Logic Pro from A to Z – T is for Tremolo
The sort of cyclical variation of volume associated with tremolo effects can be generated via a plug-in, or easily be set up directly in a synth’s programming. It is often desirable to build tremolo directly into a synth patches programming in order to maximize internal routing, signal flow, and processing possibilities. Here I’ll look briefly at the plug-in, and then show you how to use the EXS 24’s modulation matrix to quickly and easily construct an internal tremolo routing.
Tremolo is defined as “A cyclical variation in the level (amplitude) of a sound over time”. It is a classic pulsing effect that we often associate with twangy electric guitar tones. There are tons of terrific plug-ins built in to Logic. And the Tremolo plug-in, in the Modulation sub category, it great for generating variations in amplitude.
The symmetry and smoothing parameters control the shape of the modulation. The rate knob, when dialed to the left, can sync to tempo for rhythmic subdivisions. And don’t forget about the offset field in the plug-in’s extended parameters section. It can add some syncopation to the rhythm set by the rate value.
The depth slider easily controls the mix between the amplitude modulation effect and the unmodulated sound. The addition of the phase offset parameter shifts the emphasis of the cyclical modulation to panning rather than strictly amplitude; which is a very cool effect! The panning is easily overridden by setting the phase offset to 0” (12:00 o’clock), resulting in a more traditional tremolo effect.
To fully understand how traditional tremolo programming is generated, let’s turn to the EXS 24. Load in your favourite instrument and look for the first available empty routing pathway in the Modulation Matrix.
The first step is to choose what specific parameter is to be modulated. Click in the “Dest” field to set the destination of the routing. Set it to Volume. The next step is to assign a modulation source that will be used to affect, in this case, the volume of the patch. Since tremolo is traditionally a repeating cyclical effect, an LFO is the best choice. I suggest using LFO 2, since LFO 1 is usually used to create a vibrato effect by modulating the patch’s Pitch in a similar cyclical pattern.
Trying it out at this stage won’t yield any audible results. You need to use the vertical triangular slider to dial up some depth. In other words, how much of the LFO source we want applied to the volume of the patch. You will hear deeper and deeper volume oscillations the higher you push it up above the halfway point. The Wave buttons in the LFO 2 section will control the shape of the modulation. And the rate knob will control the speed. Values to the left of centre will sync to musical subdivisions of the project tempo. Experiment with the different waveforms and rates to get a feel for the effect generated by each of the possible values.
Tying the tremolo effect to a physical MIDI control allows you to use it more sparingly, generating it only as you need it while you are performing your part. Click on the “Via” field in the centre of the routing column and choose an available physical knob or slider on your keyboard controller. If you choose CTRL #1 to use the mod wheel, be aware that the EXS 24 assigns it by default to control vibrato (i.e.: pitch modulation). So you can either remove or bypass it from the vibrato routing, or use it for both routings simultaneously. I would suggest using a different physical controller if possible for maximum independence between the two effects (vibrato and tremolo).
To control the tremolo with this new assignment, the depth slider needs to be reset. It turns into a double sided triangle, and is used to set a range of depth that the “Via” controller will work within. Set them to full minimum and maximum values for the entire range of depth to be available through the range of your physical controller. Or, set more precise minimum and maximum values in order to limit the depth to a specific range. Now when you are playing your part, use one hand to control the MIDI knob or slider assigned in the Via field to trigger the tremolo in real time as you need it.