The 1U format ‘filter core’ Journeyman
filter. This offers the basic filter module without the extra CV
and audio mixing that the full width 2U module provides.
The completely unlinear response and
discrete circuitry gives the Journeyman a unique sound of its own.
Partially modelled after a classic Japanese filter design from
the mid to late 1970s, the Journeyman can be configured in either
-6dB/octave high pass or -12dB/octave low pass modes by the
flicking of a switch. When two of these VCFs are used together,
one in HP and the other in LP, then the effect is superb.
The filter heart is made entirely from a
single ended discrete design and uses four matching diodes as the
control elements. The filter behaves differently depending on the
input signal level hence the ‘drive’ pot on the front panel.
Turning this up allows the filter to be overdriven. At full
resonance the filter will oscillate across most of the audio band.
The design is intended to fit into a 1U
wide ‘filter-core’ module or a more fully featured 2U wide panel
with seven control pots.
The 1U ‘Filter Core’ format is our
way of handling filter modules. Although the 1U module can be
used as a filter module on its own, it is expected that users
will make use of external mixers to control CV and audio levels
going into the filter. In this way, you will be able to have a
collection of space saving 1U filter cores that can be used with
any generic mixer module. The popular Oakley Multimix is the perfect
choice for such a mixer module.
For the 2U design three audio inputs are
provided each with its own attenuator. Three CVs can control the
cut-off of the filter. One is fixed at approximately 1V/octave,
the other two have input attenuators. CV2 features a reversible
type attenuator with inverting/non-inverting properties.
Issue 2 of the Journeyman is a significant
update to the original issue 1 design with, amongst other things,
improvements to setting up, less CV breakthrough and better power
supply noise rejection.
The module accommodates either our standard
Oakley/MOTM power header or a Synthesizers.com power header.
Current consumption is approximately 20mA per rail.
The issue 2.1 PCB is 79 mm (deep)
x 143 mm (height). The frequency, resonance, drive and CV depth
pots are normally board mounted for easier construction.
As with all Oakley projects the
PCB is double sided with through plated holes, has tough solder
mask both sides, and has bold component legending for ease of
construction.
The suggested front panel design for the 2U
version of the Journeyman VCF.
Sound Samples
All the following samples
recorded with a small Oakley set up comprising of one VCO, one VC-LFO,
one Journeyman filter, two ADSR/VCA and one midiDAC to control
them all.
Using the low pass
output. Simple sequence with an input from the sawtooth output of
a single Oakley VCO. The filter is manually being swept via the ‘freq’,
‘resonance’ pots and altering ADSR sweep depth.
This time using the
high pass output using the same simple sequence whilst the cut-off,
sweep depth and resonance controls are tweaked.
Various one shot hits
and blats at different settings of frequency, resonance and drive.
Low pass output; a
bit of resonance, fixed cut-off frequency and a bit of reverb for
ambience.
The Journeyman ‘Filter Core’ VCF as a
single width MOTM format module in a natural finish Schaeffer
panel. Note also the use of the optional Sock4 socket board to
help keep the wiring to the sockets neat and tidy . The various
empty resistor and header locations you can see are used in the 2U
wide full version.
Project Downloads
Journeyman
issue 2 Builder’s Guide
Journeyman
issue 2 User Manual
Construction
Guide Our handy guide to building
Oakley DIY projects
Parts
Guide Our handy guide to buying
parts for Oakley DIY projects.
Links to schematics are
available to purchasers of the PCB or module and will be sent via
e-mail when the board(s) are shipped.
Use ‘save as…’ button to
download and view the files. IE users need to right hand mouse
click and then choose ‘save as’.
Front Panel database
A Schaeffer front panel can be made for
this module. The databases can be found by downloading the
following links:
5U format 1U wide (Filter
Core) module in traditional black
5U format 2U wide (Full
Version) module in traditional black
To read these files you will need
a copy of ‘Frontplatten designer’ from Schaeffer. The program also features on-line ordering, so its
now even easier to buy your panels from Scheaffer.
The company are based in Berlin in Germany
and will send out panels to anywhere in the world. Delivery to
the UK normally takes around ten days. For North American users
you can also order your Schaeffer panels from Front
Panel Express.
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