Stereo Widening with PHA-979 by Voxengo
Last Edited: Dec 1, 2023
You can apply many techniques to achieve a stereo-widening effect. This process is beneficial in making your instruments or vocals sound more prominent and spacious. The good news is that many analog and digital effects can help you achieve this today. Some software plugins are doing a great job of achieving stereo widening and phase alignment. One is Voxengo PHA-979, and we will discuss its features in the following tutorial.
Voxengo PHA 979
PHA-979 is a professional audio AAX, AudioUnit, and VST plugin that allows you to apply an arbitrary phase shift to sound material. What is meant by the phase shift here is a simultaneous shifting of all frequencies across the active frequency range of the signal by the given value in degrees. Furthermore, the linear-phase design achieves this. Besides the phase shifting, PHA-979 features positive and negative time delaying, which eliminates the need to move in-track events in the sequencer when doing time alignment over recorded tracks. PHA-979 also provides mid/side channel balance and panning controls that permit you to record stereo microphone pairs into a single stereo track without resorting to dual mono recording (on separate tracks), which usually becomes time-consuming in further editing.
Let's Start
In the following tutorial, I will apply PHA-979 by Voxengo to a short Electric Piano sequence followed by a beat done in our SoundBridge: DAW.
The Interface
As we can see, it is a relatively simple interface divided into three main sections.
Left and Right
The first section is reserved for channel delay. The "Left" and "Right" knobs control the delay time (in milliseconds) independently applied to the left and right channels, respectively. The plugin can use negative time delay (shift the channels "back in time") due to the constant technical processing latency the delay module introduces in the first place. To set up delay times easier, you may use the "Delay Time Calculator" provided with the plugin. However, in this calculator, you must enter sample positions of any two sound events (transients) you want to time-align to each other.
Phase Alignment
The second section offers parameters for the phase alignment. So, the "Left" and "Right" knobs specify the phase shift value (in degrees) for the left and right audio channels, respectively. The "L 180" and "R 180" switches enable 180-degree phase inversion (flip) of the left and right channels, respectively. The "Corr" button opens the "Correlometer" pop-up window where you can see the sound wave's appearance.
Out
The third section is named the "Out". This block controls output stage parameters. The "Side Mix" knob adjusts the amount of side channel signal present in the output signal (in percent). When the knob is at 100% (no mid-channel present), the resulting entire side channel output will be 6 dB louder in comparison to the 50% position to account for a usually quieter side channel signal. The "Pan" knob controls output signal panning (in percent L-R). The plugin uses the "0 dB" pan law for stereo panning. The "Out Gain" knob adjusts the overall output signal gain (in decibels).
The "Force Mono" switch enables processing of the left audio channel only. The "L/R Swap" switch allows left and right channel swapping before the "Side Mix" and "Pan" adjustments are applied. The "Mono Mix" switch enables the mixing of left and right channels to mono on output. The "L/R Diff" readout shows signal loudness difference between the left and right channels in decibels (3-second integration). This readout shows negative values if the left channel is louder than the right channel. Note that this readout does not have the means to display channel phase difference, which may make a given channel sound louder even if its loudness level is equal to an opposite channel. The "RMS" readout shows the output RMS signal level (3-second integration) of the left and right channels (in decibels).
Audio Example
After explaining the PHA-979 parameters, let's hear how our El. The piano sequence sounds unprocessed and then processed with PHA-979 by Voxengo. I advise you to use high-quality headphones or a pair of studio monitors in order to hear the difference in full effect.
~El. Piano - Unprocessed
~El. Piano - Processed with PHA 979
~Full mix
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