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Wednesday, January 15, 2014

Multi-effects Explained, Part 5


Technique : Effects / Processing


This is the last article in a five-part series. Read Part 1, Part 2, Part 3 and Part 4.

Today's choice of multi-effects units is bewildering, and they come at all prices from less than £100 to a couple of grand or more, but most of the confusion can be dispelled by thinking about what you really want to do with the unit once you've bought it. In most studio situations, effects are used during mixdown rather than when recording, not just so that you can change things at the last minute, but also because recording with a stereo effect takes up two tracks rather than one. Sometimes a track shortage or a mid-project bounce will force you to commit to an effect, but most of the time, they'll be used for the final mix. What you have to work out is -- what do you need when you're mixing?

Whatever else you need, it's certain you'll want at least one really good reverb to use on vocals, and perhaps on the drums too. Ideally, two different reverbs are a good idea because your vocals may need a different treatment to your drums. While reverb is invariably a part of a multi-effects unit's repertoire, the other effects aren't going to do you much good if you need to use the reverb on its own. There are two main choices, the first of which is to buy a separate, dedicated reverb processor to handle your reverb requirements, then use a multi-effects unit for treating keyboards, guitars and so on.

"An hour or two spent swapping patches could be quite productive."

The second option is to buy a multi-effects unit that can be configured as two or more different effects. Most of these allow you to feed one effect via the left input and the other via the right input, which is fine as most stereo effects are created from a mono source. The left and right effect channels then do their stuff in stereo, and the two stereo outputs are combined at the main outputs to be fed back into the mix via a single stereo return. Providing you don't want to EQ or otherwise process the effect outputs in different ways, this doesn't actually lose you any flexibility, and it saves on effects returns. Figure 1 shows a 2-channel processor set up in this way. Some processors can function as up to four individual effects units with four discrete inputs.

If you choose the multichannel multi-effects route, it pays to be aware that these devices share out their processing power between the different effects in different ways: you may find that once your dream multi-effect is set up in one channel, you don't have enough power to drive a really good reverb algorithm in the other. While you can get away with a crude reverb as part of a multi-effects patch, for use on vocals or drums you need the nicest-sounding reverb going. Unless your effects processor has enough power for the job, you'll probably reach the stage where either the reverb or the multi-effects has to be compromised.

Another consideration with this type of effect is how you patch it into your system. Reverb is almost always fed direct from a post-fade aux send, but when you're using multi-effects on just a single track, it's sometimes better to patch them into the channel insert point so as to avoid mix buss noise. Clearly, if you have a conventional dual-channel effects box, you can only use it one way or the other, not both. Should you want this kind of flexibility, you'll need to make sure you buy a unit that has multiple stereo outs rather than shared outs, so that you're not limited in how you patch things together. Of course, it may be that the expense of going down this route means it's just as affordable to buy a dedicated reverb plus a more conservative multi-effects processor.




Effects patches can take a long time to create, and because they're held in battery-powered internal RAM memory, they can occasionally get corrupted by power surges, or fail altogether if the battery dies on you. These internal batteries last around five years on average, but when they do fail, there's no warning -- one day the unit is fine, the next the display comes up with Chinese restaurant menu characters and your user patches have gone forever. ROM-based factory patches will of course remain, but who only uses those?

You probably already know that I'm going to recommend that you back up your patch edits by doing a SysEx dump into a sequencer or MIDI data filer, but how many of you have actually done it? Even if you're one of the minority who doesn't work with sequencers, the chances are that you'll know somebody who has one and who will let you create a safety copy. Restoring the patches is usually as simple as playing the sequence back into the effects unit, and it only takes a few seconds.

SysEx dumps also provide a means of getting third-party patches into your machine, so if you have friends who use the same model effects unit as you, an hour or two spent swapping patches could be quite productive. Of course you can't load patches from a different make or model of unit, even if they appear to use the same basic parameters, because the System Exclusive commands, as the name suggests, are exclusive to that one machine.

"For use on vocals or drums, you need the nicest-sounding reverb going."

If you're interested in getting hold of more patches, your first port of call should be the manufacturer or distributor, where the product specialist should be able to put you in touch with any user groups that exist. There's also a high probability that the product specialist will have their own stash of useful patches, and if you can get on the right side of them, they might be prepared to swap a few with you -- catch them in a really good mood and they might just send you a disk full. More professional effects processors can use a plug-in card system for storing patches, and with units such as Lexicon's PCM80, the price of a card buys you not just a new bank of patches, but sometimes even completely new algorithms that give effects you could never have got before.

A popular hunting ground for virtually free patches is the Internet, where special-interest groups often set up libraries of useful stuff, including patches, that you can download for your own use. If you can get the data onto disk in a PC-friendly format, Ataris will read it directly and Macs should be able to read it if they have either recent system software or a utility such as PC Exchange or AccessPC. Last but not least, use the SOS free ads to let fellow readers know that you have patches to swap -- most people would like to get more flexibility from their machines, so you should have no trouble getting a response.




During this short series, I've covered both the building blocks of multi-effects, and the ways in which they can be combined. While there's no need to feel guilty about using the factory patches if they do what you want, the chances are that you'll be able to come up with something more appropriate to your own needs if you're prepared to spend a little time experimenting. If you're brave, you can jump right in and start creating new effects from scratch, but you'll be surprised how much can be achieved simply by editing the main parameters of some of the presets, then saving the results. The obvious things to try are changing delay and reverb decay time, and changing the relative levels of the different components of the effect. These edits can be made in moments, yet by doing them you can transform an OK patch into something that's exactly right for your application. 

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