Constructional difficulty: 1U version, easy to moderate. 2U version, moderate
The SVF in its new 1U 'filter core' format.
This is a two pole multimode filter capable of high pass, low pass, band pass and notch output modes. All four outputs are available simultaneously. This new version of the very popular Oakley design is based around the classic two pole state variable filter topology as used in a variety of vintage synths including the Oberheim SEM and OB-X. At high resonance the Oakley SVF will oscillate over the whole of the audio band and is temperature compensated.
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 Oakley Multimix is an ideal choice for a handy mixer module.
The SVF in its full 2U format.
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 1V/octave, the other two have input attenuators. CV1 features a reversible type attenuator with inverting/non-inverting properties.
The 1U version behind a natural finish Scheaffer panel. Note the optional 'saturation' switch added to the front panel.
Sound Samples
All the following samples recorded with a small set up comprising of two sawtooth VCOs, one SVF filter, two ADSR/VCA and a midiDAC to control them all. All the sounds were recorded without any effects added.
svf-lp-sweep.mp3 491KB Using the low pass output. Two simple one note hits with the SVF set to medium to high resonance.
svf-bp-res.mp3 541KB Using the band pass output. Two more simple one note hits with the SVF set to medium to high resonance.
svf-lp-seq.mp3 1.29MB Using the -12dB/octave low pass output. Simple 16th note 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.
svf-ntch-lfo.mp3 658Kb Using the notch output to give a phaser type effect. The SVF is driven from a triangle wave output from a VCO, first fast, then slow and then fast again.
svf-osc.mp3 624Kb This one will make you jump - watch your volume levels. This sample is using the low pass output and with the SVF set to full resonance to give self oscillation. The SVF is modulated by a swept sawtooth VCO and an ADSR.
Prices
SVF ready made 1U module................ 150GBP
SVF issue 4 PCB
................................... Currently sold out. New
stocks with 16mm pots arriving in March.
SVF issue 4 pot kit ................................. 9GBP
SVF issue 4 pot bracket kit
................... 3GBP
The Pot Kit contains the three Spectrol 248 or BI TT potentiometers to complete one 1U filter core module. The Pot Bracket Kit contains the correct type and quantity of Oakley-Spectrol pot brackets and extra Spectrol nuts required to complete one 1U filter core module.
Click here for full price list and ordering details. All prices include VAT at UK rates. Shipping and postage is additional to these prices.
Project Downloads
SVF issue 4 User Guide
Use 'save as...' button to download and view the files. IE users need to right hand mouse click and then choose 'save as'. 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.
Front Panel database
A Schaeffer front panel can be made for either of the two variants of the SVF module. The databases can be found here: 2U format or 1U filter core. 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.
To read this file 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.
The issue 4 printed circuit board ready for fitting to a panel. Note the ability to use two pin headers for easy connection to the off board pots in the 2U panel design
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