Envelope Follower - PulpLogic Entry Point User Manual

Introduction:
The Eurorack platform is rich in sound shaping tools that can be used to create new and innovative effects for
stringed instruments. The Entry Point allows you to take advantage of this sonic landscape by acting as a bridge
between your electric or bass guitar and Eurorack modular synthesizer. Instead of buying a single effect pedal
to achieve a desired sound, now you can patch multiple modules to build your own unique effects with the
individual characteristics you desire. The Entry Point performs three primary functions when connecting your
instrument to a Eurorack system. First, it acts as a low noise preamplifier to bring your instrument up to
Eurorack signal levels. Second, it generates an envelope voltage that follows your playing dynamics for use as a
control voltage. Third, it extracts the fundamental frequency of the note played and outputs it as a square
wave signal for processing in the modular.
Preamplifier:
The Entry Point's preamplifier is designed to amplify musical instruments up to Eurorack signal levels. When
connecting traditional passive instruments or other low signal level devices, the ACTIVE/PASSIVE switch should
be set to the passive position. When connecting active instruments or other devices that output line level
signals the switch should be set to the active position. The switch position affects both the envelope follower
and the square wave generator and should be set prior to making any other adjustments. The GAIN control
knob sets the amplitude of the signal coming out of the the SIG jack. The amplitude of the SIG output is
displayed on the LED signal strength meter.

Envelope Follower:

The envelope follower generates a control voltage that correlates with the dynamics of your playing. An
envelope is output when the amplitude of the input signal is greater than the threshold set by the THRESH
knob. Exceeding the set threshold is displayed by illumination of the blue threshold LED. The RATIO control
sets the amount gain that is applied to the control signal that has exceeded threshold. A wide range of
envelope shapes can be achieved by the manipulation of these controls. For an envelope shape that follows the
overall dynamics of the input signal, the THRESH control should be set to the minimum threshold (full
clockwise) and the RATIO control should be adjusted to set the maximum envelope size. To create an envelope
that responds to the most dynamic parts of the input signal, raise the THRESH control so the threshold LED
illuminates only on the loudest parts of the input signal. Then adjust the RATIO control for the desired
envelope amplitude. The envelope follower control voltage is available as both a positive control ENV + and
negative control ENV - . The range on the ENV + output is 0 to 5V and the range on the ENV – is 5V to 0 or 0 to
-5V as set by H101.
ENV – : 5V down to 0V (default configuration) ENV – : 0V down to -5V (user option)
Square Wave Generator:
The square wave generator extracts the fundamental frequency of the single note being played and outputs it
as a ±5V square wave on the SQR jack. The TRACK control knob allows for adjustments to be made to the bias
of the extraction circuit. When this control is in the counterclockwise position the circuit is very sensitive and
an output can be triggered with an extremely light touch. As the control is rotated clockwise, the sensitivity is
reduced resulting in more precise tracking; however the sustain of a note will be shortened. The quality of the
tracking is largely dependent on a number of factors such as the instrument configuration, setup, and playing
technique. Playing with a soft touch and using only the neck pickup will generally offer good results. Poor
tracking will result in an output that jumps between the fundamental and the second harmonic (octave up). At
times this might be just the thing you're looking for, so have at it.