Multi-Effects Processor Buying Guide

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Multi-Effects Processor Buying Guide

For the inexperienced, buying a multi-effects processor can be quite a daunting prospect at first. As anyone with any interest in buying an effects processor already knows, they are devices (usually rack mounted units) that enhance or transform any audio signal fed to them, whether from a microphone, an electric guitar or any other electronic audio source, such as the audio output of a music player or a computer. In other words, they produce great audio effects that can improve the natural audio characteristics of the original signal, or transform the original sound so that it sounds anything from slightly different to profoundly different. The range of possible effects available is huge, and different manufacturers include various combinations of effects in their models of multi-effects processors. Prices depend not only on the number of included effects offered in any particular model, but also on the quality of effects. Some manufacturers may offer similar effects to others, but use different names for some of them, which can add more confusion and uncertainty. A little time spent understanding the typical effects available, what they do and what they're called, however, makes the task of choosing one a lot less daunting.

Sound Enhancement and Transformation Effects

Some effects are used creatively to produce different sounds, while others are used to improve specific characteristics of the sound, such as volume, tone, and pitch accuracy. Some multi-effects processors are dedicated to a very limited range of effects, while others produce a large range of customisable effects. Typical effects offered in a multi-effects processor can be broadly classed as enhancement effects and transformation effects. Many enhancement effects, however, can also be used as transformation effects if used at higher than optimal settings.

Enhancement Effects

Many of the effects available are considered to be enhancement effects because they improve the natural characteristics of the sound. These include compressors, which control dynamics and volume; filters such as graphic equalisers that can customise the treble, mid or bass frequency balance; filters that reduce background noise or vocal sibilance (de-essing); and one of the most popular effects of all, reverb, which provides a fuller sound, as if the track was being played in a large hall.

Transformation Effects

Transformation processes don't try to preserve the natural characteristics of the original sound. Instead they alter the audio signal's waveform to make significant changes to the sound. So-called modulation processes include flanging, phasing, and chorus effects. Digital delay and distortion are also classed as transformation effects. Pitch shifting can be used for both transformation effects, such as harmonising and transposing as well as enhancement effects, such as autotune for detecting and correcting incorrectly-pitched notes. Keep in mind that few enhancement effects receive such a bad press as auto-tune used to excess by vocalists.

Effects Guide

With such a vast range of effects available, the following check-list of the most popular effects types can be helpful in deciding which effects are required.

Flanger, chorus, and phaser effects

The audio signal is mixed with a version of itself that is slightly (and varyingly) out of time, out of tune or out of phase. Each of these techniques produces a distinct effect. Flanging and phasing produce distinctive sweeping effects, while chorus produces the illusion of multiple instruments of the same type playing together. Other modulation effects, as they're called, are also available, such as ring modulaters, which have an equally distinctive range of modulation effects. Use all these effects very subtly unless the aim is to produce sound effects that range from harsh and horrible to weird and wonderful.


Reverb and delay effects

Reverb, which is mostly an enhancement effect, and digital delay, which is mostly used as a transformation effect, are closely related and are often combined. Reverb reproduces the expansive acoustics of playing or singing in a variety of spaces, such as a large hall, a canyon, a bathroom, a cathedral, and more. Digital delay reproduces the audio signal after a specified time. It's the classic discrete echo-repeat effect. For example, a melodic lead-guitar phrase can be copied and continuously looped while the guitarist continues playing over it.


Overdrive, distortion, and fuzz

These are three loosely-applied terms for the kind of distortion heard in rock guitar riffs and solos. In general, choose overdrive for a meaty but mild rock sound, or fuzz for full-on heavy metal distortion.


Pitch shifting

The audio signal is reproduced at a different frequency and played in place of the original for transposing effects or, more commonly, at the same time for harmonising effects. The pitch can be shifted coarsely in increments of a semitone or finely in increments of a cent (one hundredth of a semitone).



Filters, such as graphic equalisers, vary the tone of the audio by altering its frequency characteristics. For example, if a clear treble sound is required, boost the high frequencies; for warmer low pitched tones, boost the bass frequencies. Countless variations over the whole audio frequency spectrum are possible. Use filters to clean up noise, clicks, and pops on pre-recorded music too.


Compressors and expanders

Compressors boost and reduce volume levels so that the loudest sounds won't be too loud and the softest sounds won't be too faint, but will be clearly audible. Expanders work in the opposite way. They increase the difference between the softest sounds and the loudest. This can produce an appealing ambience, but it also risks unintended distortion as well as losing soft sounds completely.


Where to Find Multi-Effects Processors

Multi-effects processors are specialised electronic audio devices. Unlike popular consumer electronic devices, such as mobile phones or digital cameras, multi-effects processors are not going to be found in many High-Street shops. Musical instruments shops often have some but their range of models is fairly limited. They are more likely to be found in any quantity in audio equipment centres. Unfortunately, pro-audio equipment centres are few and far between. In fact, the greatest trade in effects processors is now done online. The range of devices available, both new and pre-owned, is huge, and, if buying from a reputable source, a multi-effects processor can be purchased easily, quickly, and without problems.

Finding a Multi-Effects Processor on eBay

The most straightforward way to locate multi-effects processors on eBay is simply to use eBay UK's prominently displayed search box, which sits at the top of every page. Start from the homepage and enter the search term "multi-effects processor" into the search box. The search returns a list of multi-effects processors of all kinds. Note that in addition to the unsorted results displayed, the categories and subcategories that contain multi-effects processors are displayed to the left of the search results. Categories make it far easier to search within the results for the type of multi-effects processor required. The most relevant category is Musical Instruments, which has two subcategories: Guitar and Pro Audio Equipment. The Guitar subcategory contains mostly foot-pedal processors designed for live guitar performance. For rack-mounted or table-top multi-effects processors, click on Pro Audio Equipment. To focus only on multi-effects processors with specific effects, make use of the check-boxes that are now displayed above the categories. Depending on which processors are currently available, and also how their owners have chosen to list them, these will include the most popular effects, such as reverb, delay and chorus. Click any one of those and then click on the Choose more link that is displayed underneath to see the full range of effects currently available. Click any check-boxes for the effects that are required to be combined in a single multi-effects processor.


As any experienced musician knows, even the most impressive and sophisticated effects are no substitute for musicianship. Without any musical expression behind them, multi-effects processors simply offer interesting noises and sound effects. On the other hand, when placed under the control of someone who takes music seriously, whether that's a singer, an instrumentalist, a studio recording engineer, a home-studio enthusiast or a producer, multi-effects processors can add depth and a completely new dimension to the music being processed. In other words, don't be over-impressed or overawed by the sounds they are capable of. Be in control of them. Use them tastefully and with subtlety to ensure a professional sound that can't fail to impress any listener.

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