Adapt a Waveblaster soundcard to the ST

The PC-world is filled with simple things with fancy names, and Waveblaster is one of them. It's a impressive sounding name for a impressing sounding technology from Creative Labs, but in reality it's nothing but a combined MIDI- (crippled ofcourse, this is PC- technology) power- and audio-connector. The purpose of the Waveblaster-port (which is present on most/all Soundblaster-cards and -clones) is to connect a daughterboard with proper MIDI-sound. By building a Waveblaster-port yourself you can connect these cards to your ST/Falcon/whatever.

What do you need?

  1. A computer with a standard MIDI interface.
  2. A PSU that can deliver +5v, +12v and -12v.
  3. A piece of Veroboard or similar, some cheap parts.
  4. Some experience with a soldering iron.
  5. A Waveblaster MIDI-card.
Point 2 will probably cause a few headaches, as the standard PSU in the (Mega)ST/Falcon doesn't have -12v. I have been informed that the TT- and MegaSTE-PSU will deliver -12v. You'll also need some space for the card, so this project is probably best suited for those of you that have recased machines with PC-powersupplies.

It's also possible to convert a Waveblaster-card into a complete standalone MIDI-unit (Elektor Electronics, July/August 1997), but buying a ordinary GM/XG module is probably cheaper.


This is the layout of the Waveblaster port:
[Waweblaster pinout]

    Waveblaster pin-layout

  • 2,4,6,8,10,12,16,18,20,22,24,26: Ground
  • 3: MIDI in
      The MIDI-input is TTL, so you'll need some circuitry to convert the standard MIDI current loop to TTL.
  • 14,1,7,11,15: Not connected
  • 5,9,13: +5V
  • 17: +12V
  • 21: -12V
  • 19: Audio out, right
  • 23: Audio out, left
      The audio-outputs are standard line-level, but can't deliver enough juice for headphones.
  • 25: Reset
      Reset is active low.

The complete circuit

This circuit has everything you need to connect a Waveblaster-card to your ST/Falcon. It consists of three main-parts:
MIDI "current loop" to TTL converter
The optocoupler IC1 with the additional parts D1, R4 and R5 converts MIDI "current loop" to TTL. This is cruical, I tried several solutions before I resigned and ordered myself some optocouplers.
Buffer and MIDI-THRU
IC2 buffers the converted TTL-signal before it's fed to the Waveblaster-port, as well as providing a MIDI-THRU together with R2 and R3. MIDI-THRU must be used as your machine's new MIDI OUT if you need one.
R1/C6 resets the card at power-up. You could replace C6 with a switch and reset manually, but I wouldn't recommend that as the card can easily be reset by software if needed.
[complete circuit]
Click on the circuit to download a larger version.
R1 - 10KOhm
R2, R3, R4 - 220Ohm
R5 - 1k8Ohm
C6 - 10uF/25V
C7 - 100nF
D1 - 1N4148
IC1 - CNY17-2 (I've used a CNY17-3)
IC2 - 74HCT00

Some connectors, wires and a piece of Veroboard.

Yamaha DB50XG

My Waveblaster-card is a Yamaha DB50XG, which is rather expensive but also rather good :-) Any Waveblaster-card should work, but I have only tested the Yamaha and can't guarantee anything.


Some useful software for XG-cards and MIDI in general.
  • DB50XG Control.
    Tiny application for resetting the DB50XG to XG or GM mode.
  • SMF-Player
    Simple and useful MIDI-player. Doesn't multitask though.
  • Sweet Sixteen
    Simple and good sequencer, also good for playing MIDI-files. The timing is excellent and it runs well in a multitasking environment.

XG songs


Updated 13/01/99