Highly-modified STS Serge system

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Highly-modified STS Serge system

Post by wsequeira » Sat Mar 28, 2020 6:43 pm

Folks requested more detail regarding the STS Serge panel mods in my STS Serge Anima. Moved the thread here from Banana Pics in case it's useful to others who are interested in mod’ing their STS systems and creating their own instruments.

The Anima is a highly-modified six-panel STS Serge system, roughly the equivalent of eight standard STS panels, housed in two M-panel STS cases, for a total footprint of only 35.5” wide x 17.75” deep.


Over the years Kevin and I conversed often about his Mighty Serge and the evolution of such unique instrument. Also conversed with Rex on and off regarding small systems and what flexibility means. I like the sense of having an instrument — a complete and stable system that affords creative possibilities but also limitations that foster creativity. I find that large modulars overwhelm me (my own shortcoming) and that the open-ended-ness that many cherish about modulars makes me feel like it is never complete, never over, never finished. So the idea of creating a unique instrument began taking shape — to have a complete system, the smallest most powerful I could come up with. I wanted my own instrument. And so the Anima was born.

The Anima is composed of two portable cases. One case consists of Hartland shop panels (HART), a typical Animoo/Animate/TKB system. The second case consists of Oakland-era custom panels (OAK) — custom Animator, 8-channel interface and three-programmer panels. Each case had to stand on its own as a complete system, and both OAK and HART had to complement each other to form a complete instrument. HART also had to be able to “mutate" itself into a STS Red or Blue Voice system.

Building a dense system brought its own challenges. There are 280 knobs plus 619 controls and LEDs in a 35” x 17.75” area. Power was an issue, had to move into a large PS12 to ensure ample power. Visually so many black knobs felt claustrophobic to me, so had to invert the knob color scheme and use an unorthodox knob combination (still experimenting) to calm down the visual complexity. Had to include mods to reduce the amount of patching (and banana cables). And use passive modules (TinyMixers, passive vactrols, etc.) to move simple, common functions off-panel.

Mods belong in three categories: 1) New functionality that the panels didn’t have,; 2) Bringing up front functionality available in underlying boards but not available in the front panel; and 3) Performance mods to simplify patching, reduce the number of patch cables, cycling, routing, etc. A list of the mods per panel:


* Hartland shop panel
* New boards added — Analog shift register, random voltage generator, ring modulator
* NTO — AC/DC frequency VC switch for tremolo effects w/o losing osc tuning
* ASR — embedded in NTO
* TWS Switch — Route upper waveshaper blue OUT to ASR Sample In
* RVG — embedded in VCF BW
* RVG Rate Knob — embedded in WAD
* RM — full module embedded in WAD
* DSG — Exponential/linear BIPOLAR OUT switch, three-way switch with CYCLE at top and manual TRIGGER at bottom

* Oakland shop panel later upgraded to Hartland specs, this is the very first Animoo panel
* New boards added — Ring modulator, NCOM, pulse divider
* NTO, PCO — AC/DC frequency VC switch added, for tremolo effects w/o losing osc tuning
* NTO — HI/LO switch
* NCOM — embedded in NTO
* VCM Wave Multipliers — Bottom/middle wave mults VC IN attenuator knobs added
* RM — embedded in VCM; set to RM and unity gain input (standard Animoo behavior)
* Pulse Divider — Division select rotary switch w/OUT jack (all divisions selectable, including the missing ÷16), custom jack lineup
* SSG — Cycle switch, RVG switch
* DTG — Rise/Both/Fall switch, cycle switch per slope
* VCF Q — Cycle switch, BAND/LO OUT attenuator knobs
* AGC IN — Input gain increased


* Hartland shop panel, with vertical row LEDs
* New boards added — Quantizer, mixer, Schmitt trigger, custom internal clock
* Quantizer — ABCD out quantize switch, AB outs quantize switch, CD outs quantize switch, 1/6 select switch + jack, 1/3 select switch + jack, quantizer channel in/out
* Vertical Reset — resets vertical clock when pulse received in RESET
* Summer — 3 in 1 out unity gain AC mixer (summer out also sent to Clock Source Switch to generate custom clock signal)
* Clock Source Switch — 3-way switch: Internal clock, External clock (normal TKB behavior), and SUMMER clock
* Custom Internal Clock — adjustable from ~0.5Hz to ~30Hz
* Custom Summer Clock — Takes output of SUM, cleans through Schmitt Trigger, then outputs
* Clock Rate Knob — sets INTERNAL clock frequency OR sets SUMMER CLOCK threshold for schmitt trigger clock generation
* VC Clock Rate jack — provides an offset to Clock Rate knob
* Clock Out — copy of clock signal currently running the TKB


