit, with the minimum of multi‑function buttons. The signal chain can be thought of as: guitar preamp, stereo effects processor, and speaker simulator, where the amp simulation comes as part of the general effects package. The preamp emulates a number of popular amplifier and stack types, while the speaker simulator can be turned off when the unit is to be used live with a guitar combo or stack. A built‑in guitar tuner is included — one of the best I've ever used, by the way — and the buttons are illuminated, so that you can see at a glance which effects are active in any given patch.

As supplied, the GX700 comes with 100 factory presets and a further 100 user memories, which are filled with duplicates of the factory patches. Patch selection is via the front panel controls or MIDI, and Roland do a rather nice foot controller (FC200) which is ideal for live performance. Powered from an AC adaptor, the preamp has a mono input, which is duplicated on the front panel for ease of connection. The output may be mono or stereo, and there's a level‑matching control on the back panel, to allow the GX700 to work with mixing desks or guitar amplifiers.

The effects were generally first class, and struck the right balance between flexibility and complexity.

Further connections are provided for an effects loop, allowing other effects or processing to be combined with the existing effect, and the patch information includes in/out switching for any externally connected effect. An interesting addition to the connection system is that the output can be set up in software to match guitar combos, guitar stacks, or the loop insert points of either. This affects both the level and tone of the output, as single‑speaker combos and multi‑speaker stacks have quite different characteristics. You can also switch off all of the above for live use. Another considerate touch relates to the speaker simulator: this may be on or off within each patch you set up, but you can switch the speaker simulator on or off for all patches at a stroke if you need to.

There are connectors for MIDI In, Out and Thru plus two further jacks for connecting pedals. Control 1/2 jack allows an optional patch up/down dual pedal to be connected, whereas the Exp pedal input takes a volume pedal, to provide variable control. Strangely, there doesn't appear to be a dedicated bypass footswitch input, though you can set up the GX700 so that the Control 1/2 input operates as a bypass. However, if you do this, you lose the ability to step up and down through the patches remotely.

Patches may be copied from one memory location to another or they may be exchanged, and numerical values, including patch selection, are dialled up on a data wheel rather than up and down buttons. Individual effects may be bypassed using the 12 dedicated front panel buttons, and unlike some units which work only on preset effects configurations, the GX700 allows you to freely change the order in which the various effects blocks are connected.

Editing the parameters for each effect is simply a matter of pressing the required effect button, and then trawling through the available parameters using the parameter arrow keys. The data knob is then used to change the parameter value, and each effects block has a meter function which allows you to check that you aren't overloading the next block in line. After editing, use the Write button to save the patch to any desired user location, and then hit Play to get back into performance mode. A nice touch is that selecting the Tuner mutes the output, so you can tune up silently. Patches can be named with up to 12 characters.

No modern effect processor would be complete without some degree of real‑time MIDI control, and with the GX700, you can select up to four parameters per patch for MIDI/pedal control. You can also set the range over which the parameters are modified by the external MIDI controller.

Effects & Processors

Let's have a look at some effects and sound processing facilities available in the GX700.

  • Noise gate: with user control of threshold setting.
  • Compressor: with variable attack and release characteristics, plus control over sustain and tone. In common with all the other effects blocks, this also has a level parameter.
  • Wah: this classic effect is familiar to guitarists everywhere, and can be recreated quite convincingly with the GX700, either under LFO or pedal control. The resonance of the wah effect can be varied, as can the frequency range over which the effect sweeps.
  • Distortion: I suspect this section is based around the concepts used in the Boss analogue pedals. The choices available include Vintage OD, Turbo OD, Blues, Distortion, Turbo Distortion, Metal and Fuzz. In addition to an adjustable drive level, the distortion settings also have a basic 2‑band bass/treble equaliser.
  • Preamp: this is where COSM modelling comes into play, because here you can select from several amplifier characteristics, including JC120, Clean Twin, Match Drive, Big Lead, MS1959 (I), MS1959 (II), MS1959 (I+II), SLDN Lead and Metal 5150. The available controls include the usual Bass, Middle, Treble and Presence, as well as the Volume/Master Volume method of setting the amount of amp distortion, and a 'Bright' switch. A gain parameter is also included, which affects the distortion amount.
  • Loop: this isn't an effect at all, but rather a means of switching in an external effect or processor. The Loop function connects via the rear panel jacks, and has adjustments for both send and return levels, which is a sensible inclusion.
  • 3‑band EQ: despite the fact that the overdrive section and the preamplifier both have tone controls, there's also a 3‑band equaliser with a fully parametric mid section.
  • Speaker Simulator: this again offers several choices: Small, Middle, JC‑120, Built‑In 1‑4, Big Stack 1‑2, MS Stack 1‑2 and Metal stack. There are also three possible virtual mic settings, for close miking and more distant miking, and separate level controls are provided for the mic level and the direct level.
  • Noise Suppressor: this comes at the end of the amplifier chain, but before the effects. However, because the effects can be connected in any order, it can be used elsewhere if you have a reason for doing so. Personally, I'd be inclined to use it after the modulation effects (for anything that doesn't involve level modulation, such as panning or vibrato), but before any delay or reverb effects. As far as the user parameters go, these are really down to Threshold and Release time, though you can also choose to key the gate from either the noise reduction block's own input or from the guitar input jack.

