You can apply many techniques to achieve a stereo widening effect. This process is highly useful in making your instruments or vocals sound more prominent and spacious. The good news is that today, there are many different analog and digital effects that can help you to achieve this. There are software plugins which are doing a great job in achieving stereo widening as well as phase alignment. One of them is Voxengo PHA-979 and we will discuss its features in the next tutorial.


Voxengo PHA 979


PHA-979 is a professional audio AAX, AudioUnit and VST plugin which 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.

Beside the phase shifting, PHA-979 features positive and negative time delaying that eliminates the need to move in-track events in the sequencer when doing time alignment over any set of 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 next tutorial, I will apply PHA-979 by Voxengo to a short Electric Piano sequence followed by a beat, and all this is done in our SoundBridge: DAW.



The Interface


As we can see it is a rather simple and straight forward looking 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 plug-in can apply negative time delay (shift the channels “back in time”) due to constant technical processing latency the delay module introduces in the first place. To setup delay times easier you may use the “Delay Time Calculator” provided with the plug-in. However, in this calculator, you need to enter sample positions of any two sound events (transients) you would like 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 channel, respectively. The “Corr” button opens the “Correlometer” pop-up window where you can see how the sound wave looks like.




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 full side channel output will be 6 dB louder in comparison to 50% position to account for a usually quieter side channel signal. The “Pan” knob controls output signal panning (in percent L-R). The plug-in uses “0 dB” pan law for stereo panning. The “Out Gain” knob adjusts the overall output signal gain (in decibel).

The “Force Mono” switch enables processing of the left audio channel only. The “L/R Swap” switch enables left and right channel swapping before the “Side Mix” and “Pan” adjustments are applied. The “Mono Mix” switch enables 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 decibel (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 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 output RMS signal level (3-second integration) of the left and right channels (in decibel).


Audio example


After the explanation of the PHA-979 parameters let’s hear how our El. 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