8051 User Manual (Issue 2) - AMS Neve

Issue 2 Page 78051 5.1 Compressor User GuideControl LinkWhile the SC link buttons control the audio inputs toeach sidechain, the CV link buttons choose wherethe D.C. control voltage generated by eachsidechain is routed. The CV link buttons alsodetermine which gain makeup control affects eachchannel, in the same way that the SC link buttonsassign the threshold controls.For the output of a sidechain to be correct, it must befed back to the channels it is derived from. Pressingan SC link button will therefore illuminate thecorresponding CV link button and lock it on.80Hz80Hz1000151/201510012015120NeveIN/OUT0155/60151534SC TRIMS dBIN/OUTEXTACTRLEXTBCTRL15151122FILTER TO CHANNEL3BYPASS1 2 3 4 5 6MSIDECHAIN LINK1 2 3 4 5 6A A A A A A1 2 3 4 5 6B B B B B BMST3CONTROL LINK1 2 3 4 5 6A A A A A A1 2 3 4 5 6B B B B B B4SIDECHAIN FILTER45566Most compressors apply gain reduction based entirely on the signal level at their inputs. A leveldetector examines the input and drives an output VCA that is assumed to have a complimentaryresponse (a 'feed-forward' system). The 8051 uses a feedback topology, monitoring the output ofeach gain cell and continually adjusting the control voltage returned to give the required gainreduction.This means that the control voltage linking has to follow sidechain linking to maintain a closed loop.Once this feedback is in place the sidechain output can be linked to other channels using theremaining unlit CV link buttons. These channels then follow the same dynamic envelope as the SCLinked channels, but without their audio content affecting the compression.A channel may also have control voltage linked from both sidechains. In this case the sidechainproviding the most gain reduction at any moment controls the channel, and the greater of the twogain makeup settings will be applied.The CV Link buttons are disabled unless either a channel or the key has been routed to theassociated sidechain, or when in external mode.