Cloning the Serge Dual Universal Slope Generator (DSG)

[Coriolis]

I've become more and more convinced of the importance of versatility in modules, especially after looking at this site:

www.serge-fans.com

Since Serge synths come in panels, with several different modules mounted in one panel, they're not going to get changed around, or replaced if the user doesn't like them. So they need to be really versatile - if possible able to do more than one thing.

A good example of this seems to be the above mentioned DSG. I've never used a Serge, but this module seems to be basically an AR-generator with VC of both A and R times, plus the addition of re-triggerability. Scroll down this page a bit, to see it.
http://www.serge-fans.com/wiz_cv_trig.htm

Seems simple enough, but at the same time incredibly useful (VC-AR, VCO, VC-LFO, a sort of VC-LPF, and heaps more).

So I'm thinking, that it should be possible to come up with a work-alike in this forum (a schem would be nice, but I've never seen one). It could be fun , yes?

So:
-An AR-gen with cv control of Attack time and Release time. Has a trigger input.
-2 cv ins, one 1V/oct and one with an attenuator.
-A switch that assigns voltage control to either A, R or both.
-A Gate that goes low, when an Attack-Release cycle starts, and goes high when it ends. Patch Gate out to Trigger in, and you've got an oscillator.

I figure, to find out what really goes on inside it, one should study the "wizardry" notes on that page. I'm not sure I fully understand how it does all those things.

It would be cool to have all this functionality packaged like this - not a gazillion knobs and switches, but the ability of a module to be transformed into whatever function is needed. Serge call this "patch-programmability".

Whaddaya say?

C

[cebec]

I'm not a DIY'er but you may find these original Serge kit instructions useful.

http://www.cgs.synth.net/synth/serge/kit_index.html
http://www.cgs.synth.net/synth/serge/kit/dusg.html

I do have a Serge with two DTGs (+ modifications to make them 99% of a DSG) so if you have any specific questions about how they behave, I can take a shot at answering them.

Oh, please note that these are for the original (80's) Serge and do not represent any changes or improvements STS has made since taking over in the early 90's.

[Coriolis]

Thanks, that could prove useful!
I never noticed that part of Ken's site...

C

[mono-poly]

I really loved to trigger them in a rythmic patch with a clokc signal.
And then modulate the envelopes so they were going short and long kinda random.
And that they had to complete their cycle in my patch to get retriggered.

[cebec]

[cebec]

[Coriolis]

Hmm..so the DTG is just a shaved down DSG? What mods do yours have, Cebec, and would you prefer to have the gate-to-trigger feedback functionality in a switch, or with a separate gate-out jack? A separate jack should be more flexible, right?

What do you think, mono-poly?

C

[mono-poly]

I am not sure if the DSG also could be triggered the same way so it had to complete the cycle.
I know the DTG had that optin but didn't have CV for A or R just both.
And also it didn't have a 1 volt/oct input.

[cebec]

I think a separate jack would be more flexible. As is, you can just use a 4" banana cable to link them.

My DTGs are modded differently from one another to cover as much of the DSG functionality as possible. The only thing they're missing between them is the 1v/Oct calibrated input which I didn't care about. 3 of the TGs have the audio input mod which I think is essential, one TG has a 3-way switch to allow VC of Rise/Fall/Both slope(s), and one TG has a bipolar output.

[Coriolis]

I see your point about omitting the 1V/oct input - this module looks more like a cv processor/generator to me. But in a pinch one might want to set it up as a vco.

So:
Any guesses as to what's going on electronically?
Correct me if I'm wrong, but if a trigger signal is applied to the DSG, the AR envelope is fired, and at the same time, a gate voltage goes low - to 0v. It stays low until the envelope reaches 0V, then, if Gate out is patched to Trig IN, the Gate going high triggers the envelope again.

So, if set up like an oscillator, the A and R controls are actually used to shape the osc waveform, and also changing pitch of the osc.

Coming to think of it, Ray Wilsons retriggerable AR already does the same thing, sans voltage control. On my Soundlab, the AR does double duty as a variable waveform LFO.

http://www.musicfromouterspace.com/analogsynth/ar_new.html

So if we could replace the two 1meg pots with OTA's or something, and add the gate circuit, we would be getting close! Or what?

I'm getting excited!

