There's a complete list of synth engines used by Casio?

[Jensen_PD]

Hello.

 

I'm just curious, but until some time ago, I didn't know that something like the IXA synthesis engine existed. I know some, like the consonant vowel synthesis, the PD or the SD, but I don't know much beyond the mid 90's,

 

Also, If someone knows: I'm interested to know if Casio employed some cut-down variant of the PD synthesis in the keyboards sold between the mid and late 90's.

 

[Display Name]

This page: https://generror.wordpress.com/2010/07/05/history-of-casio-keyboards-1/

And this page: https://generror.wordpress.com/2010/07/08/history-of-casio-keyboards-2/

 

^^^ Good reading! 

[Chas]

Also, If someone knows: I'm interested to know if Casio employed some cut-down variant of the PD synthesis in the keyboards sold between the mid and late 90's.

 

Casio developed the mid 80's PD CZ sound source into 1988's VZ-1 (it used iPD - Interactive Phase Distortion). I'm 99% certain the VZ-1 was the last Casio to feature any form of PD, and after the VZ-1 Casio pretty much dropped its "pro" keyboard line-up until the MZ2000 (approx. 1999 onwards) and then the XW's in 2010/ 11. Most Casios from 1990's onwards used some form of PCM (that might be what the "IXA" sound source was), then the MZ 2000 was released and used "ZPI Sound Source - (Zygotech Polynomial Interpolation) - no, I've no idea what that is either but it does sound good!

 

The XW's then went on further and used HPSS, a great step forward in terms of programmability and flexibility, and also still using PCM for some excellent sounds.

 

I wonder where Casio will head next? 

[Jensen_PD]

This page: https://generror.wordpress.com/2010/07/05/history-of-casio-keyboards-1/

And this page: https://generror.wordpress.com/2010/07/08/history-of-casio-keyboards-2/

 

^^^ Good reading! 

 

 

That's a good page, and I already knew about it; if you see the 2nd part, at the end it says: "The next and final part of this series tells of the few interesting machines Casio built from 1989 to the mid-1990s", but unfortunately, the 3rd part was not even published, because the last post of that blog dates from 2010/08/17, this is why I asked for casio synthesis engines beyond the 90's. Anyway, is good to re-post again that link because more people can discover that great blog, and thanks to share the info.

 

 

Casio developed the mid 80's PD CZ sound source into 1988's VZ-1 (it used iPD - Interactive Phase Distortion). I'm 99% certain the VZ-1 was the last Casio to feature any form of PD, and after the VZ-1 Casio pretty much dropped its "pro" keyboard line-up until the MZ2000 (approx. 1999 onwards) and then the XW's in 2010/ 11. Most Casios from 1990's onwards used some form of PCM (that might be what the "IXA" sound source was), then the MZ 2000 was released and used "ZPI Sound Source - (Zygotech Polynomial Interpolation) - no, I've no idea what that is either but it does sound good!

 

The XW's then went on further and used HPSS, a great step forward in terms of programmability and flexibility, and also still using PCM for some excellent sounds.

 

I wonder where Casio will head next? 

 

I see, thanks for the info! one thing of your response that has drawn my attention was the ZPI synthesis, and now I'm interested in searching info about it.

 

By other hand, when I asked about the PD after the 90's, I was thinking on a keyboard that I recently purchased, the casio CTK-500, can you watch this video until the end?:

 

 

The piano, the drums and some other presets are based on samples or a mix of waves (I think), but what about the rest? I'm don't know what to think, is some sort of cut-down PD, or I'm mistaken?

[Display Name]

 "ZPI Sound Source - (Zygotech Polynomial Interpolation) - no, I've no idea what that is either but it does sound good!

 

 

In simple terms, it is a way to compress, store, and recall large amounts of complex data. 

[CairnsFella]

In simple terms, it is a way to compress, store, and recall large amounts of complex data. 