* Oakland custom panel, one of the first Animator modules created
* New boards added — custom 1973 dual VCA board
* DTG — Mods change DTG into full DSG: Rise/Both/Fall switch, Cycle switch, 1v/oct in, Bipolar out
* DRG — PINK noise, Trigger Switch to manually sample S/H one step at a time
* SSG — Cycle switch
* Dual 1973 VCAs — Custom board provides VCAs with simultaneous LOG/LIN cv ins and a DC IN for each
* PCO — AC/DC frequency VC switch added, for tremolo effects w/o losing osc tuning

* Oakland custom panel
* New boards added — ACPR, Dual Comparator, TimeGen Clock
* Interface Attenuators — one attenuator per channel, 8 total
* ACPR — embedded in PCO
* PCO — AC/DC frequency VC switch added, for tremolo effects w/o losing osc tuning
* PDIV — add ÷16 out
* Dual COMP — Full comparators surround MIXER
* VCM Wave Multipliers — Bottom/middle wave mults VC IN attenuator knobs added
* TimeGen Clock — Full TGC embedded in VCF BW; Rise/Both/Fall and Cycle switches added to R slope
* MIXER and VCAS recapped to modern STS standards


* Oakland custom panel
* New boards added — Quantizer, ASR, +5V
* Quantizer — ABCD out quantize switch, AB outs quantize switch, CD outs quantize switch, 1/6 select switch + jack, 1/3 select switch + jack, 2x quantizer channels in/out
* Quantizer Tune knob — fine tune quantizer outs
* ASR — embedded in second and third programmers
* +5 Switch + Jack — 2-way switch: Selects +5V constant through jack out, or provides a momentary manual trigger through jack OUT


* Conversion from PS2A power to PS12 power.
* Banana grounds added
* Removable one-screw Internal brackets, to easily install/remove the third upright panel during transport.

* 17 new circuit boards added
* 165 new holes drilled (33 knobs, 91 jacks, 2 LEDs, 12 bat handle switches, 22 switches, 5 mini-switches, 1 trigger switch)
* 161 new labels added
* knob color scheme inverted to ease visual density

This was one crazy experiment that took ~5 years to complete with God's help. Thanks to Kevin Braheny-Fortune for his wise advice and mods derived from years of experience with his Mighty Serge, Rex Probe/STS for his support, Nick Liebrecht, captnapalm, papz, tobb, aethyr, LoveMySwitches and all who lent a hand or an ear to see this through.

Stay safe! :guinness:
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Last edited by wsequeira on Sun Mar 29, 2020 7:58 am, edited 3 times in total.
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Re: Highly-modified STS Serge system

Post by GrantB » Sat Mar 28, 2020 7:14 pm

Thanks for the details. I love nerding out on this type of stuff.

We like to laugh when people say their modular system is "done", but this, I could believe.

Enjoy your extended journey beyond the Oort cloud.

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Re: Highly-modified STS Serge system

Post by depth20 » Sat Mar 28, 2020 7:26 pm



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Re: Highly-modified STS Serge system

Post by deltaphoenix » Sat Mar 28, 2020 7:31 pm

That is amazing! I would love to see a video of it in action.

I also would love a cycle switch for my SSGs.

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Re: Highly-modified STS Serge system

Post by MindMachine » Sat Mar 28, 2020 11:40 pm

Bill - that is a majestic post and system. I'll need several reads to gather it all in. Those 'Davies' are amazing in their own right. Nice to see a CV Interface module and I love the Pulse Divider. So many mods - what a dream machine. You certainly knew what you wanted with so many years of thought. I need to send my unit to Kevin for repairs. Maybe I'll be inclined for more mods now.

A truly inspiring system. I am almost breathless. Congrats and thank you so much for sharing the details and great images. Try to get some sleep.
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Re: Highly-modified STS Serge system

Post by rampy » Sun Mar 29, 2020 8:10 am


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Re: Highly-modified STS Serge system

Post by Jd1979 » Sun Mar 29, 2020 2:38 pm

Omg!!! That is amazing and packed with functionality!! Do you have any vids or sound files of this guy in action?

