Envelopes-ADSR etc. Polyphony/TH ADSR board
Rene Schmidtz Fast ADSR
gabbagabi AR-ASR
Vactrol Based Envelope Follower


OK, posting the classic Thomas Henry Design of a 4016 and 555 based ADSR. This appeared in Polyphony (PAIA's DIY and Synth mag) March-April 82; I have also seen it in at least one of Tom Henry's design books. I suggest buying either the back issue or one of TH's books, the article has a quite detailed description of how the ADSR works.

I spoke to Jon Simonton before he died (sad thing, but still, I am glad to have gotten to speak to him and get to know him a tiny bit while he was alive, he was super friendly and enthusiastic); John gave me permission to post this schematic.

Files for your face:

  • Eagle schematic is here
  • the eagle BRD file is here.
  • The PNG file for the schematic here.
  • Wiring diagram is here.
  • About the layout and circuit:

    The circuit as designed by TH requires 2 signals to fire it: a Gate signal (0V to maybe 1V or more? Needs to be a diode drop above ground....) and simultaneously, a single inverted TRIGGER pulse to allow the 555 to start its cycle. So TH's design, as per his original article in POLYPHONY, expects an inverted trigger signal and a positive going gate signal at the same time. This seemed a bit odd to me when I was first laying out the board since I don't have gear or seen a lot of Midi to CV that generates these signals simultaneously or even asynchronously; for instance, on my kenton Midi to 1V/oct CV the gate and trigger signals are all GND to positive V.

    But dealing with this design feature (???) was easy enough, Just tie Q3's collector to the "input side" of C11.

    I also added a second resistor/NPN to the circuit you see here to accommodate AND signals (something I needed for my own particular build) but you probably won't need that, so feel free to leave Q3 and R1 out.

    Here is a gerber of TH's design. There is a mistake in it that is on me! Pin 7 and 8 of the 4016 need to be tied to ground, but the gerber has the 4016 V-- tied to -15 which won't work. To fix this, if you do make a PCB from the gerber, cut the trace to V-- on the 4016 and jump the pin to ground. but instead of modding, I'd suggest just grabbing the SRC and BRD, getting Eagle Lite, and recreating the gerber. The board layout above corrects this mistake. Otherwise as far as I know this circuit is 100% good to go, I have built this and it makes a nice steady ADSR signal when provided a 0-5V gate.

    one final note: I revised the board a bit (REV5) to accommodate a positive going trigger signal and it also fixes the 4016 GND goof.. Schematic here, board here. I haven't tested this revision yet but my mod to TH's design is super simple, I inverted a positive going trigger signal before it hits cap C11. I'd guess if you built it it'd work but of course as a very wise tech once told me: never trust anything but your Fluke.


    I got this one right off the Internet, emailed Rene, and he said OK to post it.

    See Rene Schmitz original page for this ADSR here. This is one of those "holy smokes--this should work great!!!" things I felt I should build so I did...and it does sound really good, quick attack response and fast decays. I have posted more about variations on this design on my blog site here.

    The schemo's below assume you can find 2M analog taper pots (I could, but it wasn't easy). there are instructions on Rene's post about using 1M pots (use audio taper; he doesn't mention that I think, but to my ears you want audio taper for A, D, R and linear for Sustain), I also did a few tests to see if I could find a difference with different cap, pot and resistor sizes and post that somewhere. Discussion of that is here.

    Download-o-mania for the Renay-DSR:

  • Eagle schematic and BRD files are here

  • nota buena:This one tests working. I promised Rene I wouldn't try to make money off his design, so please use this Eagle data in a manner befitting to fellow geeks everywhere.

  • PDF of Schematic, wiring diagram, BOM, and donpachi's dual pot trick are here.

  • gabbagabi High Performance AR-ASR

    E-M contributor gabbagabi ("G.Gabba") doesn't just think outside the box, with this guy there is no box at all. Highly creative.

    gabbagabi and I started to exchange IMs after I posted some blogs about Rene's fastest ADSR you find above.

    gabbagabi has his own ASR/AR that is superfast, depending on the pots and caps used, easily getting attacks that don't click, with a decent VCA, into the 2-3ms range.

    gabbagabi sent me some schematics and a "humanized" Eagle design he had been working on; humanized meaning the PCB design pretty much was laid out the same way as the the schematic. The humanized approach, which I had never seen before, again remember that Gabba doesn't do things the same way as many of us, makes the board bigger but also easier to mod and troubleshoot. OK, At first I couldn't figure out how his AR worked from schematic or sim, but figured I'd try to build it anyway.

    I had a few fabbed so I could mess around and guess what, it works and sounds great (and the humanized design made it easier to understand and troubleshoot). Blog postb with more details and blah-blah-ginger is here. I used 100K audio taper pots for A and R, and 10uF and 100uF caps on a DPDT switch to form the "Tao", but you should mess around with these values and see what you like. More details in the post. For me, Any way I sliced it, this design is recommended, very musical. I might work on getting 2x or 4x of these on a single board down the road.

    Downloads for this design follow:

  • Eagle schematic and BRD files are here
  • PDFs of Schematic, wiring diagram, notes etc. are here. I include a simple TL072 buffer-offsetter-inverter used to take the 0-5V inverted output and turn it into a 5V-0V inverted output.
  • BOM for this build is here. One gotcha: for trannies, a 2N3906 matches the PCB silkscreen, but a 2N3904 needs to be flipped. You could use a BC550 (as per the BOM) without flipping. overall follow the BOM or please make sure your tranny's EB and C matches the schematic.
  • Gerber files are here.
  • My attempt at explaining how Gabba's design works, not nearly as simple as I thought, is here.

  • VACTROL based Envelope Follower

    Here's a design I came up with in about 2004, I was getting into seeing what I could do with Vactrols and thought a vactrol based envelope follower might be handy. I stripboarded the original design which I used for many years but after 15 or so years figured it was time to make it into a real module with a double sided PCB etc.

    You can get more information from the blog post here; if you want to hear what this sounds like, go to the clip here. For the clip all the sounds are processed one way or another with the vac-ef--you hear auto wahs, distortion that is controlled by amplitude, amplitude to pitch conversions, side-chains etc. Every studio needs some sort of amplitude to CV converter right?

    Downloads for this design follow:

  • Eagle schematic and BRD files are here
  • PDFs of Schematic, wiring diagram, and a couple of trace fixes needed if you build this are here.
  • Gerber files are here.