C

[vtl5c3]

[Coriolis]

I guess you mean this one:
http://www.ori.org/~aaronc/synth/EnvyLope_V3.pdf
I suppose it does pretty much what I want, but I'd like to cut it down to just AR - I find that the AR on the Soundlab for instance does what I want for an env gen, without Sustain and Decay controls. But I'm not sure what to remove and what to keep in this circuit, in order to do that.
I assume that quad transistor core comes from here:
http://jhaible.heim.at/tonline_stuff/jh_vc_hadsr.pdf
(Cram mentions it coming from Haible).
Damn, I wish I understood more of this stuff!

Btw - this:
http://jhaible.heim.at/tonline_stuff/hj5vadsr.gif
looks almost exactly like the Paia design from here:
http://www.charlielamm.com/synth/adsr.php3
..of which I've already built two, so maybe I could mod those, to get me some of the way?

I'd like to extract just the A and R parts from the Haible/Cram designs, and take it from there (I like the fact that unmatched transistors can be used instead of OTA's). Anybody wanna help me?

C

[loss1234]

did you ever have any luck with this? the more i look at these modules, the more i feel like this is something i have to have in my system. has anyone made something similar thats around as a schematic or pcb?

thanks

[Coriolis]

Nah - I'm not much of an EE, and I decided I had too many other things to do on my modular, before tackling this.

In the meantime topp offered the 281 clones, which look like they do much of what the DSG's do (except actual lag/slew processing I think), so I ordered some of those.

Also, Ray Wilson released this recently:
http://electro-music.com/forum/topic-23059.html
and if I hadn't ordered those 281's I might have taken a shot at these instead.

Initially, my main desire was for some sort of retriggerable AD/AR EG, and the extra features of the DSG would have been very nice.
Incidentally, there is the Envylope by Aaron Cram. This looks like a full ADSR version of the DSG (or something close). I would give you a link to the schem, but Aarons' site has been down for some time.

I'm attempting a pcb layout for this, but it is a rather daunting task for me, and I want to do a good job of it, so the going is slow.
I'm not even sure I want to build one myself, but I'd be happy to contribute a layout to the community.

Back to the DSG: I guess it wouldn't be too hard to do a workalike of it, if you took a simple AD/AR circuit and replaced the Attack and Decay/Release pots with vactrols. At least those are simple to work with for a dumbass like me, who is too thick to figure out how to do it with ota's or that quad transistor core mentioned elsewhere in this thread.

C

[loss1234]

thanks

so you are saying that the DSG is really just a voltage controllable envelope gen with each stage of the envelope cv controllable?

i have the schematic for the envelopy and i have thought about building it many times but without a pcb layout, it just looks too complicated!!


maybe i will look into adding vactrols to a test envelope gen but i wish SOMEONE had a work-alike schematic for this.


it seems that someone on here should know how it works (exactly) since its been around for so long and is deemed a classic module


PLEASE Let me know how the pcb artowrk for the envelopy turns out.


so you think that circuit has even MORE power options than the original DSG?



it just sounds like it would be such a useful module!!


thanks again

[ericcoleridge]

[toppobrillo]

wow, there seems to be so much interest in this thing- i think maybe i will try to make a work-alike based on the resources available- hmm let's see now...

[mistercooper]

I'm very interested, though I can't offer any design help really.

[bugbrand]

What I'd really like is a reasonably simple drum-style EG (AR) with VC release. That'd be so useful for drummy stuff.
But, yeah a DSG would be very interesting.

[Coriolis]

topp - do keep us updated, if you make an attempt!

C

[loss1234]

on the ken stone site, under the serge history, there are pictures and some documents on the negative and postive slew/slope modules.... there is a schematic for the negative one...supposedly those are similar (combined) to the dsg.

[bugbrand]

Hmmm, yes, I'm realising that the NegativeSlew may be exactly what I'm after (and maybe more with the looped option on top!)

[Sound]

About this module is very similar to the Bananalogue VCS. My favourite module. http://www.bananalogue.com/vcs.html . It is amazing!!!!

[loss1234]

pm sent

i dont know if i am allowed to post arron crams schematic publicly or not as he took them all down..anyone know? i messaged it to you though.

someone should make a press n peel of the envelopy!

i need to learn how to do that eventually

[blue hell]