www.megadrum.info

I found some time to evaluate my Megadrum setup recently, make some improvements / tackle some problems, namely the infamous random rapid triggering of all triggers I get sometimes - what I gather is electrical surges through my mains supply.

Anyway I noticed something since moving some triggers around, one of my toms is really hot, on input 8.

Gain 0, Thresold 24, I get an auto high level of 521.

The same tom is cooler on other inputs, likewise If I plug a cymbal in, the bow piezo becomes hot. Anyway, I thought I'd cure that with an in-line resistor.

With a selection of resistors in my hands, I got to work testing... long story short, I'm at 47k now, and that's the highest Ohms I thought I would possibly need to cool a trigger...

The tom is still too HOT. Medium to hard hits are still somewhat the same, with a large hot spot.

The new settings for input 8 are:

Gain 0, Thresold 0, I get an auto high level of 539. (Yes, high level went up slightly with 47K resistor)

I tied two 47K resistors together to make 94K, and all I seem to be doing is making the tom less sensitive to light hits but the dynamic range (and hot spot) remains the same as before. Is there something I'm overlooking here?

Right now I'm reverting to plan B - placing my CY-15R on inputs 6 and 8. I'm actually thinking of physically disconnecting input 8 from the pin since it's not used as trigger on the 3rd zone anyway.

So this isn't a problem I need to solve, but at the same time, it's not something I'm comfortable passing onto the next owner, if I happen to sell my module in the future.

This may not be relevant but aren't inputs 6 and 8 on the Positional sensing route?

I think all my inputs go through the positional sensing board on my model.

A positional sensing addon board adds precision rectifiers only on inputs 4, 6, 8, 10 and 12. All other inputs are unmodified.

Hello! Try using something like 5.6K in parallel with the piezo. It will "linearize" the output and bring down the max. level. It shouldn't decrease the dynamics...

maru_engineering wrote:Hello! Try using something like 5.6K in parallel with the piezo. It will "linearize" the output and bring down the max. level. It shouldn't decrease the dynamics...

Hey, thanks for thinking about my issue!

So this would mean attaching a pair of resistors (with the same resistance) onto the head/tip pin, and then the two ends back onto the head wire, that goes to my PS board? I shall give it a try!

If that works, I may put my toms back in the default position then, followed by my cymbals.

The trouble is, if I move my cymbals too far down the list of inputs, I get a severe drop off in the rim signal levels - not even gain 8 is hot enough. So using two zone cymbals stops at input 18 for me.

I really wish I had a multimeter so I didn't have to shoot in the dark with this, but I have yet another new solution in the mail that I should be able to test soon.

Hi again!

In my case, I had the rim piezo from the snare too hot; I used a 100k trimmer parallel with the piezo to find the kind of response I was looking for, then I measured the dialed resistance from the trimmer... That's how I got to the 5.6Kohm value.
For your setup it will be different, I just wanted to point you in the direction of trying parallel resistors instead of serial (which was not working for you).
The resistor(s) should be connected Tip-Sleeve for the Head Piezo or Ring-Sleeve for the Rim Piezo.

I have the feeling that for high mechanical "stimulation" of the piezo element, the charge that builds up cannot "escape" as the Megadrum input impedance is quite high and, at least in my case, there was no difference between medium-strong and very strong hits... The parallel resistor trick "linearized" the piezo response on the upper end of the dynamic range...

Just try it and let us know how it works... Take the the 5.6K value as in "don't be afraid to get that low with the value if needed". Perhaps in your case a bigger value (like 20K) is enough...

Best Regards

After much experimenting... I'm pretty satisfied!

As you can see in the image above, I went kinda crazy with the resistors. But with good reason!

I significantly increased the dynamic range on all my toms, and cured the hot input for tom 2!

It turns out, it needed a voltage division of 11:1 to bring it in parity with the other inputs, so it was seriously hot!

I also added a voltage divider to the snare, because pressing on the mesh caused hundreds of midi notes and other triggers to start triggering like fireworks, so I figured it was worth a try cooling that input slightly (10:9 ratio) to take the edge off, and now... low and behold, pressing the mesh head only sends a few notes now - so I cured that problem enough without compromising the dynamics too much, because I rather liked the way it played before and didn't want to spoil it.

As a bonus, my snare mesh head was cooled to the point where I can now rest my palm on it while playing cross-stick (even though it's just a standard piezo / piezo 12 inch snare) just like a PD-140 on a TD-50! Unbelievable. I feel my work has been rewarded. - This is at gain 1, threshold 1. Yet I still get trigger response right down to the bottom end of the stick bounce, right down to a soft buzz roll.

Problems arose though...

The rim piezos were now all, too hot. It messed up my mid point threshold on all the drums, big time.

So I soldered four more 20k resistors to take some of that energy away, but this time just to ground, using the internal resistor - which give me just enough cooling.

The thing is, now my midpoints have to be on 0 threshold basically, with midpoint width between 10 and 13. Triggering head or rim isn't the trouble, it's finding just the right spot for rim-shots which is the difficulty. It works! But rim-shots have to be hit just right. It was like this before the resistors were added btw, it's partly due to the construction of my diamond drums triggers and rubber hoop protectors, but I wasn't running with 0 thresholds.

One more thing, I can run my snare at gain 8, threshold 0 without any self triggering... yep.

I don't use gain 8 because auto level goes beyond 1023 limit but it's just bizarre to have such a clean signal on just that input lol. I can easily trigger brushes sweeps with ease like this, so I'm ready for that, if I ever found a VST that did a realistic brush sweep (most of them seem to be single midi events). I can still use pressroll to do it mind, but I like the manual control where possible.

P.S. Soldering was a £$%#ing nightmare! No, I didn't solder the resistors in place till I knew I had the right values, but my goodness! I needed an extra hand, a tiny pair of tweezers, the liquid solder to balance on the tip of the iron while I "placed it", trying to keep the tip tinned, which it frequency failed to do and beaded up! Trying not to contaminate the solder during the weld (which I'm afraid it did because I didn't have any flux)!

*deep breath*

Then it wouldn't bond, so I had to keep re-flowing till it would... without the wire connection peeling off, without melting the plastic on the jack (which it did a bit) without dropping the resistor (yep), without touching anything else with the hot iron (yep)... ARGH !!!

Anyway. Many, many expletives later... I'm happy.

Would have made funny DIY video I guess

Just curious... would adding pots to each drum be another solution to this?

robbase29a wrote:Just curious... would adding pots to each drum be another solution to this?

Yes. And I think adding pots or trimmers to the pads themselves is an easier solution and at the same time pots make it easier to fine tune the resistance without having to test and swap out loads of resistor values. I made a trimpot array board so that every input goes through a 10k trimmer, but it was a nightmare to build by hand... If I was starting again I'd just install a trimmer in each offending pad (not all of them need it).