Prophet 5 Rev.2 vintage from the American brand SEQUENTIAL CIRCUITS, everything works perfectly. A very beautiful and mythical machine. Opportunity verified by Zicplace. Very good condition. Magic.
Sequential Circuit's Prophet 5, created by Dave Smith, produces a fascinating analog sound in a dreamlike body with a case that combines wood and steel. Even with sounds stored as presets, which can be easily modified after calling them, you can still recognize mythical sounds from Pink Floyd albums, the intro to "One of my Turns", etc.
A lot of presence, a violent Unison mode that we like to listen to and let run, just press one of the 61 keys and wait for the hair to rise on your body. The presets offer very different sounds, tablecloths, organs, basses, sound effects that we like or not, but it has become a legend with its strings and basses. There were 3 models that we spot with the serial numbers: the Rev.1 a little unstable that we don't like to have in return workshop in after-sales service, the Rev. 2 reputed to have a "better sound", and the Rev. 3. At first use, we see that it has some in the stomach with its 2 VCO, and we turn the potentiometers slightly. In Rev. 2 there is a key to tune it, and a key that outputs an A 440Hz. Funny but also necessary because analog is more unstable than digital.
Requires some output effects because the vintage machine does not have them, unlike the recent Prophet 6.
The Manual Service is very detailed and the purely analog genesis of the sound is well introduced: 5 sets of VCO1, VCO2, Mixer, VCF, VCA, controlled by a microprocessor. Why 5 sets on Rev.2? Because it is 5-way polyphonic.
The sound generating components of Rv.3.1, 3.2 and 3.3 are for the 16-pin CEM3340 VCOs manufactured by CURTIS ELECTROMUSIC SPECIALTIES (1979-1988), which are found on other vintage synthesizers such as Roland SH-101, Roland MKS-80, Moog MemoryMoog and others Oberheim, PPG, Crumar and even on some Rhodes. The 24 dB/octave resonant filter is also assigned to a Curtis CEM3310 circuit. The American Doug Curtis, creator of these chips, who died of cancer in 2007, leaves a beautiful mark in the field of electronic music. His contribution earned him a spot at the San Jose Rocks Hall of Fame. The envelope of the sound generated previously is the classic ADSR also entrusted to a Curtis CEM3310 for which it is the specialty (there are actually 2 ADSR, one per oscillator, to be exact).
The devil lies in the details: there are minimal differences around the chips used, for example the use of transistors on Prophets that do not exist in the MemoryMoog. A new version G of this chip allows the maintenance of these machines (price approximately 25 euros on the Internet at passionate electronic component retailers).
The components used in Rev.1 and Rev.2 are Solid State Music SSM2030 generating sawtooth, triangle or square waves (sawtooth) powered by + and - 15 volts. These magical components, which we would call simple nowadays, were made to create sound, precisely for the electronic music industry, in Santa Clara, California in 1977. There are re-releases in 2016. It should be noted that the Datasheets of the VCO chip manufacturers briefly explain the content, the function, and give an example of wiring "around" the chip, allowing engineers to have a field day to test and get the diversity and best of sound. Each analog synthesizer model has a unique design, a difference, a soul and an originality of sound. Without these components, the synthesizers would not have been affordable, PCB circuit sizes and the number of electronic components would have had to be increased. Nor could polyphony have been industrialized (being able to make chords and not just one note at a time).
Prophet 6, recently released in 2015, with a good price-quality ratio, simulates the instability of the VCOs of the time digitally with a SLOP function. An arpeggiator is added, more memories and interesting presets, and it has a digital LFO and a basic step-by-step sequencer. However, it is amusing that imperfection contributes to the sound quality of Prophet 5.
Sources: Prophet manual service, datasheets from VCO chip manufacturers, and also testing a real Prophet Rev.2 midified with factory presets.
Note: the 134-page manual service of Prophet 5 Rev. 3 simply explains how to test the machine without opening it and check its proper functioning, step by step: verification of the VCO1, VCO2, etc. with drawings positioning the buttons. It's as simple as a manual for the first space shuttle that also used ZILOG Z80 processors. In case of failure, it is advisable to have a minimum of experience and a 2-way oscilloscope.