 

Hmm.. interesting then, that it is an anagram of ZIP

[Jokeyman123]

I've been experimenting around playing and restoring an older PX575 which uses the ZPI technology-it sounds pretty darn amazing. Holds up well or better than some of my other "pro" stuff. The acoustic/electric pianos are certainly as usable as my PX350 and XW-P1. The drums/percussion sound very "clean" and even many of the orchestral sounds which are usually not so good even on more expensive instruments, are surprisingly realistic. Great lead sounds too, although the XWs are of course more felxible in real time control. The ZPI technology was also used in the WK3300, 3800 and a few others I've found out recently (I think Brad here has an MZ2000). 

[Brad Saucier]

Yes.  I have owned my MZ-2000 for 15 years.  Bought it new in 2000 from Musicians Friend catalog.  

[Display Name]

I've been experimenting around playing and restoring an older PX575 which uses the ZPI technology-it sounds pretty darn amazing. Holds up well or better than some of my other "pro" stuff. The acoustic/electric pianos are certainly as usable as my PX350 and XW-P1. The drums/percussion sound very "clean" and even many of the orchestral sounds which are usually not so good even on more expensive instruments, are surprisingly realistic. 

 

Realize that many (if not most (if not all (lol))) of the actual samples/sounds are  the same across many generations of keyboards. It's the way they are stored, accessed, and processed that is different. 

[Jensen_PD]

Hello again.

 

Now that I have a correct power supply to test the keyboard for a extended period of time, I can say this:

 

I have some doubts about this keyboard, but think that it uses looped and short samples for all the presets, because in some presets you can hear the loops and the aliasing as you approach the higher octaves.

 

By other hand, some other presets give me the impression that are like 2 or 4 OP FM, but it sounds a bit "grainy", and I don't know if it's due the DAC output or the bit depth / or hertz to which the samples were recorded.

 

I will update this post with some audio samples soon.

[Jokeyman123]

Being painfully familiar with FM technology (been playing SY77s for years and still do) and recalling my CZs-there were some similarities in end-product sounds although I found the PD Casio technology much easier to work with when programming. FM was designed by University of Stanford professors I seem to recall, and it works like it was designed by professors (no offense any professors out there)-but I find it much better going to the rock 'n roll doctor myself   Most of the sounds were not the same out of the box. I thought the CZs had a certain clarity an  identity that the FM sounds lacked. And it was much easier to get the sawtooth, square, sine, pulse modulation sounds working on the CZs than with FM at least for me. The one thing missing was the atypical "FM tine" electric piano sounds so typical of the Yamaha DX series. I could not approach that particular sound no matter how I programmed the CZs. Casio has come long way in capturing "bread and butter" sounds, plus some decent analog sounds and of course PCM sampled sounds. In case you did not know, the XW-P1 is filled with CZ sound wave samples. And yes, those are the real deal, the same I remember hearing with the CZ-1, CZ-3000 and the CZ-101.

[Jensen_PD]

Ok, I have recorded some short samples, and I've also recorded some demo's from the JUKEBOX.

 

By other hand, I want to clarify that "E2 - Strings 2.ogg" sounds like that; it's like a low rate sample with a filter, and it sounds like a sample from the CASIO SA series, wich by the way, some sounds of the latter sounds like some presets of the CZ series, LOL.

 

Then, the names of the files that start with "BANK (letter)" are the songs, the rest are quick tests using the presets of the same name.

 

 

https://www.dropbox.com/sh/surbuyha8i7koiy/AAA9WoziXl6gaNqkmHL-I4sca?dl=0

 

 

 

Also, I need help: I noticed that the samples of the bongos in the drumkit have a "click" in the attack, like when you cut the silence of the start of a track and you do it wrong, (and you hear that click) someone can say if this normal on a CTK-500?

