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FX Shopping For Illusions: Buying A Multi-effects Unit

Tips & Techniques By Craig Anderton
Published October 1994

In two minds about which multi‑effects box to choose? Craig Anderton provides some helpful pointers on what features to look for during your next shopping spree.

The number of multi‑effects units on the market has multiplied to the point where there's now a bewildering array of choices. Often, you may find that several units provide the sounds and general features you want, which makes choosing a specific device all that more difficult. The following pointers describe some features whose inclusion might tilt your buying decision in favour of one unit over another. While no multi‑effects device available includes all of these features, some come pretty close. And armed with the following advice, you will be better equipped to make an informed purchase.

Input/Output Features

  • Ability to accommodate low and high level inputs. Although many multi‑effects units are optimised for guitar, there may be times when the same effects would sound good on high level output devices such as drum machines, tape tracks, etc.
  • XLR balanced outputs. When interfacing with professional studios, XLR balanced connectors provide for compatibility with pro‑level mixers. Although not essential for project studio applications, XLR outputs can come in handy.
  • Paralleled input and output jacks. Effects that have paralleled input and output jacks on both the front and rear panels are very convenient. Use the rear panel connections for permanent installations, and the front panel ones if you need to quickly patch the device into a system.
  • Headphone socket. Why not get a headphone amp thrown in for free? This lets you audition patches quickly, practice at night without disturbing the neighbours, and tune up on stage in an emergency without anyone else having to hear it.

Sound Quality

  • Smooth changes from one preset to another. When you change from one preset sound to another, does the device burp/glitch and make undesirable sounds, or does it switch elegantly from one patch to the next? Make sure you try this test with complex time‑based effects such as delay, tapped delay, pitch transposition, reverb, and so on, as these are most prone to glitching when switched. Also see how the unit responds to MIDI Program Change commands (you can generate these with a MIDI footswitch or keyboard).
  • Hiss‑free distortion. Set up a distortion patch and check if a noise gate is being used in the processing chain. If it is, bypass the gate to see how much noise the distortion really generates.
  • Lack of Bypass switching noise. Hit the Bypass switch with no signal going through the unit; you should not hear any clicks or pops. Also try bypassing in the middle of a chord. The sound should change quickly, but not generate any clicks. You also want to avoid units where there is a perceptible delay going in or out of Bypass mode.


  • Expansion options. Some multi‑effects units let you build on their basic capabilities by allowing for additional memory modules, inserting cards to increase the number of programs or algorithms, software updates, and so on. While most signal processors are not easily expandable, those that are help to forestall obsolescence.
  • Performance trade‑offs due to memory limitations. Some multi‑effects may be advertised as having a zillion different effects permutations, but they may not all be available simultaneously. Generally speaking, the more sophisticated the effects you want to use, the fewer you can use at the same time. It may be impossible, for example, to use pitch transposition, reverb, tapped delay, and distortion simultaneously.
  • Effects routing options. Some multi‑effects allow only serial connections of effects (ie. one after another, in a chain), while others allow serial, parallel, series/parallel, and other options. Also, most multi‑effects provide certain fixed effects algorithms (combinations of effects), while others let you make up your own algorithms. The latter approach, though rarer and generally more expensive, is a more flexible way to go.
When you change from one preset sound to another, does the device burp/glitch and make undesirable sounds, or does it switch elegantly from one patch to the next?
  • Stereo operation. Most multi‑effects processors synthesize a stereo field for effects such as reverb, chorus, flanging, etc, which is fine with guitar. However, if you plan to use your unit in the studio or with keyboards, you'll probably want to have true stereo operation, with independent processing for the right and left channels. Some multi‑effects even let you apply different effects to the two channels — for example, guitar through the right channel could go through chorus, and vocals through the left channel could feed through reverb. The importance of true stereo operation, or dual mono operation, depends mostly on your intended application.
  • Memory backup method. A good multi‑effects box should offer an easy, convenient way to back up its programs, such as via MIDI System Exclusive storage or removable memory cartridges.

Hardware Features

  • Reliable buttons. Press some of the buttons. Does each press have a positive feel, or do the buttons act intermittently? If so, they will only grow worse with time and are best avoided.
  • Cool operation. Ask the shop to leave a unit on for 30 minutes or so and feel the back and top of the chassis. If it's cool to the touch, that's a sign of a conservatively rated power supply with adequate heat sinking, both of which promote more reliable long‑term operation.
  • Internal power supply. You may want to avoid effects that have external power supplies (often referred to as 'wall warts'). External supplies hog space on plugboards, and if the supply is a custom design that provides an unusual voltage, you're in trouble if it gets lost or broken. Furthermore, external power supply cables often use flimsy mini‑connectors that don't seem particularly roadworthy.

