Different trigger input parameters and self resonance

[mj15003]

Hello Megadrummers,

I have experienced a strange behaviour of certain inputs of my Megadrum unit. (It is 32 input ARM based module build by Dmitri together with positional sensiong addon board).

I use DDrum triggers on acustic drumset with 682drums mesh heads.

The problem is that I need to lower the Threshold in order to trigger weaker hits on 14" heads because of bigger head size. However, when I set the Threshold on Tom3H input below 10, the input gets into some kind of resonance and triggers continuously +- 10 or 20 times per second without being hit. When I connect the same trigger with the same cable into Tom1H input I can get even down to Threshold 2 without any resonance. And also vice versa, when I connect my first 10" tom into Tom3H input then I experience the same resonance problem, whilst on original Tom1H not at all.

The next issue is also a strange crosstalk between several other inputs and Tom3H input (mainly snare and tom2, partially also kick and tom1). I do not understand it because there is no mechanical coupling between my floor tom (self standing on own legs) and the rest of the drumset. It seems to me it is some kind of electric related crosstalk inside the module. It does not depend on cable or trigger type only on the used input.

I can confirm for example, when I plug my floor tom into Tom1H input there is no crosstalk with anything even with the Threshold 5 or 3.

I also measured the resistance of certain inputs on megadrum Tom3H gave me several megaohms whilst Tom1H had steady cca 130k, and snare as well for example. Maybe my multimeter might be wrong, but as electrician I cannot find an explanation for it.

Of course it can be partially fixed by altering Xtalk parameter but it seems to me like putting a patch on something in order to get it work somehow instead of removing the source of the problem.

Any help or tweak ideas would be appreciated because I have already run out of options.

Thanks

[dmitri]

Hello Megadrummers,

I have experienced a strange behaviour of certain inputs of my Megadrum unit. (It is 32 input ARM based module build by Dmitri together with positional sensiong addon board).

I use DDrum triggers on acustic drumset with 682drums mesh heads.

The problem is that I need to lower the Threshold in order to trigger weaker hits on 14" heads because of bigger head size. However, when I set the Threshold on Tom3H input below 10, the input gets into some kind of resonance and triggers continuously +- 10 or 20 times per second without being hit. When I connect the same trigger with the same cable into Tom1H input I can get even down to Threshold 2 without any resonance. And also vice versa, when I connect my first 10" tom into Tom3H input then I experience the same resonance problem, whilst on original Tom1H not at all.

Inputs with and without precision rectifiers (Positional sensing addon) have different sensitivities and requires different sensitivity settings. You set Threshold too low on the inputs without precision rectifiers hence false triggering.

The next issue is also a strange crosstalk between several other inputs and Tom3H input (mainly snare and tom2, partially also kick and tom1). I do not understand it because there is no mechanical coupling between my floor tom (self standing on own legs) and the rest of the drumset. It seems to me it is some kind of electric related crosstalk inside the module. It does not depend on cable or trigger type only on the used input.

I can confirm for example, when I plug my floor tom into Tom1H input there is no crosstalk with anything even with the Threshold 5 or 3.

Can you tell exactly from which input to which other inputs you experience crosstalk, what sensitivity settings are on those inputs and what MIDI Note On velocities are generated from the crosstalk?

I also measured the resistance of certain inputs on megadrum Tom3H gave me several megaohms whilst Tom1H had steady cca 130k, and snare as well for example. Maybe my multimeter might be wrong, but as electrician I cannot find an explanation for it.

You cannot measure correctly impedance, be it input or outbut, on semiconductor devices using a multimeter.

[mj15003]

Inputs with and without precision rectifiers (Positional sensing addon) have different sensitivities and requires different sensitivity settings. You set Threshold too low on the inputs without precision rectifiers hence false triggering.

Then I am just curious. What is the source of false triggering when pad is not hit and threshold is too low?

Can you tell exactly from which input to which other inputs you experience crosstalk, what sensitivity settings are on those inputs and what MIDI Note On velocities are generated from the crosstalk?

When I will get back to drums I will supply them.

[dmitri]

Inputs with and without precision rectifiers (Positional sensing addon) have different sensitivities and requires different sensitivity settings. You set Threshold too low on the inputs without precision rectifiers hence false triggering.

Then I am just curious. What is the source of false triggering when pad is not hit and threshold is too low?

It is electronic and electromagnetic noise due to interferences and inherent electronic devices properties - even a simple resistor has internal noise unless it is at absolute zero temperature.