 

EDIT: This is how it sounds: https://www.dropbox.com/s/jxk84i45pskt55w/Click%20noise%20in%20bongos.ogg?dl=0

[CYBERYOGI =CO=Windler]

The Casio jargon for sound synthesis engine is "sound source". The different engines have cryptic 2 or 3 letter abbreviations proudly mentioned in ads, but with exception of some professional synthesizers the deeper meaning and inner working was hidden from customers (not even told in service manuals). So many of these may be rather advertisement buzzwords than technologies, enshrouding that they were just minor variations of older sound engines. This list is likely inaccurate, because many old or low grade sound sources were not mentioned anywhere, so I only added them from own hardware examination. Also with modern models (large compressed samples) and pianos I am no expert. The IXA sound source (CTK-1000 from 1993) was the last engine with many classic synthesized sounds (now even with velocity and some editable parameters), although it already lacks the famous (SA-series) program loop synthesis preset sounds with complex algorithmic envelopes. After IXA Casio dropped the use of synthesized preset sounds in favour for long wavetable samples imitating natural instruments, which IMO makes newer keyboards mostly boring. With the HPSS sound source from 2013 (XW-G1 synth) fortunately a new versatile synth engine came out, which however does not fully include older (e.g. PD) synth algorithms. This list is sorted by technology rather than release date.

(I can not enter this as HTML table here, so it is a little messy.)


List of Casio sound sources:

sound source full name 1st use notes & features year

plain squarewave
? ML-80 monophonic squarewave (1:1, 100% tremolo) 1979
? ML-81 monophonic squarewave (1:1) with decay envelope 1980
multipulse squarewave
? VL-1 monophonic multipulse squarewave with switchable fixed filter. 1981
? PT-20 like VL-1 with obligato + chord/bass voice. 1982
? MT-11 2 layered bipolar multipulse squarewaves with switchable fixed filter. 1983(?)
? MT-200 bipolar multipulse squarewave with switchable fixed filter. 1984(?)
stairwave
CV Consonant-Vowel synthesis CT-201 2 mixed stairwaves with switchable fixed filter. CT-201 & 202 layer 2 such sound CPUs with each a filter. 1980
? VL-5 only 1 stairwave with switchable fixed filter (very different hardware). 1982(?)
? MT-65 programmable CV (sound IC with external CPU). 1983
? CT-6000 velocity sensitive CV variant (layering 3 sound ICs). 1984
SD Spectrum-Dynamics synthesis HT-series user programmable CV variant with VCF for synthesizers. 1987
additive synthesis
? 1000p additive synthesis (5 layered sinewaves, sounds drawbar-like). 1981
Phase Distortion (FM)
PD Phase Distortion CZ-series Casio's FM synthesis variant. 1984
iPD Interactive Phase Distortion VZ-series PD successor with programmable routing. 1988
speech synth
? TA-1000 data-reduced speech synthesis (LPC based?, PARCOR?) 1983(?)
sampler
? SK-series lofi sampler (SK-1 has also drawbar softsynth). 1986
? FZ-series 16 bit sampling synthesizer. 1987
? SK-60 lofi sampler on different PCM engine hardware. 1996
software based (wavetable + multiple synth algorithms)
PCM Pulse Code Modulation various,
e.g. SA-series Casio wavetable softsynth on a chip, including many other synth algorithms like FM variants or program loop synthesis. The generic term "PCM" was earlier used for anything sample based (e.g. Casio percussion ICs). 1988
CD Casio Digital ? MT-540 PCM engine version with external 16 bit sample ROM. 1988
Super CD ? CT-770(?) PCM engine version with velocity, effect DSP (external 16 bit sample ROM).
AP ? AP-7 PCM engine version with velocity, used in first Celviano piano. 1991
? VA-10 PCM engine version with effect DSP + Harmony Arranger. 1992
IXA Integrated Cross-Sound Architecture CTK-1000 PCM engine version with velocity, multisamples, effect DSP (external 16 bit sample ROM | last engine with many synthesized classic "PCM" sounds). 1993
A2 A² (A-square) wavetable with sample compression + effect DSP.
HL Highly compressed Large waveform A2 successor?
ZPI Zygotech Polynomial Interpolation MZ-2000 IXA successor(?) with special sample morphing. 2000
AHL Acoustic & Highly-compressed Large-waveform CTK-4000 HL successor with acoustic instrument multisamples. 2008
AIF Acoustic & Intelligent Filtering System Privia piano simulation 2009
AiR Acoustic and Intelligent Resonator Privia piano simulation 2013
HPSS Hybrid Processing Sound Source XW-G1 PCM engine successor for versatile synthesizer (partially hardware based). 2013

