AM8400 JP-4 VCO
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£169.00 inc. tax
14 HP | AM8400 Jupiter-4 VCO | User Manual (PDF) | Modular Grid | You Tube
OVERVIEW The AM8400 module is a replica of the VCO in the Roland Jupiter 4 polyphonic synthesizer that was introduced in 1978. The original VCO is a unique design that uses a 555 timer chip and a CMOS divider chip to create square waves which are then shaped into sawtooth and pulse. Most VCO’s use a sawtooth or triangle core.
OVERVIEW The AM8400 module is a replica of the VCO in the Roland Jupiter 4 polyphonic synthesizer that was introduced in 1978. The original VCO is a unique design that uses a 555 timer chip and a CMOS divider chip to create square waves which are then shaped into sawtooth and pulse. Most VCO’s use a sawtooth or triangle core.
DESCRIPTION This unique design makes for some very different sawtooth wave shapes and tonality. The Jupiter 4 is famous for its powerful sounds and efficient controls. The constraints of microprocessors in 1978 mean there were only 16 sliders that could be memorised, which limited the functionality of the VCO to a 4 octave range and 3 waveforms.
The Jupiter 4 has only one VCO per voice, so Roland added a sub-oscillator which generates a square wave one octave below the VCO frequency. The sub can be switched ON or OFF.
The AMSynths circuit is close to the original except for a new Tempco based matched transistor pair rather than the obsolete heated uA726 chip, as the exponential generator. This improves warm up time and precision.
There are phenolic control knobs with spun aluminum inlays for pitch control and range selection from 32' to 2'. There are three waveform outputs (sawtooth, square, pulse), plus a sub oscillator output.
The slide potentiometers have subtle blue LED's. The pulse width can be varied from 50% to 10% using the manual slider or a 0 to +10V control voltage.
The slide potentiometers have subtle blue LED's. The pulse width can be varied from 50% to 10% using the manual slider or a 0 to +10V control voltage.
- Sawtooth is 0 to +10V
- Square is 0 to +10V
- Pulse is 0 to +10V
This is the 2025 Edition which has external KYBD input for connecting a 1/V octave pitch CV, three frequency modulation inputs, pulse width modulation and four individual waveform outputs. The near black aluminum panel is powder coated, with white and light blue silk screen.
PRODUCT STATUS: 2025 EDITION DUE MARCH
Product Code: AM8400
Brand: AMSynths
weight: 300.0 g
Product Condition: New
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