[sdiy] Synth Keybards and Number of Keys

[Edward King]

I dont know whether cap sensing technologies would or wouldnt work as I 
havent got any data to look at yet.
where did you get your data from Grant?

The solution that I was actually looking at experimenting with is pressure 
sensitivity in the keytops (qtc pills).
In this solution, Im considering putting two pills side by side.
During normal playing, the pressure should be reaonably well balanced 
between the two pills and even if this proves not to be the case, then there 
is a workaround:
Activate the vibrato system only when the key is at the bottom of its 
travel, keep a record of how long the operators finger has been to one side 
(proportionally) and if the figures add up, take this position to be "at 
rest" (i.e no vibrato).

This is similar to what Ive done with the displacement sensing....I learned 
very early on that vibration would initiate a lot of false triggering. As I 
was including velocity sensing anyway, I just made the decision that the 
displacement sensing data would only be acted on IF contact with the upper 
bus bar was broken.

An alternative workaround may simply be to interpret the data from the 
pressure pills differently. For example, if one pill is outputting a higher 
value than another for a sustained period it may be reasonable to assume 
that the operator has simply played the key with his or her finger on one 
side or another of the key.

Im sure there are lots of other ways to do this and that I'll uncover some 
of them in the ensuing weeks!

Regards

EK


----- Original Message ----- 
From: "Grant Richter" <grichter at asapnet.net>
To: "ASSI" <Stromeko at Compuserve.DE>
Cc: <synth-diy at dropmix.xs4all.nl>
Sent: Friday, March 02, 2007 8:10 PM
Subject: Re: [sdiy] Synth Keybards and Number of Keys


> The problem with the new capacitive sensing technology is scan time  for 
> the keyboard.
>
> These things are mostly designed for ATM machines looking for a  single 
> key press at a time. Not 8 key press chords.
>
> For example, the Freescale parts specify 2-3 milliseconds per key for 
> settling time.
>
> A musical keyboard needs to scan and update every key in 1 millisecond.
>
> That is what the Serge and Buchla keyboards do anyway. I don't know  about 
> the Synthi KS scan time.
>
> On Mar 1, 2007, at 4:19 PM, ASSI wrote:
>
>> On Donnerstag, 1. März 2007 19:53, Edward King wrote:
>>> I am also experimenting with recreating string vibrato effects
>>> through sensors on the key tops and would be interested in any work
>>> that others are doing in this area too.
>>
>> I think capacitive sensing should work nicely. Check for instance
>> http://www.cypress.com/capsense
>> for more information.
>>
>>
>> Achim.
>> -- 
>> +<[Q+ Matrix-12 WAVE#46 Neuron microQkb Andromeda XTk sonic heaven]>+
>>
>> Wavetables for the Terratec KOMPLEXER:
>> http://Synth.Stromeko.net/Downloads.html#KomplexerWaves
>>
>
> 


		
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