Dave Smith Instruments POLY EVOLVER KEYBOARD - Manual (Page 12)

The Poly Evolver Voice
Before going through the individual parameters, following is a brief description of the
architecture of a single Poly Evolver voice. The signal flow diagram on the next page
is a good starting point for understanding how the Poly works.
The Analog Side
The analog electronics for each voice consist of two identical (Left/Right) synth
sections, each with an analog waveshape oscillator, a 2/4 pole resonant lowpass
filter, and a Voltage Controlled Amplifier (VCA). Control voltages are generated by the
processors to control the analog components.
The Digital Side
Surrounding the Analog electronics is a high-speed Digital Signal Processor (DSP)
that both pre- and post-processes the audio signal. Since the DSP also computes the
control voltages for the analog circuitry, it can handle a wide range of modulation with
high precision.
The DSP provides audio functions such as the Digital Oscillators, Envelope Follower,
the Peak/Hold detector (and associated external trigger generator), Highpass filter,
Distortion (with noise gate), Pan, Delay, and Hack. It also handles the tuned
feedback, as well as the additional Delay feedback paths. And all the modulation
calculations (envelopes, LFOs, routing, and so on).
Analog-to-Digital (A/D) and Digital-to-Analog (D/A) converters are used to connect the
analog and digital sections. There are two sets of stereo converters running at a
48 kHz sampling rate with 24 bits of precision for minimum impact on the analog
sound.
Each voice is completely independent, except that the single stereo external Audio In
signal is routed to all four voices.
Inputs and Outputs
There are several audio jacks on the rear panel. All are unbalanced stereo pairs (two
mono jacks). First, there are the Audio Inputs, which can be routed to the input of any
or all of the voices, for using the Poly as a signal processor.
Next, there are individual voice outputs for all 4 voices. When a plug is inserted into
one of these jacks, that signal is disconnected from the mix output. This allows each
channel to go to a different mixer channel for separate EQ/processing. It also allows
the output of one voice to be routed to the Audio Input jacks, where it can then be
routed to another voice’s input for some interesting effects.
Next are the mixed Stereo Outputs. If you only use the Left/Mono jack, you will get a
mono mix of both channels – but you really should use both channels! Finally, there is
a stereo headphone jack on the rear panel.
Note: Always turn down your mixer/amplifier volume when turning the Poly on or
off to prevent pops!
12