How To Program With Multi-Effects
If You Dont Know How to Tweak Your Sounds, Youre Missing Out on a Lot of What Multieffects Have to Offer But Its Easier Than You Think
By Craig Anderton
are woefully underutilized, partly because there is so much potential to explore, but also partly because these devices intimidate many people. Familiar knobs and switches have been replaced by LCDs and little buttons, which demand a new way of looking at effects.For example, few musicians seem to realize that contemporary multieffects allow for using a pedal, MIDI sequencer, and/or footswitch to vary virtually any aspect of a sound (overall level, number of echoes, reverb depth, distortion intensity, etc.) in real time. Many recording engineers dont exploit the fact that MIDI-controlled multieffects offer a type of highly sophisticated, yet inexpensive, type of automated mixdown. However, learning how to do these tricks can be confusing - unless you know a few basic bits of knowledge that demystify what multieffects are all about.Lets look into how digital effects work, then describe a generic approach to programming multieffects that will help you get the sounds you want.
The concept of programmability was introduced to musicians when synthesizer players became fed up with trying to change sounds rapidly on stage. Early, non-programmable synthesizers had so many knobs and switches they looked somewhat like a jetliner cockpit, and trying to call up a new sound in time for the next song drove many a player nuts. Programmable synthesizers let you edit a particular sound, then press a button to store the control setting information as a program in memory. Reselecting that program at a later date produces the same sound as when you laboriously adjusted the parameter values in the first place.As signal processors became more complex, they also became more difficult to adjust in real time. Once again, programmability provided a solution. Now we have multieffects with literally hundreds of parameters, but you can recall all their settings at the touch of a button.However, programmability requires some adjustments in your thinking. Musicians and engineers are used to immediate gratification - bend a string, move a fader, or flick a switch, and the results are immediately apparent. And even with non-programmable rack-mount effects it doesnt take too terribly long to, say, turn up the feedback for a more intense sound. The downside of programmable effects is that they trade off the convenience of instant recall for the inconvenience of time-consuming programming to get the effect you want.What makes programmability possible is the computer chip at the heart of every digital multieffects. Each effect or combination of effects is the result of a computer program that tells the computer how to create chorus, reverb, distortion, and/or other effects. This program was written by a real live human being, but you
edit it. When youre getting the sound you want out of a multieffects devices, youre actually entering data into a computer program to change what the program will do.(Actually, to say that multieffects have a computer inside is a bit of an oversimplification. Most devices have a special-purpose computer called a Digital Signal Processor [DSP] thats optimized for processing audio signals. DSP chips are very sophisticated number crunchers that can do the complex, real time calculations needed for audio work.)For example, echo consists of delaying a signal, feeding some of the delayed output back to the input to create additional echoes, and mixing some echoed sound in with the straight sound. So, a multieffects echo program would tell the computer to delay a signal for X milliseconds, feed back Y% of the delayed signal back to the input, and mix in Z% of echoed signal. The nature of the echo sound will change according to what data we put in for X, Y, and Z. A larger value of X means more milliseconds, thus a longer delay. If we feed back a small amount of signal (small Y value), well hear only a few echoes; larger Y values feed back more of the signal, creating more echoes that take a longer time to fade out. What we enter for Z determines the straight/processed mix.Upon entering the data necessary to get the sound you want, youve created a variation which is also called a program (yes, jargon can be confusing). Generally, when we talk about a unit that stores 100 programs, we dont mean the computer program the design engineer wrote but rather, the edited versions youve created. From now on when we say program, well mean your variations. These are also called patches or presets, and just to get you used to the real world, we may use these terms as well.
Fig. 1: Analog controls are continuously variable. A digitally-controlled parameter is like a knob that has been divided (quantized) into a series of discrete steps.
Each adjustable element of an effect, whether analog or digital, is called a parameter. For example, the variable parameters on an analog delay line might include initial delay time, feedback, modulation depth, etc. Before digital electronics took over the world, an effects box had one control (switch or knob) per parameter, so changing parameter values was a relatively easy process. But knob-based effects also had problems: Changing a sound (which required a lot of knob-twisting) took time, and if you came up with a great sound, trying to get it back later could be difficult. Also, knobs and switches have always been some of the most expensive components in effects.Digital electronics largely eliminates knobs. Remember our example above where we described an echo sound with X, Y, and Z parameters? With a digital effects unit, each parameter would be given a unique name or number (so you could identify it for editing), and be quantized into a series of discrete steps (Fig. 1). For example, delay time, instead of being continuously variable and selected by a knob, might be quantized into 1 millisecond steps and selected by keying in a three-digit number (e.g., 000 to 999 milliseconds) with a keypad.The reason for quantizing parameter values is because once these are identified numerically, the same computer doing all the other tasks we described earlier can turn its attention to storing these values in its memory. This lets us call up a particular program at any time. For example, suppose we told the computer that our echo programs X parameter was 210 milliseconds, Y parameter 40% feedback, and Z parameter 35% echoed signal. The computer can remember this group of numbers as a program; once you give the program itself a number, like 26, the computer will file all this information in its little brain under 26 so that next time you ask it for program 26, all parameters will be reset exactly as you specified.Sounds good so far now its time to figure out how to access
all these parameters.
As mentioned earlier, many computerized musical devices dont have knobs that you can twist to change sounds; instead, you need to find individual parameters and alter their values, usually by a process of button-pushing.Fortunately, there are only so many ways to accomplish a given task. If youre creating a sound from scratch or editing an existing sound, youre almost always going to use the same basic procedure for any device:1.
