MIDI Narrator

Introducing a new Rare Waves DIY electronics kit for 2018!  MIDI Narrator is an electronic voice synthesizer for creative audio producers.  It is built around the classic SP0256A-AL2 speech chip from 1981.  This chip was used in early arcade games and home computers, and it was distributed to hobbyists by Radio Shack as the SPO256 NARRATOR.

This vintage sound chip has a gritty, undeniably 8-bit tone quality that you can bend in various ways with the fun features we’ve added.  With the MIDI Narrator kit, you can access its sounds with creative control.

Plug in a MIDI controller and play all of the SP0256-AL2’s allophone speech sounds live!

Use it with your MIDI sequencer or DAW to add vintage computer voice effects to your compositions!

Press the buttons to trigger 8 stored phrases, no MIDI connection required!

MIDI Narrator adds special audio features above and beyond the SP0256-AL2’s native capabilities.  It has several types of pitch variation that break free of the usual monotone robot voice.  MIDI Narrator includes pitch bend, vibrato, and a random pitch effect.  The pitch effects are made possible by clocking the speech chip with a VCO instead of the usual 3.12MHz quartz crystal.

It also includes a beat-synced stutter/glitch effect, and arpeggiator-style sequencing that’s great for making rhythmic loops out of the SP0256-AL2 allophone sounds.

MIDI Narrator has 8 memory locations for user-generated phrases.  You can program it in step-time from a MIDI controller.  Trigger the phrases to play back from its onboard buttons, or by MIDI commands.

Modular synth users can experiment with its Gate Out patch jack, and you can add an optional CV Input for tuning the voice.  (CV In is not 1V/octave).

MIDI Narrator’s main purpose is to create sound effects and short sentences. With that in mind, please note it does not have a text-to-speech function, and the voice’s melody is not playable by MIDI keyboard.


PDF Documents

Have a look at the top-quality, detailed PDF documentation for this project.  We’ll walk you through the assembly sequence step-by-step with clear instructions. We’ve also included helpful information for those who’d prefer to build it into their own custom case enclosure.

To learn how to create speech with the SP0256-AL2, it is best to refer to the original documentation that Radio Shack published with the chip.  Begin on page 6 at the section titled ALLOPHONE SPEECH SYNTHESIS.

SP0256-AL2 original Radio Shack datasheet

Note: the unit pictured above has a special ZIF socket for the speech chip. Your kit includes standard IC sockets for the microcontroller and speech chip only. The ZIF socket isn’t included.


MIDI Controller Maps

The MIDI Narrator User Manual PDF contains helpful charts you should refer to for sequencing speech with the SP0256-AL2 allophones.

A MIDI keyboard with 60 or more keys is helpful to easily access all the sounds.  Here’s an example of the piano keyboard allophone map from the User Manual:

If you have an 8×8 pad controller, we’ve prepared a convenient allophone map chart for your reference:

Here is the reference chart for the allophones in a DAW piano roll edit window: