Toros Iteritas Alia#

Three-operator phase-modulation oscillator

Overview#

Toros Iteritas Alia is a three-operator, three-algorithm phase-modulation oscillator. Taking inspiration from our favorite things about FM synthesizers and doing away with complicated interfaces and mysterious controls, Toros prioritizes immediacy and, of course, epic sounds. Designed with drones in mind, Toros is the perfect tool for long, evolving textures and dark drones – or big, clangorous tones if that suits your patch better.

• Type: PM oscillator
• Size: 10HP Eurorack
• Depth: 1.5 Inches
• Power: 2x5 Eurorack
• +12 V: 105 mA
• -12 V: 10 mA
• 5 V: 0mA

Etymology#

Toros - from latin Torosaurus: "perforated lizard"

Iteritas - from Latin itero "repeat" with suffix -tas "state of being"

Alia - from latin alia "supreme"

“Lizards reign supreme, as always”

Power#

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.

Interface#

Pitch

Global pitch control and CV input for all oscillators. Turn the encoder for fine adjustment, press and turn for semitone jumps.

Freq 1/2/3

Offsets the frequency of each oscillator. Control becomes finer towards noon and coarser towards the extremes, useful for dialing in long, slowly beating timbres.

Blendex 1/2/3

Controls the amount of mix level vs. modulation level of each oscillator.

Chill/Buzz/Chaos

Selects the routing algorithm used. More information can be found in the tone generation section below.

Range 4/12/24

Sets the range of the three Freq knobs. In the left position, the range is +/-4 semitones. In the center position, +/- 1 octave. At right, +/-2 octaves.

Jump

Offsets all oscillator pitches by one octave while pressed or a high gate is present at the input.

Fun Out

A basic saw oscillator at the fundamental frequency set by Pitch.

Out

The main output for all oscillators. You could say that the real fun is heard here. Or perhaps the fun is really the friends we made along the way? We’ll never know.

Patch tutorial#

Set all Blendex controls to minimum, all Freq controls to noon, and the switches to the Chill and 4 settings. Experiment with different Blendex settings, and use the Freq controls to add beating and more complexity to the output.

Switch through Buzz and Chaos modes to explore different timbres.

For more extreme tones, set Range to 12 or 24. The noisiest results will come from high Freq settings in Chaos mode with Range set to 24.

Input and output voltages#

Alia’s trigger input has a threshold around +1.8 V.

Its modulation CV inputs have a range of 0 V to +5 V.

Its pitch CV input has a range of -2 V to +5 V.

The envelope output has a range of 0 V to +5 V.

The audio output varies depending on settings, and can reach a maximum of about 14 V peak to peak.

Tone Generation#

Toros employs three routing algorithms to create its timbres. Each algorithm is similar in structure, but results in extremely different timbres.

Chill#

Chill mode uses four oscillators. Each of the first three oscillators can be routed straight to the output or to the fourth oscillator’s phase-modulation input by changing the Blendex setting.

Buzz#

Buzz mode also uses four oscillators. Each of the first three oscillators can be routed straight to the output or to the next oscillator’s phase-modulation input by changing the Blendex setting.

Chaos#

Chaos mode uses three oscillators. Oscillators 1 and 2 can be routed straight to the output or to the next oscillator’s phase-modulation input by changing their corresponding Blendex settings. Oscillator 3 can be routed to the output, or routed back to oscillator 1’s phase-modulation input using Blendex.

Design notes#

Doing a variable sample rate pure FM/PM oscillator has been on our todo list for a very long time. When we were looking for the next Alia firmware it was a pretty obvious place to start because FM is one of our favorite synthesis techniques. Debel was also an FM oscillator, but it was also a very complicated sort of FM using a bunch of hybrid/additive techniques. One of FM's great joys (and pains) is that the editing interface has an absurd number of parameters. For example, Stephen’s favorite FM synth, the Yamaha FS1R, has something like 3000 parameters per preset. Imagine that in hardware! Alia has only 6 knobs, so the design was going to have to be creative to fit a lot of FM control onto that interface.

One of the problems with conventional FM interfaces is that a lot of knobs cause entire sets of parameters to become useless. As an example, consider a series of oscillators (C->B->A). If the modulation index of B into A is zero, then all controls of oscillators C and B become useless, and 2/3 of the interface now has no value. In traditional FM synths that use menus and few physical controls, this isn't too big of a deal: there is no cost associated with adding additional parameters, so the possible lack of value is mitigated by a lack of cost.

The first problem to solve: how do we make an index control do something interesting even when its value is zero? Toros solves this by trading the traditional index parameter for a Blendex control. Blendex is a crossfader: when it is high, the oscillator output is fully modulating the next oscillator in the algorithm. As Blendex decreases the modulation index also decreases, but we proportionally increase the oscillator's output to the main output. You can think of this knob as blending between two FM algorithms based on the Blendex setting. See those fancy diagrams for more details!

Toros’s development presented many challenges. Toros was the first Alia to use the interleaved sample rate technique that was used on Loquelic Iteritas. This led to the expected headaches dealing with wanting to delay for periods smaller than we can on the new hardware (IRQs are too expensive!). Stephen found it very reminiscent of solving the same bugs on the old Iteritas platform for Loquelic, and once he realized he was looking at the same bug it was pretty straightforward to solve.

The single hardest feature of Toros was the frequency controls. This offered no real challenge from a technical standpoint but we had weeks of arguments over the range and the curve. After a while we figured out that the main axis of discontent was based on usage. Do you want a super subtle slowly ululating mega drone? Or a wild bassline? For slower, more textural timbres being able to dial in very small pitch offsets was the most important thing. For more tonal sounds having a wider range was really useful. This is what led to the differing behavior on the second switch: on every other Iteritas or Alia oscillator, this is an octave switch. For Toros it becomes a range/curve selection so the user can select the sensitivity that suits their patch best. The left-most position has a range of +- 386 cents, or a major third, with a very shallow curve so that most of the knob range is taken up by smaller offsets. On the right-most setting the range becomes +-2 octaves, and the knob is linear in pitch space.

Toros was one of those projects that was instant fun during development. It took very little time to get to the point where it was useful and fun. While testing, it was always making music even if we weren’t.

Warranty#

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#

• starthief
• Tim Bartlett