Mini Modular NAND

I have been thinking about the NAND synth and giving it some additional capabilities.  This is my plan for a mini modular based on the 4093 NAND.  Each of the four NAND gates would be made into a separate oscillator.  Each oscillator would have three switches three knobs/pots and three jacks.

Switch 1 On/Gate: Determines if it is on all the time or if it can be controlled by the gate input.
Switch 2 Square/Saw: Switches a capacitor on the Cv input (I need to add this cap to the circuit shown above.)
Switch 3 VCO/LFO: Switches the feed back to a larger capacitor to make it into an LFO.
Knob 1 Pitch
Knob 2 Volume
Knob 3 Modulation amount (pitch)
Jack 1 Gate input
Jack 2 Cv Input
Jack 3 Output

This is the basic schematic for this.  Assume the gate starts in state Hi Lo then the 1n cap charges until it goes Hi at which point the output goes Lo.  The rate of charge and discharge is controlled by the pitch pot or by the transistor depending on the base current.  The LED monitors the output and turns on or off based on the output.  The LFO switches in a larger capacitor so it takes longer to charge.  The wave shape applies a low pass to the input signal.  I may have made some mistakes in this drawing but this is basically how it works.

This basic structure is repeated four times.

Next comes the filter which I described in a previous blog.  This consists of three simple resonant low pass filters and a clipping op amp differentiator.

This one does not have the voltage control transistor in it yet so I am still working on that.  It also shows a QF connection on filter 2 which should be bypassed.  The way this filter works is to have both a resonant low pass (with assymetry switch) and a low pass (Q turned all the way down).  Then subtract the two signals and clip them with the op amp.  This creates a complex waveform (supposedly).  Finally feed the result out through the final filter with resonance.  Need to add an additional input for external signals as well as transistors so I can modulate the cut off frequency.  The filter will from the base of the module.

RS is a rail splitter.

Planar Crystal 020

The planar crystal is a device which can transport someone spatially, temporally, and inter-dimensionally upon touching.  Those who touch it accidentally may wander the multiverse searching for the way home.


Motif ES7 with PLG-150DX (used for Skrillex sounds, Waldorf Pulse, Dune (Plug-in), mixed in Reaper, Kicks from Pulse and Little Phatty, some effects using Lexicon Vortex.  Drums using BFD Eco and MPC500.  Sound effects include home made electronic drones, filter modulated bulldozer samples and glitched effects.  Audio damage Replicant, Michael Norris Drone and glitch plugins.  Final noise sweep is a Thing 1 Noise generator modulated through a Korg EMX1.  Vocals recorded with DP004 digital recorder and modified using Michael Norris FX and Replicant.  Voxengo Elephant used for mastering compression.  EHX Stereo Talking Machine used on arpeggios near the end to give vocal effects.

Planar Crystal

I am currently working on a psytrance piece.  This piece is somewhat inspired by groups like Infected Mushroom, Ott, and Shpongle.  It is still a work in progress and may be so permanently.  I am using the creation of this piece to help me learn Reason better.

(Note: The latest version is above in a more recent post.)

I started by listening to some psytrance songs to get a better feel for the type of music I wanted to create.  I decided Heavyweight by Infected Mushroom was close to the feeling I wanted to create.  I picked up a simple kick snare rhythm from another song and started working on that.  I set up a couple of kick tracks with one set up as a straight 4/4 beat and the other a somewhat more complex rhythm.  I then set up a snare track to complement the kick.

I set up a track for the hhats and combined hhats and snare and sent to an outboard processor (Lexicon Vortex flange delay effect).  It took me a while to figure out the correct configuration that would allow me to send output to the processor and record the input while monitoring it.  I kept generating feedback loops when I would try to monitor the effect.  I ended up having to go through a mixer with a headphone output to listen to it.

