We're always available at: addac [at] addacsystem [dot] com © 2011 addacsystem.com
Price: 300,00 €



This is one of Eurorack's most underrated random modules!

The ADDAC501 does random CV generation and outputs it through four independent channels. You can control the desired range of voltages and time frequency at which new values are generated.

It can also be triggered by an external CV source and the output voltages can be either free or quantized (if you prefer to have a standard C Major scale).

Finally you can choose between pure randomness or a brownian distribution, for both the voltage and time intervals.



Maximum and minimum voltage
Maximum and minimum time interval
Four independent outputs
Standard or Brownian distributions
External clock input

. Four variable settings: Voltage Maximum, Voltage Minimum, Frequency Maximum and Frequency Minimum, controlled either manually through the front panel knobs or externally from a CV input.

. Four independent CV outputs.

. Standard / Brownian Voltage - selects the type of random algorithm used.

. Quantization On / Off - allows to quantize the zero to five volts range to a Major Pentatonic scale using Moog’s 1v per octave standard.

. External Clock On / Off - allows to sync to an external clock.

. Standard / Brownian Time - selects the type of random algorithm used for the clock timing.



. Format: Eurorack
. Width: 8 HP
. Depth: 5 cm

Control Voltage I/O:
. CV inputs: 0 - 10v
. CV output: 0 - 5v (0 - 10v through jumper)
. Gate in threshold: 2.5v


. Compatible with +-12v and +-15v power supplies

. Max current: 150mA

. Bus Board Cable: 8 × 2 IDC (Doepfer style) connector



ADDAC501 Version 1 videos:

Firmware Update

Firmware Update

The pdf below features all info regarding upgrading the ADDAC501 Module, including necessary hardware, physical connections and download links.

ADDAC501 Firmware Update Guide:


Last Firmware Update:
Version: B_0, February 11th, 2017
-> New mode defines how expansion gate outputs operate:
    1. Normal mode: Random outputs on change
    2. New mode: expansion gate outs output a clock signal everytime the correspondant CV output changes. 
Fast flick Clock Internal/External switch up and down to switch between modes. 

Past updates:
    A_3 features and corrections:
-> Corrected a clock input issue.
-> While using an external Clock Input user can now set a fixed clock delay using Time Min Knob, Time Max Knob sets maximum Random Clock Delay
-> Time pots now work exponentially: X^3, better definition on smaller time intervals.
-> Expansion now autodetects on and off while module is running.
-> Expansion Smooth pot now rests at center: Rotating to the left features a new portamento ring modulation; Rotating to the right features the standard smooth/glide function.

Custom Panel

Custom Panel

In case you're wondering: Sure! We can get you a custom coloured front panel for the ADDAC501.
It has an additional cost of 40€ and takes 4 to 6 weeks to be ready.

It can be done in either Black, Green, Blue, White, Silver Gray, Yellow, or Gold.

Please note: we don’t stock custom coloured panels. For every custom order we need to make a single panel order from our panel provider. This explains the panel price and lead time.

Prices shown exclude VAT, outside EU all orders are VAT free.