Vox Ampliphonic Stereo Multi-Voice

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The Vox amps manufactured in America during the 1960s were loaded with innovative features. These amps often offered far more than reverb and tremolo. A number included treble and mid range boost switches, fuzz tone, Repeat Percussion and Tone-X. Outboard effects, such as the Wah pedal, were also offered. Vox offered a plethora of ways to modify the amplified tone of an electric guitar.

In 1967, looking for new markets, Thomas Organ entered the band instrument business with their "Vox Ampliphonic" line. Vox introduced a line of 66 woodwind and brass instruments with audio pickups, allowing these instruments to be played through a Vox amplifier. But their goal went beyond amplifying band instruments through an amp. Thomas Organ also wished to develop outboard effects devices that would radically modify the tone of reed and brass band instruments just as MRB, fuzz tone, and Repeat Percussion had done for guitar. Vox developed three signal processing products to accomplish this goal: the pocket sized Octavoice I amd II and the Stereo Multi-Voice.

The 1968 Vox Ampliphonic catalog described the Stereo Multi Voice as follows: "A revolutionay idea in Music! Vox's Stereo Multi-Voice lets one musician sound like an entire section. Here's how it works: Preset tabs for the octaves and voices that you want. Then with the tap of a foot, change or mix octaves; swing back and forth between different voices. You can make a sax sound like a clarinet or like several musicians playing all at once."

The electronic design of the Stereo Multi -Voice was based on the tone generation circuitry used in Thomas home organs. These organs used twelve individual tone generator circuit cards, one for each tone in the scale. Each of these cards had a "master tone oscillator" circuit that generated the highest pitched tones in the organ. The signal from each of these master tone oscillators was then fed serially through a number of analog frequency "divider" network circuits. Each frequency divider network would drop the frequency of the master tone oscillator by one octave. Through the use of five of these serial frequency divider networks in each of the twelve tone generator circuit cards, the pitches needed to complete a five octave organ were derived.

The Stereo Multi Voice worked on a similar principle. The Multi-Voice was inserted in the line between the instrument and the amplifier. The Stereo Multi-Voice substituted the signal from the brass or reed instrument pickup for the "master tone oscillator" in an electronic organ. The audio output from the instrument was fed through either a single doubler network to raise the pitch an octave, or one or two serial dividers to drop the pitch one or two octaves.

As an example, one could drop the amplified tone of a tenor sax one octave using the Stereo Multi-Voice and make it sound like a baritone sax when played through through an amplifier.

In addition to pitch adjustment, the Stereo Multi-Voice offered eight tone shaping switches to modify the tone of the instrument run through the processor. A four button foot switch similar to those supplied with Vox amps was also included for remote switching of effects.

The Stereo Multi-Voice not only worked with amplified woodwind and brass instruments. It also gained favor with guitarists.

The Vox Showroom offers additional resources for the Vox Ampliphonic signal processors. Click on the links below.

  • 1968 Vox Stereo Multi-Voice Catalog Page
  • 1968 Vox Ampliphonic Instrument Price List
  • 1968 Vox Ampliphonic Product Line Price List

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