UNSTABLE Synth v.1.1.3 - Yamaha CS-80 Clone (PC/MAC/LINUX)

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Unstable Synth

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Morphoice wrote: Thu May 28, 2026 7:13 pm As I already replied in the other thread, I checked it in FL Studio 25.2.5 and confirmed it works fine. Please make sure it was installed correctly - as FL Studio's very own message suggests, before publicly reporting a bug.
I think I identified what the problem was. It was installed correctly, but it was trying to load with a default preset I'd saved from an earlier version, which now seems to be incompatible with this version, hence the error message. I've seen that happen with other plugins. It's loading fine now.

I am experiencing an issue with some presets loading with the VCA level set to 0, or with the LPF set too low, thus making no or very little sound when loaded. Affected presets are CPC Jump, Init, Saw, Square, PeeWee Pad and Pulsed Organ.

It does sound very nice indeed :tu: If I could make just one feature request, it would be the option to disable the velocity sensitivity. But that's just a personal preference of mine. Actually one more: the option to mouse scroll through the presets on the little preset bar at the bottom.

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Morphoice wrote: Thu May 28, 2026 7:24 pm
Echoes in the Attic wrote: Mon May 25, 2026 1:03 am Never seen a commercial plugin not be code signed for apple. Pay the 99 bucks man, I don't want to have to quarantine software I buy.
I have no records of any purchase from you. Allowing unsigned software is a standard macOS setting that takes about 10 seconds. It's documented on the download page and on Apple's own support site. Plenty of indie plugins ship unsigned. If that's a dealbreaker for you, fair enough, but telling me how to spend money you never earned me isn't really how this works.
Right - How this works is telling you, as a potential customer why I didn't buy your software. It's the cost of one license that you sell. You literally make it back with a single customer. But what you chose to do with that information is up to you, so I agree, let's move on.

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It's shockingly good. I still like the original version for its edgier sounds but this new version rivals hardware. The default patch reminds me of the Rufus du Sol sound, which is a Prophet-6.

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Where'd you find a CS-80 to measure and do physical modeling? Or can you do those measurements off youtubes and sound clips? I literally don't know but I'm curious since you made the statement: "with an improved physical model of the original Yamaha CS-80's voice cards and instabilities after months of thorough measurements and analysis of the original hardware."

What did you measure and how?

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MattCable wrote: Fri May 29, 2026 2:48 am Where'd you find a CS-80 to measure and do physical modeling? Or can you do those measurements off youtubes and sound clips? I literally don't know but I'm curious since you made the statement: "with an improved physical model of the original Yamaha CS-80's voice cards and instabilities after months of thorough measurements and analysis of the original hardware."

What did you measure and how?
He wrote about it in the other thread:

viewtopic.php?t=618204&start=60

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That just looks like oscillator waveforms? Not some kind of physical modelling. Also, I've never heard that the CS-80 was particularly unstable in a way that wasn't simply falling out of tune and requiring tuning, like other analog synthesizers.

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MattCable wrote: Fri May 29, 2026 2:48 am Where'd you find a CS-80 to measure and do physical modeling? Or can you do those measurements off youtubes and sound clips? I literally don't know but I'm curious since you made the statement: "with an improved physical model of the original Yamaha CS-80's voice cards and instabilities after months of thorough measurements and analysis of the original hardware."

What did you measure and how?
The component modeling in UNSTABLE is based on years of hands-on experience with the original hardware. I've been restoring and working on vintage synthesizers since 1998, including owning a CS-80 for several years, and I'm in regular contact with other owners who maintain and service theirs. The measurements and analysis were done on real hardware -- this isn't something you can extract from YouTube videos, and I'd appreciate the question being asked in good faith.

I understand there is a certain skepticism and general negativity toward newer developers in this space, and that's fair -- but I won't be intimidated into justifying decades of work to satisfy bad-faith questioning. I'm not in a position to share the specific methodology and tooling behind the modeling -- that represents years of hard work. What I can say is: try the plugin and let the sound speak for itself. If it doesn't convince you, that's completely fair.

If you're genuinely interested in plugin development and audio DSP modeling, there's a huge, very open and very friendly community of professionals out there -- but you'd need to strike a much better tone to be welcomed into it. Stanford's CCRMA has excellent courses on physical modeling and digital signal processing if you want to understand the depth of work that goes into something like this.
Last edited by Morphoice on Fri May 29, 2026 9:15 am, edited 1 time in total.

