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#1388755 - 03/05/10 10:30 AM Re: Yamaha GH(E) versus GHS key action [Re: hpeterh]  
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That's a very good point. Assuming I am right that it is sensing the key release continuously (or quasi-continously, more likely), then wouldn't it be great if this information was available as MIDI! (assuming we had something to interpret it)

I do not think it is simply measuring the release velocity, because, as I said, I could hold the key at intermediate positions, and the decay rate was different for each position.

Maybe I was listening through extremely rose-coloured headphones. I'll go back and have another go.

Greg.


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#1388768 - 03/05/10 10:44 AM Re: Yamaha GH(E) versus GHS key action [Re: sullivang]  
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Just thinking about sending ONLY note-ons, I have a suspicion that it's probably still best to send the note-offs, for timing reasons. In the Disklavier case, the poor piano is being asked to INTANTANEOUSLY release the key and do another strike, which is a bit absurd. (in fact, at the end of the recording, it seems that the Disklavier simply stretched the timing out so that it could play each note)

I wonder whether the Disklavier SENDS only note-ons when it is doing rapid repeats, without the damper?

Greg.


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#1388831 - 03/05/10 12:01 PM Re: Yamaha GH(E) versus GHS key action [Re: sullivang]  
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Originally Posted by sullivang
That's a very good point. Assuming I am right that it is sensing the key release continuously (or quasi-continously, more likely), then wouldn't it be great if this information was available as MIDI! (assuming we had something to interpret it)

I don't think MIDI has enough bandwidth to handle 88 continuous controllers without objectionable delay. You can't do much with a 31.25kHz Baud rate (at best <2k messages per second).

Originally Posted by sullivang
I do not think it is simply measuring the release velocity, because, as I said, I could hold the key at intermediate positions, and the decay rate was different for each position.

Very interesting. Scanning 88 controllers isn't that big of a deal, but I would imagine using that conductive plastic as a variable controller rather than a switch would lower the reliability of the action. You would need a different and higher bandwidth communication channel between the keys and the sound generator too, something that would introduce a fair amount of complexity for such a subtle effect in a low-end DP. With MIDI in already there in the sound section, and MIDI out already there in the keyboard section, simply connecting them together is the natural and easy thing to do.

On second thought, if they were smart about how they sent MIDI from the keyboard, e.g. prioritize the types of messages sent such as note on if available, and continuous messages otherwise, and drop any continuous messages if they are queued up for too long, perhaps MIDI could work internally. And they could use some kind of single byte shorthand MIDI to gain more bandwidth.

#1388838 - 03/05/10 12:15 PM Re: Yamaha GH(E) versus GHS key action [Re: dewster]  
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Originally Posted by dewster
Scanning 88 controllers isn't that big of a deal, but I would imagine using that conductive plastic as a variable controller rather than a switch would lower the reliability of the action.


It is normally done this way:
All contacts are arranged in a matrix together with diodes.
If you have e.g. 64 contacts to scan, the matrix would be 8 x 8 and you need 16 digital IO Ports to scan 64 contacts.

A relatively small processor can do this.

But you cannot arrange 64 continuous resistors in a matrix.
Just consider how expensive a keyboard with polyphonic aftertouch is....

This cannot be done inexpensively, thats what I believe.

Also the CASIO's are targeted for a market that doesnt demand such a feature.

For example nonpolyphonic channel aftertouch for high-end clavinovas is demanded frequently by users. Yamaha doesnt think about implementing this feature ;-) And this would be relatively cheap to implement.

Peter


Last edited by hpeterh; 03/05/10 12:30 PM.

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#1388874 - 03/05/10 12:58 PM Re: Yamaha GH(E) versus GHS key action [Re: sullivang]  
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Originally Posted by sullivang

I wonder whether the Disklavier SENDS only note-ons when it is doing rapid repeats, without the damper?


For the high end Clavinovas Yamaha supports an extended MIDI Standard. This standard supports higher than 7 Bit resolution for velocity and might have other features that are unknown to me.

I dont know how they do it with the disklavier, but it is well possible that they use extended methods that are not subject of discussion here.

Peter


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#1388876 - 03/05/10 01:02 PM Re: Yamaha GH(E) versus GHS key action [Re: hpeterh]  
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Regarding MIDI bandwidth, USB does not have the 31.25kbaud limitation. ;^)

I agree that it seems unlikely that continous release sensing would be implemented, especially on a low cost Casio. Working against my assertion is that it only has one intermediate step for the sustain pedal (half depression). If they had gone to all the trouble of implementing continuous release for the keys, they surely would have done this for the sustain pedal as well.
So, at best I expect to find one intermediate decay rate for a partially released key, when I re-test it.

