Noise Tools 1U Manual
Overview
Noise Tools collects and connects a number of practical modular synthesis utilities beneath a
single 1U, 22 hp panel. Specifically, it contains:
●
A clock and random pulse source with adjustable rate
●
Analog pink and white noise source with very accurate spectrum
●
Analog sample / track and hold with very low droop
●
Analog slew with adjustable slew rate
Most people consider noise to be “undesirable,” and product developers expend great effort to
design circuits that minimize noise. So why would anyone want to own Noise Tools — a module
designed specifically to create noise?
Indeed, unwanted noise is undesirable. But not all noise is unwanted. Synthesizing the sound of
wind or waves are a couple of the more obvious uses for a noise generator, but the possibilities
go far beyond. The crack of a snare hit; the breathiness of a flute sound; an added sizzle to a
resonant pad — all are within the sonic domain of noise.
But noise has many other benefits beyond simply being heard. Noise happens to make a
wonderful modulator. When noise is used to modulate a filter’s cutoff frequency, or an
oscillator’s pitch or pulse width, then all sorts of raspy, buzzy, gritty timbres are obtained.
Noise is also a key ingredient in sample & hold circuits, so one is included in Noise Tools.
Sample & Hold (S&H) is a technique most commonly used to generate stepped, random
voltages. The circuit works by (you guessed it) sampling an input signal’s voltage each time you
send it a clock pulse, and holding that voltage until the next clock pulse. So, naturally, Noise
Tools also contains the requisite clocking tools! Two of the most common destinations for the
S&H output are a filter’s cutoff frequency (creating stepped, clocked timbral changes), and the
VCO frequency (which produces random notes at clocked intervals).
Of course, you might not always want your voltages to change so abruptly at each clock pulse.
Maybe you’d prefer they wobble about gradually and with more grace? To do that, you need a
slew circuit, and once again Noise Tools has you covered.
With all these features, plus the ability to create random pulses, clock to external pulses,
perform more esoteric track & hold duties, and slew external voltages, Noise Tools far exceeds
the capabilities suggested by its humble name or its tiny 1U form factor.
Page 6