I also figured out how to use Reaper's folders so that I could group all of the drums under one master track.  That way I can "collapse" the folders down so they don't take up so much space as well as control the overall drum volume with a single envelope.  That makes this much more powerful for producing music.

I then used Dune to create the introductory bubbly bass synth sound and played a few notes until I found a groove that sounded good.  I used Reaper's MIDI editor to add filter sweeps to the sound.  I went through my collection of samples and tried to find some that would make good sweeps to be used before a transition.  I put a few sweeps at different spots throughout the song.  I also added some background sound effects with a drone generating plug-in.

Next I wanted to get some analog synth in the song so I went to the Motif and figured out how to send the output from the arpeggiator to Reaper to record an arpeggio while listening to the instrument.  I recorded the MIDI sequence into Reaper then used Reaper to play back the sequence to the Waldorf Pulse Plus.  I modulated the sound of the Pulse with the filter knobs while it was playing and recorded the result directly to Reaper.

Rossler Circuit Revisited

I have been working on this one for a while now but when I actually build the circuit it does not sound quite like it is supposed to so I think I will redo this one using the above design.  The Rossler attractor is a chaotic oscillator.  I put my circuit on an oscilloscope and it definitely is not exhibiting chaotic behavior.

Rig with Motif Pulse and MPC

I have been attempting to make a psytrance song lately.  This is a picture of my keyboard rig.  The wood ends on the Pulse make it much more control friendly.

The MIDI connection is as follows:

Motif MIDI In <- MIDI Out of Computer
Motif MIDI Out -> MIDI In of Computer
Motif MIDI Thru -> Pulse MIDI In
Motif Local Control = Off
Reaper is Running on the computer with a track set to:
  I/O = MIDI Out
  Record enabled
  Record input: Audio or MIDI
  Monitor enabled
  Input = MIDI In (All Channels)

That way I can play the arp on the Motif (Note the Motif arp can be set to a different MIDI channel than the regular MIDI channel!) and either record it to Reaper or listen to it on the Pulse.

MPC is not connected in this photo.

Very Bizarre Filter Revisited

A while ago I came up with a design for a very bizarre filter which attempted combine a fuzz distortion with resonant low pass filter.  Unfortunately the prototype did not pan out.  This is a second attempt at a bizarre filter.  The idea is not to create a certain type of filter but to deliberately introduce distortion into a filter. 

This design is based on the new filter Ray Wilson is using on his Noise Toaster.  The Noise Toaster is an excellent sounding box which gives you a lot of options in a small space.  I was looking for a simple filter design so that I could try out some experiments without using a whole pile of chips.  The advantage of this filter is that it uses only one op amp.  I had been experimenting with Ray's Weird Sound Generator filter since it is very simple.  This new filter is an improvement over the WSG filter.

The first modification I decided to try was putting in some diodes.  I found that putting a diode and a potentiometer that could be switched on and off in the resonance section allowed for a lopsided resonance which should give some unique character to the sound.

The second modification I wanted to do was to subtract a low pass signal from the resonant low pass signal. That should result in just the resonance from the signal.  Next I wanted to add some hard edges to the signal so I passed it through the an op amp at high gain.  Finally I added another resonant filter at the end to reintroduce resonance on the newly created peaks.  Leaving in all of the controls gives nine different controls for messing with resonance and distortion.

The left trace shows Ray's original filter, the next trace shows the diode modified filter, the next trace shows the clipped resonance signal and the next image shows the re-filtered signal.

I have not built this device yet, I will have to wait to see if it works out.  If I build it I will post a video.  I am hoping to add a filter to a NAND synth so I may use this one.

Heavily Modified APC

This is a heavily modified Atari Punk Console.  Modifications include pitch and mod Cv inputs, resonant low pass filter from the Ray Wilson's Weird Sound Generator, dual low frequency oscillator with cross feedback, selector knob for up to six different capacitor pairs ranging from control frequencies to high pitched oscillator frequencies.

 The circuit for this is on the bottom right: