The world's come a long way since putting a spot of reverb on a track meant getting in the builders to knock up a specially-tiled reverb room. These days, a box the size of a car radio can easily contain the echoing ambience of a cathedral, the intimate atmosphere of a smoky club, or the refined reflections of a concert chamber, plus any number of artificial spaces and outlandish treatments. The modern effects processor is a wonderful thing which most of us take completely for granted, with the power to make or break a recording.
The necessity of effects for the modern musician is reflected in the size of the effects market: there are almost 100 effects processors currently available new in the UK -- and that's without counting the profusion of traditional guitar pedal effects such as fuzz and wah pedals, and the many specialist sound reinforcement delay processors available. The sheer number of units offering what appear to be similar facilities may prompt you to ponder on whether quantum mechanics might be a rather more straightforward leisure time activity. But if you keep a reasonably clear idea in your head of your intended purpose and the features you really must have, choosing the right effects processor shouldn't be any more difficult than cracking the Grand Unification Theory in your lunch break... Just joking, honest.
A guide like the six-page one following this introductory article doesn't tell you everything about a piece of equipment. The facts given for each are simply to allow you to compare effects units across a range of facilities and prices -- they can't give an idea of what a unit is like to work with, or how it sounds. It's up to you to check this out.
Let's take a look at the significance to you of the points we chose to highlight in our guide.
MAIN EFFECTS (AND VARIETY)
Lots of effect types obviously increases the versatility of your unit, especially if you don't intend to do much of your own programming. Exotic or unusual effects such as vocoding and sampling can give a unit an edge, and processes such as compression can help you to get more use from an expensive unit, especially if you do not have a dedicated studio compressor, for example.
MAXIMUM SIMULTANEOUS EFFECTS
How many effects you can use at the same time has implications for the depth and complexity of your effects treatments. However, if you're strictly a 'bread and butter' reverb/delay/chorus-type person, it isn't going to matter much to you if you can't use 25 effect types at once, and for some processors, limiting the number of effects available at one time allows them to concentrate all their resources on one or two killer treatments.
If you have a processor that is not true stereo, but has stereo inputs, the signals going into the inputs are actually mixed into mono inside the effects unit before being processed. The processed signal, now treated with reverb, flanging and so on, may well emerge from the unit in stereo, but any stereo information in the original input signal (for example, the pan positions of the parts in a multitimbral setup from a stereo synth) will have been lost. You can hide this to an extent by using the effects processor's Mix control to mix a certain amount of the original 'dry' (untreated) stereo signal with the treated output, but you'll still have lost a certain amount of true stereo imaging.
This doesn't happen with true stereo effects processors, where a stereo input is treated in stereo all the way through the processor's circuitry. But since studio effects processors are usually patched into the auxiliary send loop of a mixing desk, and few of the affordable mixers on the market offer stereo aux sends (so the effects processor is only treating a mono input signal from the mixer's aux send anyway), true stereo processing may not be that important to you. It comes into its own, however, when patched in-line with a stereo source -- the output of a synth, DAT machine or even a mixer, say -- or with desks that feature stereo sends.
These days, the ability to change patches remotely over MIDI is pretty much expected. Having said that, certain units listed in the following guide lack MIDI altogether. Not surprisingly, the majority of these are floor-mounted, guitar-orientated devices, although a few of the simpler, low-cost rackmount processors also miss out on MIDI. It all comes down to what you're looking for, and what you want to pay -- MIDI usually adds to the cost. If you're doing
a lot of MIDI sequencing and would like to be able to change effects smoothly, frequently and automatically in the course of a song, or if you're a stage keyboard player who needs to easily change effects patches to go with each new number, MIDI patch changing would obviously be very useful.
As with synths, increasing numbers of MIDI-equipped effects processors also offer the facility to control parameters such as reverb decay time, flange depth or delay feedback in real time, using MIDI continuous controllers. This facility allows you to record subtle or extreme changes of effects into a MIDI sequence for sophisticated effects automation. Some units offer just one or two assignable parameters, but others allow virtually all parameters to be controlled in some way over MIDI.
RESOLUTION OF CONVERTORS
Effects processor specifications usually tell you the 'resolution' of the unit's A/D (Analogue-to-Digital) and D/A (the reverse) converters, measured in 'bits'. A/D and D/A conversion is the process by which real-world audio is first converted into digital information, so it can be processed by digital equipment, and then converted back to analogue sound for the benefit of our ears. Sixteen-bit A/D and D/A converters are standard for digital effects these days, though you increasingly see 18- and even 20-bit. The Sony DPSV77 actually has 24-bit A/D converters.
