Audio Software

The SublimeSlime Mid/Side Decoder VST Plugin

The SublimeSlime Mid/Side Decoder VST Plugin is shown below running within the shareware VST host MiniHost. This plugin was developed to make it easier for tapers and other non-professional recording enthusiasts to take advantage of the current generation of low priced, high quality, multi-pattern condenser microphones to make compelling stereo recordings using the mid/side recording technique.

MS Decoder

Perhaps the most familiar stereo recording technique uses two identical microphones, one on the left and one on the right. Unfortunately, as the references in the sidebar attest, mic separation and distance from the sound source are critical parameters that have a dramatic impact on stereo imaging. The other problematic issue is mono-compatibility, which is especially important for radio and video, as the recording needs to sound good coming out of a single speaker. When a spaced pair stereo recording is played back in a mono system, L and R channels are added together, and the phase differences between the channels can produce a "chorus effect" where some frequencies are boosted and some reduced. As a result, spaced pair mic placement is tricky, and the recording's stereo image is largely determined during the recording session and is difficult to manipulate during mastering.

The mid/side stereo recording technique is a frequently favored alternative because it provides guaranteed mono compatibility, and gives the mastering engineer control over the stereo field. One reason it is not used as frequently as other stereo recording techniques is that it requires two microphones with different patterns mounted in close proximity to each other. One channel, the mid channel, is typically recorded using a cardoid microphone which is quite common. The other channel, the side channel, needs to be a figure-8 pattern mic, which is somewhat less likely to be a standard part of the non-professional's microphone cabinet. The magic of mid/side approach is how the side microphone's figure-eight pattern has two sides of opposite polarity that cause different degrees of phase cancellation according to relative position between mic and source, thereby encoding stereo location information. In essence, the mid microphone provides mono, and the side microphone carries the stereo location imaging. After recording, during mixing or mastering, by adjusting the ratio of mid signal to side signal, you can dial in as much or as little stereo effect as you like. Mono compatibility is guaranteed because of the way M/S decoding works. One of the stereo channels is M+S, and the other is M-S. When you add the two, +S and -S cancel, leaving you with pristine mono without any multi-mic phase effects.

I wrote the SublimeSlime Mid/Side Decoder VST to make it easier for me to use the mid/side stereo technique when recording live at jazz clubs in San Francisco. Professional engineers have an arsenal of far more sophisticated tools they use as part of an expensive mastering process. My VST offers single nob stereo field control and has been designed to make it easy to correct for common cabling errors made in the field. Pushbuttons allow you to hear the effect of swapping mid and side channels on input, and left and right channels on output.

MS Decoder

Currently, the SublimeSlime Mid/Side Decoder VST is Windows only, and a demo version is available for download below. The demo version stops decoding after 5 minutes but can easily be converted to the full version by becoming a registered user and purchasing it via Paypal. The online plugin authorization process requires that the computer running the VST be connected to the internet.

Select the channel the mid signal was recorded on. Adjust the stereo field by changing the mixture of mid and side signals. If the stereo field seems reversed, try the other channel.
the free evaluation copy
to be able to purchase online from SublimeSlime.com and authorize plugins
the full version - requires simple registration
to view your authorizations and purchases

For more information about stereo recording, you may find the following links helpful:

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