False kick triggers when releasing HH pedal

[Rovalo]

Dear all,

Months ago I had to let my MD project rest, but recently I picked it up again. By then I was still struggling with understanding correct trigger settings and I found some issues likely to be hardware related, others due to my lack of understanding MD settings. I will address the issues in separate topics to avoid confusion.

I did a firmware and MDM update (just before MDMFX) and also completed the MD breakout-box, so I cannot always tells what changed what.

To address my first issue, I'm facing similar problems as described in below topics. When I release the HH pedal I get false kick tiggers (with max dyn level/time I need to increase threshold so much that soft kicks are below threshold).

HHat pedal and kick threshold interfering? http://www.megadrum.info/forums/viewtopic.php?f=3&t=1390
Electrical Crosstalk on hihat input http://www.megadrum.info/forums/viewtopic.php?f=3&t=2627&start=10

I understand from Dmitri's explanation that electrical crosstalk from HH to kick is more likely to occur because they are adjacent inputs. So before presenting my settings and logs, I guess it makes sense to first eliminate electrical crosstalk between these inputs to the max. Why is electrical crosstalk more with HH pedal open and what can I do inside my MD box to reduce this effect?

Thank you in advance for your kind advice!

[dmitri]

1. There is more crosstalk from an open HiHat because higher voltage goes to the input when the pedal is open.
2. You can adjust mechanical position of the HiHat controller device (potentiometer, hall sensor or optocoupler) so that with the fully open pedal it outputs lower voltage.
3. Raising Threshold on the Kick input also may be enough to eliminate the crosstalk to the Kick input.

[Rovalo]

Thanks. I checked my settings-values for the FD8 controller and have some thoughts, please advice.

With 5kE resistor between ring/tip the MD displays shows HH level values from 5 (closed) to 626 (open), HH setpoints are low=10 and high=575.

1. If I increase the resistor value (e.g. 25 kE) the voltage to MD input will be lower but resolution will be reduced, right? If so, what minimum resolution/range is sufficient?

2. Would it help to physically separate the Pad1 connector pin 39 wire (HH low) routing within the MD box to the HH jack from the other input wires/jacks, especially the kick input? I ask this because you also mentioned that the channels are close on the PCB so that might be of much bigger influence on the electical crosstalk.

3. Would it help to shield (ground) the pin 39 wire directly after the Pad1 connector to the HH jack?

4. Would it help to set CC red.lvl. higter than 0?

5. Any other suggestion?

After the possible hardware optimisations for sure I will test the best software settings...

Thanks in advance for your advice.

[dmitri]

1. If you can get a range more then 100 between Low and High it will be more than enough. For FD8 even less will be enough since it is not a fully variable controller as far as I remember, just a few levels.
2. The crosstalk from HiHat is mostly from too high pedal voltage and too low threshold on the Kick. Separating wires on jack will hardly help.
3. Unlikely.
4. No, CC suppression has nothing to do with crosstalk.
5. a. Reduce voltage on the pedal input. b. Increase Threshold on the Kick input. c. Move your Kick to another input.

[Rovalo]

Dmitri, do we get the same result when you write 5a. Reduce voltage (how?) and I plan to 1. Increase resistor value (or even remove resistor?)?

[dmitri]

Either remove the resistor or increase its value.
Btw, what is the Threshold and Gain settings on the Kick input and why you don't just increase the Threshold?

[Rovalo]

OK. I tried it with 22kE resistor which reduced the MD HH level to ca. 300. Btw, I see the PD8 level changing variably and not with a few levels.

Since it is still not enough I will change the resistor until I get approx. max level 100.

Before changing firmware and completing the break-out box (basically improvements with respect to electrical crosstalk) I had no issue with these false triggers. I still do not understand what causes this. I'm also not 100% sure that my settings are correct.

To answer your question about the kick threshold, I will post screenshots of MDM to show the settings. With 22k, gain 4 and dyn level/time at max I have tot increase threshold to avoid false triggers to such an extend that the soft kicks at the KD8 in my normal playing style are below threshold level and thus not registered as kicks. So I miss many kicks, which was never the case before.

[dmitri]

What was the last firmware version where you didn't have the problem?

[Rovalo]

I just returned from vacation...

I do not remember the previous firmware version, it was the original version when you shipped the MD module to me on July 28th, 2016.

[dmitri]

If it was shipped in July 2016 then it came with the firmware version 20160529. Here it is:

megadrum_20160529.zip

Please downgrade to it and confirm that problem is not there in the original version.