[silent]

On 5/9/2020 at 8:38 PM, CYBERYOGI =CO=Windler said:

The Casio jargon for sound synthesis engine is "sound source". The different engines have cryptic 2 or 3 letter abbreviations proudly mentioned in ads, but with exception of some professional synthesizers the deeper meaning and inner working was hidden from customers (not even told in service manuals). So many of these may be rather advertisement buzzwords than technologies, enshrouding that they were just minor variations of older sound engines. This list is likely inaccurate, because many old or low grade sound sources were not mentioned anywhere, so I only added them from own hardware examination. Also with modern models (large compressed samples) and pianos I am no expert. The IXA sound source (CTK-1000 from 1993) was the last engine with many classic synthesized sounds (now even with velocity and some editable parameters), although it already lacks the famous (SA-series) program loop synthesis preset sounds with complex algorithmic envelopes. After IXA Casio dropped the use of synthesized preset sounds in favour for long wavetable samples imitating natural instruments, which IMO makes newer keyboards mostly boring. With the HPSS sound source from 2013 (XW-G1 synth) fortunately a new versatile synth engine came out, which however does not fully include older (e.g. PD) synth algorithms. This list is sorted by technology rather than release date.

(I can not enter this as HTML table here, so it is a little messy.)


List of Casio sound sources:

sound source full name 1st use notes & features year

plain squarewave
? ML-80 monophonic squarewave (1:1, 100% tremolo) 1979
? ML-81 monophonic squarewave (1:1) with decay envelope 1980
multipulse squarewave
? VL-1 monophonic multipulse squarewave with switchable fixed filter. 1981
? PT-20 like VL-1 with obligato + chord/bass voice. 1982
? MT-11 2 layered bipolar multipulse squarewaves with switchable fixed filter. 1983(?)
? MT-200 bipolar multipulse squarewave with switchable fixed filter. 1984(?)
stairwave
CV Consonant-Vowel synthesis CT-201 2 mixed stairwaves with switchable fixed filter. CT-201 & 202 layer 2 such sound CPUs with each a filter. 1980
? VL-5 only 1 stairwave with switchable fixed filter (very different hardware). 1982(?)
? MT-65 programmable CV (sound IC with external CPU). 1983
? CT-6000 velocity sensitive CV variant (layering 3 sound ICs). 1984
SD Spectrum-Dynamics synthesis HT-series user programmable CV variant with VCF for synthesizers. 1987
additive synthesis
? 1000p additive synthesis (5 layered sinewaves, sounds drawbar-like). 1981
Phase Distortion (FM)
PD Phase Distortion CZ-series Casio's FM synthesis variant. 1984
iPD Interactive Phase Distortion VZ-series PD successor with programmable routing. 1988
speech synth
? TA-1000 data-reduced speech synthesis (LPC based?, PARCOR?) 1983(?)
sampler
? SK-series lofi sampler (SK-1 has also drawbar softsynth). 1986
? FZ-series 16 bit sampling synthesizer. 1987
? SK-60 lofi sampler on different PCM engine hardware. 1996
software based (wavetable + multiple synth algorithms)
PCM Pulse Code Modulation various,
e.g. SA-series Casio wavetable softsynth on a chip, including many other synth algorithms like FM variants or program loop synthesis. The generic term "PCM" was earlier used for anything sample based (e.g. Casio percussion ICs). 1988
CD Casio Digital ? MT-540 PCM engine version with external 16 bit sample ROM. 1988
Super CD ? CT-770(?) PCM engine version with velocity, effect DSP (external 16 bit sample ROM).
AP ? AP-7 PCM engine version with velocity, used in first Celviano piano. 1991
? VA-10 PCM engine version with effect DSP + Harmony Arranger. 1992
IXA Integrated Cross-Sound Architecture CTK-1000 PCM engine version with velocity, multisamples, effect DSP (external 16 bit sample ROM | last engine with many synthesized classic "PCM" sounds). 1993
A2 A² (A-square) wavetable with sample compression + effect DSP.
HL Highly compressed Large waveform A2 successor?
ZPI Zygotech Polynomial Interpolation MZ-2000 IXA successor(?) with special sample morphing. 2000
AHL Acoustic & Highly-compressed Large-waveform CTK-4000 HL successor with acoustic instrument multisamples. 2008
AIF Acoustic & Intelligent Filtering System Privia piano simulation 2009
AiR Acoustic and Intelligent Resonator Privia piano simulation 2013
HPSS Hybrid Processing Sound Source XW-G1 PCM engine successor for versatile synthesizer (partially hardware based). 2013

