Phaser & Flanger
Phaser
Phasing was the next purely electronic effect after the wah- wah and fuzz box, and it originally set out to emulate tape phasing. In the phaser, a signal is again split onto two paths (like a chorus and flanger): one straight and the other diverted via a phase-shift network that can be varied under the control of a low-frequency oscillator (LFO). The result is a continuous tonal change based on the frequency cancellation that occurs when the phase-shifted signal path is out of phase with the straight signal path.
Because the cancellation process is frequency-dependent, the process creates a deep notch in the frequency response of the output, and under LFO control this notch moves across the audio spectrum, creating a tonal sweep. As with chorus, phasing has the effect of taking away the immediacy of a sound, making it sound disembodied, which is why it became so popular for psychedelic music.
(The famous analogue phaser, the Mu- tron Bi-Phase.)
Phasing tends to work best in a sparse musical arrangement that has plenty of space. In a busy mix, the phased sound will slither around in the background unless it’s mixed very high.
Although best suited to harmonically rich sounds, such as overdriven guitar, the effect may also be used on some synthesized sounds to create movement. And even though it does tend to push a sound to the back of a mix, the ever- changing tone means that the listener is more likely to be aware of its presence than an instrument that has a constant sound.
In the 70s phasing was everywhere – guitars, drums, vocals, even sometimes a whole section of a song, and though it might not be used nearly as much these days, you might want to try it on a drum fill or a vocal part, for example.
Parameters
Sweep Depth or Range
This parameter is used to control how far the notches sweep up and down in frequency. In some cases, you may be able to select actual frequency values, and in other cases, the base frequency may be set to some value and you can only control how far from that frequency the sweep will go.
Speed/Rate
This parameter simply controls how quickly the notches sweep up and down over the frequency range. The rate sets how many times the notches sweep up and down per second. The speed at which the actual notches are moving is determined by this rate control.
Feedback/Resonance
The phase-shifting effects can be made more intense by using feedback – adding part of the filter output to the input again. This control determines how much of the filter output is routed to the input again.
Stages (4, 8, and 16)
As a general rule, the more stages you have, the more
notches you get in the frequency response and the stronger the phasing effect.
Flanger
Chorus and phasing might be polite little effects, but flanging can have real attitude. It came onto the scene a while after phasing, and employed the then brand-new technology of the charge-coupled analogue delay line to produce the amount of delay necessary to emulate tape flanging more closely.
Legend has it that the flanger was born when the Beatles were producing an album. A tape machine was being used for a tape delay and someone touched the rim of a tape reel, changing the pitch. With some more tinkering and mixing of signals, that characteristic flanging sound was created. The rim of the reel is also known as the ‘flange’, hence the name ‘flanging’.
As with phasing, two signal paths are used – one dry and one processed – but this time the processed sound is delayed by several milliseconds as well as being modulated.
The underlying technology is almost identical to that of chorus, except that chorus tends to use slightly longer delay times and doesn’t feed any of the output signal back to the input. A flanger creates its deep, almost resonant whooshing effect by feeding some of the delayed output signal back to the input and the effect is pretty dramatic.
If you were to look at the spectral characteristics of the output signal, you’d see a whole series of strong peaks and notches in the response; these move across the audio spectrum under the control of the modulating LFO.
Because the effect of flanging is so distinctive, it’s unwise to overuse it. Like phasing, flanging works best on harmonically-rich sounds, but it is also strong enough to show up clearly on clean guitar, drums, or even vocals.
Parameters Delay
This controls the minimum level of intensity of the effect. Looking at the frequency response, this value determines how high the first notch will go. As the delay is increased, the first notch drops down. In some cases, the delay parameter can be set to zero, in which case the notches will sweep the uppermost frequency range, and essentially disappear momentarily. In other cases, you may not be able to control the delay parameter.
Sweep Depth/Width
The sweep depth determines how wide the sweep is in terms of delay time – essentially the width of the LFO. This sweep
depth is the maximum additional delay that is added to the signal in addition to the delay in the delay parameter. It determines how low the first notch in the frequency response will reach. A small value for the depth will keep the variance in the delay time small, and a large value will cause the notches in the frequency response to sweep over a larger area.
Note that when you vary the delay parameter, both the upper and lower limits of the first notch are changed, but when you adjust the depth, only the lower limit is affected. So when you are setting up a flanger to sweep over a particular range, first set the delay so that the high point of the sweep is where you want it, and then adjust the sweep depth to set the low point of the sweep.
LFO Waveforms
Some flangers will allow you to choose the LFO waveform. This waveform determines how the delay in the flanger varies in time. The triangle & sine are probably the more common choices in flangers.
Speed/Rate
The speed control is pretty straightforward. This parameter refers to the rate at which the LFO waveform repeats itself, or equivalently, how many times per second the notches sweep up and down.
Feedback
Some units will give you an option for taking a portion of the flanger’s output and routing it to the input, this is the ‘feedback’ parameter. In some cases, you can also specify whether to add or subtract the feedback signal. A large amount of feedback can create a very ‘metallic’ and ‘intense’ sound. Of course, as the feedback gain approaches 1, the system can become unstable, possibly resulting in overflow or clipping.
General comments.
- The general problem is that the use of effects such as chorus, phasers and flangers can sometimes be a bit cliché, so finding artistic justification for their use isn’t always easy. Just be aware of not overdoing it unless you have a real artistic reason.
- Here again, for more control, it is usually better to use auxiliaries to feed these units so you can blend the direct sound with the effects, and even process the effect signal even further.
- For example, applying a phaser to a delay return can really turn the effect into something else, without disturbing the original signal. The best I’ve heard was a drum fill going into an Echoplex that was feeding a Mu-tron Bi-phase: AWESOME.
- Something else you might want to try is to put a flanger before a reverb or delay, as this can provide interest without making a sound seem over-effected.
- Don’t always rely on expensive multi effect processors and/or plug-ins – there are a lot of good value guitar pedals with a lot of interesting tones.
The Bottom line
When setting up a mix, try to get the sonics sounding close to right before you add any effects or signal processing. Once you’ve got this right, add further vocal compression if needed and also apply just enough reverb to make the vocals sit comfortably with the backing track. When you’re happy with the overall timbre and balance, adding effects for ‘effect’ should be easier. Remember that in most cases, effects are there just to add the final gloss; they won’t compensate for a poor balance or bad basic sounds. Home demos often use far too much reverb, and the result is a cluttered mix with no space.
For all the technology we have to play with, our most valuable tools are still our ears, so I’ll end as I started, by suggesting that you spend some time listening to how different styles of music have been mixed and how the most successful reverb treatments have been chosen to enhance the arrangement.
Bibliography
Cousins, M. (2005), Ten Minute Master, No50: Delay’: Music Tech Magazine.
Internet Sources:
www.audiogeekzine.com
www.davidmileshuber.com
www.playrecord.net
www.prosoundweb.com
www.recordinginstitute.com
www.soundonsound.com
www.uaudio.com
www.wikipedia.org