Specify the program (patch) to be edited. This reserves a memory location that temporarily holds the parameter edits.2.
Select the programs structure, which is called an algorithm. The algorithm will determine the sounds overall character. You may have a choice of several fixed algorithms (e.g., compressor distortion chorus EQ reverb) or you may be able to choose the order and type of effects. Fig. 2 shows a couple different algorithms that define the effects structure.
Fig. 2: Two different algorithms. Each one creates a different type of effect, and has variable parameters so you can alter the sound.
Specify a parameter within the algorithm that you want to change (echo time, amount of distortion, noise gate threshold, etc.).4.
Enter a new parameter value and listen to what effect this has on the sound.5.
Repeat steps 3 and 4 until all the parameters have been adjusted to give the type of sound you want.The most common data entry tools are a calculator-style keypad for entering numbers, and/or scrolling or arrow keys to help locate the different parameters (well see how these work in a little bit).
SELECTING DIFFERENT PROGRAMS
A very basic function on all units is calling up different programs. When you turn on a digital multieffects, odds are youll be greeted with either the last program you selected or a default program (e.g., program #01). Depending on the unit, to select a new program you might punch in a certain program number with the keypad, or scroll through the different programs with the arrow keys.You can think of the programs as forming a list, with a window that scrolls over the list (Fig. 3). The up and down arrow keys move the window over the list to select a particular program. For example, if youre on program 14, pressing the up arrow key selects program 15; pressing the down arrow calls up program 13. Some units may use a knob to select programs instead. Then again, some devices may arrange their programs horizontally instead of in a vertical list, and use right/left arrow buttons to move from one program to another. In any case, the basic principle remains the same.
Fig. 3: Using up/down buttons to select a program.
PARAMETER SELECTION AND EDITING
Now that we have a program, its time to select and edit parameters. Each unit has a slightly different way of doing things, but heres a typical real-world example based on a generic multieffects.Suppose a multieffects has two displays (left display for program number, right for other parameter values), two sets of up/down buttons, and one set of left/right buttons. You would begin by selecting a program, as shown on the left display, with the first set of up/down buttons (Fig. 4). The up button selects the next higher-numbered program, and the down button, the next lower-numbered program.
Fig. 4: Program and algorithm selection with a generic multieffects.
Upon calling up a program, the right display might then show the name, number, or even a block diagram of the algorithm used in the selected program (remember, each algorithm represents a particular combination of different effects). If you wanted to choose a different algorithm, you could do so with the second set of up/down buttons.Each algorithm has an associated list of parameters. Since we used the right-hand set of up/down buttons to select an algorithm, it follows that well use the left/right buttons for the next stepparameter selection (Fig. 5).
Fig. 5: Each algorithm will have several parameters whose values you can change.
As you press the left or right button, the display identifies the selected parameter. To change the parameter value, use the right hand set of up/down buttons; the display will show the parameters value. After editing the value, press the left or right button again to select the next parameter on the list (Fig. 6).
Fig. 6: In this example, the display shows several parameters (other multieffects may show only one parameter per screen, or more parameters). You select a parameter for editing with the left/right buttons; the one being edited has an underline (cursor). In this case, its chorus depth, which has a value of 35. The up/down buttons change the parameter value.
This process illustrates two important points:
- There is a definite order for parameter editing. You must first choose the program, and if applicable, the desired algorithm before you can choose a parameter whose value you want to change.
- Note how the display in many multieffects anticipates your needs. If you press one of the right hand up/down buttons with an algorithm number showing, the display knows that you want to edit algorithms. If you press one of the left/right buttons with an algorithm number showing, the display knows that you want to edit the parameters within that algorithm. If you have a parameter selected and you press an up/down button, the display knows you want to edit values.
This demonstrates the good news/bad news of digital effects: if you know what youre doing, editing flows in a logical fashion. If you dont know what youre doing, and you press the wrong button at the wrong time, you may get lost in the program and not be sure what youre adjusting (or how to get back to a familiar reference point).Different units use variations on a theme. Some boxes have dedicated buttons for turning individual effects in an algorithm on and off (effects select buttons). If you wanted to edit one of these effects, you might press an edit button to select a parameter editing mode, which would then change the effects select buttons into effect edit buttons. For example, pressing the compressor on/off button while in edit mode would select the compressor for editing. Each successive press of the compressor button would access another compressor parameter, and up/down arrow buttons would set the value.Although the specifics are different from the example given above, you still:
- Select a program
- Select an algorithm or effect
- Specify a parameter
- Change the parameters value.
No multieffects unit (or synthesizer) strays too far from this basic concept. Once you figure out how your multieffects performs these steps, youre on your way to being a programming expert.
As button-pushing is tedious, manufacturers often include shortcuts. For example, scrolling through 99 programs with up/down arrows can take some time. So, one unit might increase the scrolling rate the longer you hold the button down, while another might double the scrolling rate if you press the unused arrow button while holding down the desired arrow button. And because even little buttons cost money, a manufacturer might use a shift button (like the shift key on a computer keyboard or typewriter) that changes the function of a set of buttons so that five buttons and a shift button can do the work of ten buttons. Any shortcuts should be documented in the manual.Parameter-controlled effects may be confusing at first, but dont give up. You have a lot more power at your fingertips, and greater repeatability. Sure, it takes more time to program or tweak a sound initially, but once you find a great sound and store it in memory, you wont have to find it again.
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