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Help me understand the Serge '73 eg
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge Goto page 1, 2  Next [all]
Author Help me understand the Serge '73 eg
grilojoe
I'm sure this is a total noob question, but I'm asking anyway.

I've hunted around and read what I could find, but I'm having real trouble wrapping my head around the '73 envelope generator. I've stared at the schematic over on the CGS website, but only sort of understand what's going on. If I had one in front of me my questions would probably be different. It's a module that I think I might want to build. That is, if I can at least understand basic functions and how to patch it.

To be more specific, I don't understand the Window section, what Hold does or what the difference is between Start and Cycle.

Any explanation would be extremely helpful and welcome.
electroqin
Have you try this ? http://www.serge.synth.net/documents/1976sergemanual.pdf
It has been extremelly helpfull in my case.
Navs
I've had my eye on this too. My first thought when I read the description was of the Plan B Model 10. If so, this might help you understand it:

https://web.archive.org/web/20070824032709/http://www.ear-group.net/mo del_10.html

That said, if it is like the M10, Tim Stinchcombe might be a good read:

http://www.timstinchcombe.co.uk/index.php?pge=m10

I had a couple of M10s - loved, but ultimately hated them. I think there are better designs and ways to get some of the additional functions e.g. a comparator and some AND logic to get gated bursts from any AD envelope etc.
dmitri
Serge 73 EG Is still my favorite EG.
The WINDOW is a gate output that happens while the envelope is open rather than after.
The length of the WINDOW gate is VC controllable.
& there is a pot to manually determine the length of gate.

Sending a gate to the HOLD jack will hold the EG at whatever state it is in at that moment.

CYCLE & START jacks do the same thing. There may have been two just to make live patching easier.
the bad producer
CYCLE and START are slightly different, START is more like a one-shot, it will trigger one envelope when pulsed, whereas CYCLE will cause the ENV to CYCLE when high, and for as long as it is high. It's great for rhythm modulation - trigger sequencer to START, with burst generator like fills (at rate set by RISE/FALL) when CYCLE is gated high.
Navs
Interesting. It really is sounding more and more like the Plan B M10.

Is 'hold' a S&H or does it just interrupt the flow into the integrator?
Mongo1
Hold just freezes the envelope.

The window thing is interesting. It's one of those features whose use is not immediately apparent. If you play around with it you can start getting some interesting gate delays and things like that. That's the beauty of Serge - if you sit down and think about
a feature for a while, you start figuring out all sorts of oddball ways to use it.

One thing to note about it though -the window length is limited by the length of the attack part of the envelope.

Gary
Navs
Yes, that's what I was asking - how it 'just' freezes the envelope. hihi Can someone with circuit reading chops oblige? Seems like an interesting Function.

http://www.cgs.synth.net/modules/cgs76_env.html

If the window is a gate that's high during the attack, it's a freebie offered by the circuit. See the output of LM3900 pin 9 in the first graphic of Tim's VCS explanation:

http://www.timstinchcombe.co.uk/index.php?pge=vcs
Navs
I've added the freeze function to my VCS:

http://navsmodularlab.blogspot.de/2015/04/a-171-2-vcs-expander.html

Ran out of logic for the window, but I guess a simple comparator would do.
grilojoe
gentlemen, thank you all for your replies. While I don't grasp everything yet, I at least don't feel like such an idiot anymore about this module.
cleaninglady
And having both the 73 EG and the DUSG I realised I like the 73 more as time goes by. Interesting beast , much more tweakable.
dbernhardt58
In my lessons with Doug Lynner, we have discovered that his Mystery Serge 73 Envelope Generators have different behavior for the Window Size potentiometer than I have on my EG's. In the Mystery Serge EG's, the Window Size pot and input affect only the Window output; there's no effect on the voltage output.

I have the Elby Euroserge EG; a Loudest Warning 4U EG with the Ken Stone pcb; and the 73-75 Homebuild (three EG's). For all of my EG's, when you have a gate into the Hold input, and then tweak the Window Size knob, it affects the EG's voltage output. I am using the EG voltage output for CV control of a VCA which is taking audio-range input signal.

This behavior makes it harder to match Doug's "A Simple Patch for Complex Rhythm" Patch of the Week. Can anyone confirm how their 73 EG works in this context? Is this a bug or a feature? If it's a feature, how do you take advantage of it?
Gandalf
Have a look at this Patch Of The Week video from Doug Lynner
the bad producer
Interesting dbernhardt58, mine doesn't do this, but I have buffered my output on the panel through an attenuverter (so I can invert the envelope) - maybe the buffer stops this affect? Does Doug have a buffer added to his as a mod - I notice he has the output hardwired via a pot to the Duration input, is there anything else going on behind the panel?

Just to confirm, when you say 'voltage output' you mean the main EG output?
dbernhardt58
the bad producer wrote:
Interesting dbernhardt58, mine doesn't do this, but I have buffered my output on the panel through an attenuverter (so I can invert the envelope) - maybe the buffer stops this affect? Does Doug have a buffer added to his as a mod - I notice he has the output hardwired via a pot to the Duration input, is there anything else going on behind the panel?

Just to confirm, when you say 'voltage output' you mean the main EG output?


Yes, the main eg output
the bad producer
Hmm, I could try testing it without the buffer (disconnect it) and report back.
chorus7
So on the 73 ENVs what is the Duration output? or is it an input? It has a +/- knob under it?
Chaotic
chorus7 wrote:
So on the 73 ENVs what is the Duration output? or is it an input? It has a +/- knob under it?

It is cv control for rise and fall
dbernhardt58
When the 73 EG is in audio range, patching an LFO or other CV signal into Duration will change the frequency (pitch) of the EG outputs.
chorus7
Many thanks for the help we're not worthy
cebec
What's the approximate minimum / maximum frequency for the EGs when self-cycling?
the bad producer
Mine goes from about 0.2Hz - 780Hz.

I see what you mean dbernhardt58, when the envelope is held I'm finding that a CV applied to WINDOW CV IN will affect the (held) voltage output, though if the WINDOW CV pot is below about 9 'o' clock it doesn't. So yeah, finding the issue too when the EG is held with a gate or pulse into HOLD as you have. It's quite interesting if sending a slow CV into the WINDOW CV synced to a hold pulse (ie DUSG triggered by hold pulse), you can get some nice/strange trills out the EG.
cebec
the bad producer wrote:
Mine goes from about 0.2Hz - 780Hz.


Thanks!
kroffe
dmitri wrote:
Serge 73 CYCLE & START jacks do the same thing. There may have been two just to make live patching easier.


Looking at the schematics in the 73-75 build instructions it certainly looks this way:
http://www.73-75.com/wp-content/uploads/2017/04/73-75-build-instructio ns-4.pdf

And double-checking built hardware confirms this.
the bad producer
The 10N cap means START will trigger no more than one envelope, however long the gate signal. A positive voltage applied to the CYCLE socket will cycle the unit for as long as the input is held high (eg by a gate signal).
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