VAX firmware for Kraftor: user guide
The VAX firmware lets you speak text, shape voices and trigger sentences from MIDI notes. Save sentences and voice settings in FRAM for standalone playback, or send text and commands over USB.
Choose the tool that suits your task: VAX Designer for saved sentences and voice settings, VAX Phoneme Translator for phonemes, pitch and duration and Echo for the serial terminal workflow.
Install the firmware
For Kraftor with VAX. Do not use this firmware for EMY or Terminal.
Three tools for working with VAX
| Tool | Use it to |
|---|---|
| VAX Designer | Edit and audition sentences, adjust voices and save them in FRAM. |
| VAX Phoneme Translator | Prepare phoneme sequences with pitch and duration. |
| Echo | Send text and serial commands, and create temporary MIDI phrase mappings. |
All three tools run online in your browser.
VAX Designer: edit, audition and save
Open VAX Designer · Designer user guide
Connect → edit → audition → save
- Connect Kraftor with a USB data cable. Open the Designer in a browser with USB MIDI support, click Connect Kraftor and allow access.
- Select a slot in the library on the left. Choose Slot under Voice parameters to edit its voice settings.
- Enter a sentence, choose a voice and adjust the controls.
- Click Audition draft to hear your changes.
- Click Save to Kraftor. Use Play saved slot to hear the stored sentence.
Edits stay as browser drafts until you save them. Once saved, Kraftor can play the sentences over MIDI without the Designer connected.
Saving sentences in FRAM
FRAM stores 100 slots, each with a sentence and its voice settings. Sentences accept up to 200 ASCII characters; the Designer also checks that the text and voice design fit the slot’s storage limit. Saved slots survive a restart.
Auditioning works without FRAM. Saving requires initialized FRAM. The Designer’s Format action erases existing memory, so export a backup before formatting an existing bank.
Use Bulk paste… to prepare several sentences, then audition and save each slot. Export backup saves your bank and mode to a file; Print saved slots creates a reference with sentences, settings and MIDI notes.
VAX Phoneme Translator: pitch and duration
Prepare phoneme sequences with pitch and duration to control pronunciation and make VAX sing. VAX accepts ordinary text, native DECtalk commands and phonemes. The Designer also provides DECtalk help beside its sentence editor.
For phoneme sequences with pitch and duration, open the VAX Phoneme Translator.
Echo: serial commands and temporary phrases
The legacy serial workflow lets you type text and commands directly. Open Older firmware / serial tools → Connect serial in the Designer, or use Echo at 115200 baud. Disconnect serial before using the Designer’s main connection.
Temporary MIDI phrases
Enter phrases separated by @:
@one@two@three@four
This loads up to 12 temporary phrases into RAM, mapped to MIDI notes 36–47. They disappear after restart and never write to FRAM. Temporary phrases take priority over saved slots on matching MIDI notes; Play saved slot and /pN still play the saved FRAM slot.
Serial commands
Type /h for the command list supported by your installed firmware. Enter serial commands in the terminal; the Designer’s sentence box is for text and native DECtalk syntax.
/h Show serial help /f Show firmware version /l List saved FRAM slots and current mode /m Show MIDI channel, controls and temporary mappings /g0 Select and save Slot mode /g1 Select and save Controller mode /pN Play saved slot N (0–99), e.g. /p0 /vN Set live voice (0–8) /r200 Set live speech rate /d ap 90 pr 0 Set live voice design /o Reset live design parameters /i Show terminal voice settings Text + Enter Speak the text @one@two Load temporary MIDI phrases
Play over MIDI
Set your sequencer’s MIDI output to Kraftor, through USB MIDI or TRS MIDI type B. Send notes and controller messages on Kraftor’s MIDI channel.
- Notes 36–127 play slots 0–91. For example, note 36 plays slot 0 and note 37 plays slot 1.
- Slots 92–99 have no MIDI note mapping. Play them from the Designer or with the serial
/pNcommand. - A new note replaces the current speech. During rapid presses, only the latest pending trigger is kept.
- Releasing a key does nothing; speech continues.
The four physical DIP switches select channels 1–16. After changing them, restart Kraftor and click Refresh in the Designer to read the channel.
Voice parameters: Slot or Controller
This choice applies to all slots. It is saved on Kraftor and restored at startup.
| Mode | Parameters used for playback |
|---|---|
| Slot | The voice, rate and design saved with each sentence. |
| Controller | The live parameters set by MIDI CC messages. The slot supplies the sentence. |
Saved sentences and their voice settings remain stored in both modes. In Controller mode, the Designer’s voice controls are disabled; saving an edited sentence preserves its stored voice settings. Both audition and saved-slot playback follow the selected mode.
CC16–22 affect the next trigger. Controller values are held in RAM. Restarting Kraftor or sending CC121 clears design adjustments and returns to Paul at rate 75 with its natural voice settings.
| MIDI CC | Parameter |
|---|---|
| 16 | Voice: Paul, Harry, Betty, Ursula, Dennis, Kit, Frank, Rita or Wendy (values 0-127 across nine voices) |
| 17 | Speech rate |
| 18 | Average pitch |
| 19 | Pitch range |
| 20 | Breathiness |
| 21 | Head size |
| 22 | Laryngealization |
| 121 | Reset controller parameters (any value) |
With the current CC map version 2, CC16 uses these bands: 0-14 Paul, 15-28 Harry, 29-42 Betty, 43-56 Ursula, 57-71 Dennis, 72-85 Kit, 86-99 Frank, 100-113 Rita, 114-127 Wendy. Earlier CC map version 1 uses direct values 0-8. Serial /v0 through /v8 and saved slot voice numbers still select the voice directly.
Each selected voice keeps its natural design settings unless you adjust a parameter with CC18-22 or serial /d. Adjusted parameters stay active across voice changes until reset. Voice commands embedded in a sentence take priority over sliders and controllers in both modes. For controller-driven speech, keep voice, rate and design commands out of the sentence and use plain text or phonetics.
DECtalk reference
Console: optional visual output
Play phrases with Teletype or a MIDI sequencer while Console displays the spoken text. The current VAX firmware sends each sentence back over USB serial, including phrases triggered through MIDI or typed into a serial terminal. Console removes DECtalk commands from the displayed text.
Teletype or sequencer → MIDI → Kraftor → USB serial → Console
Console software and instructions · Open Console
- Connect Kraftor to the computer with a USB data cable and open Console in Chrome or Edge.
- Choose Serial → Connect Port and select Kraftor. The Serial indicator turns green.
- Choose Text Input → String → Word slicing for large words one at a time, or Full sentence to display the complete phrase.
- Trigger a saved phrase with Teletype or a sequencer. Kraftor speaks and Console receives the text.
Word slicing uses the speech rate sent by VAX for an approximate pace. It does not detect word boundaries in the audio or account for punctuation pauses. For a clear demo, start with short plain-text phrases.
Use Console’s text styles and effects to give the display its own character. Its audio input can also drive the scope and audio-reactive backgrounds. MIDI control and Console’s serial display can run together; close Echo or other software using Kraftor’s serial port before connecting Console.
