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Talk:Casio SD Synthesizers

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Wrong claims about SD synthesis

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I am operator about a large website about music keyboard collection and [circuit bending] and have examined the sound hardware of many classic Casio keyboards quite thoroughly. I own a Hohner KS-49 midi (white variant of Casio HT-700 with different preset sound set) and a Casio HT-6000. In the article are several errors about SD synthesis.

The HT-700 was a hybrid of the HZ-600 and the MT-600 (hence the prefix HT).

Nope. The HT-700 was a separate development and the MT-600 was simply a cheaper version of it, based on the same ICs with only some omitted controls to cut down cost. Likely the MT-600 can be even upgraded to an almost complete HT-700 by only adding the missing potentiometers and button switches. (However without the LCD it would be hard to use.)

Here is my KS-49 page: http://Weltenschule.de/TableHooters/Hohner_KS49midi.html

The DCO has preprogrammed control of the individual harmonics within the waveform, and some of (but not all of) the available waveforms are "moving", meaning that the amplitudes of the various harmonics are designed to change as the DCA envelope progresses. For example, one waveform has an octave-unison effect where the higher harmonics fade in over time. This predefined temporal motion of the harmonic spectrum yields the term "Spectrum Dynamic." The user has very limited influence over the spectrum dynamic using the DCA envelope, but doing so is a trial-and-error process, and remains somewhat of an undocumented mystery (it seems that Casio was deliberately vague about the workings of SD, and the extent to which it actually affected the overall waveform, to protect against another lawsuit like the Yamaha lawsuit against Casio's phase-distortion synthesis).

Nope, Casio likely kept it secret to enshroud how technically outdated the SD techology genuinely was. That is to say, it was basically just identical(!) with their "Consonant Vowel Synthesis" used in already the very first Casio keyboard Casiotone 201 from 1980. In this synthesis engine each voice consists simply of 2 layered multipulse squarewave timbres with independant digital volume envelopes, those are routed through a switchable fixed analogue filter. (See WarantyVoid FAQ about multipulse squarewave - unlike plain squarewave, the waveforms are bit loops those can have multiple up- and down- sections, however the step heigth stays the same - much like with the Atari POKEY chip and Atari VCS2600 sounds).

The whole secret of SD synthesis is that each so-called "waveform" genuinely consists of 2 layered subvoices those each already contain a fixed preset volume envelope. At least on my KS-49 the waveform of each subvoice is a multipulse squarewave. (The HT-6000 may include additional waveforms - I haven't examined it closer yet.) The reason why SD synths lack a low bass range is because it would have revealed the atificial sounding buzziness of squarewave based timbres, which Casio likely wanted to keep secret. However by modification of the tuning trimmer circuit (clock fequency divider) it is likely possible to tune the instrument down by several octaves. I will likely add this upgrade to my HT-6000 later - multipulse squarewave bass drones lovely and is very nice for tekkno.

Also see:

"Very warm retro sound"

Wrong! At least the chorus effect of my Hohner KS-49 midi (like Casio HT-700) belongs to the coldest and thinnest digital sounding specimen of its kind. My similar sized Casio MT-520 sounds tremendously much warmer despite it is based on the same technology. However my Casio HT-6000 (haven't tried much with it yet) indeed seems to have some warmer timbres.

This is my keyboard site:


I have corrected most of the errors in the article now. (=CO=Windler,89.50.255.42 16:39, 4 August 2007 (UTC))[reply]

Re the above

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A line you previously inserted speculated SD synthesis was based on something you call "multipulse squarewaves". Yet the only references I can find to this term are all from your webpage. Can you explain what it's supposed to mean? I suspect something was lost in translation... Probably just meant multiple pulse waves mixed together. In contrast, your unusual term implies a sort of pulse wave with sections of different widths. Just wondering. Anyway, it would not be useful to include that term in the article when it is not conventional or easy for readers to understand. — Preceding unsigned comment added by 194.74.217.242 (talk) 15:45, 15 October 2014 (UTC)[reply]

Sorry, just noticed your FAQ about this that is linked above. Interesting info. Still if including unofficial and less obvious terms like that in general documentation, it'd be best to explain what it means. Thanks! - Also, if duty cycle is anything other than 50% symmetrical, they are not square waves. So "multipulse squarewave" makes no sense. :-P Dropping the "square" would be OK. — Preceding unsigned comment added by 194.74.217.242 (talk) 11:20, 22 October 2014 (UTC)[reply]

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CT-630 needs to be added

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The Casio CT-630 is the full size version of the MT-600, with the same presets. It has a split function instead of pitch bend, full access to the lower tones, MIDI thru, sustain, and more drum sounds. Not to be confused with the CTK-630 or CT-360. 2600:6C4A:407F:8EE2:C922:7319:E874:719F (talk) 19:50, 1 February 2023 (UTC)[reply]

I'm working on adding the CT-630 info. I love these keyboards! Jackispax (talk) 02:49, 22 February 2023 (UTC)[reply]

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