www.megadrum.info

hello,

is there a way to directly test pads/piezos? I have built mesh head triggers with a 6 spoke crossbar. rim piezo mounted on reverse of spoke and head mounted on a small mount about 3" above crossbar. Wired as head ceramic to tip, rim ceramic to sleeve, both brass to gnd. I'm getting no response from any of my pads in MD - nothing in the midi monitor at all even when tapping the piezo directly. However, my roland pads (a pd-80 i think, older one, and a vh12) show up as expected. tested inputs and cables which leads me to think its an issue with the pads but I'm not sure how to test them with my equipment. I only have multimeter at home and my understanding is that a piezo's pulse is far too short for such a device to detect anything. I may be able to borrow an oscilloscope over the weekend but until then (and if that doesn't pan out) is there any way to test the piezos directly? I got them all from one source in china so my fear is a bad batch or something.

I think you would need an osciloscope, yes, for a definitice answer.

Hi
I think you should be able to see something on your multimeter when hitting your pad. You can test on your Roland device first to verify your multimeter. I have tried this on my fluke multimeter and I am seeing a positive value when reading volts on the piezo.

Angr77

angr77 wrote:Hi
I think you should be able to see something on your multimeter when hitting your pad. You can test on your Roland device first to verify your multimeter. I have tried this on my fluke multimeter and I am seeing a positive value when reading volts on the piezo.

Angr77

I'll try that when I get home from work. My multimeter is pretty crappy so I don't know if it will read such a quick pulse. Thanks to both of you for input though.

Barring the dead or to cool piezo possibility is there anything else I should be checking?

Continuity between the ceramic and brass parts of the piezo and the ends of the leads.

ignotus wrote:Continuity between the ceramic and brass parts of the piezo and the ends of the leads.

Ah smart! Thanks!

tried it out - continuity failed but the multimeter did show -0.012vdc at rest ranging to about -1.5vdc depending on velocity of hit. Will have access to an scope tomorrow but i'm starting to think it's that the pads are simply too cool for megadrum to register. if thats the case what could I do? I know how to soften a hot signal but i'm not too sure how to boost a signal from a piezo.

what is the construction of these pads?

As far as I can see, if continuity failed any reading with hits is irrelevant. If there's no continuity that's the problem right there. Even tiny piezos output enough voltage to be read by MD.

You can put harder foam or adjust position of the cone, also you can place a piezo on some hard surface. So yes you can make your pad more sensitive.
I doubt that pad is so cold that MD cannot read anything. Usually MD can catch even lowest taps. Problem must be in wiring, cables, joints. Even piezos are alive with -1,5V which is a voltage that MD will recognise for sure.
My advice will be to make another piezos pad system without installation to the pad. Test it, pay attention to soldering and connectors and you will be fine.
Loose solder joint is problem here, so sometimes have connection and sometimes not (or bad wire).