in my experience with the WK-1800, the A2 sound source can sound widely different across keyboards, with different models using different methods of "smoothing" the stepped output of the DAC. the WK-1800 uses an LPF, whereas one of the oldest models known to use the same DSP chip (which is what is used to generate the digital audio data) used a full spectrum filter if I read the SM correctly

 

It also seems like some A2 synths might be using some kind of acoustic modeling or other behaviours.

[silent]

On 10/11/2022 at 4:34 PM, IrreverentHippie said:

in my experience with the WK-1800, the A2 sound source can sound widely different across keyboards, with different models using different methods of "smoothing" the stepped output of the DAC. the WK-1800 uses an LPF, whereas one of the oldest models known to use the same DSP chip (which is what is used to generate the digital audio data) used a full spectrum filter if I read the SM correctly

 

It also seems like some A2 synths might be using some kind of acoustic modeling or other behaviors.

the reason the WK-1800 sounds the way it does is because of how it works. DSP outputs digital sound data, DAC converts the data into two analog wavforms for left and right chanels (as directed by the DSP), Filtering IC smooths the waveform to try and get rid of aliasing artifacts. However the WK-1800s filter is so good at smoothing that it will take the corners off of a square wave.

 

the regulator IC on the WK-1800 uses a triangle wave oscilator too.

 

all outputted sound goes through the power AMP

 

[silent]

On 5/9/2020 at 8:38 PM, CYBERYOGI =CO=Windler said:

The Casio jargon for sound synthesis engine is "sound source". The different engines have cryptic 2 or 3 letter abbreviations proudly mentioned in ads, but with exception of some professional synthesizers the deeper meaning and inner working was hidden from customers (not even told in service manuals). So many of these may be rather advertisement buzzwords than technologies, enshrouding that they were just minor variations of older sound engines. This list is likely inaccurate, because many old or low grade sound sources were not mentioned anywhere, so I only added them from own hardware examination. Also with modern models (large compressed samples) and pianos I am no expert. The IXA sound source (CTK-1000 from 1993) was the last engine with many classic synthesized sounds (now even with velocity and some editable parameters), although it already lacks the famous (SA-series) program loop synthesis preset sounds with complex algorithmic envelopes. After IXA Casio dropped the use of synthesized preset sounds in favour for long wavetable samples imitating natural instruments, which IMO makes newer keyboards mostly boring. With the HPSS sound source from 2013 (XW-G1 synth) fortunately a new versatile synth engine came out, which however does not fully include older (e.g. PD) synth algorithms. This list is sorted by technology rather than release date.

(I can not enter this as HTML table here, so it is a little messy.)


List of Casio sound sources:

