Ataraxic Iteritas#

Digital Oscillator Inspired by the last millennium


"Yep." - Patrick Leonard

Ataraxic Iteritas is an extension of the original Ataraxic Translatron. Ataraxic Iteritas starts with one of three bit tables shaped via variable interpolation that is then scrolled through, amplitude modulated, folded, and distorted by the CV-controllable front panel controls. Subby basses, metallic drones, unrelentingly digital timbres and more are all to be had from the Ataraxic Iteritas. Guaranteed to make the fax machine jealous.

  • Type: VCO
  • Size: 10 HP
  • Depth: 1.5 inches
  • Power: 2x8 Eurorack
  • +12 V: 150 mA (80 mA when using 5 V supply)
  • -12 V: 5 mA
  • 5 V: 90 mA


Power connector

To power your Noise Engineering module, turn off your case. Plug one end of your ribbon cable into your power board so that the red stripe on the ribbon cable is aligned to the side that says -12 V and each pin on the power header is plugged into the connector on the ribbon. Make sure no pins are overhanging the connector! If they are, unplug it and realign.

Line up the red stripe on the ribbon cable so that it matches the white stripe and/or -12 V indication on the board and plug in the connector.

Screw your module into your case before powering on the module. You risk bumping the module's PCB against something metallic and damaging it if it's not properly secured when powered on.

You should be good to go if you followed these instructions. Now go make some noise!

A final note. Some modules have other headers -- they may have a different number of pins or may say "not power". In general, unless a manual tells you otherwise, do not connect those to power.

Voltage supply#

Ataraxic Iteritas can run its processor on the 5 volt eurorack power rail to reduce noise and load on the 12 volt bus. Gently push the switch tab in the direction of the desired rail to use.

Picture of voltage supply switch


Illustration of Ataraxic Iteritas' interface

An encoder knob. Adjusts the pitch of the fundamental oscillator. Default is fine mode: steps are sub-perception so Ataraxic Iteritas is difficult to bump out of tune. Push and turn for coarse adjustment: each step is a semitone. CV input is a 1v/octave standard input.
Displaces samples in time, and amplitude modulates the signal by white noise. Useful for adding an aggressive, broken edge to the output.
Changes the emphasis of the harmonic structure of the output. At 12:00 the filter is off. To the left, it brings out more high harmonics, and to the right, it brings out more low harmonics.
Adjusts the interpolation between waveforms. Sonically, this ends up being almost identical to morphing from triangle to saw to square.
Soft fold

Soft fold uses the following polynomial:

\[ f(x) = \frac{x}{48}(-x^4 + 8x^3 - 9x^2 - 50x + 100) \]

This is applied to a unipolar signal with gain controlling the fold amount. This gives an asymmetric soft fold. Soft fold is useful for adding interest to simple sounding waveforms, and works well in conjunction with the Noise knob.

Blends between waveforms in the bit table selected by the Mode switch.
Time mod
Similar in sound to PWM or hard sync. Modulating this parameter creates phaser-type sounds.
Selects between three different sets of waveforms, arranged in bit tables. The waveforms generated are all unique and unapologetically digital in nature. They are then modified by the Shape and Waveform parameters. For more details on the different modes, see the Design notes section below.
Range (Bass/Alto/Treble)
The range switch sets the lowest note. Each position is two octaves above its left neighbor.
Resets the state of the oscillators on a rising edge. Used for sync modulation.
A low-impedance audio source. The output varies based on parameters as Ataraxic Iteritas compensates for loudness.
CV Inputs
All parameters are CV-able. Knobs act as offsets unless stated otherwise. Ataraxic Iteritas expects an incoming voltage of 0-5v for non-pitch parameters and 0-8v for pitch.

Patch tutorial#

First patch
Patch Out to your mixer. Play with the knobs. Magic.
Second patch
Apply CV to any/all of the inputs to make Ataraxic Iteritas come to life. A couple of great sources of modulation are Mimetic Digitalis and Clep Diaz. Patch a 1v/octave sequence into the Pitch input to bring out the melodic side of Ataraxic Iteritas.
Other patching tips

Ataraxic Iteritas pairs very well with filters and lowpass gates. A couple of our favorites are the WMD TRSHMSTR, the Doepfer A-101-6, and the Rabid Elephant Natural Gate. Try patching the Ataraxic Iteritas out to your favorite filter and see how you can shape the sound.

