Dave Smith Instruments Poly Evolver, Operation Manual

Page: 11 / 72

11
Inside the Poly Voice
Before going through the individual parameters, following is a brief description of the
Poly’s architecture of a single Poly 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, etc).
Analog-to-Digital (A/D) and Digital-to-Analog (D/A) converters are used to connect the
analog and digital. As can be seen, there are two sets of stereo converters; they run
at 48 kHz sampling rate with 24 bits of precision for minimum impact on the analog
sound.
Each voice is completely independent, except the single stereo External Signal Input
is routed to all four voices.
Inputs and Outputs
There are a bunch of audio jacks on the rear panel. All are stereo pairs (two mono
jacks), and unbalanced. First, there are the External Inputs, which can be routed to
the input or 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 External Input jacks, where it can then be
routed to another voice’s input for some interesting effects.
There is also a Mix input; this input is simply mixed with the Poly’s output with no level
control. It is a convenience feature, for example when you have two Polys chained, or
an Evolver and a Poly chained.
The last jacks are the Stereo Output mix. If you only use the Left/Mono jack, you will
get a mono mix of both channels – but you really should use both channels!
Note: A lways turn down your mixer/amplifier volume when turning the Poly on or
off to prevent pops!