modulation effects

Basics of the modulation effects

Enhance your music production with effects. Producing music with use of modulation effects can bring to your audio production your personal touch.

Chorus

Chorusing began as an electronic means of recreating the sound of two virtually identical signals such as a c tracked vocal. Tracked vocals give a natural chorusing effect since even if the singer is extremely accurate there will e be slight variations in pitch and timing which cause some cancellations and reinforcements of the waveform. 12 string guitars are a good example of chorusing in the real world. The strings are tuned in pairs to the same note but they are different gauge so they will never sound exactly the same. Electronically, and now digitally, chorus is created by re-combining a slightly delayed and pitch modulated version of a sound with its source. The mix between the wet and dry signals should be roughly 50:50 or there will be no effect. The pitch modulation of a chorus is achieved using an 110 produces a regular cyclic pattern. This distinguishes it from natural chorus where the modulation is more random and chorusing of this type has become an effect in its own right. It is always better to double track properly if you have the Chorus is commonly used on guitars and keyboards and can give an idea of movement, richness and stereo width. However it can also de-localise the sound so it's often best reserved for background parts. For example, it can be use good effect to add richness to backing vocals, even if they are already double-tracked! It also famously works well on fretless bass.

 

Flanging and phasing

Flanging is actually a specific and distinctive type of phasing. It is an effect that originated du the era of the tape machine and which has been copied electronically and digitally. It is created by mixing two identical signals one of which is delayed by a tiny but varying amount. Flanging was first achieved by copying an audio track or second tape machine, playing the two tracks back in sync and mixing the outputs. The engineer would then manually pressure against the flange of the reel on the second machine slowing it down slightly. This would change the pitch ar momentarily place it out of phase and time with the first machine. The outputs of the two machines were then mixed together. The result was a number of constantly changing phase cancellations and reinforcements a bit like a sweeping comb filter. To the ear it sounded like a swooshing 'drainpipe' or swishing tunneling sound. In flanging the peaks and troughs of the comb filter are in harmonic series. One of the first instances of flanging on a commercial pop record was the tom fills of the Small Faces 1967 hit ltchycoo Park. Phasing is general perceived as a more subtle effect than flanging. It is created in a similar way. An electronic phaser split the signal into two and shift the phase of one signal (delay it by a tiny amount) by using an all-pass filter and then recombine the signals. The all-pass filter allows all frequencies through at their original amplitude but introduces differ phase shifts at different frequencies. When the filtered and non-filtered signals are recombine peaks and troughs are f along the frequency spectrum. These are not in harmonic series in contrast to flanging. The degree of the phase shift modulated with and LFO causing the characteristic sweeping sound of a phaser.

With flanging and phasing the intensity of the effect (the amount of cancellation) depends on the balance between the original and the delayed sound. The depth control adjusts the amount of variance from the central delay time. The ratio control refers to the speed of the LFO modulating the time delay. This causes the speed of the sweep to change. Fee allows you to recirculate the delay for a more exaggerated effect.

Both Logic and Pro Tools include Modulation Delay plug-ins as part of their standard set. It is possible using this typ plug-in to create chorus, phasing and flanging effects. Logic also helpfully provides dedicated chorus, flanger and phaser plug-ins.

Flanging and phasing can be applied to many types of sounds successfully. The more subtle settings tend to be used on vocals, backing vocals and cymbals. Wilder settings can be commonly heard on bass and electric guitar. They both work well on harmonically rich sounds so overdriven guitars are ideal. In fact many guitarists have flangers and phasers as stomp boxes for that very reason. Flanging is particularly successful on bass, giving a hollow tunnel like effect. This has become something of a cliché so perhaps it's advisable to steer clear — unless you're going for that 80s bass sound!

 

Tremolo and Vibrato

They are both also well known modulation effects. They are simpler than flanging and phasing and originate from being a part of many a musician's normal repertoire of expression. Tremelo is essentially amplitude modulation and vibrato pitch modulation. Many singers employ both techniques in the course of a performance. On stringed instruments such as guitars and violins vibrato is produced by wobbling one's finger on the fretboard whilst holding down the string. Confusingly the tremolo arm of a guitar actually produces pitch modulation which is vibrato. As an effect tremolo is not surprisingly great on guitar. Many amps have a tremolo built in like the Vox AC30 for example. Vibrato effects were often built into electric organs such as the Hammond B3. A Leslie rotating speaker cabinet would have the effect of creating both pitch and amplitude modulation simultaneously. These days plug-ins are available to simulate these phenomenon. A chorus with the output set to 100% wet would essentially produce vibrato. Logic Pro 7 includes a Tremelo plug-in, a Scanner Vibrato plug-in and a Rotor cabinet plug-in as standard. Logic's tremolo plug-in offers a variety of modulation wave shapes and can combine amplitude modulation with auto-panning to create movement in the stereo field, making it a very useful plug-in. Some pitch correction plug-ins such as Autotune include a vibrato option which you can set to kick in after a note has been sustained for a certain amount of time.

Ring modulators

This is an unusual effect which is good for producing experimental and weird sounds. It's most famous usage is as the voice of the Daleks in Doctor who. It has to be used with care though as the results can often be atonal. A nng modulator works by processing two input signals and combining the sum and difference of their frequencies at the output. If you input two sine waves at 900Hz and 600Hz the output would be made up from two tones at 300Hz and 1500Hz for example. This doesn't sound very interesting but if the input signals are harmonically rich then all those frequencies will contribute to the sum and difference process and very interesting results ensue. Ring modulators can be great for adding something different to synth patches, for creating special effects voices and they can be interesting too on percussion and cymbals.