The GML Model 2030 is based on the proven GML Series III control and audio architecture, this no-compromise dynamic range controller continues the GML engineering tradition and expands familiar Model 8900 capabilities, including multi-channel operation.
The GML Model 2030 control architecture provides a user-defined ‘0’ level reference, designed to accommodate various mastering chains. The internal jumper-settable Master Threshold Reference adjusts the ‘0’ dB reference, or “rotation point” from 4dBu to 20dBu in 4dB steps.
Higher positions of the Master Threshold Reference (12dBu, 16dBu & 20dBu) are recommended when sources are professional D/A converters (which often have 0dBFS from +18dBu to +26dBu); higher positions of Master Threshold Reference set the gain reduction threshold high enough for the most subtle gain reduction activity.
The 4dBu position of the Master Threshold Reference is best suited for mix-bus and tracking applications or mastering at much lower nominal operating levels.
The internal Master Threshold Reference is located on header block J12 “Master Thresh Ref” near the voltage regulators (rear-right corner) for each channel, on the 20304 sub-assembly. It is required that the Master Threshold Reference be set the same for all GML Model 2030 channels in a multi-channel installation.
The default shipping position is 4dBu; specified accuracy for the GML Model 2030 is maintained for all Master Threshold Reference settings.
All controls of the GML Model 2030 except Fine Threshold and Fine Output use high-quality switches with discrete precision resistors for tight matching, both Left-to-Right and unit-to-unit.
The Threshold and Output functions are broken into two separate control ranges; a Coarse switch with 2 dB steps, and a Fine potentiometer for flexibility and near-infinite resolution over a +/- 2 dB range.
- The Output control provides a –6 to +14 dB range of gain, directly affecting the VCA.
- The Timing control changes the time constants of the Fast and Slow RMS detectors, adjusting both attack and release values simultaneously.
- The Release Hysteresis control enables a variable degree of program-controlled release, dependent upon the degree by which the audio signal falls after a peak.
- The Fast Crest Factor control modifies the threshold of the Fast RMS detector relative to the Slow RMS detector.
The Peak Crest Factor control shifts the threshold of the Peak detector relative to the Slow RMS detector.
The Knee switch selects either Hard or Soft Knee operation:
- Soft Knee mode produces a smooth, continuously variable preset gain characteristic, with the Threshold control setting the dB value for the onset of compression, relative to the Master Threshold Reference. The Ratio control has no bearing on this mode.
- Hard Knee mode allows the user to determine a fixed linear compression characteristic, set by the Ratio control. The Threshold control provides input gain for signals below the Master Threshold Reference.
The Sidechain switch inserts the external signal to the control path input, replacing the audio signal for control purposes. The Coupling control connects pre-Knee function control signals to a local (Internal) or global (External) coupling bus.
The External coupling bus is carried on the rear panel RCA connectors. The highest signal on the bus (greatest gain reduction) will predominate. All Threshold, Ratio, and Output controls must be set to match multiple channels.
The Control switch allows close Left-to-Right tracking by using only one Knee processor to simultaneously affect both VCA’s. It may be activated in concert with Coupling such that transient content in both channels will alter the processing envelope.
The Output control of the GML Model 2030 must be set to match both channels. The Dynamics In switch provides a “hard-wire bypass” of the unit when disengaged.