Do these numbers really matter to you? For the average user, probably not. While there is almost certainly a perceptible difference between the sound quality and noise performance of 16-bit and 20-bit converters, when you're about to stick a hissy old synth through your effects unit, or use it to process a mix from a cassette multitracker, it's probably academic. Indeed, most people were quite happy with effects units with 12-bit converters when that was the affordable norm. If you're working in a more demanding audio environment, you're more likely to feel the benefit of processors with higher-resolution converters. Incidentally, when specifications talk about '24-bit internal processing', this really only affects the speed and efficiency with which processing inside the unit is carried out. You can expect a signal-to-noise ratio of around 90dB from a well-designed professional 26-bit machine. An older 12-bit unit, on the other hand, might just scrape a signal-to-noise ratio in the high 60s of dBs, and will also exhibit a higher level of quantisation distortion. A good 16-bit processor can achieve near-CD sound quality, but the amount of noise and distortion can vary depending on the quality of the converters used and on the circuit implementation in which they are used, which is why some 16-bit processors are notably noisier or dirtier-sounding than others.
SAMPLE RATE & FREQUENCY RESPONSE
Digital audio systems reduce sound to a series of 'snapshots' represented by a binary system of 1s and 0s -- you can think of it as the audio equivalent of a cine projector, where successive still pictures create the illusion of movement. The more frames per second, the smoother the movement. In audio terms, the more samples taken per second, the higher the frequency response of the sampled audio. The number of samples taken per second is known as the sample rate, and measured in Hertz. To cover the entire 20kHz human hearing range, you need a sample rate in excess of 40kHz (hence the 44.1kHz sample rate used in CD manufacture). However, effects don't have to work over the full audio frequency range to sound good, as the Ensoniq's DP/4+ aptly demonstrates: it's a highly-respected, fine-sounding processor which finds its way into many pro studios, and yet its sample rate is just 32kHz, which translates to a frequency response of around 15kHz. You might reasonably expect a unit with an upper limit of 15kHz to sound less bright and sparkly than one with a 20kHz upper limit; however, subjective sound perception is a strange thing, and units with seemingly less-than-ideal frequency responses have proved to be perennial favourites with musicians -- Lexicon's classic PCM70 and the more modern Alex and Reflex (with an upper limit of just 15kHz), are three cases in point. The only answer with effects processors is to use your ears.
FACTORY PRESETS & USER MEMORIES
For most people, it's important for their multi-effects processor to have lots of factory presets, since these have been programmed by professionals or by the designers of the unit, who are in a great position to know its full capabilities. The presets can give you promising starting points and set you off on tangents for your own programming, and good presets also give you new musical ideas. Nearly everyone who sits down with a new effects unit and their instrument of choice ends up with a handful of new tunes or riffs -- so an effects unit can be as much a musical as a studio purchase. The importance of user memories is obvious if you want to experiment with sound creation, though some processors let you dump your custom programs over MIDI. However, the more user memories on board, the merrier. It may be too obvious to state here, but if the spec says 'none' for user memories, the chances are that you can't do too much to the treatments on offer -- in other words, you're looking at a largely preset unit.
The addition of footswitch control sockets on effects processors may seem like a throwback, but some onstage musicians (guitarists and keyboard players alike) prefer not to rely on MIDI on stage for the relatively simple tasks of stepping through patches and muting effects. Many processors also provide a volume pedal input (or two), allowing a volume pedal to be assigned to one of a choice of parameters, for a degree of real-time control without the need for additional MIDI hardware. Even some floor-mounted guitar units which already have integral footswitches provide an extra input for an expression or volume pedal. Obviously, you should know if you need this. Happy hunting!
The fast turnover of the effects processor market means that there is plenty of choice when it comes to buying second-hand, and recently-discontinued models can often offer almost the same capabilities and sonic quality as the current generation -- not surprising when some manufacturers seem to revamp their entire range every six to 12 months. A second-hand digital signal processor is also a good bet on the longevity front: since there are few moving parts, there is little, physically, to go wrong. We can honestly say that, apart from one burnt-out external power supply, we have never had experience of a multi-effects processor going wrong. We may be exceptionally lucky, of course...
