What does a compressor pedal do

Compressor, Limiter, Sustainer & Tremolo

by Marc-Oliver Richter,


Our Pedal Showis at the door! So that nobody gets lost in the big confusion of effect types, we will publish a few basic articles in the next few days - this time on the topic Compressor, Limiter, Sustainer & Tremolo!

Compressors and limiters are some of the devices that affect volume. In contrast to the buffer and booster, they not only take care of the volume itself, but also the dynamics of the signal.

A limiter does not allow signal peaks above a certain threshold value and thus protects everything behind it in terms of electronics from overload. Limiter are z. B. often used by bassists, because overmodulation in the dynamic slap technique is not necessarily desired. A compressor attenuates the signal peaks and releases the signal again below a certain threshold value. So that a compressor does not make the signal too quiet through the damping, there is a boost circuit behind the limiter circuit so that the dynamically damped signal can sound as loud as the original signal. The technology originally comes from the studio area.

It wasn't until the 1970s that z. B. with the MXR Dyna Comp, the first pedals for guitarists on the market. With studio compressors there are usually four control options: "Threshold" (from which level is controlled more quietly), "Ratio" (how much the output signal is reduced to the input signal), "Attack" (time until the control starts), "Release" (Time until the signal returns to its original level). Most floor effects are more user-friendly and have fewer controls because some parameters are preset. The combination of compressor and sustainer is also common, as both are based on the same functional principle.

Sustain is the term for the time during which a note played can be heard. Basically, guitarists are interested in having the longest possible sustain. A compressor that actually only reduces the dynamics of the signal, i.e. H. Making strings that are struck quieter can lengthen the decay time of a tone if it is set with a high ratio, fast attack and very long release and a higher level than originally.

Compressors are popular with guitarists to e.g. B. in picking techniques to compensate for volume fluctuations as a result of improper play. Compressors can of course also take over the tasks of boosters and, with their high volume levels, help to tickle the preamp a bit. For this task z. B. gladly taken the MXR Dynacomp, which is almost identical to the legendary Ross compressor. But Boss pedals are also welcome guests on the pedalboards of well-known musicians.

Also Tremolo effects edit the volume of the guitar tone, but not in the form of a dynamic limit but by modulating the volume: A tremolo makes the signal loud and quiet at an adjustable speed. As a result, there is an interesting shimmer in the tone with delicate settings, while it can support the tone rhythmically with strong settings. We still suffer from the confusion that Leo Fender once caused when he called his vibrato system on the Stratocaster tremolo, but his tremolo effect in the amplifiers vibrato. To put it simply again: a tremolo modulates the volume!

The tremolo effect is one of the oldest guitar effects ever and was already integrated in many models of the early Fender and Vox tube amplifiers. In addition to this soft and warm vintage tremolo, which is still popular today, there is also another requirement profile for tremolos, namely the hard, "chopping" tremolo of modern design. Examples of songs for the two extremes are 'Gimme Shelter' by the Rolling Stones for a subtle vintage tremolo and 'Boulevard Of Broken Dreams' by Green Day for modern tremolo work. Controllable parameters of tremolos are usually the speed at which the volume fluctuates and the extent of the volume fluctuation. Some tremolos also offer a very practical control of the master volume adjustment.

Since the human ear generally perceives a sound with fluctuating volume to be quieter than a non-modulated sound, it is helpful if the tremolo offers the option of increasing the volume of the effect sound so that the bypass and tremolo sound sound equally loud. Almost every manufacturer has a tremolo pedal in its range today. B. the Boss TR-2 tremolo.

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