Inputs behaving strangely

[Russ15]

I am setting up my drums again after redoing the triggers on them and am running into some odd issues. I currently have 18 inputs in use and have disabled all inputs that are not yet configured. Tom1 and Tom2 are working very well however when plugging a drum into Tom3 or Tom4 there is constant triggering. I must raise the threshold to at least 20 for the constant triggering to stop.

What is odd is when I plug Tom1 (threshold set at 5 and working very well) into the Tom3 or Tom4 input it will constantly trigger until the threshold is set above 20.

I should also note that when plugging the drum connected to the Tom3 or Tom4 input into Tom1 or Tom2 on the Megadrum module, it works perfectly.

This constant triggering will also occur if NO drum is plugged in; only the TRS cable plugged into the Megadrum input at Tom3 or Tom4.

I am using the latest firmware version (20180121) with a 56 input megadrum, MCU:STM32F205RCT6.

Thanks for any help in advance.

[dmitri]

I guess you MegaDrum has the Positional sensing addon. The addon "cools" inputs 4, 6, 8, 10 and 12. As a result with the same Gain on those inputs you can set Threshold lower compared to other inputs but HighLevel will also be lower.

[Russ15]

Dmitri you arecorrect about the positional sensing add on, I didn’t realize it cooled the input. The biggest issue I have with the Tom inputs that are not cooled (in my case 14 and 16) is suppressing false triggering. I do have voltage dividers set up on each pad, would making these pads cooler produce similar parameters as the positional sensing inputs?

[dmitri]

You don't need to set Threshold equal on inputs with and without positional sensing. But if you have voltage dividers on the pads the you can try to reduce the signal from them if they are too "hot". Note that since you reduce the signal at the other end of the cable, if the cable is not shielded enough the noise may stay at the same level and will not allow you to reduce the Threshold.

[Russ15]

Very true, thanks Dmitri.

The only reason I want to try to set the parameters close to the positional sensing inputs is the setup process. It is very easy and I am getting excellent triggering with very little work. I suspect cooling the inputs will put me on the right track. Thanks again.

[jarosz]

I guess you MegaDrum has the Positional sensing addon. The addon "cools" inputs 4, 6, 8, 10 and 12. As a result with the same Gain on those inputs you can set Threshold lower compared to other inputs but HighLevel will also be lower.

Man, I wish I had known it earlier. My hi-hat triggers low velocity notes much better on input 6 with PS board than on 2.

[ignotus]

Man, I wish I had known it earlier. My hi-hat triggers low velocity notes much better on input 6 with PS board than on 2.

Could you elaborate? I only have the PS circuit on my snare, but if it could benefit the hi hat (if I lower threshold too much it auto-triggers and if I raise it, it misses some light hits) I might make one for it.

[jarosz]

I like the hi-hat technique presented by Todd Sucherman:

https://www.youtube.com/watch?v=YU5_NJfNunQ&t=2260s

so the second, unaccented stroke is sometimes really light.

I'm using PCY-135 as a hi-hat cymbal. I'm using PCY-155 as ride, and it worked much better in this aspect, but I thought maybe it's because I've bought the former B-stock. I haven't thought about switching inputs, because it's mapped by default in software (2 - hi-hat, 6 - ride) and I thought there's no difference.

With PS board made by dmitri I can set treshold for PCY-135 on input 6 at 1 (alt sampling alg turned on) with no auto-triggering from noise. Before it had to be 3 or above and I had around 20% missed light hits with Todd's technique.

[Russ15]

I have had similar results on my hi hat. Using a PS input I can lower the bow threshold down to 4. On non PS inputs the minimimum threshold on the same cymbal is 14.

In my experience the pads on PS inputs can also be set to a lower threshold than non-PS inputs.

What I’ve done is put all my pads and hi hat on PS inputs. I use a snare and 3 toms currently for the pads. I’m using pcy135s for all my cymbals and diy pads using the triggers Ignotus designed.

I have also found it much easier to setup PS inputs. If I could I’d have all inputs setup for PS for the sake of set up,sensitivity and uniformity.

Dmitri could you explain how the circuit “cools” PS inputs? My pads are not too hot so using my voltage dividers doesn’t really help getting things close to how the PS inputs work.

[dmitri]

The PS board "cools" (reduces) signal near the main board. This way it reduces both signal and noise equally. If you place a voltage divider closer to a pad/cymbal, it "cools" signal more then noise. If you use a voltage divider it is better to place at the module's end of a cable.
You can set Threshold lower on PS inputs but it doesn't mean it has better sensitivity compared to inputs without PS where you have to set Threshold higher - it just a consequence of reducing both signal and noise equally on PS inputs.