www.megadrum.info

lajox wrote:Hi Totti,

Megadrum responds much better with the voltage dividers between the pads and the module. I've got mainly Roland pads and couldn't get them to work quite right without the dividers. Could only test a single pad though but it triggers very consistently now with SD2. I used 55 of these:

http://www.tme.eu/html/DE/acp-trimmpote ... pelny.html

You can also get a cheap knob for them there, and, which was my main criteria, I could fit all 55 into the front panel of my meagdrum module.

I just placed my order for a Megadrum and will now have to look into building voltage dividers. Dmitri's diagrams seem to have 47kohm trimpots. Is this the exact "value" I should get? What kind of "range" does it provide to adjust hot mesh pads? Should it be multi-turn?

I'll have to build an external box on top of the Megadrum unit, so maybe using 47kohm potentiometers would be better (easier to adjust)? Lots of questions from a newbie...

In fact you may need only one pot if you use only one type of pads. With this you'll find the right proportion for the divider and then use constant resistors on the remaining pads. The proportion doesn't need to be exact, you just need to make the pads sufficiently cool and then you can play with Gain/HighLevel/Threshold to get full dynamic resolution.

dmitri wrote:In fact you may need only one pot if you use only one type of pads. With this you'll find the right proportion for the divider and then use constant resistors on the remaining pads. The proportion doesn't need to be exact, you just need to make the pads sufficiently cool and then you can play with Gain/HighLevel/Threshold to get full dynamic resolution.

So for a 5 pad set (all triggers the same kind) the "chain" would go like: 5 female stereo jacks connected to one 47kohm pot which is connected through 5 constant resistors to 5 female stereo jacks? Sorry, if this question is stupid - but I'm willing to learn.

No chains. With one pot you find the proper position to make a pad cool enough and then measure resistances between the wiper and the two end terminals. Then use two constant resistors, with values close to the measured ones, on each of the rest of the pads of the same type.

dmitri wrote:No chains. With one pot you find the proper position to make a pad cool enough and then measure resistances between the wiper and the two end terminals. Then use two constant resistors, with values close to the measured ones, on each of the rest of the pads of the same type.

OK, I see.

Earlier in this thread you wrote:

I should also mention that in fact you can get away with just a regular resistor connected in series with a piezo because it will create a voltage divider with a internal resistor on the MegaDrum input. In this case you can just place the resistor inside a cable jack. Only you will have to experiment first to find the right resistor value

Does this apply to a SINGLE piezo pad or also piezo-piezo? I would be much happier if I could stuff everything inside the cable jack but with a dual trigger I will be needing two resistors per input so they won't all fit in there.

It is per piezo of course so in a dual piezo-piezo pad (if both piezos are too hot) you will need a voltage divider per piezo or a resistor in series with each piezo.

Okay, I know it's an old thread, but I'm just catching up...
So, based on everything I've read here, does it make sense that I can just set up the variable resistor like this so that the resistor is just mounted actually within the drum?

Also, the resistor wiring that I've shown there is based on this diagram that I found. However, one question that I have is how do you know which post is #3 and which is #1? They're not marked or indicated on the pot at all. Does it matter?

Of course you can mount the potentiometer in a pad. I fact some pad manufactures do it and I believe this IS the right way to do it.
From my test though the schematic shown in viewtopic.php?f=3&t=958&start=10 works better for gradual adjustment than the schematic you have drawn.

So maybe more like this?