VOXX, the 16-Band Vocoder for the Atari Falcon 030

VOXX Vocoder for the Atari Falcon 030(Re)Introducing VOXX The world's first real-time software vocoder featuring a 16-band 24db/octave spectrum analyzer, band patch matrix, variable envelope followers, panorama and a 3D skin! Download it now!Sample VOXX VOXX Robot | VOXX Chord









After remaining illisuve for more than 15 years, legendary Atari programmer, Hans Achim Mueller, has popped back into the scene to release the long lost Atari vocoder, VOXX, as freeware. Get VOXXed!Plug your mic in, get creative, share your vocoder tunes on AMN Live!Originally sold by mail in 1994, Achim and his VOXX software quickly disapeared at the same time Atari stopped producing computers. Since then, only the limited demo version was available for download. No one was ever able to find Achim until recently, when out of curiosity he ran a keyword search and found this Atari-Forum VOXX thread.  Achim wanted to help, unfortunately he no longer had a full version copy of VOXX.  Luckily, a fellow Atarian still had a full version of VOXX which he sent back to Achim to bless as "freeware".  The Atari Music Network is pleased to promote and provide this legendary software to the Atari community.


The Fascinating History of the Vocoder:

Originally, vocoding technology had nothing to do with music.  Nowadays, vocoding is generally understood to be a type of synthesizer effect used to transform human speech into a myriad of futuristic and metallic monotone robot-like voices.  But the technology is far from futuristic!

In 1928, Bell Labs began experimenting with the concept of electronically encoding voice (or'vo-coding') for mass transmission across several different radio frequencies using a series of frequency filter bands. The idea was to conserve bandwidth and reduce the cost of long distance communication (yes, even back then they had bandwidth problems).  Vocoding also provided a secure means of communication in World War II between Churchill and FDR, preventing German intelligence from deciphering their conversations in real-time.  Eventually, vocoder technology found its way into television, movies, live theater and popular music as a sound effect.

Learn more about Vocoding!


AMN catches up with VOXX programmer, Hans Achim Müller, after more than 15 years

Q: What originally inspired you to develop a vocoder for the Atari platform vs. Mac or PC?
A: In 1993/94, the Atari Falcon was the only personal computer that offered a separate, high-quality DSP audio matrix on board whereas PCs and MACs where only capable of 'beeps' or low-quality 8/16-bit playback.  The Falcon was the ideal development platform at an affordable price for the various other DSP-based audio projects I had originally planned to create (including some soft synths).

Q: What are the most unique and/or impressive features of VOXX?
A: Besides being the first affordable real-time software vocoder in the world, it has a patch matrix which is not found very often as well as individual controls for each frequency band's envelope velocity. Additionally (compared to most Hardware vocoders) you can save your different settings.

Q: I understand you once demonstrated VOXX at the Frankfurt Musik Messe. What happened there?
A: Actually, I'm not sure if it was there or at the CeBIT. Anyways, I wanted to find an Atari music vendor to make a distribution deal with.  I recall meeting either Charlie-Labs or Steinberg (can't remember which) and asked him to take a look at VOXX. He took me to a nearby Falcon where I tried to demonstrate it. Unfortunately this Falcon had some problems with synchronization, so VOXX only outputted noise. But he was very impressed with the soft 3D-skin and studied it for several minutes (can’t remember if I left him a copy or not). After that I never heard from him again. I later presented VOXX by myself at an Atari fair in Düsseldorf where I sold about 10 copies. I also traded some copies with other exponents against their programs and Hardware add-ons. It was a nice experience!

During this time, I had built a thin tower case for my Falcon which was covered with small stones (those used for dioramas) so it looked like if it was made from granite or something similar. This attracted people more than my vocoder - everyone wanted to touch and feel that case!  Someone even asked me how long it would take to make 10 of them and what would be the price. When I was back home, I made another 2 prototypes but just then Atari announced they would stop producing computers.

Q: You mentioned once that one of Kraftwerks' members, Florian Schneider, asked you to port VOXX to the Apple platform. What ever happened with that?
A: I have to rewind a little: The German magazine KEYS (which I want to thank once again for the support) asked me to send a copy and a screen-shot of VOXX for a review. In the next issue it appeared in the column “Software of the month” with a good review!  Soon after, someone from the magazine called me asking if he could give my phone number to Florian Schneider from Kraftwerk. The next day, Florian called me to learn more about VOXX and its features. He then tried to convince me to make it for a MAC. I explained that it couldn’t be done for other systems due to the absence of a DSP. I told him it would be faster and cheaper for him to buy a Falcon and I would give him VOXX for free. He wanted to hear some examples and I promised him to record a cassette and send it to him.  That night, I recorded various silly phrases (as all we vocoderians do) and sent them to him. He never contacted me again.

Q: Why did you stop development on VOXX?
A: After having finished VOXX, I began work on a soft synth program but my Falcon began to fail by losing voices (channels) more and more until it didn’t work anymore. Even VOXX failed and would only produce noise at the output. Shortly afer, Atari announced it would stop producing computers so I decided to wait for another platform for my projects.  Eventually time passed on and here I am now.