sound source full name 1st use notes & features year

plain squarewave
? ML-80 monophonic squarewave (1:1, 100% tremolo) 1979
? ML-81 monophonic squarewave (1:1) with decay envelope 1980
multipulse squarewave
? VL-1 monophonic multipulse squarewave with switchable fixed filter. 1981
? PT-20 like VL-1 with obligato + chord/bass voice. 1982
? MT-11 2 layered bipolar multipulse squarewaves with switchable fixed filter. 1983(?)
? MT-200 bipolar multipulse squarewave with switchable fixed filter. 1984(?)
stairwave
CV Consonant-Vowel synthesis CT-201 2 mixed stairwaves with switchable fixed filter. CT-201 & 202 layer 2 such sound CPUs with each a filter. 1980
? VL-5 only 1 stairwave with switchable fixed filter (very different hardware). 1982(?)
? MT-65 programmable CV (sound IC with external CPU). 1983
? CT-6000 velocity sensitive CV variant (layering 3 sound ICs). 1984
SD Spectrum-Dynamics synthesis HT-series user programmable CV variant with VCF for synthesizers. 1987
additive synthesis
? 1000p additive synthesis (5 layered sinewaves, sounds drawbar-like). 1981
Phase Distortion (FM)
PD Phase Distortion CZ-series Casio's FM synthesis variant. 1984
iPD Interactive Phase Distortion VZ-series PD successor with programmable routing. 1988
speech synth
? TA-1000 data-reduced speech synthesis (LPC based?, PARCOR?) 1983(?)
sampler
? SK-series lofi sampler (SK-1 has also drawbar softsynth). 1986
? FZ-series 16 bit sampling synthesizer. 1987
? SK-60 lofi sampler on different PCM engine hardware. 1996
software based (wavetable + multiple synth algorithms)
PCM Pulse Code Modulation various,
e.g. SA-series Casio wavetable softsynth on a chip, including many other synth algorithms like FM variants or program loop synthesis. The generic term "PCM" was earlier used for anything sample based (e.g. Casio percussion ICs). 1988
CD Casio Digital ? MT-540 PCM engine version with external 16 bit sample ROM. 1988
Super CD ? CT-770(?) PCM engine version with velocity, effect DSP (external 16 bit sample ROM).
AP ? AP-7 PCM engine version with velocity, used in first Celviano piano. 1991
? VA-10 PCM engine version with effect DSP + Harmony Arranger. 1992
IXA Integrated Cross-Sound Architecture CTK-1000 PCM engine version with velocity, multisamples, effect DSP (external 16 bit sample ROM | last engine with many synthesized classic "PCM" sounds). 1993
A2 A² (A-square) wavetable with sample compression + effect DSP.
HL Highly compressed Large waveform A2 successor?
ZPI Zygotech Polynomial Interpolation MZ-2000 IXA successor(?) with special sample morphing. 2000
AHL Acoustic & Highly-compressed Large-waveform CTK-4000 HL successor with acoustic instrument multisamples. 2008
AIF Acoustic & Intelligent Filtering System Privia piano simulation 2009
AiR Acoustic and Intelligent Resonator Privia piano simulation 2013
HPSS Hybrid Processing Sound Source XW-G1 PCM engine successor for versatile synthesizer (partially hardware based). 2013

now there's AiX, and Vocal Synthesis (which the CTS-1000V uses)

AiX allows the synth to store lots of different sound data, and apply different effects to each track

Vocal Synthesis uses ai and PCM samples to simulate the human voice box

[Just Alex]

Well what I can say about AIX, as I've fiddled a bit into firmware of CT-X5000, there is no "DSP" or anything hardware at all, all these "sources" and "DSP" -s are done purely in software, and keyboard runs some kind of RTOS.

 

[Chas]

DSP = Digital Signal Processing. All DSP is software/ algorithm based. Whether it is accessed via a menu in a synth, via a VST/ plugin in a DAW, or even via a standalone box (i.e. many digital guitar effects pedals), it's still digital processing of an audio signal via software.

Edited November 27, 2022 by Chas

[Jokeyman123]

Just Alex, I am impressed with your knowledge of firmware and coding you are ahead of me there. Thus i am going to pose a problem to you but since it is not directly related to a Casio product, I will PM you about it. Thought I'd post here so you would notice. I'll get it out later today. it is a perplexing issue re firmware for a drum machine which if you can help me solve, will make alot of musicians very happy. I'll detail in my PM.

[CYBERYOGI =CO=Windler]

The term "DSP" is relative. Some may use it as a generic term for postprocessing effects within softsynths. Even very poor sounding Bontempi 1980th toy grade lofi keyboards were advertised to have a "digital signal processor".

 

By the way, I found the likely world first single-chip softsynth. It is the "Sound FX Phasor" by the unknown British company Electroplay made in 1980 (1 year before Casio VL-1!) - a soundtoy in the shape of a handheld barcode scanner computer, which foil touchpad has only 16 buttons (15 act as "white" keys, no sharps), and the synthesizer is running on a tiny PIC microcontroller with only 768 byte ROM + 32 byte RAM.

