ADDAC220 Dual Envelope Follower +

Normalizing Envelope Follower

This is our new Stereo Envelope Follower, an analog/digital hybrid for better dynamic range analysis. The incoming audio signal gain can be set with the [GAIN] control, the signal is then fully rectified and passed through an analog envelope follower with a fixed short attack and decay.

This analog signal is then sent into a 12bit ADC (analog to digital converter) of an MCU (microcontroller unit) from here on the signal is processed digitally. Whenever the ADC detects clipping the [CLIP] led will turn On.

The digitized signal is then passed through a Savitsky-Golay filter for noise reduction smoothing the incoming signal. Next the signal is slewed using the [ATTACK] and [DECAY] controls. The MCU keeps a history of the last sampling points and detects the minimum and maximum values of the signal which reflect the current dynamic range and maps the signal minimum and maximum amplitude to 0V and the maximum voltage detected. Avoiding the discharge of the analog envelope capacitor.

This new mapped signal is then processed via the [RESPONSE CURVE] control balacing the response like one would with a standard AD envelope with LOG/EXP control. The [ENV. GAIN] attenuverter control goes up to x2 amplification and sets the attenuation / amplification factor of the output range, the red led monitors this level. The led uses pwm control for faster response and better visualization of the output signal across the full output range.

Finally the [OFFSET] allows to displace the signal’s voltage up or down.

The [THRESHOLD] control sets the level to compare to the output signal and turns the [GATE] output On when the signal is above the threshold.
The [GATE LED] show the output state.
The [CV OUT] carries the Envelope signal (0 to +10V) while the [INV. CV] Output carries an inversion of the signal (-10V to 0v).
The [AVG. OUT] outputs the average of both Left and Right CVs (0 to +10V) while the [INV. AVG.] outputs the inverted average signal (-10V to 0v).
The [STEREO / DUAL MONO] switch allows to use the left channel controls to operate the right channel for stereo operation or keep them independent in dual mono. In Stereo mode only the Right channel gain will be independent.

Left input is normalled to the Right input.

https://www.addacsystem.com/en/products/modules/addac200-series/addac220