A quick look through SOS's free ads and dealer advertising reveals an excellent selection of good buys. A particular pair of favourites from the recent past are Boss's SE50 and SE70 -- the latter has only recently been discontinued. Both are half-rack units, both feature a vocoder, and both can be used as two independent processors. The SE70 improves on the basic set of effects -- compression, flanging, chorus, phaser, delays and reverbs -- both in number and in quality. The vocoder is more comprehensive, there are mono-tracking bass and guitar synths and a vocal remover, and the noise figures have been much improved. Both units are deservedly popular and move quickly when they turn up second-hand, the SE50 for around £220-250 and the SE70 for under £400 (£399 new as a discontinued item from certain retailers).
Another favourite is Kawai's RV4. This unit offers four completely independent effects processors, either internally linkable or accessible via their separate stereo inputs and outputs. The RV4 also has a pleasing sound and digital ins and outs, making it a good one to look out for. Though quite expensive on its initial release (around £800), the RV4 has been recently available at a number of dealers for something in the vicinity of £400, which is a bargain -- but be warned that stocks are finally running rather low.
Other attractively-priced processors spotted in recent SOS Readers's Ads include the ancient Alesis Midifex for £50 (pretty elderly in terms of spec, but if you're on a small budget...); various units from ART, including a ProVerb 200 for £120 and Multiverb LTXs for £90-120; a Digitech DSP16 at £95 (not bad for a preset processor with128 reverb and delay programs, EQ, MIDI, and a 20Hz-16kHz frequency response), and a DSP256 at £180; a Peavey QFX 4x4 -- a very capable unit which can be used as four independent processors and originally cost around £900 -- for £290; and a Lexicon LXP1 for £220 -- a cost-effective way to get the Lexicon reverb sound.
Here's a few other features you might like to look out for when choosing your effects processor.
Many processors allow you to save your custom effects programs via a MIDI SysEx dump to a computer or MIDI data filer. If a unit has this capability, limited user memories needn't be a problem.
Units such as Ensoniq's DP/4+ and Digitech Studio 400 are designed so that it is possible to process more than one signal simultaneously with totally independent effects. In the case of the two units mentioned, up to four signals can be treated at once, but there's an increasing number of processors that allow you to treat at least two signals at once. Such a facility obviously increases a processor's value for money quotient.
CUSTOM ALGORITHMS & EFFECT CHAINING
Most effects processors restrict you to their choice of effects in a pre-selected order. In recent years, however, a growing number of flexible units give the user the freedom to place effects in any order they like -- to create custom effects algorithms from scratch. If you are frustrated by the lack of flexibility offered by fixed effect routing, hunt out a unit such as Digitech's Studio Quad or the Alesis Q2, which will let you put whatever effects you want wherever you want them in the effects chain -- within the limits of the processing power on offer.
A strange feature to point out, but some effects processors do not actually offer a headphone socket. It may seem obvious, but if your processor is so equipped, then it is always going to be easy to just plug in a guitar or keyboard, put on some headphones and jam with full effects, without having to turn on the whole studio.
TYPE OF INS AND OUTS
Professionals will look out for professional connectors, such as balanced XLR connectors. While some affordable processors do feature balanced jack sockets, you generally have to climb a little higher up the price tree to get XLR connectors. Another option to look out for is digital connections: the Sony DPSV77 and Alesis Q2, for example, are so-equipped and can thus be easily interfaced with digital recorders and mixing desks, entirely in the digital domain.
Volume 1 of Paul White's Creative Recording series, Effects and Processing, and his more recent Recording and Production Techniques give you lots of advice on what to do with your effects unit when you've bought it! The books are available from SOS Mail Order at £9.95 and £11.95 respectively, plus £1.95 UK p&p (£5.50 for Europe, £8.50 for the rest of the world). The order numbers are B315 for Effects and Processing, and B200 for Recording and Production Techniques.
Craig Anderton's article on buying an effects unit in the October 1994 issue of SOS gives some deeper information on exactly the features you might want to look out for before buying. And for even more info on effects and using them properly, see the following SOS articles:
'Effective Treatment: Using effects with keyboards', July 1994.
'Delaying Tactics', April 1994.
'All About Reverb', September 1993.
'Recording Techniques Part 14: Effects', January 1991.