[sdiy] QTC and delurk

[Edward King]

Veronica,

sorry I havent contributed to your problem any since my last post, but I 
have a client who have been running me ragged for a few weeks!

The first thing that springs to mind is that there isnt a way of adding qtc 
to an instruments fretboard without modifying it in some way (or suffering 
string interference). This I guess would mean shaving the fretboard, then 
laying the qtc and finally the overlay. gluing veneer directly to the qtc 
would be one suggestion (and I think that would be okay), but it leaves the 
question of the frets. Given that the qtc material is some 1.something 
millimetres thick + the thickness of whatever material your contacts are 
attached to, you woul dhave to pick an instrument with adequate fretboard 
material. This of course alters the playability of the instrument in 
question and you would be right if you baulked at the idea.

If you're as experienced at working with instruments on the construction 
level as your previous posts suggest, then rebuiling a neck shouldnt be 
beyond your capabilities and this may be whats required given that contacts 
would need to be placed underneath the qtc material on every fret (or even 
the other way round) or continuously (in the case of a fretless) with the 
math taking care of the voltage - pressure - pitch functions. Given that the 
qtc material is _almost_ linear in terms of its output, I would suggest a 
lookup table with _best fit_ algorithm as Ive gotten very good results with 
that for my individual aftertouch, hammer impact velocity and vibrato 
systems.

The response times of the qtc material are very good, but of course this 
depends on what you're using to monitor it. The data I collected from a 
standard 8bit ADC on a PIC microcontroller was perfectly sufficient to 
effect a less than 1ms event-process-response mechanism.

Regards

Edward



That is to say that the
----- Original Message ----- 
From: "Veronica Merryfield" <veronica.merryfield at shaw.ca>
To: "synthesizer diy electronics" <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, May 06, 2007 7:20 AM
Subject: Re: [sdiy] QTC and delurk


> >Welcome!
> Thank you
>
>>Are there going to be strings, or will you be pressing directly on the 
>>fingerboard.?
> With strings. I want to be able to play it as a regular bass and inject 
> the
> string pickup signal as sound source into the signal processing chain.
> However, that wouldn't stop one playing the fingerboard :) I figure on
> experimenting with various thicknesses of fingerboard vaneer to make the
> sensors give me a reasonable range of pressure sensing. I'm thinking that
> there might need to be a pressure sensing calibration function too. Hmmm
>
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