Pseudo stereo audio processing techniques generate two stereo channels from a single mono one, for the purpose of generating a wider spatial impression, while creating an illusion of multi-directional audible perspective. However, pseudo stereo can also be used as a creative audio manipulation tool in itself.
As most of you are no doubt aware, there are a lot of methods you could use, in order to make a signal ‘more stereo’. With many M/S processing plugins that are on the market nowadays, it is not hard to shift the MID/SIDE balance. For example, this bx control V2 could come in handy, and is also a MID/SIDE decoder/encoder.
Of course, this works only on signals that already have some stereo information. When we are dealing with signals that have no stereo information to be enhanced using the MID/SIDE method, we are left with options to create pseudo stereo effects.
~ This is a mono recording of a piano.
I would like to mention that the most common pseudo stereo effect is the HAAS effect, an illusion that takes advantage of our ability to tell where a sound is coming from based on time delay. Digitally, introducing latency in the order of 3-10 ms to a left or right channel makes an illusion of stereo.
~ This is the piano with the HAAS effect applied – containing 13ms of latency.
To add even more presence, we can introduce a similar effect by detuning the left and right channels (tuning one up and the other down just a tiny bit).
~ This is the piano with 5ct of detuning applied.
While this method produces wonderful effects in stereo, it is not so reliable when the signal is converted to a mono signal (when left and right are summed). This is important since most of the clubs where modern music is played at usually have to sum down left and right to mono, due to the way the speakers are placed and configured.
~ This is the detuned piano converted back to mono – BIG no no for EDM clubs.
At this point, I would like to introduce an equally nice sounding pseudo stereo method that translates to mono perfectly. You can use a parametric EQ that has a separate control over its left and right channels. There is a really nice preset in the Waves Q10 plugin that you can use as an excellent starting point.
As you can probably see from the preset, the whole point of this method is to periodically remove frequencies from one channel (left) while leaving them to play on the other channel (right). This means that whatever we remove from the right channel we leave on the left and vice versa.
~ Piano with Q10 pseudo stereo effect applied.
In essence, when the 2 channels are added up to make a mono signal again, it produces a really deep stereo effect and deals with unwanted phasing and chorusing.
~ Q10 sample converted to mono – hear the difference?
Surely, the attenuation we apply with these notches does not have to be as steep as it is in this preset (-18 dB). At any time you can select all of the gain fields by click-dragging over the gain input boxes and dragging the values down. The frequencies where these notches lie can also be altered; I would suggest click-dragging over all of the frequency text input fields to moving all of the notch filters simultaneously as to not lose the general intention of the periodical frequency removal.