Tipología de concesiones por especies explotadas

One of the first questions neophytes learn to ask about synthesizers is, “How many effects does it have?” The answer gives a crude indication of the sonic prowess of the machine. Unfortunately, the answer can also be a bit misleading.

A digital device can do several things at once, even though it can’t. The trick is, if it’s cleverly programmed it can switch back and forth among two or more tasks, executing a bit of one task, then setting that task aside and moving to another. It’s rather like a painter painting six paintings “at once” by running rapidly from easel to easel, adding a few daubs of paint to one painting and then dashing off to the next.

To our slow-as-a-slug human senses, a digital device that’s operating this way will seem to be doing all of the tasks at the same time.

In some cases, then, a synthesizer that boasts “three separate effects processors” may only have a single effects chip, which is giving you the impression that it’s three separate chips by jumping from one audio processing task to another at a blindingly rapid speed. In a few cases, the synth may have no dedicated effects chip at all: The main chip that houses the oscillators and filters (all of which are digital processes) may also do the effects. In the case of software synthesizers, this is absolutely the case, because all of the processes are running “simultaneously” on the computer’s CPU.

Each effect requires a certain amount of computation time, however, and better-sounding effects require more computation time. In many synths, the total number of effects processes that can be carried out at once is fixed: The manufacturer makes the decision that there will be three effects, and you get to figure out how to make the best musical use of them. In other instruments, the user is given some limited control over the number of effects. Bearing in mind that higher-quality effects take more computation time, you may be allowed to choose, let’s say, a higher-quality reverb that uses up the whole effects chip or a lower-quality reverb that can run at the same time as a couple of other less computationally intensive effects.

By the way, the word “expensive” is sometimes used as a synonym for “requiring lots of computation time.” Within a given effects system, the statement, “This is an expensive reverb,” means that the reverb sounds good but also takes up a lot of the system’s resources. Another term you’ll hear from time to time is DSP. This is an acronym for “digital signal processing.” A synth with three effects processors will sometimes be referred to as having “three DSPs” or “three effect DSPs.”

Even in an instrument that has, in theory, a fixed number of effects, tradeoffs between effect quality and total number of effects will quite likely be allowed. In such an instrument, the list of effects might include the following items:

chorus overdrive chorus + overdrive

If you choose the “chorus + overdrive” effect, you’re not magically increasing the speed of the effects chip so as to be able to run both the chorus and the overdrive effects at once. What’s happening is that you’re getting a lower-quality chorus, which is running in tandem with a lower-quality overdrive. The two together take up the same amount of computation time as the higher-quality chorus or overdrive by itself.

JARGON BUSTER: An algorithm is a mathematical procedure. In math, it’s simply a way of solving a problem. In computers, it’s a procedure or method designed to produce some type of

output. In a technical sense, digital oscillators and digital filters are produced by algorithms. For that

matter, in a technical sense a patch in an analog modular synth is an algorithm. In digital music circles, however, the word is usually used in a narrower sense, to refer to two types of processes:

effects, and the configurations of oscillators and envelope generators that produce frequency modulation. (The latter is discussed in Chapter Four.)

As a result, a synth that will do “three simultaneous effects” may in fact allow you to do five or six lower-quality effects at once. A reputable manufacturer will still call this a three-effect synth, but a salesperson might try to inflate the number to impress you. Trying to be smart, you might ask, “Yeah, but how many separate separate effects processors does it have?” The real answer to this might be, “one,” if all the effects are being computed on one chip — and yet the correct answer may be three, if you can always use three different higher-quality effects at once and send a separate audio signal to each of them (a topic we’ll look at more closely below).

In the list above, the items “chorus,” “overdrive,” and “chorus + overdrive” are usually called effects algorithms. For each effects processor (or what appears to the user as a separate processor), you can choose a separate algorithm — reverb, chorus, flanger, or whatever. If an instrument has 43 different algorithms in its list of effects, another correct way of answering the question, “How many effects does it have?” is to say, “Forty-three.” Only two or three effects may be available at the same time, but for each of these, you may be able to choose any of the 43 items in the list.