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tumface wrote: Fri May 29, 2026 6:08 am That just looks like oscillator waveforms? Not some kind of physical modelling. Also, I've never heard that the CS-80 was particularly unstable in a way that wasn't simply falling out of tune and requiring tuning, like other analog synthesizers.
Those waveforms are the output of the physical model at its current state compared with the hardware. And the CS-80 is well documented as far more than just "out of tune." Each voice card exhibits individual differences in filter tracking, envelope response, and oscillator behavior due to component tolerances and thermal sensitivity. That's precisely what makes its charm. But if you have insight into the CS-80 that I as a developer don't, by all means -- indulge me. Always happy to learn. Otherwise, I'd suggest spending some time with the hardware before drawing conclusions and I'd also appreciate if the public hostility stopped. I'm not going to continue engaging with uninformed challenges to my work -- I have a plugin to build.

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"Instabilities" implies it's changing as you play, right? The differences between voice cards don't change that quickly. You'd hear a difference depending on which voice card a note is allocated to, per note. Hopefully not much of a difference, unless you threw the cards out of calibration on purpose.

Having multiple analog voice cards isn't unique to the CS-80. That's how most keyboard polyphonic analog synths worked.
Morphoice wrote: Fri May 29, 2026 6:58 am I'd also appreciate if the public hostility stopped. I'm not going to continue engaging with uninformed challenges to my work -- I have a plugin to build.
I don't think that was very hostile.

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I built UNSTABLE to capture the soul and character of the CS-80 as I experience it, and I'm very happy with where it is and how it sounds, it has been well received among fellow producers, developers and audio professionals. If you enjoy it, great — if not, that's fine too. I'm always open to bug reports, but I won't be discussing the technical details of the modeling publicly. If you have specific questions about the CS-80, there are qualified technicians out there who'll be happy to walk you through it — for the right fee.

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Is it not a bit weird to say you won't be answering technical questions about your synth, in a thread about your synth? I wasn't even really asking about the details, but questioning that recreating oscillator waveforms is necessarily physical modeling.

Morphoice wrote: Fri May 29, 2026 7:20 am If you have specific questions about the CS-80, there are qualified technicians out there who'll be happy to walk you through it — for the right fee.
I wasn't asking questions about the CS-80. It was about the plugin, the subject of the thread.

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tumface wrote: Fri May 29, 2026 7:56 am Is it not a bit weird to say you won't be answering technical questions about your synth, in a thread about your synth? I wasn't even really asking about the details, but questioning that recreating oscillator waveforms is necessarily physical modeling.

Morphoice wrote: Fri May 29, 2026 7:20 am If you have specific questions about the CS-80, there are qualified technicians out there who'll be happy to walk you through it — for the right fee.
I wasn't asking questions about the CS-80. It was about the plugin, the subject of the thread.
I never said I won't answer technical questions about the plugin — there's a growing manual on the website for that and we gladly offer technical support over official channels to every customer. What I said, was that I won't share the methodology behind the modeling. Those are two different things. Please read more carefully before putting words in my mouth. If you're interested in learning about physical modeling and DSP in general, Stanford's CCRMA is a great place to start.

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Morphoice wrote: Fri May 29, 2026 8:57 am If you're interested in learning about physical modeling and DSP in general, Stanford's CCRMA is a great place to start.
I wasn't asking about learning resources for DSP, no.

But since you've brought up "physical modeling," are you saying that 'Unstable' uses physical modeling? You've referenced that phrase several times in this thread. I've never heard that term used to describe an analog polysynth. Physical modeling is used to describe synths that are reproducing physical acoustic phenomena, like membranes and tubes being struck.

Morphoice wrote: Fri May 29, 2026 8:57 am Please read more carefully before putting words in my mouth.
I'm reading very carefully. I didn't put any words in your mouth.
Last edited by tumface on Fri May 29, 2026 9:14 am, edited 3 times in total.

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Forum decided to double post (I've noticed this happening more recently) delete me

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tumface wrote: Fri May 29, 2026 9:11 amI've never heard that term used to describe an analog polysynth.
Yamaha used that term for AN1x, actually.

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