Yamaha PSS-140 (FM keyboard with nice grainy lo-fi synth sounds & accompaniment)

This Yamaha PortaSound from 1988 is basically yet another small 2 operator FM keyboard with 100 preset sounds. It is nothing exceptionally great, but features some nice FM synthesizer timbres those can be e.g. nice for tekkno and turn very grainy by reduced bit resolution when the digital volume control is set low. The 10 OBS preset rhythms are made from classic, very electronic sounding FM percussion those can be also played through the 5 rubber drumpads. There is also a single finger accompaniment.

main features:

SER.NO. 661204 box stickers: 0661204, FMK


Although the case design of the Yamaha PSS-140 resembles much the PSS-80 and the wonderful PSS-100, it has a very different sound style due to different technology (FM instead of squarewave). A special sound feature of the PSS-140 is the digital volume control, which steals bits from the DAC resolution and thus makes the timbres very grainy when set low, and it does this without shorting their envelope duration, because it keeps all timbres audible on the lowest available volume level instead of muting it. Much like an analogue volume knob, this control also works with held notes and doesn't interfere the sound in any way (beside some quiet pop noises), thus it makes also a good realtime sound effect. (I haven't examined the hardware yet.)

The 100 preset sounds of this instrument resemble much the Fujitone 6A sounds (see there). Although they are only plain 2 operator FM timbres (without sophisticated envelope tricks like mandolin ring or sirens), the sound bank features beside semi- natural instrument imitations also many nice synth effects including odd wahwah stuff with rastered timbre sweeps and a lot of zipper noise (e.g. "hand bell", "wind bell", "fireworks") and metallic spring noises (e.g. "leaf spring", "handsaw"). There are also e.g. nice brass and organ timbres on this thing. Remarkable is e.g. the "small church", which is a bizarre cross of pipe and Hammond organ with a buzzy and sonorous bass range (resembling multipulse squarewave). Unlike more professional FM instruments, there are neither sustain or vibrato buttons nor synthesizer controls, but many preset sounds include built-in vibrato or sustain effects.  A bit confusing is that the sound names are in alphabetical order instead of sorted by topics, and strange is also that you need to press an "enter" button to select sounds, despite the 2 digit numbers would be sufficient enough to unambiguously select any of the 100 presets.

The percussion has the typical electronic FM timbre known from the OPL3 "MIDI synth" of early PC soundcards. I discovered that with empty batteries the base drum (normally a percussive and thin pop noise) fails and produces a long hum and then stays mute until the instrument is switched off. Possibly this reveals that the FM sound chip contains some semi- analogue envelope circuitry at least for its percussion.

The 10 preset rhythms are pretty generic and also the single finger accompaniments are nothing special, beside that their bass and chord timbres change among different rhythms (brass, e-piano etc.). With rhythm off, there is a manual single finger chord mode which timbre also depends on the currently selected (but not started) rhythm. The OBS rhythm buttons can be also used as a realtime sound control since they respond pretty fast and even change the timbre of currently held chord notes. In opposite to this, during rhythm it takes always until the end of the current pattern before a rhythm change takes effect, which limits here the use of these OBS buttons for live play tricks.

Other instruments with similar case shape but different sound hardware (great multipulse squarewave timbres) are the Yamaha PSS-80 and the wonderful PSS-100.

 removal of these screws voids warranty...    
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