Subjectively Speaking

Like most Roland/Boss gear, the GX700 is well thought‑out and nicely built, with plenty of flexibility. I tried the unit with both my Fender combo and directly into my mixer, to check if this was a practical way of getting instant guitar sounds onto tape — and with some reservations, it was. The clean sounds are quite excellent, and the compressor really works nicely to produce tightly controlled, shimmering chords which can be further refined by adding a light touch of chorus and reverb.

The heavily overdriven sounds can also work very nicely, though I found I had to edit the factory presets to get anything remotely to my taste. I found the presets very harsh and edgy, which might be fine for heavy metal, but with a little fine tuning, especially in the EQ department, I was also able to get a pretty convincing Dire Straits 'Money for Nothing' sound out of my Strat. On the other hand, I just couldn't get a sweet blues tone out of this box, without rolling off so much top that the resulting sound was dull and lifeless. At lower overdrive settings, you can get a workable tone for single notes, but chords tend to sound very scratchy or grainy, even through the speaker simulator. The effects were generally first class, and struck the right balance between flexibility and complexity. The pitch shifter works better than most (though it isn't perfect), and the 'roll your own' harmony feature (see 'Reverb, Delay & Modulation' box) is very effective.


In the studio, I could find lots of uses for the GX700 — it could give me lots of usable sounds I couldn't get any other way — but it falls short when you ask it to come up with more subtle or musical overdrive sounds. It's great for heavy rock, hammering, tapping, widdly‑widdlying and power chords that could slice concrete, but it isn't great at blues, and it doesn't do the world's best Pink Floyd impression. Similarly, it isn't as convincing as it could be on '60s and '70s raunchy rock sounds, so if you want to sound like the Stones, ZZ Top or even Marc Bolan, you'll have to be prepared to spend some time programming and experimenting with programming.

Of course the GX700 isn't alone in attracting these criticisms, and pretty much every guitar multi‑effects unit I've tried sounds wonderful at the extremes, but is somewhat deficient in creating 'real world' amp sounds. Against the competition, the GX700 stands up very well, especially in the effects department, but if the one‑box solution that will satisfy everyone actually exists, I've yet to find it!

Reverb, Delay & Modulation

Roland have always been very strong on modulation effects, and the GX700 provides massive scope in this area. In addition to the expected Flanger and Phaser, you get to play with pitch‑shifting (up to two octaves either way), vibrato, ring modulation, the Humanizer (vowel filter), and the wonderful Harmonist, which can add up to three extra harmonies to a single note lead line.

Of course, it needs to know what key you're in, so you have to program that into the patch, and if you have something more specific in mind, you can (if you have the patience), enter your own harmony scales. The tracking on this feature is surprisingly good, so it should appeal to anyone wanting to recreate their own Gary Moore‑style guitar solos. You may notice that I haven't included chorus in the list of modulation effects, and that's because it has a section all to itself. Roland pretty much invented Chorus, and as you'd expect, there are no complaints here.

The Delay block can provide up to two seconds of delay, and you can set up to three different delay times for left, right and centre. There's a tap tempo facility, variable feedback and high cut/damping filters to help simulate tape delay effects. Tremolo/Pan provides LFO level modulation, with a choice of triangle or square wave modulation, while Reverb gives a choice of two rooms, two halls and a plate setting with a maximum reverb time of ten seconds. Though there aren't as many tweakable values as you might expect on a dedicated studio processor, you can adjust the most important characteristics such as pre‑delay, diffusion and the high/low frequency filtering.


  • Easy to use.
  • Immensely flexible.
  • Really good effects.
  • Great clean sounds.
  • Loads of different overdrive effects.


  • Sounds best on either the clean or very distorted settings.


A flexible and sensibly priced studio guitar preamp/effects unit. Best for heavily 'produced' guitar sounds.