Secret Squirrels Serge Schematics

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tardishead
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Secret Squirrels Serge Schematics

Post by tardishead » Sat Jul 06, 2019 2:37 pm

Whats the deal with Serge original schematics. You can get almost any original schematics nowadays - except Serge!
Were they never published?
I'm very grateful to the guys who brought Serge to the DIY market but there are a few noticeable differences from the originals. Some "Serge" modules have been improved but some are simply not as good as the originals. And I'm not talking carbon comp resistors and inobtanium. Its basic functionality.
Are there any clones that really are true to the originals? Is Random Source true to originals? Seeing that the man himself is doing some work for them?
Serge 73 Envelope is the sore point for me. I built some clones but they do not behave like the originals. They're cool in themselves but they do fall slightly short.

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Post by Repeater » Sat Jul 06, 2019 6:53 pm

One potential reason is that Serge himself doesn't want to share them publicly. Some of his designs are almost 50 years old too. It's possible that some of the details have been lost. He's around if you'd like to ask him.

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Re: Secret Squirrels Serge Schematics

Post by dksynth » Sat Jul 06, 2019 6:58 pm

tardishead wrote:I built some clones but they do not behave like the originals. They're cool in themselves but they do fall slightly short.
In what ways do they fall short?

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Re: Secret Squirrels Serge Schematics

Post by tobb » Sat Jul 06, 2019 7:11 pm

dksynth wrote:
tardishead wrote:I built some clones but they do not behave like the originals. They're cool in themselves but they do fall slightly short.
In what ways do they fall short?
They sound different (filters for example) but other things and modules in general are upgraded in a good way.

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Post by tardishead » Sat Jul 06, 2019 7:15 pm

Repeater wrote:One potential reason is that Serge himself doesn't want to share them publicly. Some of his designs are almost 50 years old too. It's possible that some of the details have been lost. He's around if you'd like to ask him.
Yeh definitely - how do you get his attention?
I'm very happy with most of my Serge builds but not quite the 73 Envelope
Last edited by tardishead on Sat Jul 06, 2019 7:17 pm, edited 1 time in total.

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Post by dksynth » Sat Jul 06, 2019 7:16 pm

I did not mean so general a question.

In what way does the 73 envelope schematic fall short of an original?
Last edited by dksynth on Sat Jul 06, 2019 7:25 pm, edited 1 time in total.

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Post by tardishead » Sat Jul 06, 2019 7:19 pm

dksynth wrote:I did not mean so general a question.

In what way does the 73 VCF schematic fall short of an original?
Do you have a clone?
Look at Doug Lynner's video Simple Patch for Complex Rhythm or a few others he demonstrates the Envelope. Far more tweak able, more options. More musical

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Post by dksynth » Sat Jul 06, 2019 7:32 pm

tardishead wrote: Look at Doug Lynner's video Simple Patch for Complex Rhythm or a few others he demonstrates the Envelope. Far more tweak able, more options. More musical
His are modified pretty thoroughly, maybe that is part of it? I'm looking for specifics. "they sound better" and "they are more musical" doesn't tell me what specifically you feel that the differences are.

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Post by Repeater » Sat Jul 06, 2019 10:33 pm

tardishead wrote: Yeh definitely - how do you get his attention?
He regularly chimes in on the Serge Modular Synthesizers facebook group.

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Post by MindMachine » Sat Jul 06, 2019 10:41 pm

Serge used to give you the schematics when you ordered modules. At least he did with my order. I might have a few somewhere.

EDIT - mine are just wiring diagrams for kits after all.
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Post by tardishead » Sun Jul 07, 2019 1:58 am

dksynth wrote: His are modified pretty thoroughly, maybe that is part of it? I'm looking for specifics. "they sound better" and "they are more musical" doesn't tell me what specifically you feel that the differences are.
It would be great if someone with 2 clone modules could check this behaviour.
When using one ENV on cycle as master and another as slave - when I switch the slave into cycle, it affects the masters tempo as well as its own. Its as if a diode is missing from an output.
Also when I have 2 different divisions set on two ENVs and patch the WINDOW OUTS into the HOLD of the other they both completely stall. On the Doug Lynner videos this is not the case - its seems like duty cycle range of the Window Out is different. I can overcome this with a NOT logic but cannot achieve exactly the same results.
I spoke to the guy who restored and modified the Mystery Serge he said that the schematics were different enough to account for these differences. The only mod is an internal patching of OUTPUT to DURATION through an attenuator which gives exponential curves and more fine tune of the divisions.
Indeed I read elsewhere on this forum someone experiencing similar anomalies:
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 was totally inspired by the Doug Lynner videos to get these modules - these particular behaviours and others make the ENV modules the centre point of most of his work - it was a bit frustrating for me to discover that I was unable to achieve some of these techniques. Don't get me wrong - the clone modules are pretty cool in themselves but not quite the same.
Quite simply, I would love to see the original schematics without bothering, insulting or stepping on any toes, and make my own deductions/modifications. But getting hold of a schematic is near impossible.

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Post by cygmu » Sun Jul 07, 2019 3:13 am

I have not messed with these modules but the solution to the mystery must be in the way the Cycle switches are wired in Doug Lynner's Serge. There must be a diode in there somewhere, or something like that.

Think about it this way. If you patch two EGs to cycle by patching END to START (or is it END to CYCLE, probably doesn't matter), and then set up the master/slave by patching END of EG1 to START of EG2, then in fact all four of those points are connected. The circuit has no way of knowing which one you think is the master and which the slave.

But Doug's patch is not like that -- he uses his switches. The only conclusion must be that activating the switch is not identical to patching END to START with cables.