Q: Does VOXX take advantage of the optional FPU math co-processor?
A: No, the complete vocoder program (assembler) was in the DSP. The rest of the system (C and TOS) was only for the GUI

Q: Your website shows you're still a vocoding enthusiast. Do you see yourself ever getting back into developing for the Atari platform now that the new Coldfire (FireBee) machine is about to be released?
A: Hmm, that is a difficult answer. In my work I have to do a lot with Hardware and programming already. Programming techniques and languages have developed so fast that it would be hard for an “old” programmer like me to find the time to get back into it.

Of course I took a look at the Firebee's development to see what they've implemented in it. The DSP emulation isn’t done yet AFAIK which is essential for VOXX to work. It sure would be nice to have a Falcon in such a little box. I also took a look at the VST-SDK recently, to figure out how much effort it would take to remake it as a plug-in. I've also thought about making a standalone hardware vocoder but then again, a lot of synths, effect units, and VST-plug-ins already offer a vocoder. Would it be worth the effort to launch another one? Currently I own a Korg Radias which has a vocoder with both the carrier and vocoder inside it - you just have to add your voice. Unfortunately I can’t compare it against VOXX because I sold my Falcon.

Q: If you or someone else could develop VOXX further, what new features would you like to see implemented?
I would add the features I had planned for VOXX in the second version: a formant effect section (compressor/limiter, filter) to improve intelligibility, an internal MIDI synth section as a carrier generator, and 44,1kHz sample rate implementation. An output effect section would be nice too.

Atari VOXX Vocoder ScreenshotDownload VOXX Vocoder for the Atari Falcon 030

Copyright and Restrictions

VOXX is public domain. It can be copied and distributed freely as long as no changes are made to the code without the written permission of its copyright owner, Hans Achim Mueller.

VOXX Specifications

  • Software Version: 2010 Relaunch of the Original Freeware Edition
  • Number of Bands: 16 Formant Filters and 16 Carrier Filters
  • Filter Types: Digital-IIR, 4-Pole Band-Pass
  • Center Frequencies:  125, 160, 210, 275, 360, 460, 600, 780, 1020, 1325, 1725, 2250, 2900, 3800, 5000 and 6400 Hz.
  • Sampling Rate: 20.77 kHz, 16 Bit Stereo
  • DSP Usage : 100%
  • Dimensions (pixels):  630 x 460 x 1 (W x H x D)
  • Memory Consumption:  apx 512 kB

Set-up and User Tips

  • Early models of the Atari Falcon's audio inputs are designed for microphone signals which are highly sensitive. If you connect them with the LINE-Output of instruments, CD-players or other audio devices be careful with the levels! In this case the better way is to insert 200K resistors in series with the audio-source and the Falcon 030.
    Read more about Atari Falcon audio modifications.
  • To use the Falcon 030 as a vocoder, you need a L/R Mono to 1/8" Stereo Y-spliiter audio cable to merge your Formant and Carrier signals together into the stereo input jack on the back of the Falcon. Connect the Formant sound source (i.e. microphone) to the Left-input of the Falcon 030.  Connect the Carrier sound source to the Right-input (i.e. synth, guitar, sound, or noise source).
  • Avoid using use a thin or muffled voice as your Formant audio source - it will not utilize the full 16 band spectrum and will sound cheap.
  • If your using your own voice, try not to sing or vary the pitch according to the music.  If your frequency moves with or against that of the Carrier's, it will create numerous unintelligable sounds. Remember that most of the tonal properties of your voice are discarded from the Formant sound source allowing only the vocalization to be extracted and applied to the Carrier sound source.
  • Drums and percussion can also be used as the Formant to create rhythmic vocalizations of an instrument.
  • Carrier sources should be rich in harmonics. Use clear and sharp sounds like strings, brass, and electronic sawtooth or pusle waveforms. Be careful with square, triangle and sine waveform based sounds like flutes, whistles, and organs.  Their harmonics are very small in relation to the fundamental pitch which will end up dominating the spectrum and the resulting sound will be only in the bands near the fundamental's frequency band. Remember, a pure sine wave has no harmonics.
  • The Carrier's pitch determines the pitch for the resulting effect.  You can play melody, chords, or any combination of the two.
  • VOXX is a stable program, however, if it suddenly crashes or produces noise, simply perform a cold reset.
  • Run VOXX only from TOS 4.04 (the Falcon's official single tasking OS).  Due to the intense communication between VOXX and the DSP, it is unlikely there is enough computing power left to multitask. However, if anyone finds a way to run VOXX on MultiTos with another music or MIDI program smoothly, contact the Atari Music Network at atarimusicnet[at]yahoo[dot]com.

How Does the VOXX Vocoder Work? What are its Features?

The VOXX vocoder is composed of following main sections: the Formant, or analysis section, which extracts the spectrum variations from the vocalization source (speech, drums,
etc); the Carrier, or voice section, which applies these variations to the target sound (strings, pulse waves, noises etc); the routing Matrix, which interconnects both sections; and other sections, for signal conditioning like GAIN, MIX, PAN and VU-Displays etc.

