Universal Audio UAD POWERED PLUG-INS ver.6.1 - Manual (Page 521)

UAD Powered Plug-Ins Manual - 521 - Chapter 52: SPL Transient Designer
The SUSTAIN
Control Circuitry
The SUSTAIN control circuitry also plays host to two envelope generators. The
envelope tracker Env 3 again follows the original waveform. The envelope
generator Env 4 maintains the level of the sustain on the peak-level over a
longer period of time. The control voltage of the VCA is again derived from
the difference between the two voltages. Sustain amplitude is increased for
positive SUSTAIN settings and reduced for negative settings.
Figure 174 on page 521 illustrates the original waveform and the envelope
creation to control the SUSTAIN processing. Envelope generator Env 1 fol-
lows the original waveform, Env 2 is generated with prolonged sustain.
Figure 175 on page 521 shows the difference between Env 4 and Env 3 that
defines the control voltage of the VCA.
Figure 174. SPL Transient Designer Sustain Envelopes
Figure 175. SPL Transient Designer Sustain Control Voltage