Malekko / Wiard NoiseRing
In latter model synthesizers, digital noise sources began to appear in place of analog ones. Traditionally, a psuedo-random shift register set up for optimal length. By optimal length, it is meant that every state of all available bits will appear at some time, but the order is unknown. Essentially a counter that counts in an unknown order. This represents the maximum state of information "entropy" available for that number of bits.
But music has close self-similarity over short periods of time. That is, it repeats itself with changes appearing slowly. This shift register generator is designed to give control of the rate of appearance of new information. It has a tight set of controls over how random it actually is and how fast change occurs.
But music has close self-similarity over short periods of time. That is, it repeats itself with changes appearing slowly. This shift register generator is designed to give control of the rate of appearance of new information. It has a tight set of controls over how random it actually is and how fast change occurs.
Noisering Analysis by Babaluma
Comparator
“In electronics, a comparator is a device which compares two voltages or currents and switches its output to indicate which is larger.”
The Noisering has two comparators: one to determine the Chance value and to determine the Change value. The output of a comparator is 0 or 1.
Shift register
“In digital circuits, a shift register is a cascade of flip flops, sharing the same clock, which has the output of any one but the last flip-flop connected to the "data" input of the next one in the chain, resulting in a circuit that shifts by one position the one-dimensional "bit array" stored in it, shifting in the data present at its input and shifting out the last bit in the array, when enabled to do so by a transition of the clock input.”
The Noisering has one 8-bit shift register. The state of the register is translated by two DACs into a voltage in the range of 0-10 volts. One DAC (output 1) provides 256 voltage values, the other (output 2) provides 9 voltage values. ‘00000000’ is the shift register state that represents 0V, ‘11111111’ is the shift register state that represents 10V.
The shift register ‘shifts bits’ at a rate determined by the Rate pot or at a rate determined by the clock input.
Chance
The Chance pot by default attenuates an internal DC voltage. You can also supply a voltage via the Chance input. In either case the Chance voltage is compared against the voltage of an internal analog noise source. If the Chance voltage is greater than the analog noise voltage, the Chance comparator output is 1. If the Chance voltage is smaller than the analog noise voltage, the Chance comparator output is 0.
This means the more clockwise you turn the Chance pot, the greater the Chance voltage, the greater the chance the output of the Chance comparator is 1. The output of the Chance comparator is used as a ‘new value’ for the shift register input.
Change
The Change comparator works exactly the same way: an internal DC voltage or a voltage supplied via the Change input is attenuated by the Change pot and this voltage gets compared to the analog noise voltage. The output of the Change comparator determines if the shift register input gets a ‘new value’ (Change comparator output is 1), or an ‘old value’ (Change comparator output is 0).
A ‘new value’ is the output of the Chance comparator. An ‘old value’ is the last bit from the shift register. This bit gets recycled so to speak.
In practice this means that when the Change pot is turned fully counter clockwise, the input of the shift register only gets values from the last bit. This results in a repeating pattern in the shift register. If you monitor one of the DAC outputs at audio rate you will here a steady tuned tone.
The more clockwise you turn the Change pot, the more new values will arrive at shift register input, which leads to ever more changing patterns in the shift register.
Another worthy thing to note: the more the shift register is occupied by zeros, the greater the chance the DACs output a low voltage (‘00000000’ represents 0V). And of course the more the shift register is occupied by ones, the greater the chance the DACs output a high voltage.