Or not. Some synth effects are set up in such a way that each effect processor has its own list of algorithms. You may find, for instance, a dedicated reverb/delay with 17 algorithms, a dedicated chorus/flanger/phaser with another nine algorithms, and a third, more versatile processor with 43 algorithms, some or all of which are the same as the 17 reverbs and nine choruses. So does the synth have three effects, or 69, or some number in between?

In most instruments, you’ll find several algorithms for a single type of effect — several different reverbs and so on. Even when you adjust the user-programmable parameters so that they appear identical, two reverb algorithms will probably sound somewhat different from one another. This is because each algorithm includes some settings that are not user-programmable. In a few instruments, however, what are displayed in a list as separate “algorithms” may in fact all be based on a single underlying algorithm.

When you choose a different item from the effects list (for instance, the “dark room” reverb as opposed to the “Grand Canyon” reverb), the difference in sound might be due simply to the fact that the reverb is initialized with different values for the user-programmable parameters. In other words, you may be loading a reverb preset rather than a new reverb algorithm. The owner’s manual probably won’t tell you this; the only way to find it out, if it’s important to you, is to adjust the user parameters of the two separate reverb selections so that they’re identical, and then use your ears.

Signal Routing

Generally speaking, effects are the last part of the audio signal chain. Sounds are created in the synthesizer voice section, the sounds of the separate voices are combined, and then the combined signal is sent through the effects section. The output of the effects section is fed straight to the instrument’s audio output jacks. Within that broad outline, however, you may encounter many different options.

The signal paths through which the synth voices are sent to the effects are usually called either buses or sends. “Bus” is a general term for any path through which an audio signal flows; the word can also be a verb, as in, “We’re busing this signal to this input over here.” “Send” is more specific; it’s a shorthand term for “effects send,” which is a bus that’s used as an input for an effects processor. Each effect will also have an output bus. The signal coming from the effect will appear on its output bus, and your synth may give you further options for what to connect that output bus to.

Buses can be either mono or stereo. A mono bus carries a single audio signal. A stereo bus is actually just two mono buses side by side, a left bus and a right bus, which have the same source and destination.

In a hardware mixer, it’s usually a simple matter to send the left and right sides of a stereo signal to different destinations, in the unlikely event that you need to. I’ve never seen a synth that allowed stereo buses to be split in this way, but I’m sure somebody has built one. In most modular synths, however, especially digital modulars, “stereo” buses are often separate mono buses running side by side, so splitting them is a simple matter.

In effects signal routing, the signal that is being sent to the effect — that is, the signal to which the effect process has not yet been applied — is called the dry signal. The output of the effect is called the wet signal. Most effects processors include some method of controlling the relative levels of the wet and dry signals. Often, but not always, this is in the form of a wet/dry balance parameter. The wet/dry balance is conventionally considered to be in the range 0-100%. When the balance is 100% wet, the output contains only the output of the effect, with none of the input signal. At 0%, the output contains only the signal that was input to the effect, and the effect itself has, if you will, no effect. When the wet/dry balance is 50%, the output contains equal amounts of the dry (uneffected) and wet (effected) signals. In some instruments, 0% is referred to as 100% dry, and 50% is referred to as 50/50.

If your synth seems not to have a wet/dry balance control per se, it will probably allow you to set the wet/dry balance in some other manner. For instance, you may have separate level controls for the dry and wet output buses. With this type of setup, a little care is needed. A few instruments provide both a level control for the dry bus and a wet/dry control within the effect processor. In this situation, if you turn up the dry bus (which is routed around the effects rather than through them) and also set the wet/dry control within the effect to less than 100% wet, the dry signal will appear at the output through two signal paths

— via the dry bus and also after passing through the effect. You might not expect this to be a bad thing, but it is. The problem is that the effects processor will most likely delay the signal passing through it by some small amount. Even the dry signal will be delayed as it passes through the effect. As a result, when the two dry signals are recombined, there will be some phase cancellation, which will alter the sound, usually in an undesirable way. (Phase cancellation is explained in Chapter Two.)

