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Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 2:57 pm
by privatex
Well as I can see everybody have problems with too hot piezo signals but my... I tried with so many types of different piezos and I got very nice signal on diy toms but on the snare i just cant get it right.
I connect piezo from sd to the line in, and on wave analyzer I got very hot signal, voltage is max 2V (line in ofc). Every piezo connected on megadrum have low signal strength, I dont know why. On my 12' diy snare I never get nice strokes near to the rim, cone contact with mesh is also hot irritating spot.
As I can see configuration of megadrum is no big deal but mechanics of crossbar, piezo seat...is crucial. I did it like from the book and get some extremely good triggering on toms. Also foam cone material is basic, with regular sending block foam it seams that my piezos need some stronger material.
What about impedance and frequency of piezo elements? Which of them to buy? In my local store they got 27mm,2.5MHz,500 ohm max,30v.
Positional sensing didn't work ( with reverse polarity of piezos too). I also tried different types of wiring but nothing.
All I ask is some basics tips from real life (which piezos, wiring way for dual set up, materials for cone...).
I can feel potential of this device but cant get it.
Here is my configuration of snare with eg with almost 100% hard strokes (about 70-80%), got triggering only in 10cm radius from centre. Rim piezo with 252 threshold (very good signal, but hey its 252). I have MD almost one month now and I never heard ps in action (one month of constant experiments, hmmm).
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Re: Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 3:06 pm
by dmitri
privatex wrote:I connect piezo from sd to the line in, and on wave analyzer I got very hot signal, voltage is max 2V (line in ofc).

2V from a piezo on a Line In? There is something seriously wrong with your pads/piezos/wiring. A piezo on a high impedance input like Line In should produce ~30-50V signals.

Re: Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 4:03 pm
by privatex
I know but it was some freeware wave analizer so i gues that voltmetre is not that precize, but still 2V o.O. Wiering is like in MD manual with reverse polarity of head piezo. I think that head piezo is quilty, Ill change him with new one and see whats going on. I was suprised with sensitivity of piezo connected on line in, if i can get that level on MD Ill be very happy. My 10' tom work realy good, threshs are on 300 (h+r) and I got realy fine sound, sesitivity and feel. They are same piezos (snare and tom), same crosbars, foam... must be piezo. However ps get me concerned, does anyone get ps work good? I can feel that one day Im gona be proud on my MD and diy pads/cymbals but its a long way to get a ,perfect triggering,

Re: Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 4:13 pm
by dmitri
privatex wrote:However ps get me concerned, does anyone get ps work good?

Of course. I tested it with Pintech 10", Roland PD-125X and Drumtec 14" snares and on all of them it worked very well.

Re: Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 6:20 pm
by privatex
I can't get it work, no noticeable results.
It was piezo, I changed and now it work relatively fine. Don't know what to do for positional sensing.

Re: Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 6:49 pm
by dmitri
For the positional sensing to work at all, besides of centrally located piezo requirement, the mesh pad build quality must be very good and it must not suffer from issues which cause it to produce very weak signals. As I said before it works very well with mesh snares built by Pintech, Roland or Drumtec.
If your pad doesn't produce signals with positional data in them, then MegaDrum cannot just guess it.
Take screenshots of the first full half wave of signals captured by an oscilloscope (standalone or software) from your pad when you hit it centrally and near the rim and I will tell you if your pad produces signals with positional data in them.

Re: Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 7:46 pm
by privatex
I understand you, my pads are very well done but theres always some litlle thing that make problems as usual. What software can read signal from MD, I have only soundcard oscilloscope which cant even recognize megadrum?
Here is some eg of snare configuration with sound files, also I notice that when I play separately rim and head its fine bat in the same time there is problem (suppose that crostalk have that effect). Here is audio file with eg of just rim, just head and playing them together + another file with litlle snare sound with conf like on previous attached pic. Ty Dmitri for answer, Ill do that test and make some screenshots for you.
Code: Select all
http://speedy.sh/exHPY/h-r-together.wav

Code: Select all
http://speedy.sh/XzU6a/snare.wav

Re: Problem with low piezo signal

PostPosted: Tue Sep 23, 2014 9:11 pm
by dmitri
1. You use oscilloscope to capture signal from your pad, not from MegaDrum. I think you can find many free software oscilloscopes on Internet. Please note, that soft oscilloscopes which use a sound card are limited to ~1V so you must reduce signals from a piezo, e.g. using resistors.
2. Positional sensing is not about hitting a head or a rim. Positional sensing works with head hits only depending on where you hit a head.
3. Don't post wav files, post screenshots as captured by an oscilloscope. And I don't need full length signal. I just need first half wave.

privatex wrote: I notice that when I play separately rim and head its fine bat in the same time there is problem (suppose that crostalk have that effect)

Sorry, I didn't understand what problem you described.

Re: Problem with low piezo signal

PostPosted: Wed Sep 24, 2014 2:22 pm
by privatex
Here is a screenshot of head piezo cooled with resistors, this represent 3 single strokes with fingers.
I know whats positional senseing, my question was why MD wont trigger head and rim in same time when I hit them.
Here is soundcardoscilosccope readings of head piezo, wav file was eg of problem that I subscribe in previus sentence.
Thank you for reply, I know that after almost decade of MD history you must be sick of those questions and problems, but I must ask for good of my machine and my playing :)

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+ stroke with stick
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Re: Problem with low piezo signal

PostPosted: Wed Sep 24, 2014 10:45 pm
by angr77
Hi.

To determine the rim/bow problem...it would be nice to see how your config looks like below the bow/edge panels.

Regarding the PS function on the head...please raise the minscan to about 50...15 is too low!

Angr77