You are here

Digitech Studio Quad V2

Multi-effects Unit By Hugh Robjohns
Published September 1997

Four inputs, four outputs, up to four simultaneous effects... Digitech have kept to the magic number for this upgrade of their user‑friendly multi‑effects processor, but is it a superior being? Hugh Robjohns finds out.

It's only 18 months since the Digitech Studio Quad was first reviewed in this august journal (in February 1996) but Digitech have already released an upgraded version of it — version 2, in fact. To refresh your memory... the Studio Quad is a 4‑input, 4‑output digital multi‑effects unit which may be configured to operate as two independent stereo processors or as multiple mono in, stereo out effects units. The machine can generate up to four different effects at once, and all the usual reverbs, time‑delay based effects, auto‑panning, pitch‑shifters and so on are available.

The main improvements on the original are the 10 new effects modules in addition to the original machine's 50, plus a total of 180 factory preset programs; the new Studio Quad also has better input and output routing and has undergone some tidying up in the MIDI department. And if any version 1 owners out there are beginning to feel a bit miffed, fear not — for a very reasonable £49.95, you can have your machine upgraded to the new spec.

Black Box

The basic look and feel of the machine haven't changed since the first edition: it retains the clear backlit LCD panel and the chunky illuminated push buttons to the right (described originally as resembling partially sucked Glacier Mints). On the far right‑hand side is a parameter wheel for editing the various effects settings.

The rear panel has four sets of electronic balanced inputs and outputs on quarter‑inch TRS jack sockets with switchable sensitivity (‑10dBV or +4dBu). The audio connections are supplemented by MIDI In and Out/Thru sockets together with another jack for a footswitch or remote control facility. Input and output levels are set via the Levels menu, but an automated mode is available where the machine samples the input signals for a few seconds and sets the gain accordingly.

The external power supply module connects via a 4‑pin DIN plug. (When will manufacturers realise that we all hate external power units, even if it does make it easier for their equipment to pass the EMC regulations!) The left‑hand side of the case, and the heatsink to the rear, get quite warm in use, although not hot enough to cause a problem. The analogue converters are the same as the original machine's, with 18‑bit, 128‑times oversampled delta‑sigma A/Ds and 20‑bit, 64‑times oversampled D/A stages. The sampling rate is 44.1kHz, but there are no provisions for digital interfacing.

As multi‑effects units go, the Quad is really well designed.

Some of the effects (principally those that tend to involve large amounts of feedback, such as the flangers) are noticeably noisier than the others; even so, I don't think anyone is likely to complain about the noise performance of the Studio Quad, which I found to be wholly satisfactory and well up to the standards expected of this type of equipment.

Big System

Ergonomically, the version 2 machine is identical to the original Studio Quad — as multi‑effects units go, the Quad is really well designed and relatively easy to set up, configure or customise. The most important thing to get to grips with is how the processing power is divided and allocated, because each of the effects routines requires a different proportion of the machine's signal‑processing power and this has a direct influence on which effects can be run simultaneously.

To this end, each effect is defined as quarter, half or full, and any combination of effects can be used provided the processor requirement doesn't add up to more than one. For example, you could have a single powerful effect using the full processor, or two effects from the half‑processor category (working either in series or parallel on the same channel, or on two different signal paths at the same time). Alternatively, you could use four quarter‑processor effects in various combinations on one, two or four channels. There are actually 12 different configuration setups to choose from, with four quarter processors allocated to four different signal paths as Configuration 1, and a single full‑processor effect installed in channel 1 as Configuration 12, with all the other possible combinations available in between. If you don't want to design your own configurations, it's very easy to recall a suitable factory preset and replace the stock effects with your own alternatives — a technique I found to be a lot quicker and easier than designing effect chains from scratch.

The quality of effects, the versatility of programming, and the remote control via MIDI combine to make this a unit that, once screwed into the rack, is going to stay there.

Every effect can be achieved in a full‑size processor module (obvious, I suppose) but there are 22 effects that can only be obtained in this environment — specifically the most complex algorithms, which need a lot of DSP power to operate and consequently don't leave room for anything else. Another 17 processes require half the processing power, leaving 21 that will run happily in a quarter‑processor environment, including the compressor, gate, a couple of reverbs, the chorus and flange programs with built‑in delay facilities, and the simplest of pitch, detune, chorus, flange and equaliser programs.

