Midi that goes thwack

I’ve not done that kind of (euclidian?) distance stuff before, but I think it’s a fairly solved problem (??).

I would imagine a bela, or even one of those new super fast Teensy 4s would be up to handling the maths involved.

The stuff you remember, was it air/condenser mics, or contact mics? I guess there are pros/cons to each, just mainly thinking of having a minimal footprint so it doesn’t impact the playability of the drum (too much).

I vaguely remember in was rubber.
Here are speeds: https://www.engineeringtoolbox.com/sound-speed-solids-d_713.html
So you need a pretty quick sampling rate. Could be fun, but seems a hard problem for me for now…

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i guess autocorrelation could estimate time-of-arrival at different points.

then you are doing TOA sonar/radar stuff, which is well studied indeed

Hi everyone,
thank you Rodrigo for you Boppad video.
I was thinking about buying one too to control some synths. I was wondering how i could use it with a e-drum hihat trigger to have more expressivity ?
I guess I would have also to also get a drum module and plug my hihat trigger jack in it and then send midi from the drum module to my synth ? I don’t really know how e-drums work ans if they can send midi to other pieces of gear.

I’ve not worked with hihat triggers at all, but presumably you could use an Arduino (or Teensy) and convert whatever it’s output is to regular MIDI?

My understanding of hihat sensors is they are analog “pressure” sensors.

You can also go a fully DIY route:

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Yes I could do that but if possible I want to use solutions that already exists.
Because the Boppad has a midi expander, I was thinking about using a e-drum module(like the Roland TMC6) to convert hihat pedal in midi signal and pack it with the boppad to then send it to a hardware synth.
But it seems very unlikely that a drum module would mix both type of signal as if it was a simple e-drum hi-hat, maybe you’re right I’ll have to convert audio to midi from the hihat trigger and mix it with the boppad signal.
This could be a good start :

So… My Boppad is… well… slowly being beaten to death: The USB connector can be flaky, and the black outer bezel is detaching. AND, as K-M never ever fixes firmware bugs, it still has the bug where it decides to issue totally nonsensical radius values.

(Yeah, I submitted a bug, they acknowledged that they could reproduce it - and their solution was to tell me to unplug and replug the unit, as it resets back to normal… like I’m going to do that in the middle of a performance!!! And yeah, they kinda outright said they’ll never ever fix it or rev. the firmware.)

SO - Anyone have any good alternatives? The feature set is right. I don’t want a $1k+ machine with it’s own sound generator. I don’t want “an electronic drum set” - I want a MIDI control that I can drum on with sticks. I want multiple zones (four is fine) - and I’d love radius or x/y as well as velocity.


it’s not a matter of price… (though that “merely” $500 DrumKAT requires a $600 DITI controller to actually do anything…) – Just the KAT line seems to be very awkward - lots of cables, heavy parts… and yet with a feature set that doesn’t look like the kind of flexible thing folks in this thread are looking for. The sensors have no position sensing, and it isn’t clear if they do anything post-hit. The DITI unit is aimed at setting up a traditional style drum layout - including sensors on standard drums.

What I want is a well made Boppad, or a Sensel Morph made for beating with sticks.

Mine is still structurally sound (though I did get a replacement sent out because mine was getting “polka dots” which was an issue with the first run I guess).

I have been pretty disappointed with the radius data, and after sending them some videos a while back, it seems like the radial (?) resolution is primarily 5 steps which it interpolates between, and that’s most aparent when you play softly as you get these crude jumps in position that have little bearing on where you’re playing. I’ve made a workaround abstraction where if the velocity value is repeated (unlikely in the “real world”) I +/- a random amount. Not great, but it sounds a bit better as it’s less machine-gun-y.

I’ve been talking with a friend about working out some kind of DIY alternative as I’ve not seen anything that does this well. I did find the Mandala drum but prior to this they weren’t available, and checking now the webpage has been taken over by spam…

So all of that is to say, that I too am keenly interested in alternatives.


Do you mean the yellowish dots that appear on the surface? I didn’t know you could get a replacement for that and the newer units didn’t have it! It’s so annoying on mine :-/

Overall I agree the Boppad feels a little half baked quality wise. Not even commenting on how, on windows, it’s impossible to have both the editor and Ableton running at the same time which makes it a complete nightmare to program efficiently… I mean at first it might have been ok but years after the initial release if just feels lazy and a little disrespectful.