Even if your synth doesn’t allow you to set up signal routings that cause phase cancellation, setting the correct wet/dry balance is important. A sound with too much effect can sound good when you’re checking out the synth in the store, because the sound programmers at the factory wanted the instrument to sound big and impressive. But if you use that sound in a recorded track without lowering the wet/dry balance (“lowering” means lowering the wet part of the signal and increasing the dry part proportionally), or

especially if you use several factory sounds without doing so, you’re quite likely to end up with a mix that’s a muddy mess. When evaluating effects settings of any kind, always consider how the patch sounds in conjunction with the other musical parts that will be heard at the same time.

A few synths, mostly consumer models, are set up in such a way that the dry output is always at full level, while the wet output (the effects output level) is programmable. In this situation, the wet/dry balance can be no wetter than 50/50. For most musical purposes, this is not a huge problem, but once in a while it can hang you up. For instance, you might want the cavernous sound of a snare drum passing through a reverb 100% wet, without the dry signal.

Many synths have effects bypass buttons on the front panel. A bypass button sets the output of the effect temporarily to 100% dry. This is a handy shortcut when you want to listen to a sound both with and without the effect, in order to judge whether certain parameters need a little more massaging: Not only does the bypass button save you the trouble of digging through the menu to find the wet/dry control, pressing the bypass actually leaves the wet/dry parameter set where it was before, so that you don’t have to remember the setting in order to restore it when you’re done listening to the dry sound. And if you’re playing in an auditorium where there’s a lot of natural reverberation, being able to bypass the synth’s reverb for the entire gig with one button-press may be very useful.

In some instruments, an effect on/off button is provided instead of a bypass button. The result is usually the same. Pressing bypass will give you the dry signal by itself.

Many synths sum the output of their voices to mono before sending them to the effects. In a few instruments, you can not only pan individual oscillators left or right within the dry bus but also choose the effect send bus that each oscillator will use. Another common option is to allow each of the sounds in a drumkit multisample to have its own effect send level and/or bus assignment.

When a synth has more than one effects processor, the question of how signals are routed through the effects section becomes more interesting. In Chapter Five, in discussing instruments with more than one filter, we introduced the concept of series vs. parallel routing (see Figure 5-10, page 96). Like filters, two effects can be connected in series or in parallel. If they’re routed in series, the output bus of the first effect becomes the input bus of the second effect. If they’re routed in parallel, each effect receives its own input signal, and the two outputs are sent to whatever physical output you’ve chosen. (Output busing is discussed below.)

In some synths, the effects routing is fixed. You may find, for instance, a distortion effect, a chorus effect, and a delay effect connected in series, so that the output of the distortion feeds the input of the chorus and so on. In other instruments, the effects configuration is partially or entirely user-programmable. The effects might always be connected in series, for instance, but you might be able to choose the order of effects in the series. In a more flexible instrument, such as a Roland JV series synth, you’ll have separate control over the dry output level, the output level for the chorus (the amount of chorus signal being passed directly to the instrument’s physical outputs), the send level for the bus that goes from the chorus to the reverb, and also the output level for the reverb.

If there are three effects, still more possibilities present themselves. You may be able to patch two of them in series and run the third parallel to those two, or run two in parallel and then mix their outputs before sending it to the third.

For many standard types of sounds, this amount of programming power is overkill. When you’re laying down an electric piano track, a little chorus and reverb are most likely all you’ll need. But if you’re working in a genre — pop music, to name one — where fresh sounds are important, being familiar with all of the tools in the tool kit can pay big dividends. Running a flanger in parallel with the reverb or EQing the heck out of a signal before sending it to the distortion effect may be exactly what you need to put your recording over the top. So don’t neglect effects.