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Comment by amelius | Hacker News Reader

Since it's using keyboard keys I'm guessing it doesn't have any analog touch sensitivity (?) Not sure if that would be even needed on this type of instrument though.

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Yes, there is no analog touch sensitivity on the sax: keys are either open or closed. The pressure sensor is for volume and note attack.

There exist analog keyswitches, have you considered playing with those?

I'm really interested in this idea for other DIY instrument purposes.

Razer has keyboards with optical ones, and some people have made them by putting inductive sensors underneath mechanical switches, but I couldn't find any analog keyswitches for sale. Do you have some examples?

How can you deal with a large number of analog inputs to a Raspberry Pi or similar?

I don't remember how many analog input pins exist but a separate circuit that digitizes many analog inputs to a serial stream would be how I'd do it, personally.

While it would be interesting to play with analog keyswitches, it would depart from the experience of a real sax, where the "half pressed" key is of not much use. And it would dramatically increase the complexity of the design.

But the full design is published, just in case anyone wants to try :)

From what I understand of playing a saxophone the variability would come from the mouthpiece. On a type of instrument like a saxophone the valves should always be cleanly opened or closed.

Half fingering is a thing, but very rare and fine to be out of scope for a project like this

This is also true of the EWI, all of the keys are just metal plates that detect contact, and also generally true of saxophones (although very much not the case with clarinets, which have open finger holes)

It seems the keyboard is pressure sensitive (reference to a pressure sensor in the HW section)

Pressure sensor is in the mouth piece.

I've always thought saxophone keys were on or off

Actually the pressure sensor is on the PCB. Pressure is transferred from the mouthpiece through a flexible silicon pipe. You can see the details in the assembly instructions here: https://github.com/jcard0na/haxo-hw/blob/main/docs/assembly....

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