However, there is another side to this story, so let's be fair: transformers generate hum, and having one mounted inside a box means that you need more shielding to keep it from interacting with other components inside the box. Furthermore, if you have several rackmount units mounted on top of one another in your rack, the transformer inside one box can interact with a poorly‑shielded box mounted above or below it, creating unwanted hum. So external power supplies do have their plus points.

  • Clear, readable display. LCD displays should be backlit, but that's not all — you should also be able to see the display from a wide variety of angles. Some designs are inherently easy to see; others include contrast or viewing angle controls to compensate for different viewing angles.
  • No mechanical noise. Listen to whether the unit emits any buzzes or hums. We're not talking about buzzes that show up in the audio path, but the sound of the unit itself — buzzes may be the symptom of a low‑quality transformer (or some loose screws, which tells you something about the workmanship). And while you're at it, gently shake the unit a few times to make sure there's nothing loose rolling around inside.
...if you plan to use your multi‑effects unit in the studio or with keyboards, you'll probably want to have true stereo operation, with independent processing for the right and left channels.
  • Companion foot controller. A footswitch designed to work with a specific multi‑effects unit may offer features that aren't available with a more 'generic' MIDI footswitch.
  • Three‑conductor power cord. The third ground pin offers a great deal of protection from electrical shock (even though it can increase hum if you're not aware of proper grounding procedures). Also, detachable power cords are preferable; when packing up, you don't necessarily want to have a cord trailing around. The downside is that it's easier to lose a detachable cord (so always keep a spare in your toolkit).
  • 110/240V switch. Maybe your band will never tour abroad, but perhaps it will, in which case having this switch certainly beats buying a transformer/adaptor.
  • Externally‑mounted fuse. Fuses can blow for a variety of reasons, and it's convenient not to have to open up a box when this happens (especially if it's already mounted in an equipment rack!). A disadvantage, though, is that a fuse post sticking out of the back of a unit makes it more vulnerable to damage if something smashes into it.
  • 19" rack‑mount capability for half‑rack units. Half‑rack units are cute and cost‑effective, but make sure they can be mounted in a standard rack if necessary.
  • Lots of user‑editable program memory. 128 programs may seem like a lot — and it is — but just as with computers, you can never have too much memory. Also make sure you like the factory presets; they're usually in there permanently.
  • The ability to name presets. Calling up a preset and seeing 'Small Tiled Bathroom' (for a reverb patch) or 'Rude Metal Fuzz' (for a distortion patch) is much more descriptive than a number.

MIDI Features

  • Response to MIDI Program Changes. This allows you to use a MIDI footswitch to call up effects programs as desired. Because MIDI is a standardised protocol, you can use one manufacturer's footswitch with another manufacturer's multi‑effects unit.
  • Response to MIDI Continuous Controllers. You may not appreciate MIDI Continuous Controllers now, but someday you will. They let you access individual effect parameters over MIDI, and control them with a specially‑designed footpedal (or you can automate these changes if you drive the effects unit with a sequencer). Check that each patch can have its own Continuous Controller assignments, so that you can (for example) use a pedal to vary delay time in one patch, amount of treble boost in another, reverb depth in yet another, and so on. This lets you add a great deal of expression when playing live.

Also, check for smoothness of response — if you vary the delay time, for example, does it change smoothly and predictably or jump from one setting to another?

  • MIDI System Exclusive (SysEx) dump options. With multi‑effects, one or two hundred programs may seem like a lot of different sounds, but you can use them up faster than you might think — particularly if you develop custom libraries of sounds for multiple keyboards or guitars. Being able to dump the memory contents of your multi‑effects unit over MIDI to a SysEx storage device (such as a computer running appropriate software, dedicated MIDI data filer, or a keyboard workstation with SysEx storage capabilities) lets you recall a group of settings at any time.
  • MIDI Thru socket. If you have more than one MIDI‑controlled effects unit, a MIDI Thru socket simplifies the distribution of MIDI messages to other units. The alternative is buying a separate MIDI Thru box — and the fewer boxes, the better. Note that some effects units offer a 'MIDI Echo' or 'MIDI Merge' function that turns the MIDI Out socket into a MIDI Thru; this will also do the job.