YAMAHA FS1R rack mount synthesizer module. This is an excellent example of the very rare FS1R, a unique Yamaha synthesis technology that was never offered in a keyboard version. It offers 8-operator FM synthesis (much more sophisticated than the 6-op FM in the DX series with 88 algorithms as opposed to 32) and something called "Formant Shaping Synthesis" (the FS in the name.) Rather than try to describe what the FS1R can do--it's really unlike any other synth you're likely to have heard--here's some info from the owner's manual:

FS (Formant Shaping) and FM (Frequency Modulation) Synthesis

Although based on Yamaha’s newly developed FS (Formant Shaping) synthesis technology, The FS1R actually integrates two tone generation concepts for extraordinarily broad voicing versatility. Formant Shaping synthesis gives musicians unprecedented capability to produce and control sounds with characteristics and flexibility similar to that of the human voice. It can also produce instrument voices that have the response and rich pitch-dependent timbral variations — in short, the “musicality” — of natural acoustic instruments. The bonus is that the base FS technology has been realized using an architecture which also lends itself ideally to FM synthesis, similar to the type introduced in the legendary Yamaha DX-series synthesizers and TX-series tone generators. Thus the FS1R can create anything from totally new simulations of human vocal sounds to classic DX electric piano voices, and anything in between.

FS Synthesis

The term “formant” refers to the distinct spectral patterns which define the recognizable sounds of human speech, such as the vowels “a” or “i.” In human speech, the vocal cords themselves are only capable of creating the basic driving sound and defining pitch (similar to the oscillator in a music synthesis system). The formants which define the sounds of speech are created by the shape of the vocal cavity (i.e. the trachea and mouth). In traditional speech synthesis systems this is simulated by using an oscillator to perform the function of the vocal cords, and a series of controllable bandpass filters to create the required format shapes. Consonant sounds such as “k” or “t,” and fricatives such as “f,” are based on slightly different principles, requiring a noise generator rather than an oscillator, and depending more on amplitude envelope shape than formant shape for recognizability. Formants play an important role in defining the sound of many acoustic musical instruments as well as the human voice.

Rather than a cumbersome system of oscillators and filters to synthesize the effect of formants, the FS synthesis system consists of 16 formant “operators” — 8 “voiced” operators, and 8 “unvoiced” operators (3 to 5 formants are generally considered to be more than enough to synthesize speech). Each operator digitally simulates the effect of both the driving source (oscillator) and filter in one easily manageable unit. The voiced operators produced pitched sounds which can be played on a musical scale via a MIDI keyboard or other MIDI controller. The unvoiced operators can be used to produce noise components of speech-like sound, or they can be used in much the same way as noise generators in more orthodox synthesis systems (e.g. to produce percussive sounds or sound effects). The term “operators” is borrowed from Yamaha FM synthesis, because the FS1R’s voiced operators can be combined in a variety of “algorithms” to create sound in exactly the same way as in the original FM synthesizers such as the DX7.

The FS1R is really a kind of "if you know, you know" instrument that has achieved an almost cult-like status due to its rarity and ability to create unique sounds and textures. To be honest, I'm not really keen on selling it, but I simply do not have the time to dive as deeply into it as I would like, and this presents an opportunity for the buyer or collector who understands what they are looking at. For fun, I have included a picture of the incredible custom controller for this instrument designed and built by brilliant German engineer Robert Skerjanc. I do not own one of these (I wish) but have included the pic just to give you an idea of the number of variables and sound shaping possibilities that this instrument offers.

The original printed operators manual and a standard AC power cable will be included.