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Post by tardishead » Sun Jul 07, 2019 4:01 am

Yeh thats what I was thinking too for that issue
Something like:
A diode between the START jack and the START point on the PCB
Cycle switch connects from END to START points on the PCB (bypasses diode)

As for the WINDOW function I wanted to see the original schematic to see if there were any differences. Apparently there was also a 4v reference voltage on the original. There must be something to do with the duty cycle range.

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Post by Prunesquallor » Sun Jul 07, 2019 4:46 am

I think Doug's system does differ in some ways. I believe there's at least one other thread somewhere about problems in replicating his patches and it came down to the modules.
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Post by tardishead » Sun Jul 07, 2019 5:20 am

Impossible to say for sure without seeing schematics.
KBF who looks after the Mystery Serge says no to the Envelope which is basically unmodified. Or maybe he overlooked small mods that were done before him.
Also anyone out there with real Serge 73 envelopes? Can you replicate Doug's patches.

The patch "The Autonomic Serge" I managed to replicate almost exactly. I put one of the envelopes WINDOW OUT through a NOT GATE before the other envelopes HOLD input. Works perfectly for that patch.

Perhaps the comparator input (which is fed by the WINDOW SIZE pot) is wired slightly different - in originals or just Mystery Serge?
Again, impossible to know without seeing schematics or to compare with an original module

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Post by cygmu » Sun Jul 07, 2019 7:18 am

tardishead wrote:Yeh thats what I was thinking too for that issue
Something like:
A diode between the START jack and the START point on the PCB
Cycle switch connects from END to START points on the PCB (bypasses diode).
Yes, I was just about to post this exact proposal. So if it doesn't work then you can blame me even though it was your idea!

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Post by cygmu » Sun Jul 07, 2019 7:30 am

FWIW There are some images of both sides of an R7 PCB (envelope generator) on this page:
https://djjondent.blogspot.com/2017/06/ ... -burt.html

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Post by tardishead » Sun Jul 07, 2019 10:02 am

cygmu wrote:FWIW There are some images of both sides of an R7 PCB (envelope generator) on this page:
https://djjondent.blogspot.com/2017/06/ ... -burt.html
Awesome thanks for that
Last edited by tardishead on Mon Jul 08, 2019 6:28 am, edited 1 time in total.

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Post by djs » Sun Jul 07, 2019 11:28 am

Related question- does STS (Rex probe) still operate from the original schematics?
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Post by Corrupt » Sun Jul 07, 2019 1:59 pm

tardishead wrote: Also anyone out there with real Serge 73 envelopes? Can you replicate Doug's patches.
Yup, can you refer to a specific patch/video to try?

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Post by tardishead » Sun Jul 07, 2019 6:07 pm

Corrupt wrote: Yup, can you refer to a specific patch/video to try?
Great !
Lynner1
Lynner2

If you replicate the first patch - does adjusting either Envelope affect the others frequency?
And the second one - if the window from each module is patched to the opposite modules Hold input - do they act like the video or do they turn each other off altogether?
Thanks

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Post by tardishead » Mon Jul 08, 2019 9:52 am

I put a diode between the input jack and the START one shot input
Yes works and stops the interacting between modules.
I can now replicate the 2 patches but still not without a NOT gate into one modules HOLD.
Oh well it will have to do for the moment.

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Post by the bad producer » Mon Jul 08, 2019 1:27 pm

Have you got a hotter gate signal to try for the START clock? (I'm a bit confused) but mine works as in the video with a pulse from my Ultrafade VCO (8V ish IIRC), maybe some adjustment of the resistors at the START input would sort it out?

EDIT - Ignore that, got my wires twisted, literally lol

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Post by Corrupt » Tue Jul 09, 2019 3:36 am

Hey that was interesting. Everything went fine until I wanted both cycles (one on each env generator) to be high. Then there was clearly some interaction going on.

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Post by the bad producer » Tue Jul 09, 2019 6:06 am

FWIW the only difference I can see (so far) between the original and the CGS version is that the HOLD trimmer is 25k on the original.

EDIT - I just swapped my HOLD trimmers for 25K, just to see what it would do really. Actually never really calibrated them properly, I just did with the 10K and in my mind the HOLD function works better with 25K, though that might be just the tail wagging the dog?! Be interested if you can calibrate as per Ken's instructions, I found I couldn't get a steady HOLD voltage with 10K.

Anyway, Doug does say "sometimes they'll turn each other off for a bit" which I'm finding is true, but in general I think it's working here with 2 EGs driven by a DUSG master clock. I had diodes to START anyway as I have manual trigger buttons (DIODE OR'd to START as well)... Some knob settings cause it to lock up occasionally, if I have time I'll try some more experiments... The WINDOW pot on mine needs to be fully on for it to work.

Which I did while drafting this, and found something else out. tardishead can you replicate the patch with a slight voltage (eg 1V) applied to the WINDOW CV socket? I just did that - to both EGs - and I'm not getting any lock ups now, seems to work fine. You mentioned the 4V source in a previous post, this should have read 6V. Old Serge circuits used a 6V supply for certain parts of the circuit, this would have come from a dedicated 6V line from the PSU. To obviate needing this Ken uses a voltage divider derived from the 12V. Maybe this isn't 'ideal' for the window part of the circuit. Notice that the WINDOW CV input and pot are summed through 1M resistors to pin 1 of the 3401, the pot is driven from the 6V line so adding a bit of voltage (or current depending on how you like to view things) to the socket appears to solve the issues with locking up I had, of course adding a variable CV in here makes things more interesting!

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