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Repost: decripting the "Sustain 2" feature
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omissis



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PostPosted: Mon Mar 15, 2010 5:06 pm    Post subject: Repost: decripting the "Sustain 2" feature
Subject description: Can anybody help me?
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Hello
First of all I'm begging your pardon if I post the same question here despite that I already tried into the DIY section, but I couldn't find any real contribution, so I hope that you would give me some clues about the below mentioned feature.

I'm working on a model of Yamaha CS80's assigner, called "K.AS.": actually the assigner itself is done, along with the pitch and gate generators.
Now I'm focusing on the Sustain feature: in particular I'm struggling to get the work of Sustain II feature: for short, when you play a note or a chord and release it, the note coming next kills the release phase of the previous notes.

The pitch part has been somehow easy once you get how the note code is produced, that is monophonically, what I don't understand is related with the gate on/off for the envelopes: if I simulate it I get the change of notes but, at the same time, I still hear the release of the previously called voices going, while the gate of the actually pressed key should kill previous releases.
Does this have anything concerning with the voice cycle itself or something else?
Can anybody help me?

Thanks for your support!

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Blue Hell
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PostPosted: Mon Mar 15, 2010 5:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

Right .. I didn't see this one Laughing ... please don't double post Max, next time just put up a link please, discussions in multiple places are no good for the forum. So ... what I'm going to do is ... close up that one ... and put a link to here from there ...
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Ricko



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PostPosted: Mon Mar 15, 2010 7:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

For Sustain II, I think there is no change to the release compared to Sustain I. The release is not killed by new notes. The tail of the previous note is allowed to release normally, however the pitch of the previous not goes to the new pitch.

So this gives two audible effects:

1) A single note cancels any old notes or chords. Very clean.
2) There is an enhanced chorus or unison on the new note for the duration of the remaining releases. Playing the same note multiple times fast increases this unison.

The simplest thing to do is just provide 1) but not 2): this is what I did on CS-80R. An incoming gate sets the Release to 0 for a small pulse.
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omissis



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PostPosted: Tue Mar 16, 2010 4:40 am    Post subject: Reply with quote  Mark this post and the followings unread

@BlueHell
You're right, I apologize for double posting because I acted impulsively, won't forget that next time.

@Rick
Hi, good to read from you, to be true I was wishing for your help...now here's what I've built until now:

Pitch: same exact structure as a CS-80 (mono encoding routed to SH memories)

Gate: Note on/off inverted scheme ("true"= 0) whose sequence is routed accordingly to a "Least Recently Used" chart, straight to the envelopes and to the gate control for the SHs.

Sustain II: injecting an additional "0" to the NAND before the SH to open the gate irrespectively of the notes on/off

This is what the diagrams of the CS-80 tell to me, on the other hand you seem to confirm that the structure has been built the right way ; my doubts start since a friend owning the CS-80 reported to me also that the notes are completely replaced which, diagram-wise, looks not (the Sustain slider is no more than a global control for release phases)...So what? Does the effect on the CS-80R act as an additional feature?

Thx again for your support!

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Ricko



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PostPosted: Tue Mar 16, 2010 7:23 am    Post subject: Reply with quote  Mark this post and the followings unread

The CS-60 has much the same KAS from what the schematics say, so I can certainly confirm from my old experience that it can sound like voices are just cut off, with a short release. But putting on a long release with sus II and the effect is clearer, I think: it avoids that big difference between the rich chord and weedy single notes.

Even on sustain I, the KAS uses a round robin on note allocation. For example, if you do a rapid trill with a long sustain, you will get all the voices sounding, half on one note and half on the other. (It doesn't do anything smart in reusing an old note, like a Most Recently Used system or other memory, IIRC.)

I am not sure that the input to the NAND and the S&H labelled Sus is the Sustain II switch and not the sustain pedal, btw. I have not looked over the diagrams enough to be sure one way or another.
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omissis



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PostPosted: Tue Mar 16, 2010 4:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Rick
Ricko wrote:
The CS-60 has much the same KAS from what the schematics say, so I can certainly confirm from my old experience that it can sound like voices are just cut off, with a short release. But putting on a long release with sus II and the effect is clearer, I think: it avoids that big difference between the rich chord and weedy single notes.

Even on sustain I, the KAS uses a round robin on note allocation. For example, if you do a rapid trill with a long sustain, you will get all the voices sounding, half on one note and half on the other. (It doesn't do anything smart in reusing an old note, like a Most Recently Used system or other memory, IIRC.)

I am not sure that the input to the NAND and the S&H labelled Sus is the Sustain II switch and not the sustain pedal, btw. I have not looked over the diagrams enough to be sure one way or another.


Thx again a whole lot for your explainations.
I can then conclude that my translation is correct, for what's concerning the works of Sustain effect.

Just a very last question: do you know if stealing the pitch can happen , when in Sustain 1, on a sustaining note (that is, in release state)? Or, better, if I play a chord so I can run out of all the avaliable voices and release the mentioned chord, can a new note play and steal one of the previously used notes as it appears in the LRU chart?

About the Sustain, you know, it is created by the NAND acting on the SH which is, as you know, the primeval device to keep a note code when the encoder gave out a monophonic sequence; the SH works like a channel with two floodgates: the first gets the note code to sample it, the second is triggered by the gate through which the sampled code goes to the VCO; to get Sustain II means to keep the first gate always open...

Thanks for this last help!

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Ricko



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PostPosted: Tue Mar 16, 2010 7:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yes, it certainly does allow note stealing.

Whether it is LRU or a round robin on the unallocated voices in fixed order I cannot say.

Certainly when you play a low chord with all voices, then put large portamento on, then play a high note many times, you can hear each voice get selected (and ramp up to the new note) in turn, IIRC.
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omissis



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PostPosted: Wed Mar 17, 2010 5:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Rick

This sets clearly things off: now I understood completely the process and, all in all, it confirms that the reading of the diagram was done good.
Thx really, I'll be back with the new "creature" soon....

Cheerz!!! Hail the Master

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PostPosted: Wed Mar 17, 2010 6:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

Is it hardware or software?

For other readers: Max and I have long been involved in trying to work out what makes the CS-* synths so nice, he from the CS-80 perspective and me from the CS-60 perspective.

Most people would know about the excellent Arturia VST emulation but some consider it patchy or expensive. So Max has been involved in the Memorymoon ME-80 VST (http://memorymoon.com/me80.htm) and I have my own CS-80R VST you can find on the web.

The thing is that apart from the basic configuration of oscillators and filters, there are literally dozens of important differences from conventional synths: different voice allocation, different envelopes, different PWM behaviour, different filter arrangement and response, special ring modulator, poly glide and portamento, plus extreme use of velocity, aftertouch and ribbon, and so on. (Even before getting into the ranges of knobs, layout or component-level characteristics.)

The three CS-80 emulations all approach things from different angles: I think my ring mod is closer than Arturia's, while their chorus is warmer, and the ME-80 envelope response on the filter is better than mine, etc.

But people ultimately buy easy-to-access sounds: presets not raw capabilities.
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PostPosted: Thu Mar 18, 2010 3:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Thx Rick, let me say I'm flattered by your message.... Embarassed


At the moment me and Patrice , another friend who's doing the coding, were working on a Synthedit-free experimental CS, as a testbed that demonstrates the KAS as an architecture that can be implemented.

I'd rather say I freely collaborate with people who want to make a good design of those older machines, just for the fun of it.

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