This is the 1U wide ‘Filter
Core’ version of the Transistor Superladder. One would use this
module in conjunction with external mixers for maximum control.
The Transistor Superladder or TSL
is a voltage controlled transistor ladder filter. Cut-off
frequency and resonance are both voltage controllable.
The Superladder VCF module has a
variable shape output. It incorporates a feature first seen on
the Oakley Orbital prototypes. A single pot allows you to vary
the output from one pole low pass to four pole low pass via band
pass in the middle.
The Superladder’s output is what I
call ‘Q compensated’. This means that the output volume will not
drop significantly when you turn up the resonance pot. This
design uses two inbuilt VCAs to achieve voltage controlled
resonance without the hassle. At high levels of resonance the
Superladder will self-oscillate across most of the audio band and
thus can be used as a sinewave voltage controlled oscillator.
The module design uses a discrete
transistor core which means it does not clip the signal abruptly
but saturates smoothly. This allows the Superladder to sound very
different depending on the input signal level. When used with
signals below 1.5V peak the Superladder will sound clean and
bright. However, take your signal levels above 1.5V peak and it
will start to take on a more strident tone particularly at higher
levels of resonance. Coupled with the variable slope control,
this sensitivity to input level means the Superladder can produce
a wonderful array of different tones.
The voltage controlled filter, or
VCF, may be built as a 1U filter core or as a complete 3U filter
system. The 1U ‘Filter Core’ format is my 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
Oakley Multimix is an ideal choice for a handy mixer
module.
Power (+/-15V) is provided to the board
either by our standard Oakley 4-way header or Synthesizers.com
header. Current consumption is approximately 40mA per rail.
Also available from Oakley Sound is the Diode Superladder. This is similar in function to the Transistor
Superladder but uses diodes instead of transistors in the filter
core, and sounds considerably different.
This is the 3U version of the Superladder.
This is a fully featured filter module that includes inbuilt CV
and audio mixer sections.
Sound Samples
Simple sequence with two Oakley VCOs at one
octave spread on sawtooth outputs. The filter is manually being
swept via the ‘shape’, ‘freq’, ‘resonance’ pots and altering ADSR
sweep depth.
A different simple sequence being played
using an Oakley VC-LFO as the single audio source. Again the
filter is being altered by manually controlling the front panel
pots. Some reverb and echo is being used to add ambience.
The above photo shows the
older issue 3 TSL PCB fitted to the 1U wide MOTM compatible panel
in Scheaffer’s natural finish. Note also the use
of the optional Sock4 socket board to help keep the wiring to the
sockets neat and tidy.
The PCB is 102 mm (deep) x 143 mm
(height). The frequency, resonance, resonance CV depth and shape
pots can be board mounted for easier construction.
Project Downloads
Construction
Guide Our handy guide to building
Oakley DIY projects
Parts
Guide Our handy guide to buying
parts for Oakley DIY projects
Schematics are available to
purchasers of the PCB and will be sent via e-mail when the board(s)
are shipped.
Front Panel database
A Schaeffer front panel can be made for
either of the two variants of the new SuperLadder module. The 1U
version is also available in natural aluminium finish. The
databases can be found by downloading the following links:
3U format in
traditional black
1U ‘filter core’ in
natural silver
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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