The fact that these last effects don't require much in the way of processing is potentially a little misleading, because it's tempting to think that the less the processing, the weaker the effect. While this may be true at a technical level, from the user's point of view the quarter‑processor effects should certainly not be ignored — I found them to be very capable, useful and generally of high quality. They may be lacking in some of the more esoteric adjustment parameters, but otherwise they sound every bit as good as the more complex algorithms.

The new programs add some useful facilities to enhance the overall value of the machine. I don't think I'll be selling my old Leslie 122, but the Rotary Speaker Simulator could be manipulated to provide a very credible effect within a mix. I liked the Smooth Pitch Shifter and Harmony generator a lot, and the Analogue Delays (generated by an algorithm simulating tape‑based delay) are fun too. The other new programs — Chorus/Delay, Flange/Delay, Pre‑delay, Room Echo and Compressor — are equally useful additions to the Studio Quad and all perform as expected.

FX Editing

Every effect can be modified via an editing mode that's accessed with a button next to the LCD panel. Pressing this Edit button cycles through the active effect processes, followed by their input configuration, output modes and Modifiers. While a process is flashing, its adjustable parameters are made available in up to seven pages, with each page revealing four parameters. The large numbered buttons on the control panel are used to allocate the data wheel to these parameters, which may then be adjusted using this wheel.

The Modifiers provide the means of controlling selected parameters, either with the internal
low‑frequency oscillators (which can be programmed for speed, depth and five different waveforms), MIDI control data (including aftertouch), or even the signal source volume, which allows for some very expressive effects indeed.

Like most multi‑effects units these days, the Studio Quad allows most of its parameters to be assigned to various MIDI controller data, and the usual patch‑change information can be used to recall preset memories. A comprehensive MIDI implementation chart is included at the back of the handbook to aid in setting up your MIDI system. As part of the upgrade, some of the MIDI functions have been improved: there's a new MIDI Merge function in the Utility menu, which combines incoming data with the Studio Quad's own data before outputting the mix through the MIDI Out port, and a new look for the SysEx page. There's also a tuning facility for the Harmony pitch‑shifter program: the base reference can be set anywhere between A=427 and A=453, with A=440 as the default.

In Use & Conclusion

This is the kind of unit that will impress straight out of the box, because the factory presets are well designed and very varied. For version 2, the programs have been re‑ordered so that they appear in groups of related effects, making it a lot easier to navigate around the machine.

The quality of the Studio Quad's effects belies the fact that this unit has been built to a budget. Sure, the pitch‑shifters are not exactly state‑of‑the‑art and they will sound artificial on their own, but this is a characteristic common to all but the most expensive units, and it doesn't present a problem when they're used within a mix. The reverbs (even the simplest ones) are all very credible and produce nice, believable illusions of real spaces. The chorus, flange, delay, and equalisers are all very competent too — indeed, it's hard to point at a weak effect.

Trying to scroll down through the presets to a new program was a bit frustrating at first, because the machine tried to load every program in sequence! However, this operation can be disabled, allowing you to search the presets at leisure, only loading the desired program when you press the Program button (much as on the Yamaha SPX units).

The ability to determine the order of effects is very powerful — there's a world of difference between compressing an equalised signal, and equalising a compressed one. Not only is this important from the point of view of how good the end result sounds, but it's also very educational and may provide you with ideas and techniques that can be used with conventional outboard equipment.

The quality of effects, the versatility of programming, and the remote control via MIDI combine to make this a unit that, once screwed into the rack, is going to stay there — and the fact that Digitech are prepared to support the product with retrofittable upgrades is also a very reassuring sign. You may acquire better and more expensive effects units in the future, but the Studio Quad is one of those very capable units that will always find a role for themselves in any studio.


  • A good‑sounding collection of effects.
  • Versatile and flexible effects patching and routing.
  • Original units can be upgraded at a very reasonable price.


  • The handbook could be improved.
  • Outboard power supply.


A very useful and useable high‑quality effects unit with a good range of easy‑to‑use programs, the Studio Quad is suitable for the 'Plug‑and‑play' user, but also offers a fine degree of editing to satisfy inveterate tweakers.