vocal synthesizer

dual SP0256 vocal synth

dual SP0256 vocal synthesizer  dual SP0256 vocal synth  dual SP0256 vocal synth  dual SP0256 vocal synth  dual SP0256 vocal synth  dual SP0256 vocal synth

 vocal synth introduction

 oh oh oh yeah

 phoneme harmony

booty chip

The Dual SP0256 vocal synthesizer is the descendant of an earlier circuit of mine, Analog Controlled Speech Synthesizer.  I crammed in all the features I’d want from a singing robot.  It was a good challenge because it inspired some analytical thinking about the relationship between speech and singing.  The features of this circuit are:

  • 2 trigger inputs to step through pitch and vocal sequences independently
  • speech data stored cartridge-style on EPROM
  • 2-oscillator richness using dual SP0256-AL2 speech chips with crossfade mixer
  • optimized low-pass filtering for less strident tone
  • SP0256 crystal oscillators replaced with VCOs for pitch control
  • each chip has an independent / linkable 4-step analog step sequencer for pitch
  • lower step sequencer has switchable clock divider (divide/2 to divide/16)
  • glide and LFO functions
  • speech rate (slur) control
  • built-in realtime programmable sequencers for pitch and speech trigger
  • IR Sync input for wireless infrared tempo matching

And as a bonus, it makes a hair-raising screeching sound when the power is turned off!

 power-off noise!

The Dual SP0256 vocal synthesizer is now a member of Bodytronix.  It begins to speak at 1:05 in this video clip:

To see how to replace the SP0256’s crystal oscillator with a VCO, check out the schematic for analog controlled speech synthesizer.

To compose the speech data I begin with the free PC app ChipTalk.  ChipTalk converts plain text into SP0256-AL2 phonetic data.  I paste that data into Excel, and compute some binary math thats necessary to add the ‘wait for trigger’ and ‘loop’ flags where desired.   Then I use a hex editor such as Hexplorer to organize the contents of the speech EPROM; its organized as 16 phrases of 256 bytes.  Once the EPROM image is composed, I burn it onto a 27C256 EPROM with a TrueUSB Willem programmer.

 SP0256 language chart

Sorry, the vocal synth is not for sale.  No kit version is available.  Schematic is private.