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Re: Highly-modified STS Serge system

Post by revtor » Sun Mar 29, 2020 8:36 pm

:sb: :hail: :yay: :yay:
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Re: Highly-modified STS Serge system

Post by MechaSeb » Mon Mar 30, 2020 2:45 am

Wow thank you very much for the detailed post Bill.
This is really appreciated.

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Re: Highly-modified STS Serge system

Post by tobb » Mon Mar 30, 2020 4:42 pm

Nice system :tu:

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Re: Highly-modified STS Serge system

Post by bitone » Mon Mar 30, 2020 8:46 pm

Amazing! Thanks for sharing this and all the meticulous details! This is really the most extensively modded Serge I've seen, next to Kevin's mighty Serge that is. Hats off!

Like others have said above, will have to return a few times to soak all these details in.

I do have one extra question tho, any chance for a demo or even a description of the uses of the CV>midi converter? I have always wanted to pick Rex's brain about this, but haven't gotten around to it. It was intended for external fx units? Feedback loops between external units and the Serge? I'm assuming it can send CC data etc. which is intriguing. Curious... and again thanks for all this!

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Re: Highly-modified STS Serge system

Post by phisynth » Tue Mar 31, 2020 12:04 pm

Amazing system and clever mods !

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Re: Highly-modified STS Serge system

Post by puzzlebox » Tue Mar 31, 2020 12:39 pm

Wow! that is an awesome system!
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Re: Highly-modified STS Serge system

Post by Chaotic » Tue Mar 31, 2020 3:31 pm

Great. Many new ideas here. :yay: Lovely to see others do it too.
I have also done some of these mods, but not that many. Have to find my drill and solder iron again :banana:

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Re: Highly-modified STS Serge system

Post by Zeno » Wed Apr 01, 2020 4:47 pm

Beautiful synth, great work!

I have a question: I've noticed that you've added the "pulse out" jack for your ASRs. I think that they send out exactly what came in, did you ever figure out an use for it?

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Re: Highly-modified STS Serge system

Post by wsequeira » Sat Apr 11, 2020 4:30 pm

Apologies it has taken me so long to respond, the lockdown has thrown several curve balls my way — we are ok and hope all of you and your families are well and safe too.

Thank you for all the kind comments. Will try to post examples time permitting, but please don't hold me to it as life is a bit crazy right now. Other quick responses...

GRANTB: Agree with the general rule as well, but have no choice — ran out of panel space and toy funds are depleted. But, there's always desk space that longs to be filled... been experimenting with passive modules to complement the Anima, will post a few findings at some point.

BITONE: The Animator was meant as a mechanism to control the characteristics of effects over time, such as reverb (tail, depth) and delay (repeats, depth), by using cv as a means to generate a stream of CCs. Using the module is not as straightforward as it sounds, takes some wrangling to get something useful. It also depends on the FX unit you choose control, as some are easier to control than others. Patience is definitely required. My Animator is a very early version too, adding to its complexity. Newer versions provide lights for MIDI events and a MIDI channel selector, easier to see what goes on. Re: feedback loops, was looking to use the Animator to control my Octatrack, but haven't found time to try it out yet. The idea is to bring Anima sound into the OT, then use Anima cv to control OT machines in real time. The OT adds an interesting dimension as it can work as both a mixer, librarian/sampler and sound source. Dunno. Will share findings if/when I get anything useful out of it.

MINDMACHINE: Thank you for the kind words, hope it encourages anyone wanting an instrument of their own. Hope your conversation with Kevin is fruitful.

ZENO: Yeah this was a head scratcher for me too — intuitively first reaction is to chain ASRs top down. But that's not how it's supposed to work. Think of ASRs as having two "threads" — one for cv and one for pulses. Suppose you want to gang up two ASRs. An ext cv goes into ASR1 SampleIN, then ASR1 3 OUT goes into ASR2 SampleIN, repeat for more ASRs. But pulses are different. Start with the last ASR in the chain, then go to the top — feed an ext pulse to ASR2 PulseIN, then ASR2 PulseOUT to ASR1 PulseIN. It's sort of the reverse of cv. In general, the ext pulse goes to the last ASR in a chain, and its pulse out goes then to the top of the chain, then down. As I understand it, ASR PulseOUT is the output of the series of stages, not identical to the original PulseIN — necessary to make room at the end of the line for the hold circuit to move over. For two ASRs timing differences are very small and/or subtle, probably easier to perceive the longer the chain. Don't know if this is true for other Serge ASR implementations out there. Hope that helps.
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