Ataraxic Iteritas also creates fantastic rhythms and textures in the subsonic range. Flip the Range switch to Bass and turn the Pitch down until you can hear the individual pulses of the oscillator. Processing this type of sound with reverb and delay creates unique soundscapes and atmospheres.

Genesis and design notes#

Ataraxic Iteritas started simply enough. Let's take our first product, Ataraxic Translatron and re-implement it on the Iteritas hardware platform, blowing it out with more features and controls.

This simple-sounding task ended up being one of the most technically challenging things we have done.

The hardest constraint was simply sample rate. The high-order LFSR waveforms require an extremely high sample rate to sound the way we want them to. All attempts to downsample lost their edginess. As with all of the Iteritas oscillators, the sample rate varies by pitch, but for Ataraxic Iteritas it's between 100-200khz. Having such a high sample rate means we have about 1/4 of the per-sample processing power as on BIA so every feature was a struggle to fit into the performance envelope.

Every tone control needed to be as simple as possible which led to a lot of the basic choices. Soft fold is a simple quintic polynomial that will gently fold a waveform. Noise is just simple modulation by noise in both amplitude and time domains. Time mod is a variant of the saw mod on the Manis Iteritas except it operates on the passage of time in the waveform interpolation rather than the amplitude of the waveform. The comb filter was chosen because the near-finished product was begging for a filter but we were almost out of computational power. Comb filters are simple and elegant, and when we tried it, we were so excited that we looked no further.

One of the things done for performance was to encode the waveforms Ataraxic Iteritas uses into a table. This ended up being significantly faster than computing it on the fly and made it easy to change the waveforms to produce different modes. The LFSR tables are based on the same waveforms as in the AT (in some cases octave-shifted differently). SQR is a square wave that is amplitude modulated by the harmonic series so turning the waveform knob will blend between harmonics. SQR2 is the same except the modulating pitch goes up an octave every waveform.

In the end the Ataraxic Iteritas became our most aggressive sounding oscillator. In some ways it is unrefined compared to our other oscillators but it has an undeniable edge that we know our users are going to love... and we've found that pretty things can still be coaxed out of it!

Variable sample rate#

Ataraxic Iteritas uses a sample rate that is a multiple of the fundamental (lowest) frequency produced. This moves alias power that is a multiple of the fundamental to be mapped to a multiple of this tone, therefore making the aliasing align with the harmonics of the tone. This works well for settings with a strong harmonic structure (spread fully CW or fully CCW) and adds unique aliasing character for other tones.

Tuning calibration#

Ataraxic Iteritas comes pre-calibrated and should not need adjustment. If the trimpot gets bumped and needs a tuneup, follow this procedure to calibrate your module. Pitch calibration is controlled by an linear resistor-divider network. To calibrate the tuning, attach a volt meter (preferably 4 or more digit) to the test points TPCV and TPGND on the rear panel and adjust the trim pot.

The voltage measured should be 5/16 (.3125) times the input voltage applied to the CV input. A reasonable way to tune the scale is to use an adjustable voltage source to generate 4 V then adjust the tuning trim until the test points read 1.2500 V. Ataraxic Iteritas can also be tuned using a reference supply capable of generating a 1 V difference and using a stroboscope such as the Peterson 490 to tune to an octave interval. This is method is preferred to the meter-only method.


We will repair or replace (at our discretion) any product that we manufactured as long as we are in business and are able to get the parts to do so. We aim to support modules that have been discontinued for as long as possible. This warranty does not apply to normal wear and tear, including art/panel wear, or any products that have been modified, abused, or misused. Our warranty is limited to manufacturing defects.

Warranty repairs/replacements are free. Repairs due to user modification or other damage are charged at an affordable rate. Customers are responsible for the cost of shipping to Noise Engineering for repair.

All returns must be coordinated through Noise Engineering; returns without a Return Authorization will be refused and returned to sender.

Please contact us if you think one of your modules needs a repair.

Special thanks#

  • Eric Cheslak
  • Shawn Jimmerson
  • Shawn Cleary
  • Anthony Baldino
  • Matt Lange