We have been asked how Studio Units could be used to implement sidechaining, so I will attempt to address this question here.

For clarity, sidechaining is the processing of one audio signal based on the contents of another. This is probably most commonly used to avoid pumping when compressing an audio signal with a significant bass element. The first audio signal has its gain modulated by the effect of the compressor. In this example the sidechain would be a high-pass-filtered version of the original signal, causing the level of compression to be less dominated by bass frequencies.

There is more than one way to implement this in Studio Units:

a) host the compressor and the sidechain filter in a single SU effect. Use an SU thru to send the input signal of the SU effect into the main input of the compressor and simultaneously into the input of a high-pass filter (or a low-cut eq), then connect the output of the filter to the sidechain input of the compressor.

b) host the compressor in an SU effect and send the sidechain signal from another part of the host. Use a stereo SU thru as the input to the patch and route its outputs to the main compressor inputs. Use an SU receive module to feed the compressor's sidechain. Load another SU effect on the host mixer channel that you want to use for the sidechain and add an SU transmit module to send the signal from this patch into the first patch. The quality of results obtained via this tecnique may vary due to potential latency introduced between the transmit and receive modules. In fact, this may not work at all if the host places the two patches in separate processes (as is common when using a 32 bit - 64 bit bridge).

For more details, please refer to the sections in the Studio Units manual that describle the SU thru, SU transmit and SU receive modules.

N.B. both of the above solutions rely on the compressor providing separate sidechain inputs. Otherwise there isn't much you can do.

I hope this is of some help.