MBSID & Midibox Sample Player built inside an M-Audio Keystation49

[jjonas]

Hi,

 

I had already built a and a with Mellotron samples to serve as a "digital Mellotron", but now I decided to scrap both these stand-alone units and build them both inside a midi controller keyboard instead for more convenient use – no cables or other hassle. Plus you can still use the keyboard to control external stuff as well.

 

Here's what the finished unit looks like:

 

 

The sample player has no hands-on interface, there's just 8 banks of mellotron samples available on channel 11. The MBSID however comes with the LCD plus the necessary buttons. The four red knobs don't do anything yet, but I'll assign them to filter and LFO tweaking functions later. Note that the knobs are aligned better than the buttons – that's because the front panel had holes for knobs underneath the "M-AUDIO" panel, probably because the same case is used for some more advanced model with knobs as well.

 

Below the keyboard from the inside.

 

 

On the left there's the original PCBs of the keyboard, and on the right there's what I put in.

 

 

The placement of the sample player (SP) stuff. I use the keyboard's own 12VDC switching PSU (2A) to power the whole thing (i.e. keyboard, MBSID, SP), and I think a slightly bigger cooling element for the 5VDC regulator wouldn't hurt here. While testing this part of the keyboard I had problems with the sample playback quality worsening in 3-4 minutes and eventually turning into some kind of square wave sound. I managed to correct this by changing to another SD card interface. I haven't done further troubleshooting yet to find out whether it was the microSD or the adapter that caused the problem.

 

In terms of height, there was barely enough room for the partly populated LPC17 PCB and the MBsid PCBs, but they did fit. Originally I built the SP inside a Roland PC-180A, which was ok too (though I had to cut out some plastic), but when I got the idea to build the MBSID inside a keyboard as well, I had to do it using another keyboard, because the Roland didn't have space for an LCD.

 

 

The placement of the MBSID stuff. Probably I could have used the "normal" SID modules as well, but I preferred to use the one I reorganised and etched myself because the connectors fit better. As you can see the "SIDs" are actually two SwinSID nanos. Because the realistic alternative would have been to use two 6581s, I decided to keep the the SwinSIDs to spare myself from having to go buy a 15VDC PSU and from using further heat sinks. The SwinSID sound is not as good, but it's definetely ok, and even more so as I built this for band rehearsal purposes – of course recording will be performed on an MB6582 with the real stuff in it :-)

 

 

Here's how I initially tried to put the tactile switch buttons in. There was *very* little space above the keys here in the cover panel, and it turned out that using hot-glued 5mm hex nuts and a strip of veroboard with tactile swtiches on it didn't work for that reason – it was too much to fit in. So I got rid of the hexes and the veroboard, and hot-glued the tactile switches directly on to the panel:

 

 

Even that fit only barely, but it did fit! On the previous picture you can see on the right that the four buttons (up-down-menu-shift) are still on a PCB that's been hot-glued on. However I had to change that too and just hot-glue the buttons directly on, otherwise there was a key that got stuck.

 

 

The two narrow strips of veroboard on the right are for MIDI (left) and power supply (right). I soldered wires to the the legs of the keyboard's midi out connector, and the midi messages are distributed to the MBSID and SP from the veroboard. Likewise with the power supply, though in this case I added a separate power switch for the MBSID/SP, in case you need just the keyboard on to play "external" modules or whatever.

 

 

Finally, the unit from behind. Three new items: SP out (mono), MBSID out (stereo), switch for MBSID/SP.

 

NEAT, INNIT?!?!?!?! :-)

Edited April 6, 2013 by jjonas

[ErMangaver]

Yeah, very nice job you've done :)

[Hawkeye]

Awesome work! Looks really nice and is probably lots of fun to play! I like integrated keyboards with SID modules :-)

 

Many greets,

Peter