Yamaha PSS-100, PortaSound digital recording keyboard
squarewave synth keyboard with great C64 sounds & accompaniment

This multipulse squarewave synth keyboard from 1989 has wonderful C64 homecomputer sounds, including some of the famous arpeggiator timbres those are missing on most other squarewave keyboards. Although this is not a SID Station and has no filter, it is one of the most versatile and interesting sounding squarewave instruments and (like MC-3) basically a "must have" for a real squarewave lover.

The PSS-100 was the more advanced sister model of the Yamaha PSS-80 (see there) and shares most of its features, but additionally has each 16 preset sounds and rhythms and a more advanced sequencer that can be played to. Fortunately the PSS-100 is not really rare and still occasionally appears on eBay. Don't be confused by the terms "voice variator" and "digital recorder" on the control panel; this is not a sampler.

(Note: This keyboard sounds great, but don't buy one of these so far your only intention is to get a keyboard with faithfully imitated natural instrument sounds. Remember, this is a squarewave instrument and though many of its sounds sound not even remotely like what is written on its buttons, though bought with wrong expectation it may disappoint you.)

different main features:

YAMAHA - professionelle Musikinstrumente serial no. 0001147 Mine seems to be an early specimen; it has the low serial no. 0001147.


Unlike the OBS buttons of the Yamaha PSS-80, the PSS-100 selects preset sounds and rhythms through each a letter and a cipher button, but very unusual is here that you can still change them by pressing only one of both buttons (keeping the other value), thus basically ciphers and letters behave like row and column and constitute still a sort of OBS or semi- OBS control, that is great for intuitive life performance. (But like with the PSS-80 here still all buttons make a dull blip noise.)

The sounds are digital multipulse squarewave with audible zipper noise. The ones with the same names like on Yamaha PSS-80 sound identical. The "clarinet" sounds as usual. The "trumpet" starts with a strange smack, has a fast and strong vibrato and its harsh timbre is at least slightly more natural than trumpets on other squarewave instruments. The "sax" is similar, but without vibrato and duller; it still sounds fairly realistic. The "piano" ignores key press duration. The "honky- tonk piano" on this instrument is very special, because instead of a normal chorus it here has a fast arpeggiator effect that rapidly toggles between 2 pitches to approximate the detuned chorus sound with only 1 sound channel. This is a very typical C64 sound effect that was used in many historical computer games (e.g. the bass line of the C64 "Mario Bros." title music). The "electronic organ" has a fast and weak vibrato while "accordion" is a simple squarewave toot. The "vibraphone" has a slow tremolo with such a high amplitude, that with most volume and envelope settings it completely mutes the tone in the quieter phase. The "guitar" has a percussive attack phase and fades silent too soon due to linear envelope decay.  The "rock guitar" is rather a thin and harsh organ tone that starts with a click and resembles bagpipes timbre. The "tremolo guitar" is harsh with strong tremolo and fades silent (timbre resembles the famous "frog" on Casio MT-60). The "banjo" is harsh with very short decay envelope (like the wannabe "xylophone" on the HBATEC). The "mandolin" rings fast. The "violin" has fast vibrato. The "fantasy" is a sort of slower ringing mandolin which fades silent. The "UFO" is a bizarre organ tone that starts with a strange smack, has strong vibrato and short sustain. Like with Yamaha PSS-80, also on the PSS-100 you can use the "voice variator" synthesizer to select a great variety of different timbres and envelopes to modify the preset sounds. Particularly "ufo" and "honky- tonk piano" provide a lot of additional lovely C64 timbres here.

The "digital recorder" sequencer of the PSS-100 is modelled after a cassette recorder, thus you can record, play and overwrite any section of the virtual tape (but not insert a part). The display acts as the tape counter (counts from 00 to 99); with the "forward" and "rewind" buttons you can step forward and back (hold button to step faster, but this doesn't play the recording during winding but only blips every counter step). "reset" immediately winds the tape back to "00". The sequencer records all sounds (polyphonic), you can play to it and it has battery backed- up memory.

Beside this the display indicates either the currently selected preset sound or rhythm (switched with the "voice" and "style" button like with other sound bank keyboards), but not the 2 synthesizer parameters, tempo or volume.

Unlike the boring PSS-80 monoto, the demo of the PSS-100 contains a complex medley of great POKEY- style musics (the LCD slowly counts from 00 to 99 during this) and you even can play to them. The demo consists of the following melodies:

  1. [funk synth pop with fanfares]
  2. Home on the Ranch (?)
  3. [known American march/ charleston]
  4. [mandolin tune]
  5. Yankee Doodle
Another great keyboard with complex squarewave sounds is Letron MC-38, and another multipulse squarewave instrument with fast arpeggiator timbres is the circuit- bent Hing Hon EK-001. Do not confuse the Yamaha PSS-140 with a PSS-100 variant; although the PSS-140 has a similar case, additional drumpads and even 100 preset sounds, its sounds are not editable and not squarewave, but made from ordinary FM synthesis.
 removal of these screws voids warranty...    
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