 

Beside 8 preset effect noises it has a keyboard mode with synthesizer, featuring suboscillators with multipulse squarewave and freakish siren-like howling modulations. The monophonic sounds are even more complex than VL-1. Particularly it can do sonorous organ-like bass notes and crunchy motor noises with simple decay envelope and also strange semi-metallic gongs and clangs. The grainy lo-fi sound engine employs program loop synthesis in the style of Williams early electronic pinball machines. But unlike VL-1 it is more centered on less melodic howling effects, and often resembles random glitch stuff with strange techno sound loops those can include crackle, buzz and rough pulsing or bleeping noises, so it can be somewhat compared with POKEY (the famous Atari 8-bit soundchip). But the relation is more like that of Phase Distortion to FM - despite similar principles, the character of the timbres and its parameters can substantially differ and make of it a unique sound source.

 

The Sound FX Phasor was way ahead of its time. This is the same type of British low-cost miracle like the first Sinclair homecomputers. It could have been a game changer; under different circumstances UK instead of Japan would have created the VL-Tone. But the user interface is awful. There is no sequencer, synth patches can not be saved and most obnoxious is that auto-power-off deletes the created patch (up to 31 key presses) after 46 seconds of idle. The single page manual does even try to explain the synth parameters (6 letter buttons, each 0..255?), and the software seems full of bugs those cause semi-random behaviour. Fortunately I managed to dump the rom code and make schematics to reverse-engineer this amazing technical marvel. Likely it can be emulated, and perhaps I will write a better softsynth of the algorithm to turn it into a well playable instrument.

 

Edited November 29, 2022 by CYBERYOGI =CO=Windler

[silent]

On 11/27/2022 at 7:35 AM, Just Alex said:

Well what I can say about AIX, as I've fiddled a bit into firmware of CT-X5000, there is no "DSP" or anything hardware at all, all these "sources" and "DSP" -s are done purely in software, and keyboard runs some kind of RTOS.

 

 

On 11/27/2022 at 12:31 PM, Chas said:

DSP = Digital Signal Processing. All DSP is software/ algorithm based. Whether it is accessed via a menu in a synth, via a VST/ plugin in a DAW, or even via a standalone box (i.e. many digital guitar effects pedals), it's still digital processing of an audio signal via software.

The WK-1800's DSP post effects are done using RAM directly attached to the hardware DSP chip that handles the sound generation work. so doing it in software or a hybrid method is not new.

[silent]

On 5/9/2020 at 8:38 PM, CYBERYOGI =CO=Windler said:

The Casio jargon for sound synthesis engine is "sound source". The different engines have cryptic 2 or 3 letter abbreviations proudly mentioned in ads, but with exception of some professional synthesizers the deeper meaning and inner working was hidden from customers (not even told in service manuals). So many of these may be rather advertisement buzzwords than technologies, enshrouding that they were just minor variations of older sound engines. This list is likely inaccurate, because many old or low grade sound sources were not mentioned anywhere, so I only added them from own hardware examination. Also with modern models (large compressed samples) and pianos I am no expert. The IXA sound source (CTK-1000 from 1993) was the last engine with many classic synthesized sounds (now even with velocity and some editable parameters), although it already lacks the famous (SA-series) program loop synthesis preset sounds with complex algorithmic envelopes. After IXA Casio dropped the use of synthesized preset sounds in favour for long wavetable samples imitating natural instruments, which IMO makes newer keyboards mostly boring. With the HPSS sound source from 2013 (XW-G1 synth) fortunately a new versatile synth engine came out, which however does not fully include older (e.g. PD) synth algorithms. This list is sorted by technology rather than release date.

(I can not enter this as HTML table here, so it is a little messy.)


