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oklahoma

I have a bent casio pt-80.  Makes great drum sounds. I want to find a way to midify the drums. Just some midi notes that trigger a drum sound. I got a midi input mod board (UMR2 clone) for an sk-1. That got me thinking about this.  I dont think that I can use the UMR2 board for this cause it is designed and programmed to use a keyboard matrix, or maybe the buttons that pick a drum pattern. I want to control these drums with a daw via midi. So, I have to figure out how this machine makes the drums. Says they are analog, so I'm hoping for individual circuits for each sound that I can trigger and maybe have seperate outputs. I'm going to get a cheap oscilloscope and start trying to find these signals. But then I probably need an arduino or teensy type controller to take midi notes and make analog signals to trigger the drum sounds.
It would also be super cool to have midi cc controlled switches and pots. To control the bends via midi.
I'm in over my head.
Any help would be great. Ideas welcomed. Hints,tips, and any advice please.

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Alive and well in fucksville

Don't add arduino to it without using diodes. Power going backwards might harm it. Are all the bends on one hot wire? I would also worry about too much power.

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oklahoma

I do not remember what the bends were. I am going to try this on a fresh one. I can bend it afterwards if it works.
Finding out if I can bypass the CPU and just trigger the drums is 1st step. If not, I'm probably stuck. Trying to get something coded to talk to the CPU to get it to trigger the drums is probably too much for me to figure out. 
Is arduino or teensy my best bet to take midi notes and translate those to separate triggers? And are there resources already coded that I could get tweaked enough to work for this idea?

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Oregon

This sounds like a serious project that has no benefit at all over just sampling the drums into Ableton or any DAW you like and making a drum rack. Or, sample the drums into a device like the Digitakt and sequence them that way. Or, use a classic rack sampler and load in samples of the drums to have them addressable over MIDI. There are a million easier ways to have the exact same drum sounds addressable over MIDI, and since they aren't editable drum sounds, just PCM samples inside the Casio, there is no benefit to having them play on the machine itself. It's all samples either way. If your bends are affecting the drum sounds, then just sample each drum sound with a bunch of different versions, clean and glitched, and have them all sliced up. If you use something like the Digitakt you'll be able to manipulate the samples with filters, bit-reduction, glitching, overdrive, delays, etc and you'll have lots of fun. If you use long samples that are built from the same drum sound but many versions of it in the Digitakt, you can set an LFO to manipulate the sample start point and get a different version of the drum sound each time it triggers in your sequence. That would be WAY more fun than fucking around with an old Casio (I love old Casios), leave that thing alone and don't drill a bunch of holes in it to produce sounds that are mostly unusable. Feel free to prove that last bit wrong with a video of your bent Casio sounding super rad, proper line-out audio please... You said "any advice please" and that's my advice.

Last edited by Hawk (Nov 20, 2019 11:04 pm)

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Sea of Souls

Hawk may be right about sampling.

But for the sake of scientific experimentation, I want to know more about the internal drum triggers. If you can probe pins on the ICs, you may be able to locate the physical points where we can trigger the drums. Get yourself a wire and resistor(10k-100k), connect it to a ground point and use the other end of the wire to poke pins until you get some noises. If The ground connection does nothing for you, try it with +5v and the resistor of course. The resistor should protect against shorts.

IF you are able to find physical points to trigger the drums, an arduino code to output the appropriate high or low-edge trigger on any number of output pins with a midi input.

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oklahoma

Hawk, you are brutally honest. Thanks. I 100% agree. You are correct.
My interest is more for a personal learning journey along the path of electronics. "Can I make this idea actualize in my real world?"
Because, in the end, you either need the "seriously amazing"

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oklahoma

Hawk, you are brutally honest. Thanks. I 100% agree. You are correct.
My interest is more for a personal learning journey along the path of electronics. "Can I make this idea actualize in my real world?"
Because, in the end, you either need the "seriously amazing" bends I did, or loooong fx chains to make these casio bangers happen.
  I never thought about that sample start/stop manipulation bit. Clever. I usually round robin separate samples. The other way could lead to some interesting outcomes. Especially if sloppy with the timing and getting parts of 2 sounds instead of 1.
I wish there was a Casio pt-80 schematic somewhere... "Come on, universe! I need a miracle!☝"
I will probably wait for the tiny scope and try to find the signals that way. I'm scared to bend anything that I'd like to keep. I have a working one that I bent, and one that is cold and lifeless, after just a minute of random bending trials. It serves as a reminder of the inherent dangers of actions in ignorance.
So I'm getting a fresh, clean one and trying a more informed approach. I hope.
Thanks, Orgia Mode. What you're describing is pretty close to my dream outcome. The thing there is I have about 0.001% experience coding. So...im still gonna need someone more knowledgeable to hold my hand and point the way.

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oklahoma

Hey Hawk, do you know for sure if they are PCM samples stored in a chip somewhere? I had read they were analog drums, so I was hoping for some individual circuits.
There isn't a lot of technical info for this little dinosaur.

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Oregon

Some of the early Casio boards used analog drums but they switched to PCM samples fairly quickly. I just looked up the board on Tablehooters and found this at this page: http://weltenschule.de/TableHooters/Casio_PT-80.html

"simple analogue percussion with transistor noise (base, low tom, mid tom, high tom, snare, open & closed hihat}"

So it looks like you're correct, they are analog. Personally I would still sample, please don't kill any more of these sweet little keyboards, but it's up to you of course. Have fun!

On a similar note, if you're trying to explore electronics, you might try building your own simple drum machine with individual circuits for each drum voice, it can be very simple with just a few parameters per voice, and it does not need to have a sequencer or anything like that built in, just a MIDI interface to trigger each voice. I recommend this over modifying the Casio, and you'll have better sounding drums too!!!

Last edited by Hawk (Nov 21, 2019 1:34 am)