Getting back to the Yamaha action, I'm just reading about the real grand repetition mechanism. Apparently a note can be repeated when the key has been released approximately 50%, which matches the GH/GH3 measurement we have obtained nicely, EXCEPT of course that on a real grand, the damper does not contact the strings at that 50% release point. On the GH/GH3, we're observing a termination of the note at the 50% point. I'm puzzled.

Greg.
p.s Peter - sorry if I seemed to be talking down to you about the definition of a "sensor". I thought you were trying to say that every sensor, no matter the context, has only two states - on and off. After re-reading your post, I see that you were simply saying that the key sensors on a typical digital piano are simple on/off contacts.

Last edited by sullivang; 03/05/10 01:10 PM.

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#1388894 - 03/05/10 01:22 PM Re: Yamaha GH(E) versus GHS key action [Re: sullivang]  
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My english is not very good.
I can read everything and understand even complicated stuff.
But I have difficulties to find the right terms to explain complicated stuff.
I use english for books and online only, have no other opportunities.

best,

Peter


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#1388898 - 03/05/10 01:30 PM Re: Yamaha GH(E) versus GHS key action [Re: hpeterh]  
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Originally Posted by hpeterh
It is normally done this way:
All contacts are arranged in a matrix together with diodes.
If you have e.g. 64 contacts to scan, the matrix would be 8 x 8 and you need 16 digital IO Ports to scan 64 contacts.

A relatively small processor can do this.

Indeed, this was fairly trivial decades ago.

Originally Posted by hpeterh
But you cannot arrange 64 continuous resistors in a matrix.
Just consider how expensive a keyboard with polyphonic aftertouch is....

You can similarly arrange the variable resistors in banks, and provide bias to those banks via one diode per bank. Then use a multi-channel A/D (with as many channels as there are resistors in a bank). The multi-channel A/Ds are usually a single A/D time multiplexed with an N-to-1 analog switch. For isolation at the A/D input, each resistor would need an output diode, and this diode drop would need to be accounted for in either pre or post A/D conversion.

Originally Posted by hpeterh
Also the CASIO's are targeted for a market that doesnt demand such a feature.

I fully agree with that.

Originally Posted by hpeterh
For example nonpolyphonic channel aftertouch for high-end clavinovas is demanded frequently by users. Yamaha doesnt think about implementing this feature ;-) And this would be relatively cheap to implement.

For the life of me, I don't understand how various critical decisions are made by keyboard manufacturers, particularly when it comes to leaving features off that people would really like. Perhaps it involve chicken entrails? They are watching every manufacturing penny like a hawk, which I guess is what for-profit entities should do, but still. There's something to be said for going out of your way to please customers.

#1388901 - 03/05/10 01:32 PM Re: Yamaha GH(E) versus GHS key action [Re: hpeterh]  
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Originally Posted by hpeterh
My english is not very good.
I can read everything and understand even complicated stuff.
But I have difficulties to find the right terms to explain complicated stuff.

Dude, you're english is better than that of many Americans I know smile

#1388907 - 03/05/10 01:40 PM Re: Yamaha GH(E) versus GHS key action [Re: sullivang]  
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Originally Posted by sullivang
Regarding MIDI bandwidth, USB does not have the 31.25kbaud limitation. ;^)

True, but a single channel of MIDI over USB probably does, as USB enforces quality of service.

Originally Posted by sullivang
I agree that it seems unlikely that continous release sensing would be implemented, especially on a low cost Casio. Working against my assertion is that it only has one intermediate step for the sustain pedal (half depression). If they had gone to all the trouble of implementing continuous release for the keys, they surely would have done this for the sustain pedal as well.
So, at best I expect to find one intermediate decay rate for a partially released key, when I re-test it.

Yes, I agree. I think if they are doing anything (not that I distrust you or your report in any way) they are perhaps somehow exploiting the second contact normally employed for quick repeat notes.

Originally Posted by sullivang
Getting back to the Yamaha action, I'm just reading about the real grand repetition mechanism. Apparently a note can be repeated when the key has been released approximately 50%, which matches the GH/GH3 measurement we have obtained nicely, EXCEPT of course that on a real grand, the damper does not contact the strings at that 50% release point. On the GH/GH3, we're observing a termination of the note at the 50% point. I'm puzzled.

