Expert Sleepers Otterley Eurorack Module on ModularGrid User Manual
- June 1, 2024
- Expert Sleepers
Table of Contents
Expert Sleepers Otterley Eurorack Module on ModularGrid
Product Information
Specifications
- Power Requirements:
- +12V rail: up to 82mA
- -12V rail: up to 80mA
- Does not use the 5V rail
- Inputs and Outputs:
- Jack sockets illuminated red for positive voltage and blue for negative voltage
- Audio-rate signals appear purple
- Controls:
- Speed and Spread
- Reset
- Jumper (JP1)
Product Usage Instructions
Installation
House the module in a Eurorack case of your choosing. The power connector is a
16-pin Doepfer standard. Ensure correct orientation of the power cable, with
the red edge closest to the bottom edge of the PCB carrying -12V. Connect the
other end of the power cable ensuring -12V corresponds to the red stripe.
Controls
Adjust the Speed and Spread controls to set the desired parameters. Use the
Reset function to reset the module. The jumper (JP1) on the upper PCB controls
the behavior of the Square LFO shape when the Reset input is used. Refer to
the manual for jumper settings and their effects.
Calibration
The LFO core generates a triangle wave, which is then shaped into a sine wave.
Calibration may be required for precise waveform generation.
Where to Get Help
If you need assistance or have any questions, you can reach out via email,
forums, or social media. Links can be found at the bottom of every page on the
Expert Sleepers website.
Frequently Asked Questions (FAQ)
Q: What are the power requirements for Otterley?
A: Otterley draws up to 82mA on the +12V rail and 80mA on the -12V rail.
It does not utilize the 5V rail.
Q: How do I know which jumper setting to use for the Square LFO shape?
A: The jumper (JP1) on the upper PCB controls the behavior of the Square
LFO shape. Refer to the manual for instructions on adjusting the jumper for
your desired Square output behavior.
Copyright © 2024 Expert Sleepers Ltd. All rights reserved.
This manual, as well as the hardware described in it, is furnished under
licence and may be used or copied only in accordance with the terms of such
licence. The content of this manual is furnished for informational use only,
is subject to change without notice, and should not be construed as a
commitment by Expert Sleepers Ltd. Expert Sleepers Ltd assumes no
responsibility or liability for any errors or inaccuracies that may appear in
this document.
Introduction
Congratulations on your purchase of an Expert Sleepers “Otterley”.
Please read this user manual before operating your new module.
Otterley is a multi-LFO module, designed to offer extensive modulation
possibilities, with a good amount of control and flexibility, while remaining
nicely compact.
Four of the outputs are switchable between sine and square LFOs. Their
frequencies are jointly set by the Speed and Spread knobs, which control the
base speed and the speed difference between the outputs, respectively. Both
controls also have CV inputs. These four outputs can also be switched between
bipolar (£5V) and unipolar (10V positive or negative), and can be reset to the
start of their cycle via the Reset input.
A fifth output offers another, independent, sine LFO with its own speed knob.
The module is 100% analogue.
Installation
House the module in a Eurorack case of your choosing. The power connector is 16-pin Doepfer standard‘. If using the power cable supplied with the module, the red edge of the cable is closest to the bottom edge of the PCB, and carries -12V. (“-12V” is marked on the PCB itself next to this end of the connector.) Be sure to connect the other end of the power cable correctly, again so -12V corresponds to the red stripe on the cable.
Power requirements
Otterley draws up to 82mA on the +12V rail, and 80m A on the – 12V rail.
It does not use the 5V rail.
Inputs and outputs
Otterley’s input and output jack sockets are illuminated, lighting red for positive voltage and blue for negative voltage. (Audio rate signals appear purple, since you see a rapid alternation of positive and negative.)
From top to bottom, Otterley’s sockets are:
- Speed CV input
- Spread CV input
- Reset (gate) input
- LFO outputs I to 5
For the Speed CV input, with its attenuator fully clockwise, a voltage range
of IOV corresponds to the full range of the knob. For the Spread CV input, a
voltage range of 5V corresponds to the full range of the knob. In both cases,
the knob and CV are simply added, and negative CVs are accepted (a negative CV
having the same effect as turning the knob counter-clock wise).
The LFO outputs are factory calibrated to a IOV range (+5V) but there is a lot
of scope to customise this – see “Calibration” below.
Controls
There are four knobs, which are (from top to bottom):
- Speed
- Attenuator for the Speed CV input
- Spread
- Speed (for the fifth LFO)
There are also two switches, both of which have three positions.
The lower switch chooses the LFO shape for outputs 1-4, Square when positioned
to the right,and Sine when positioned to the left. In the centre position,
there is no output.
The upper switch applies an offset voltage to LFOs 1-4, +5V when positioned to
the right, and 5V when positioned to the left. In the centre position, no
offset is applied.
This switch is particularly useful when using the square LFO shape, since
applying a +5V offset turns the output into a 0/10V square – a typical
gate/trigger shape.
Speed and Spread
The Speed and Spread knobs (and their corresponding CVs) jointly control the
speeds of LFOs 1-4. Speed is easy to understand – it simply makes all four
LFOs faster or slower. Spread controls the difference in speed between the
four LFOs. With the knob fully counter-clockwise,and the CV at OV (or
unconnected), all four LFOs run at the same speed’. As the Spread is
increased, LFO 1 remains unchanged, but LFO 2 will run faster, LFO 3 will run
faster still, and LFO 4 even faster.
Note that while the knob only applies positive Spread, the CV input is bipolar
– supplying a negative CV will make LFOs 2, 3, & 4 run slower than LFO I.
Reset
The Reset input takes a gate (on/off) signal. While the gate is high, LFOs 1-4
are halted, and their outputs take a fixed level. When the gate goes low,
oscillation restarts from a fixed phase.
A very short gate (trigger) signal can therefore be used to restart the LFOs;
or a longer signal can be used to hold them in a reset state for as long as
desired.
The image below shows the effect of the Reset input (green trace) on the Sine
LFO shape (vellow trace). Note that the LFO always starts from its lowest
point when the Reset goes low.
Jumper
There is one jumper on the upper PCB, labelled JP1. This controls the exact
behaviour of the Square LFO shape when the Reset input is used.
If the jumper is in the position as pictured above (which is the position as fitted in the factory), the Square output is held low while the Reset is high:
With the jumper on the other pair of pins, the Square output is held high while the Reset is high, and goes low one half cycle after the Reset goes low:
Calibration
Each LFO has trim pots to adjust the shape and amplitude of its sine output3.
These are factory-adjusted to give a “nice” sine shape, and a 5V amplitude,
but there is enough range in the trim pots to deliver amplitudes from about 3V
(±1.5V) to 20V (±10V). The shape trimmers can also be set to deliver an
almost-triangle shape, if you prefer that over a sine. Or indeed you could
have different outputs with different shapes/amplitudes.
LFOs 1-4 also have trim pots to fine tune their frequencies. These are not
factory-adjusted, but are provided in case you wish to attempt to get all four
LFOs to run at exactly the same rate when the Spread is zero.
Where to get help
Email, forum, and social media links can be found at the bottom of every page
on our website4.
Acknowledgments
Black and white photography by Israel Denadai5.
https://www.expert-sleepers.co.uk
http://israeldenadai.com.br/bw