elby designs ed115 sh-noise price : $150.00

the ed115 - sh-noise is a combination of a noise generator and a sample & hold module in a 4hp panel, creating a compact utility module.

white noise:
this module uses the noise produced by the base-emitter junction of an npn transistor, which is reverse-biased. the noise is amplified to a level of about 10v peak-to-peak.

pink noise:
the pink filter is a 3db/octave filter which is pretty linear across the range 10hz to 15khz to within 1db across the full 50db range. a final stage buffer-amplifier sets the output level to around 10v peak-to-peak.



violet noise:
the violet filter has two frequency dependent elements in the feedback path. the first feedback element on its own would produce a 6db/octave rise in the gain of the amplifier from 0db at 0hz via 3db at 9hz to 20db at 90hz. the second feedback element on its own would produce a 6db/octave fall in gain from 0hz to 1khz above which the gain would remain constant at 0db.

the combined effect of these feedback elements is that below 90hz the 6db/ocatve rise and 6db/ocatve fall cancel out, giving a gain of 20db. above 90hz the gain falls at 6db/ocatve to 0db at 1khz, above which it remains constant. the result being that the bass end of the noise spectrum is boosted, and `coloured' noise is available at the violet output. a final stage buffer-amplifier sets the output level to around 10v peak-to-peak.

random noise:
the random noise output is a 12db/ocatve lowpass filter which passes only the very low frequency components to produce an extremely low frequency `random voltage'. fluctuations of the random voltage are displayed on a led indicator.

by default, the random output is an analogue voltage with a nominal range of around 10v peak-to-peak. however an onboard jumper allows this output to be steered through a dual comparator to provide a digital output.

the digital-random output generates +5v output whenever the random voltage is greater than around +2v, a -5v output when the random voltage drops below -2v and a 0v output when the random voltage is within the range -2v to +2v.

the sample & hold module:
the sample & hold module takes an instantaneous sample of the input signal and presents it to the out output. the resultant output is a 'random voltage' that changes on each positive edge of the sample input.

the sample connector is normalised to the random output of the noise section while the in connector is normalised to the white output (an onboard jumper allows the user to change this to either the pink or violet outputs if desired) of the noise section. inserting a jack in to any of these connectors will allow an external signal to be used instead.

this module has a maximum current draw of 12ma. it requires 4 hp/te worth of space to fit in a eurorack frame.

download the manual here.