That should be fixed, shouldn't it? I wonder how much the universal coopting of MIDI note-on=0 for note-off has to do with it? Without clear information as to what the keyboard is doing, the sound module is forced to make assumptions that may or may not be optimal.

#1388929 - 03/05/10 02:02 PM Re: Yamaha GH(E) versus GHS key action [Re: dewster]  
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Yes - the fault was mine - I read Peter's post too quickly.

Btw, my Kawai MP9000 terminates at the 50% return point too. (and I'm almost certain it only has two sense points)

Greg.


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#1388943 - 03/05/10 02:19 PM Re: Yamaha GH(E) versus GHS key action [Re: dewster]  
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Originally Posted by dewster

True, but a single channel of MIDI over USB probably does, as USB enforces quality of service.


Is there a reason they'd have to restrict the bandwidth to such a low rate, in a configuration that does not have any physical 31.25kbaud connections (i.e - just USB)?
Also, I believe that USB has a real-time mode, where data delivery is not guaranteed.

Quote

Yes, I agree. I think if they are doing anything (not that I distrust you or your report in any way) they are perhaps somehow exploiting the second contact normally employed for quick repeat notes.


Yes - agreed.

Quote

That should be fixed, shouldn't it? I wonder how much the universal coopting of MIDI note-on=0 for note-off has to do with it? Without clear information as to what the keyboard is doing, the sound module is forced to make assumptions that may or may not be optimal.


Agreed. There is no message for "prepare for a note retrigger". smile Btw, Pianoteq's voice count incremented for each retrigger - it overlapped multiple voices. I'm not sure whether it overlapped to the same extent as it seems to when using the sustain pedal or not. (it might have been more, or less - I haven't checked)

Greg.


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#1388984 - 03/05/10 03:04 PM Re: Yamaha GH(E) versus GHS key action [Re: sullivang]  
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Originally Posted by sullivang
Is there a reason they'd have to restrict the bandwidth to such a low rate, in a configuration that does not have any physical 31.25kbaud connections (i.e - just USB)?
Also, I believe that USB has a real-time mode, where data delivery is not guaranteed.

Not sure what bandwidth they use for the stream, but evidently you can get more for bulk dumps and such. Not sure how strictly manufacturers adhere to this:

http://www.usb.org/developers/devclass_docs/midi10.pdf

Originally Posted by sullivang
Agreed. There is no message for "prepare for a note retrigger". smile Btw, Pianoteq's voice count incremented for each retrigger - it overlapped multiple voices. I'm not sure whether it overlapped to the same extent as it seems to when using the sustain pedal or not. (it might have been more, or less - I haven't checked)

The MIDI note-off message contains velocity information. I wonder if they could exploit that somehow e.g. use note-on velocity to add energy, note-off velocity to subtract/damp.

#1389201 - 03/05/10 08:58 PM Re: Yamaha GH(E) versus GHS key action [Re: dewster]  
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I have a new assertion: I'm a complete MOOSEBREATH!
I don't think the Casio has any intermediate decay rates as the key is released at all. It might sense the release velocity (as Peter proposed), but I had a slightly unfriendly shop assistant breathing down my neck and I didn't have the patience to test it properly.

I am fairly certain, though, that I was able to invoke the third sensor. I could retrigger the note with a partial release. (hooray!). I did this very slowly, too. There wasn't a big distance between the normal off point to the mid point, but it seemed quite definite.

Now, regarding repetition performance, if you go to 2:16 in this V-Piano clip: http://www.youtube.com/watch?v=PLsNgJELxpU , and watch how he tests it, I think the Casio performed well when played in that same, subtle manner. When played more forcefully, with two alternating hands, I couldn't get it to repeat with consistency. It could be the amount of bounce in the action. When I played the Kawai CN22, the action seemed very well "damped" - like an acoustic action. (and I realise this isn't even their best action)

Greg.


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#1416858 - 04/14/10 06:38 AM Re: Yamaha GH(E) versus GHS key action [Re: sullivang]  
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Earlier in this thread we were discussing the MIDI messages that a triple sensor action would send. I've received a response from Casio (via a retailer). As we kind of suspected, a partial release and subsequent key press does send a new Note-ON. Casio didn't actually state that a Note-Off is NOT also sent, but I think that's a given.

The fancy VAX-77 also behaves like this, ref:
http://www.forum-pianoteq.com/viewtopic.php?pid=10636#p10636
and I assume Yamaha's GH3 and Roland PHAIII would be the same.

Greg.


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