Akai MPX8 "Sample Player" Teardown

[DX21]

First off, this ain't no review, this is an electronic biopsy.

Ok. so I picked up this little bugger for about $100 because it seemed like a neato drum machine.

Curiously, knowing Akai and their lazy however effective design ideals of "Lets grab a bunch of off the shelf chips that do at least one of the things we want it to do and build some good gear around it" I decided to pop this bugger open.

I didn't expect much, after all it was 8 pads, 4 buttons and a Rotary knob.


However, the chips inside gave me a bit of a bit of surprise.

The main chip is a Medeli A2 Processor chippy which looks like this:
Possible Datasheet, seems to be at least close: http://www.icmedeli.com/download/M2000SPEC.pdf
The other notable chips are what appears to be a 1mb flash chip for the A2 Processor to boot off of Marked 1.0.0 which oddly in the Factory reset mode the "SD" is listed at 1.0.0 even after I installed the factory update, Note the Midi Error is because I had nothing plugged in at the time.

The Nice white text on blue reminds me of my old Commodore 64 :3 (wish I never sold the damn thing when I was a stupid teenager, I could be playing turrican right now )

The Large one marked V1.1.1 appears to be a 64MB Flash Chip
The EtronTech Chip is 16MB Ram and its datasheet is here: http://www.etron.com/manager/uploads/EM ... S_v1.4.pdf

The first line from the 1.0.01 firmware update appears as so: Medeli Electronics Co., Ltd.....AKAI MPX8.......V1.1.01.........20130609........SEL+....VAL+....................Data Number.é...A2_ISP.BIN......................A2..........A2..1MB.ini

Right now I'm poking around in the device's boot firmware, there might be a possibility to expand its Midi Implementation, install more ram for samples, Use MPEG Encoded samples (mp2, mp3), decrease load times, turn into a USB sound card, Maybe turn it into a simon says game, make it do the funky chicken, etc.

Interesting Secrets:
Select - and Volume- at power on brings you to the factory reset then the test mode.
Select+ and Volume + at power brings up the SD Firmware update mode.

Hope this is at least even remotely interesting to you.

-Dx21

[Hugo76]

This is very interesting. Will you go ahead and modify the code? And do you think it'd be possible to add more features?

[Ugly Goblin Boy]

Wow, great break down! If you could figure out how to change the MIDI channel, that would be amazing. Having it stuck on 10 is a drag...

[somebedroomdj]

Very cool thread! I don't know much at all when it comes to bending and stuff like that but how likely do you think it would be that an overdrive knob or switch could be added? I use mine strictly as a drum module and that would just be amazing.

In any case, looking forward to anything you find here.

[moremagic]

Wow, great break down! If you could figure out how to change the MIDI channel, that would be amazing. Having it stuck on 10 is a drag...

but channel 10 is the cool channel!

[DX21]

Very cool thread! I don't know much at all when it comes to bending and stuff like that but how likely do you think it would be that an overdrive knob or switch could be added? I use mine strictly as a drum module and that would just be amazing.

In any case, looking forward to anything you find here.

Underclocking or undervolting throws off the whole system, I've run it on a battery pack with deceased batteries and it seems to simply not tolerate low voltages as this is essentially the brain of a Midi Drum kit like a Yamaha DTX shoved in a little box.

I'm still sniffing the GPIO and such, maybe I can get it into bootloader mode or some crazy stuff

[DX21]

Update: I found a nifty Pad calibration menu if you hold select + and volume -,
My Velocities seem to go between 5 and 125.

It made the pads a bit more sensitive!

[DX21]

With a little messing with Audacity you can squeeze a whole average dance track into 8bit PCM @ 22khz

Its a fun way to use one of the pads, as you can play along with a track
8-bit PCM:
https://www.mediafire.com/?ab482j9j1ljfeal

It takes damn forever to load but the cool thing is it will keep playing even if you eject the memory card which is interesting...

[ABigPancake]

Hi,

It's really cool that you opened up the MPX8 . I was thinking of buying one but the main thing that put me off is that there is no battery power and people said the jog/data wheel is not great.

Based on your pictures I guess there could be room for an internal lipo battery and charging circuit
Did you get a look a the jog wheel? I wonder if it can be changed/fixed up better

Thanks so much for your post...

Adam

[DX21]

Hi,

It's really cool that you opened up the MPX8 . I was thinking of buying one but the main thing that put me off is that there is no battery power and people said the jog/data wheel is not great.