List of Casio sound sources:

sound source full name 1st use notes & features year

plain squarewave
? ML-80 monophonic squarewave (1:1, 100% tremolo) 1979
? ML-81 monophonic squarewave (1:1) with decay envelope 1980
multipulse squarewave
? VL-1 monophonic multipulse squarewave with switchable fixed filter. 1981
? PT-20 like VL-1 with obligato + chord/bass voice. 1982
? MT-11 2 layered bipolar multipulse squarewaves with switchable fixed filter. 1983(?)
? MT-200 bipolar multipulse squarewave with switchable fixed filter. 1984(?)
stairwave
CV Consonant-Vowel synthesis CT-201 2 mixed stairwaves with switchable fixed filter. CT-201 & 202 layer 2 such sound CPUs with each a filter. 1980
? VL-5 only 1 stairwave with switchable fixed filter (very different hardware). 1982(?)
? MT-65 programmable CV (sound IC with external CPU). 1983
? CT-6000 velocity sensitive CV variant (layering 3 sound ICs). 1984
SD Spectrum-Dynamics synthesis HT-series user programmable CV variant with VCF for synthesizers. 1987
additive synthesis
? 1000p additive synthesis (5 layered sinewaves, sounds drawbar-like). 1981
Phase Distortion (FM)
PD Phase Distortion CZ-series Casio's FM synthesis variant. 1984
iPD Interactive Phase Distortion VZ-series PD successor with programmable routing. 1988
speech synth
? TA-1000 data-reduced speech synthesis (LPC based?, PARCOR?) 1983(?)
sampler
? SK-series lofi sampler (SK-1 has also drawbar softsynth). 1986
? FZ-series 16 bit sampling synthesizer. 1987
? SK-60 lofi sampler on different PCM engine hardware. 1996
software based (wavetable + multiple synth algorithms)
PCM Pulse Code Modulation various,
e.g. SA-series Casio wavetable softsynth on a chip, including many other synth algorithms like FM variants or program loop synthesis. The generic term "PCM" was earlier used for anything sample based (e.g. Casio percussion ICs). 1988
CD Casio Digital ? MT-540 PCM engine version with external 16 bit sample ROM. 1988
Super CD ? CT-770(?) PCM engine version with velocity, effect DSP (external 16 bit sample ROM).
AP ? AP-7 PCM engine version with velocity, used in first Celviano piano. 1991
? VA-10 PCM engine version with effect DSP + Harmony Arranger. 1992
IXA Integrated Cross-Sound Architecture CTK-1000 PCM engine version with velocity, multisamples, effect DSP (external 16 bit sample ROM | last engine with many synthesized classic "PCM" sounds). 1993
A2 A² (A-square) wavetable with sample compression + effect DSP.
HL Highly compressed Large waveform A2 successor?
ZPI Zygotech Polynomial Interpolation MZ-2000 IXA successor(?) with special sample morphing. 2000
AHL Acoustic & Highly-compressed Large-waveform CTK-4000 HL successor with acoustic instrument multisamples. 2008
AIF Acoustic & Intelligent Filtering System Privia piano simulation 2009
AiR Acoustic and Intelligent Resonator Privia piano simulation 2013
HPSS Hybrid Processing Sound Source XW-G1 PCM engine successor for versatile synthesizer (partially hardware based). 2013

They are all Waveshapers or Distortion Synths. or they are using a hybrid method of some sort, with some PCM being played directly and others being used as controls for a wave-shaping synth engine.

[silent]

On 11/27/2022 at 7:35 AM, Just Alex said:

Well what I can say about AIX, as I've fiddled a bit into firmware of CT-X5000, there is no "DSP" or anything hardware at all, all these "sources" and "DSP" -s are done purely in software, and keyboard runs some kind of RTOS.

 

Would you be able to do the same with the WK-1800 and MZ-2000 and report back what you find? I am particularlay intrested in the WK-1800's Square wave preset

My current therory is digital Waveshaper with soft clipping and some PCM/Wavetable elements

 

[silent]

23 minutes ago, IrreverentHippie said:

Would you be able to do the same with the WK-1800 and MZ-2000 and report back what you find? I am particularlay intrested in the WK-1800's Square wave preset

My current therory is digital Waveshaper with soft clipping and some PCM/Wavetable elements

 

If they are waveshapers, PCM/Wavetable data and Polynomial interpolation would be used in the transfer function

[Just Alex]

Is firmware for that keyboard downlaodable?