Doepfer A-184-1 Eurorack Ring Modulator Module
Eurorack Ring Modulator Module
Module A-184-1 is the combination of three functions:
The same functions are actually already available in other modules (e.g. A-114, A-148, A-170). But in many systems it's not necessary to have two ring modulators (A-114) or two S&H units (A-148) or two slew limiters (A-170) available. That's why we have compiled these function in one small 4 HP module.
The upper section is nothing but half of an A-114, i.e. a ring modulator with the usual X/Y inputs and the X*Y output. Inputs and outputs of this sub-unit are AC coupled, i.e. suitable only for audio signals. A detailed explanation of a ring modulator can be found on the A-114 info page.
The lower section is a Sample & Hold (S&H) / Track & Hold (T&H) unit (same as half of an A-148) followed by a slew limiter (same as the upper section the A-170). A toggle switch is used to set the mode to S&H or T&H. In S&H mode the unit picks out a sample from the voltage at the SH input at the rising edge of the trigger signal input. In T&H mode the output follows the input voltage as long as the level of the trigger signal is high. As soon as the trigger signal turns low, the last voltage is stored. The trigger input is internally normalled to high, i.e. the unit works just as a slew limiter in T&H mode when no trigger signal is applied.
Detailed explanations of S&H/T&H and slew limiters can be found on the info pages of the modules A-148 and A-170.
Technical note: The S&H/T&H function is realized by pure analog circuitry (electronic switch followed by a holding capacitor and buffer). Consequently the output voltage drifts a bit in the holding state because the capacitor is discharged by parasitic resistors. The typical drift we measured is about 30 mV/minute and depends also upon environmental conditions like humidity or temperature. For the storage of control voltages over a long time used to control the pitch of a VCO the module is suitable to only a limited extent.