Based on your pictures I guess there could be room for an internal lipo battery and charging circuit
Did you get a look a the jog wheel? I wonder if it can be changed/fixed up better

Thanks so much for your post...

Adam

There is enough room for a few flat pack lipo batteries inside, However it would be easier to pick up a nifty USB Battery pack though if you aren't adept with a soldering iron.

The jog wheel itself can be fixed up by putting a circle of baking paper or tracing paper (note not Wax paper) under the jog wheel's knob to keep it from grinding the plastic under the knob and making it hard to cycle fast.

[ABigPancake]

Hi,

It's really cool that you opened up the MPX8 . I was thinking of buying one but the main thing that put me off is that there is no battery power and people said the jog/data wheel is not great.

Based on your pictures I guess there could be room for an internal lipo battery and charging circuit
Did you get a look a the jog wheel? I wonder if it can be changed/fixed up better

Thanks so much for your post...

Adam

There is enough room for a few flat pack lipo batteries inside, However it would be easier to pick up a nifty USB Battery pack though if you aren't adept with a soldering iron.

The jog wheel itself can be fixed up by putting a circle of baking paper or tracing paper (note not Wax paper) under the jog wheel's knob to keep it from grinding the plastic under the knob and making it hard to cycle fast.

Hi,

Thanks for the further info. I think I will get one as a portable practice pad

Adam

[freshnelly]

That is so funny! I have just pulled mine apart, searched for the processor and ended up here! I've just put mine back together, no point as your insight is great!
I'm trying to figure out how to add a MIDI program change to control the wheel remotely, but because the unit stays on the last setting on power up, if things got out of sync, it'b be useless. I thought about siphoning data off the LCD to read the "Exx" or "Ixx" number on the screen, but it seems to be an embedded driver so that could be a bit more difficult. I suppose connecting a microcontroller to the reset combination that beats the MPX to the punch might work... to do a reset every time the unit is powered up.
Anyone have any thoughts?
I was amazed they hadn't included PC in the implementation

Added Feb 21st: I have posted a page on the MPX8's "Missing Notes" issue having solved it with some hardware I just designed. Also Doubles, or low velocity repeats has been solved. http://freshnelly.com/mpx8.htm

[DX21]

That is so funny! I have just pulled mine apart, searched for the processor and ended up here! I've just put mine back together, no point as your insight is great!
I'm trying to figure out how to add a MIDI program change to control the wheel remotely, but because the unit stays on the last setting on power up, if things got out of sync, it'b be useless. I thought about siphoning data off the LCD to read the "Exx" or "Ixx" number on the screen, but it seems to be an embedded driver so that could be a bit more difficult. I suppose connecting a microcontroller to the reset combination that beats the MPX to the punch might work... to do a reset every time the unit is powered up.
Anyone have any thoughts?
I was amazed they hadn't included PC in the implementation

Added Feb 21st: I have posted a page on the MPX8's "Missing Notes" issue having solved it with some hardware I just designed. Also Doubles, or low velocity repeats has been solved. http://freshnelly.com/mpx8.htm

hmmmmmn maybe I can add a bit of fudge to the GPIO routine... so it doesnt pick up debounce or shitty hits.

PREPARES COFFEE

[DX21]

Here's me using the MPX8 as a game controller for In The Groove 2 (Like Dance Dance Revolution)

It's super accurate and I used Bome Midi Translator Pro

Here's the button settings, the top ones are now set to the Start, Back, Coin and FastForward buttons, which are set up similar to the arrows.



For you DDR Nerds: This doesn't suffer from the Axis problem at all as each button is its own midi signal.

[DX21]

Hi,

It's really cool that you opened up the MPX8 . I was thinking of buying one but the main thing that put me off is that there is no battery power and people said the jog/data wheel is not great.

Based on your pictures I guess there could be room for an internal lipo battery and charging circuit
Did you get a look a the jog wheel? I wonder if it can be changed/fixed up better

Thanks so much for your post...

Adam

Good news on this front, I took a trip to the dollar store to get myself a little AA Battery powered USB backup cellphone Charger, out of curiosity I plugged it into my MPX for science purposes....

The drum machine itself draws a good 500mA which will unfortunately eat anything but the strongest NiMH Rechargables.

I'd say a pair of 2500mA Energizer NiMH batteries Should in Theory give a few hours of use.

This won't work for very long with standard Alkalines due to the power draw.

The consistent power drain may cause Lithium's to become very warm in some cases (as lithium's are designed to be used in bursts, like in cameras, or flashlights)

but here it is, living on a pair of dollarstore alkalines, which lasted approximately a whole 30 minutes