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AM 4016 Module - Analog Noise Source
Overview This module
is an exact replica of the ARP 1016 analog noise source in the ARP 2500 Modular synthesizer.
Original Circuit The original design uses the traditional "transistor in avalanche mode" to generate white noise. This
signal is then amplified and filtered (using LM301 Op Amps) to create the white and pink noise signals. The white noise is further filtered to produce the low frequency random voltage, using a fourth LM301 Op Amp.
The ARP 1016
module has two identical noise generating circuits, and the noise signals can be selected and turned off using slide switches. These switches also control front panel lights to show the noise has been turned on.
AM Circuit
The AM module replicates exactly the original circuit, as all the components are still available. I have added trimmers to enable output voltages to be easily set, rather than ARP's original resistor selection method for trimming.
I have kept with the original LM301 Op Amp, as a high quality Op Amp is not really needed in a noise circuit… but they can easily be replaced a modern low noise Op Amp such as the NE5534 or higher quality OPA134, provided the
compensation capacitors are not installed.
I have added a simple Op Amp LED driver circuit to enable a red LED to monitor the slow random voltage level.
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