ST-1

ST-1 Speak & Tweak is an emulation of the classic SP0256-AL2 speech chip that was a popular add-on for many home computers in the early 80s.

Speak & Tweak produces sounds using a crude model of the human vocal tract with 6 cascaded digital filters, white noise generator (breath) and tone generator. It contains 59 allophones which when concatenated correctly, can create most English words.

The result is a monotonic, robotic sounding voice that can be tuned precisely to any MIDI note, and is recognisable by anyone who’s heard a speech chip from the early days of computing.

Version 1.1 also adds an audio input to allow you experiment with audio sources other than the built in pulse generator.

• Emulation of SP0256-AL2 and English rules
• Speed and pitch controls
• Lock tempo control (allows multiple voices to play at same speed, different pitch)
• Bucket Brigade Device (BBD) Delay
• Polyphonic use
• Single word per key modes
• Damage control to artificially detune the filters
• Slur CV input to repeat last allophone
• Pitch bend and after-touch support
• Low DSP usage
• Plenty of CV inputs

Version 1.1 Adds:

• Audio Input for vocoder style effects
• Tempo synchronised delay

Version 1.2 Adds:

• Pitch change on punctuation characters (‘,’ ‘.’ ‘!’)
• Sync 8th and Sync Quarter modes to synchronise word playback to music tempo