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Block - AD Envelope/VCA 1.0

West-Coast AD Envelope with Cycle Mode

(13 Votes)
1.0 (Updated 6 years ago)
October 16, 2015
Reaktor 6


Another Block in Michael Hetrick's "Euro Reakt" series! This will be the last Block posted individually. After this, the next upload will be a compilation of every Block in the series. New Blocks will be included in the compilation.

(This Block has been, by far, the most frequently requested Block in the series. I've been wanting to make this from Day 1, but it's a surprisingly complicated module to build properly. At this point, I'm very happy with its behavior and am able to use it a lot in my own music. There's one minor bug where occasionally cycle mode won't start immediately. Just switch to a different mode and switch back)

This is a traditional, West-coast style AD Envelope and VCA. An AD envelope is a simple two-segment envelope, useful primarily for percussive tones and modulations. Like many West-coast AD envelopes, this one has three modes:

AD - Triggered Attack-Decay envelope. No matter the length of the incoming gate, the full attack phase will complete, followed by the full decay phase. This is often called a "one-shot" envelope.

AHD - Gated Attack-Hold-Decay envelope. This envelope's length is determined by the length of the incoming gate. If the attack phase finishes while the gate is still high, the envelope will enter its Hold phase, and will hold until the gate goes low. At that point, it will move to its decay phase.

CYC - Looping AD Envelope/LFO. In this mode, the envelope will loop automatically. If it receives a new gate, it will return to the beginning of its attack phase.

With this combination of modes, along with a very wide range of segment lengths, it can be used as a simple percussive envelope, an LFO, an oscillator, a rhythm generator, and more.

GATE - A positive signal here will activate the envelope.
VCA IN - Input to the voltage controlled amplifier. The amplitude of this signal will be controlled by the envelope.
FREEZE - A positive signal here will hold the envelope at its current value.

A.SHAPE - Controls the shape of the attack segment. At 12 o'clock, it's linear. To the left is logarithmic (fast initial rise then slower towards the top). To the right is exponential (slow intial rise, faster towards the top). NOTE: Changing the shape of the segment will not affect the length of the segment.
D. SHAPE - Controls the shape of the decay segment. Works like the A. Shape knob, but in the opposite direction. Exponential is towards the left.
ATTACK - Controls the length of the envelope's attack segment, from less than 1 ms to 1 second.
DECAY - Controls the length of the envelope's decay segment, from less than 1 ms to 1 second.
IN - Controls the amplitude of the input to the internal VCA.
OUT - Controls the amplitude of the envelope on the OUT and VCA outputs.
RES X/RES 0 - Controls the reset behavior of the envelope when a new trigger/gate is received. RES X means that the attack phase will start from the current envelope value. RES 0 means that the envelope will hard reset to 0 before the attack phase begins. RES X is generally smoother, but RES 0 can be useful for glitchy sounds or rapid modulations.
x1/x10/x100/x1000 - Multiplies the length of the envelope segments. Yes, you can get 2000 second (over 30 minute) envelopes.

OUT - Envelope output. Amplitude determined by OUT control.
VCA - VCA output.
EOA - End of Attack. This output is HIGH (+1) when the envelope is in its decay phase.
EOC - End of Cycle. This output is HIGH when the envelope is not active. A trigger will appear here at the start/end of every cycle in CYCLE mode.
-EOA - Opposite End of Attack. This output is HIGH when the envelope is not in its decay phase.
+ENV - Positive copy of the envelope, not affected by the OUT panel control.
-ENV - Negative copy of the envelope, not affected by the OUT panel control.


Artem Moroz
10 months ago
Thank You VerY MUCH!!!
Thala Estra
6 years ago
@boba fett: maybe Beat LFO is what you are looking for. and thanks Michael for all your inspring stuff
Phil Durrant
6 years ago
This is great! Any chance of a Trapezoid?
Jay Scott
6 years ago
Richard Divine using your Blocks Michael
Bryce Upright
6 years ago
Gotcha Michael! Thanks a ton! This AD/VCA is an amazing modulation source!
Michael Hetrick
6 years ago
Hi Bryce, Jay is right! It's just to change the colors. I left that feature in from the default library's Trigger module. It's more useful on Blocks like the Turing Machine with lots of lights and outputs, as you can use the color coding of your choice. It's also useful if you have multiple copies of the same Block in the same ensemble and want a quick way to tell them apart.
Bryce Upright
6 years ago
Ah....thanks Jay!
Jay Scott
6 years ago
Thanks Michael, this and all your blocks have been making my modular dreams come true.
Jay Scott
6 years ago
Bryce Upright, I think it just change the color of the "leds".
Bryce Upright
6 years ago
I've asked in some of Micheal's other blocks but I haven't heard anything back yet....does anyone know what the numbers 1-16 on the red squares do? A few of Michael's Blocks have these adjustable numbers in the red squares but I'm not sure what they do.
boba fett
6 years ago
This is awesome. It would be even greater if one could set teh attack and release time in beats. That would make it a very fun synced LFO tool. I wonder why noone makes modules with tempo sync in mind, even the bento LFO had to be modded to have one. One would assume that in digital environments this should be a must have option. Anyway thanks, and for all the other great modules too.
Matt Cellitti
6 years ago
Great addition
Worwell _
6 years ago
Thanks for all you work on these.