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This is what mine looked like after a while:

I wrote them last year (or maybe a bit longer) just to inquire cuz I thought it might be something going on. They said it was “cosmetic” and didn’t effect performance at all, but that they would replace it if I wanted (bit of a PITA shipping from the EU).

A lot of the KMI stuff has that feel to me. Good ideas, and in some case, genius ideas (BopPad, SoftStep, etc…) but they get like 80% of the way there, and then kind of say “good enough”, which is a shame.

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Couldn’t agree more. Always wondered if I was alone. The materials selection & long term durability of KMI stuff turned me off several years ago. Where “long term” is more like two years.

It’s a shame. He’s definitely got the pedigree and staff to pull the whole thing off.


This is so disappointing to hear. I still haven’t jumped into the boppad, but it’s been in the back of my mind for when I have more space for music devices.

Sensel has continued to reassure me that the Morph is drum-stick-friendly, but I haven’t checked recently if they’ve updated their software to support actual velocity curves instead of just thresholds (which also introduce latency).

Incidentally, I usually hate on The Algorithm, but instagr*m just showed me this as a sponsored post. Seems interesting, but unfortunately marketing videos never show stress tests anymore

Absolutely, also what’s absolutely crazy and unexplainable is the lack of competitors. I find where KMI is so clever is in how it understood the “less is more” needs of a lot of musicians out there. Basic, transportable, no fuss layouts, and things we need (a surface for sticks that’s NOT just a big pad with velocity, a midi pedalboard that’s NOT a tank made of the heaviest metal the earth ever knew and still has many buttons, etc.) but they always seem like replicable ideas too, that none of the bigger or smaller competitors offer similar products is… Hard to understand. I’d exchange 50% of the eurorack production for better and more varied controllers.

Also btw yes the dots is exactly what I have on mine, they’re even more visible with time. Too bad I didn’t switched mine back then.


Interesting. When checking the photos for the Kickstarter campaign it looks fucking gigantic!

I do worry of the durability of something like that if it’s meant to be playable with fingers too.

From the look of the Sensel, I wouldn’t trust hitting it with sticks. I’m not a very heavy player, but that thing is thing… and that lip along the top is begging to be smashed in…

I think a big thing is the price point. All (most) of their stuff is quite cheap for what it is, so it’s possible competitors can’t compete on the price, but I’d happily pay more for something with monome-levels of attention to detail…

It’s worth dropping them an email. Mine was perhaps 2y old by the time I wrote them. I didn’t inquire about a replacement, I just asked “if this was ok”, and they offered.

Absolutely that. I was thankful the Boppad was this cheap, but with so many shortcomings, I’m just a bit bummed now that no one’s making a better Boppad or a better Softstep even at twice the price. I can’t understand how basically I’ve got a trillion options for finger drumming pads in all possible price brackets, or sensibility or squishiness so that I can be completely obsessive with every detail if I so wish, and so little for stick compatible transportable controllers that we’re here wondering at what strength we should hit a Seinsei Morph that wasn’t designed for that at all.



As I said, I’ve been doing some investigations for a DIY option with a friend, but that’s not gotten anywhere yet.

But I do wish someone would make something like that but better. And as you said, hell, every KMI, but better. KMI+ Pro(!).

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That’s very interesting, it seems a bit bigger than I’d want it to be really so it looses a bit of the portability factor of the Boppad, but I’ll make sure to look at more demos of it.

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I’m reanimating this thread for some advice: my wife is a drummer. We’d like something where she can trigger events in Ableton Live. It will be used in combination with a drum set. I am the one who is better at software but I hate troubleshooting and configuring. We don’t need built in sounds, but I’d like something that is robust and just sends some kind of MIDI event per pad, and where that can be edited simply.

I have had the same experience with KMI that Rodrigo and others here have had (broken USB connector that cost $100 to fix, buggy software, etc), so I am reluctant to go that route. We don’t need all the built in sounds of the Roland SPD-SX.

If the Boppad a) didn’t have bugs and b) was physically robust, it would be perfect. I’m a Linnstrument user and quite like it, so I know that “better” is like.

In the future I might be interested in connecting it with my modular but that’s down the road.

Roland SPD-6 ? (around $200
On eBay)

(Wow - my SPD-20 appears to be worth some cash based on ebay prices)

There’s also some “stick on drum triggers” which could be fun, but you’d need a brain or something to make the pulses into midi. (Used alesis brains about $60-80 - or the alesis Trigger|iO looks like a good solution - $110 on reverb)

A microphonie or ears module could get impulses into the modular perhaps?

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