The Quadtec-101 is a dual waveshaping oscillator module with four outputs. The module contains 2 digital oscillators powered by a 16-bit 120MHz DSP and realised by 4 x 8-bit DACs (upgradeable to 12 bit). Each oscillator is capable of tracking volts/octave.
ABOUT THE OSCILLATORS
The digital oscillators are coded to provide synthesis at 40,000 samples per second. Using the waveshape knob, different waveshapes are blended together to create new, complex, and often unusual sounds. Some waveshapes are stored as wavetables, gathered from a variety of sources, and others are computed in real time. As you turn the knob from fully counter-clockwise to fully clockwise, you will experience a blending of the following 9 waveshapes:
- “Videogame” Pulse
Each oscillator has controls dedicated on the left and right half of the module. Each of the two oscillators has pitch control with the knob in the top left/right and CV inputs that tracks 1 V/OCT, as well as the waveshape blend knob. The top middle knob is a blend control that blends Oscillators 1 and 2 together. At fully counter-clockwise, you will only hear Oscillator 1, and at fully clockwise you will only hear Oscillator 2. At noon o’clock you will output an equal proportion of Oscillators 1 and 2.
ABOUT QUAD SOUND
The goal of this module is to provide an easy way to distribute an oscillator around a quad sound environment. The four outputs (1,2,3,4) accomplish this task by routing the input ( the blend of oscillators 1 and 2 along with their waveshapes and pitch) through to the four outputs in a smooth rotation. You can think of these as four VCAs with 90° quadtrature shift of their control inputs. The Quad panning (as we call this movement) is controlled by a triangle wave modulating each outputs amplitude, providing a smooth transition from one output to the other. In a quad setup, this has the impression of the sound swirling around you, with no sudden jumps between each speaker.
The Quad Pan knob adjusts the rate and direction that this panning occurs. At fully clockwise, the pan will occur from left to right at approximately 1Hz. At fully counter-clockwise, the pan will occur from right to left at the same 1Hz frequency.
With the knob at 12 o’clock, the signal not only stands still, but is also output on all four outputs simultaneously. When the pan knob is at 12 o’clock, we have also entered ‘VCA Mode’ where the pan input will be considered as a control input to a digital VCA. This allows the operator to utilize this module as a mono synth voice, requiring only an external envelope or gate.
The centre output at the bottom of the module provides a pseudo-random noise source, hereby referred to as NEUZ. This NEUZ output is a source of digital noise, swinging from 0V to 5V. The small knob to the top right of the NEUZ output controls the speed at which a pseudorandom sample is taken and the output is consequently updated.
Quadtec-101 is designed to be powered from a eurorack system, or standalone on a table or lap. When using the device in standalone mode, a 9V battery is required. This battery will last about 4-5 hours of usage. There is a small switch on the top to turn off the battery supply in order to save battery life. When in eurorack mode, this switch has no effect. If you wish to power from eurorack power while a battery is installed, make sure to put the switch in ‘off’ position to preserve battery life.
ABOUT THE DIY KIT
Quadtec-101 is provided as a kit, and is designed to be easy to assemble for builders of all skill levels. There are roughly 70 components to solder and they are all through-hole. Please refer to the following documents for building this module:
- Width – 14HP / 70.8mm
- Height – 128.5mm (3U)
- Depth without case – 14mm
- 12V – 120mA
- -12V – 10mA
- Battery – 130mA