DIY cymbal piezo sensitivity

[baskeheurs]

Hi,

My DIY cymbal (14" crash,dampened,27mm piezo,choke switch) was way to sensitive to use as 3zone.

Moved the piezo from edge of bell to inside of bell,added 3mm of foam tape to reduce sensitivity.
Still to sensitive. even relatively soft Bell/bow riding gives me Bell(hard)/Bell(soft) sounds.

When I ride the bow is does the bow ,but quite fast goes to bell sound.

I don't know much about electronics so maybe you can steer me in the right direction.

Would using a 22mm piezo help.
Can I mod a potmeter somewhere in my wiring to reduce the sensitivity?

Soldering and building no prob,but the electronics parts,and values are not my cup of tea.

Thanks

[ANGR77]

Hi!

To my limited knowledge...a smaller piezo is often hotter than a bigger one, e.g. Smaller will generate a higher signal than a bigger one. Try a 35 mm instead.

The 2box bell implementation fires off when a piezo hit goes over a 0,156V(this a AC signal so it is a bit hard to measure)..a normal bow hit will be generating signals in the ranges of 0,056 to 0,100V.

So you could add a variable pot and try...I would pick a variable resistor with a range of 0-50k ohm and try. Connect it in series with the piezo.

One problem with most piezo's have is that they will start to build up some power(they will not go down to zero V immediately after a hit) when hitting them in a row. This is probably what you do experience when bells fires off after a series of bow hits.

A generic solution to address this is to use a condensator in parallel with the piezo. It will "empty" the circuit (read piezo) after a defined time, this process is dependent on the value of the condensator. I would try with a 10nF or a 100nF ceramic cap. But start with the potentiometer trick first.

Best regards

Angr77

[Coda]

Some interesting things you mentioned there ANGR77, especially that the piezos are acting as a capacitor. In this case, adding another capacitor across the piezo terminals will just increase the capacitance, and possibly act as a frequency filter, the frequency determined by the size of the cap.   

I had always assumed that smaller piezos were less sensitive, but after studying datasheets (the few that were not in chinese!) I came to the conclusion that the size of the piezo determines the frequency response of the 'microphone' attribute of the piezo. I.e a larger piezos are more sensitive to lower frequencies, smaller => higher. 

I have 20mm piezos on all my cymbals and 30mm on my drums. I don't have the problem on my ride that the OP has (the only cymbal I have which is a single piezo but its connected to a cymbal input (2) and trigger type is cymbal 14). My other cymbals are just piezos and trigger type is something else.