The Formant Section:

The Formant section is composed of 16 Band-Pass-Filters (BPF) that focus on specific frequencies accross the desired frequency spectrum and 16 Envelope Generators (EGs). Each BPF lets a part of the input signal pass-through according to BPF's center frequency (Fc) attenuating the rest of the signal's spectrum proportionally to it's distance from the BPF's Fc. In other words, the BPF literally slices the Formant signal into frequency bands. The more bands (BPF's) a vocoder has, the more precise the spectrum characteristic can be analyzed. Next, each band output (or slice) is passed to the Envelope Generator to form an envelope for each band, proportional to the formant signal's spectrum. As mentioned before, the vocalization is slow in relation to the sound, therefore envelopes are used instead of the direct BPF's output. The Attack/Decay times of the EGs are adjustable via the ENV-Faders to create different vocalization effects.

The Carrier Section:

This Carrier section also has 16 BPFs with the same Fcs as the Formant section.  Similar to the Formant sectioin, the Carrier signal is filtered (or sliced) into spectrum components but this time the BPF's outputs go to Value-Controlled-Amplifiers (similar to synthesizer VCA's but controlled by digital values instead of volts). The control value for these amplifiers is supplied by the Formant Envelopes. The result is that each Carrier-band output is modulated in amplitude by the amount of signal of this band in the Formant signal. By mixing these two componants together, the result is a symbiosis of the speech of the Formant with the voice of the Carrier - or in other words, a singing robot instrument!

The I/O Section

The I/O section is for adjusting the Input and Output Gain Levels.  It includes 2 level displays: one for Input and the other for Output, both with a Left and Right channel on each. The Left Input of the Atari Falcon 030 is for the Formant (voice) and the Right Input for the Carrier (instrument). The output is the stereo effect (combining both Left and Right signals). The 4 faders below are for adjusting the I/O levels

The Matrix

The Matrix alllows for patching/rerouting from the Formant Envelopes to the Carrier Amplifiers. The matrix is used to connect the Formant Envelopes to the Carrier Amplifiers.

For each band there is a green Formant (source) button and a yellow Carrier (target) button labeled from 0 to F, where the 0 stands for the lowest frequency band and F for the highest. With this Matrix it is possible to assign or route the Envelope of one selected frequency bands to any one of the Carrier's band amplifiers. So you can assign a low frequency amount in the Formant to modulate a high frequency band of the Carrier and vice versa. In a 1 to 1 routing the effect of a talking instrument is the most notable while the shifting of the bands in both directions by one or two (0 with 1, 1 with 2, ... E with F  or
vice versa) adds the effect of pitch shifting (which is the logical consequence of shifting the bands). Very scrambled routings may result in interesting and unexpected effects of vocalization that surely will not be understood as human speech, regardless of what source for the Formant is used.

The RST button Restores the 1 to 1 routing of the Matrix.

To reroute bands within the Matrix is simple. Once the mouse enters the routing field, it's pointer transforms into a cross that intersects with both the Formant and Carrier band buttons. If you want to connect Formant band 5 to Carrier band E, place the cross in the position where the green button "5" and the yellow button "E" are pointed by the horizontal and the vertical lines respectively and click. A Formant source can be routed to one or more Carrier targets but a Carrier target can only receive one source. This means that if a source is routed to more than one target there will be one or more sources without a respective target.

Spectrum & Settings Section:

This section displays the Formant Spectrum Envelopes and allows some global settings for Envelope Modes. The large display, shows the actual envelope value for each Carrier-band that is extracted from the Formant source, like a spectrum analyzer. The frequency for each band is displayed below. For each VOXX data file, there are 8 user programs to choose from. If you wish to save any chages you make to one, click the STORE PRG button and choose the program button where you want to save it over. When your done editing all your programs, select "Save File" under the "File" menu.

The bottom 3 buttons FREEZE, ENV SLOW and ENV FAST are used to set the global range setting of the Formant Envelope (attack/decay velocity). FREEZE sets all attack/decay velocities to zero regardless of the ENV fader settings, freezing all actual envelope values until SLOW or FAST is pressed. This function is useful to equalize the Carrier with a Formant's spectrum characteristic. SLOW and FAST set two different envelope velocity ranges with a relation 1 to 10.

ENV Section

This section consists of 16 faders, each assigned to a frequency band. According to the range selected with the ENV SLOW/FAST buttons, it is possible to adjust the attack/decay for each Formant envelope. The lowest slider position is for slowest and the highest for fastest attack/decay times.

You can move each slider individually, or "draw" a smooth line over the sliders by clicking, holding, and dragging with the left mouse button over the entire fader section.

Pan Section

Since the Formant (Left-input) and the Carrier (Right-input) are used both to form one signal, this section is for adjusting the stereo panorama position for each modulated Carrier band (result output), to create a stereo effect.  It is provided with 16 knobs (potentiometer simulations), one for each band.

Mix Section:

The result of each coded band now is ready and with this section it is possible to adjust the gain for each band to fit the desired tone characteristic. The Mix faders are adjusted in the same way as the ENV faders including the ability to "draw" a smooth line over the sliders by clicking, holding, and dragging with the left mouse button over the entire fader section.