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Aftertouch resolution?

 

Hi all,
I've recently been watching a video about the internals of the CS80
and it briefly showed the aftertouch board. It looks like it has
multiple exposed vertical lines on the pcb, and then an inverted V
shaped piece of conductive rubber that connects more lines the harder
you press down on it.

Is this system essentially digital? How many different levels can it
achieve - what sort of "bit depth" is there?

Thanks
 
Edited

Hi,
It's a ten levels analog signal. It is smoothed by a filter later in the signal path.
You'll find a detailed explanation of how it works here:
 

Thank you!

On Tue, Feb 9, 2021 at 1:39 PM Joachim Milson <joachim.milson@...> wrote:

Hi,
It's a ten levels analog signal. It is smoothed by a filter later in the signal path.
You'll find a detailed explanation of how it works here:
 

Great info!

Here's a snapshot of a spreadsheet I created and put under Files many years ago:

aftertouch_response.jpg

And here's how I did it:

cs80_pressure.jpg
 

Joachim: I read your TSB board website page with interest, thank you for the excellent explanation!

I have a customer synth here where a previous tech decided to replace all the 0.33 uF tantalum capacitors with electrolytics. It is my understanding that tantalums charge and discharge more quickly than their electrolytic counterparts.

Could you please elaborate on what you would expect to happen in the circuit with velocity timing when these tantalums get replaced with electrolytics?

Thank you!

On Tue, Feb 9, 2021 at 7:40 AM Joachim Milson <joachim.milson@...> wrote:

[Edited Message Follows]

Hi,
It's a ten levels analog signal. It is smoothed by a filter later in the signal path.
You'll find a detailed explanation of how it works here:
 

Scott: The discharging speed of a capacitor is determined by its value and by that of the resistor in series with it (T=RC). So I don't think the type of the capacitor really matters.
 

Very good, thanks for the thought and reply.


On Wed, Feb 10, 2021 at 7:06 AM Joachim Milson <joachim.milson@...> wrote:
Scott: The discharging speed of a capacitor is determined by its value and by that of the resistor in series with it (T=RC). So I don't think the type of the capacitor really matters.

 

You might be forgetting that "the resistor in series" also includes
the capacitor itself. Add an ohm or so for electrolytics due to ESR.

On Wed, Feb 10, 2021 at 1:11 PM Scott Rodriguez
<synthrodriguez@...> wrote:

Very good, thanks for the thought and reply.

On Wed, Feb 10, 2021 at 7:06 AM Joachim Milson <joachim.milson@...> wrote:

Scott: The discharging speed of a capacitor is determined by its value and by that of the resistor in series with it (T=RC). So I don't think the type of the capacitor really matters.

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