The Oakley RM-4014 Ring Modulato
This is a vintage ing modulato design with bags of cha acte . It is based on the classic
ARP4014 sub-module which was used on the ARP2500 modula and ARP2600 semi-modula
synthesise s. The design has a fully disc ete co e but uses two op-amps fo input and output
amplification.
A ing modulato has two main inputs, usually called X and Y, and one output. The output
voltage is the p oduct of the two input voltages. In othe wo ds it multiplies the two input
signals togethe to p oduce a new and diffe ent sounding output. If you have two sine wave
input signals then the output will have both the sum and diffe ence f equencies. Fo example,
if X is a 440Hz sine wave and Y a 40Hz, you would get a 480Hz and a 400Hz sine wave f om
the output. Howeve , this is only eally t ue in a pe fect ing modulato , and this ing
modulato is not that. Each input has its own diffe ing non-linea ities o impe fections. This
g eatly adds to the cha acte of the esultant output.
The Oakley Ring Modulato featu es th ee ota y cont ol pots. Each input has its own
attenuato , and the e's also a offset cont ol fo the Y input. In conjunction with the Y
attenuato , this thi d pot effectively acts as a wet-d y cont ol fo the X input. But because of
the non-linea ities inhe ent in the design it also acts in mo e subtle ways.
You can also use the Oakley Ring Mod as a standa d VCA. Just use the Y input as you CV
input and X will be shaped acco dingly. Each input can be eithe di ect coupled (DC) o high
pass filte ed (AC). The fo me allows DC and low f equency signals to be p ocessed. While
the latte p ovides a DC block to p ocess only alte nating f equencies. The standa d panel
design makes both types of input available with each having its own socket. You can use both
inputs on each of the X and Y inputs at the same time. Input signals will be summed togethe
so you can also use the RM-4014 as a simple audio mixe .
This is the prototype issue 1 R -4014 Ring odulator module behind a natural finish 1U wide OT
format Schaeffer panel.
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