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Guitar Effects - The Digital Revolution

Source: http://users.chariot.net.au/


Digital effects have revolutionised the way guitar effects are used over recent years. They are available in complex and powerful multi-effect rack units, medium power multi-effect floor units, and simple mini-packages.

Digitally processed effects have been available for many years, however, they have stepped into a new realm of digital modelling over recent years. In addition to using a mini-computer to process the signal in real time, these devices use sophisticated filtering, subtle delays, and other techniques to emulate real world equipment and environments.

One of the first commercially available devices of this type was the Roland VG-8, which emulates the entire sound from the guitar itself, its pickups (type and position), guitar effects, then different amplifiers, speakers and microphones! Roland later released their (still good) GP-100 effects processor, which emulates effects, amplifiers & speakers. Boss then released different cut-down versions of the GP-100, with their Boss GX-700 rack effect, GT-5 and recent GT-3 floor effects.

Other manufacturers have now joined this trend. Line 6 have developed several amplifiers such as the AxSys and Flextone, and also desktop effects such as the POD (and the same thing in software for home recording, called AmpFarm). Yamaha and Digitech (as Johnson Millenium) also produce digital modelling amplifiers.

Like anything different, there are pros and cons:

What's good about digital effects?

Versatility - Digital effects are incredibly versatile compared to their older analog counterparts. The available processing power can be distributed between the effects used, so if you don't need chorus for example, you can have extra reverb features.

Flexibility - Effects can generally be used in any order, without the limitations of hard wired effects. You don't have to be too concerned about matching levels and impedances.

Bang per buck - Digital effects are becoming cheaper and more powerful. They are computers which process digital data in real time. As costs decrease and power increases in the computer industry, we reap the benefits in this equipment. They already provide effects more cheaply than if the same sounds and flexibility were to be built with analog components.

No noise - Even though some digital effects can be inherently more noisy than their analog counterparts, digital noise gates are also very powerful, and can make the noise unnoticeable while you're playing, and dead silent when you're not.

New effects - It is possible to create new sounds that have never been available before. True harmonisers are a good example of this. Also, overdrive effects can have far more gain than is possible with real components, which would suffer uncontrolled oscillation (caused by "electronic feedback").

What's not so good about digital effects?

Realism - Many players find that even the most powerful processors are not as natural as a analog processors. There are lots of reasons for this. There may be one or more analog digital to digital back to analog conversions in your gear. This requires an extraordinary amount of accuracy to faithfully reproduce the enormous dynamic range of a guitar. It also takes time, so players sometimes perceive a tiny delay between what they play and what they hear.

Blackouts - Sound can be cut out for a short period when changing patches. This should not be major problem with new equipment. Changing patches, particularly if it changes the algorithm used by a processor, is effectively the same as closing a program on a computer and reloading another. This takes time, and because nothing can be processed during the changeover, there is a short silence between patch changes. This is most noticeable when you sustain a note or chord then change patches. Some newer effects can mask this blackout to a small extent by letting the echo effects (delay and/or reverb) ring out while the underlying patch is changed.

True vintage effects - Some vintage effects cannot be reproduced. Modulating delay time is something that cannot be easily achieved, however, this is precisely how the original flanging and chorus effects were produced. Instead, manufacturers have to fake these effects using different techniques to give a similar sound.

Customisation - Despite offering several parameters to modify effects, they cannot be customised any further. Some of the best vintage effect sounds came from basic effects that were customised either deliberately of accidentally by tinkerers. Jimi Hendrix is reputed to have had most of his effects customised. This problem can be quite serious in digital effects, because you are at the mercy of using emulated effects that sound the way the manufacturer wants. Generally they try to make effects sound impressive (so you buy them), but the down-side is that the great subtle vintage effects like true phasing and true chorus are simply not available. I have heard phaser effects which are clearly a watered down flange effect, however, vintage phasing and flanging were produced in an entirely different manner, making them very different effects. Likewise, most digital chorus effects are emulated by mixing a delayed and detuned signal with the original. This was only ever a side-effect of vintage chorus when you set the rate too high!

High bandwidth - It might seem strange to say that because digital gear reproduces the full frequency range well, it is a disadvantage. This is mainly troublesome with digital overdrives and distortions, where even the built-in equalisation cannot effectively remove the high frequency harshness of these sounds. I use a Roland GP-100 that has an excellent speaker simulator that does roll of these offending highs. It is strange that it is necessary to use this in addition to real speakers to get a natural overdrive sound. Rocktron make a digital rack box that advertised limited bandwidth as a feature! Of course, some players will like this new shred sound. The original analog stompboxes have the opposite problem: if you use many of these in a chain, their limited bandwidth can accumulate to give you a muddy sound.

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