My experience with megadrum so far

[airflamesred]

Hurrah!

[dmitri]

Just one more little question before I go crazy tweaking my settings, when I get false triggering the second note has a higher velocity than the first note, is there anything wrong with my wiring that I should fix before continuing?

Very possible your pad produces signals with low frequency (wide half waves) so the default MinScan of 20 is not long enough to measure the whole first half wave - it is common thing for mesh triggers. Increase MinScan to at least 40.

[der_wolff]

You can analyse the waveform from your pad with a simple soundcard oscilloscope software like http://www.zeitnitz.de/Christian/scope_de . You must only connect the pad output with micro/line-in and activate the single trigger function.
I optimised the scantime with this measurement of my Meshhead DIY pads and check the polarity of the first waveform.

[jackiecorn]

You can analyse the waveform from your pad with a simple soundcard oscilloscope software like http://www.zeitnitz.de/Christian/scope_de . You must only connect the pad output with micro/line-in and activate the single trigger function.
I optimised the scantime with this measurement of my Meshhead DIY pads and check the polarity of the first waveform.

I run my trigger signal to Pro Tools and I can pretty much see everything in waveforms.
In fact I'm thinking of a way to get a Y splitter jack cable that outputs 2 identical signal from the source and have them plugged into my audio interface and megadrum. With this setup I can record both the pure piezo signal(which sounds closes to the perception of real drum playing) and megadrum's midi data.
Then I can play from soft to loud and compare the analog signal with the midi data and build a custom velocity curve to mimic the analog signal. Hopefully I can achieve this and build a setup that's closes to the perception of playing acoustic drums that's even better than Roland's.

[everson]

That would be great! Please post your findings.

[jackiecorn]

This is the waveform I am getting from a hit, which shows two big crests with similar amplitude, this would cause me a false trigger with very close velocity.
Also some waveform appear to have a very high amplitude crest somewhere after the main impact, even higher than the original hit itself.
Which part of my setup could cause these problems?

[dmitri]

Is the first graph showing a single hit?
Did you take this graph with the pad connected to the MegaDrum input or not?
What is the time scale of the graph?
Does the "double triggering" with this graph have higher velocity second MIDI message rather then the first? If not (the first message has higher velocity MIDI message) than the "double triggering" may not be caused by the peak you highlit depending on your answers to all previous questions.

[jackiecorn]

Is the first graph showing a single hit?
Did you take this graph with the pad connected to the MegaDrum input or not?
What is the time scale of the graph?
Does the "double triggering" with this graph have higher velocity second MIDI message rather then the first? If not (the first message has higher velocity MIDI message) than the "double triggering" may not be caused by the peak you highlit depending on your answers to all previous questions.

Yes both graphs are showing a single hit, and it is recorded with the pad plugged straight into an audio interface's line in, not connected to Megadrum input.
I sampled a lot of hits, from light to hard, from side to center of the drum head, fast rolls to single hits, and the above two are chosen at random which shows some abnormal reading of a piezo signal to me, not all recorded hits have problem, but a lot of them has the "double high peak" reading.
And yes indeed I have the second MIDI velocity higher than the first for a lot of the hits, and sometimes it is just a double trigger with just a little less velocity than the first(say first hit 80, second hit 63).
Since the second signal isn't a lot less than the first, I don't expect it to be cured by a larger threshold setting, so any idea?

[dmitri]

It looks like there is a flaw in the pad construction or the piezo. The only way to suppress "double triggering" in this case without fixing it in the pad itself is to increase Retigger to a value larger than the time difference between the hit's original peak and the abnormal high peak.

[jackiecorn]

It looks like there is a flaw in the pad construction or the piezo. The only way to suppress "double triggering" in this case without fixing it in the pad itself is to increase Retigger to a value larger than the time difference between the hit's original peak and the abnormal high peak.

Yes I seem to have fixed this problem temporary by turning up Retrigger to around 17, I guess I can live with it for the moment, until I have time to investigate the real cause for the problem. Thanks.