MORE Home Keyboards that are Actually AWESOME Synths!

US Not somewhere you usually look...      07/06/24

MORE Home Keyboards that are Actually AWESOME Synths!

I've always been a little bit of a home arranger keyboard fan. My teen Saturdays were spent working in a Music Shop near Sutton Coldfield and I played pretty much all of 1995's to 1999's models. Firm fixtures in this class of instrument include; cheesy pop backing patterns, preset sounds (square wave origins, through FM and onto PCM samples) and sometimes, just sometimes, a selection of synthesizer controls for making your own timbres!

Obvious favorites of mine include the Yamaha PSS-390, which includes a series of amusing presets (golf, ghosties, alien) and a fully editable 2OP FM engine. But we can go a little more impressive here I think!

Solton K160

Please contact me if you find one of these, because I've been looking for years! On the surface, this is a standard instrument with non-editable presets for the semi-professional "playing MIDI cover songs outside an apres-ski place" market, but there's actually something odd going on under the hood.

Married to the digital oscillators (rumoured to use the same tech as the Keytek CTS - sampled waves cross-faded over time into complex tones) are 8 CEM filters! The usage of a CEM chip (the CEM3389) was quite novel in 1990, and parallel to Casio's usage of analogue filters in their HZ & HT home keyboard lines.

I said non-editable presets didn't I? Well that's only partially true, those presets can be combined into "programs" - allowing for layering & splitting, plus editable offsets for parameters like volume, transpose, cutoff & resonance. Check out the demo below (especially "WarmStrings"), and let me know if you have one for sale!


Casio VA10

Not a sampling keyboard like the popular SK range, no, the Voice Arranger VA10 is far weirder than that! states:

This very interesting Casio keyboard from 1994 has a built-in digital effect processor with microphone input, which can produce many kinds of reverberations, pitch shifting, vibrato/ tremolo, chorus, flanger (sounds like mellow tape mess, but is great for celestial sound pads) and some very weird howling feedback/ LFO sounds those resemble much to 1950th horror or psycho thriller movie effects. The instrument is also claimed to have a vocoder function, but this effect is rather fake, because unlike a genuine vocoder it seems to completely ignore the timbre of the input signal but only controls the keyboard sound volume by the microphone volume, thus it could be best described as an envelope follower or "1 band vocoder". (Despite it can sound nice and quite vocoder- like by skilful playing the right keyboard notes to simulate timbre changes.) There are also some odd and very poor sounding other effects in it; e.g. "distortion" sounds extremely harsh and digital (like a badly clipping transistor amp). The keyboard has even a monophonic "pitch sensor" feature which is claimed to convert sing input into keyboard notes, but this revolutionary function works so badly that it is basically unusable because it continuously jumps into wrong octaves.

I haven't gotten hold of one of these yet, but it's definitely on my list! Check out the demo below, I love the naive, gritty charm of the pitch-shifter...


Fujitone 6A

This one bend's the rules a bit, because to synthesize anything, the unit requires modification. The 6A is a portable 2OP FM keyboard, equivalent to Yamaha's late 80's PSS range:

The preset sounds are made from classic 2 operator FM synthesis; some preset sounds combine 2 polyphony channels to form a 4 operator sound. The sound engine also employs an additional LFO for mandolin ring or siren effects. Great is that (like most FM keyboards) the timbres are time- dynamically playable, i.e. the timbre of notes changes depends on how long a key is pressed, which provides a relatively expressive playability despite the keyboard is not velocity sensitive. The natural instrument imitations are barely natural and some are very off; many have the for FM typical hollow bass range. Although this description doesn't sound too exciting, the instrument itself has nicely warm timbres those sound fat and expensive like a big electronic organ. In the following I will only mention sounds those are special or strongly differ from what the name suggests.


It turns out, by cutting some data lines, then wiring up some dipswitches, you can make a bizarre FM synth!

With this simple digital synthesizer now many weird new sounds can be created by selecting a preset sound, switching DIP switches off, selecting a different sound and switching them on again. Depending on the DIP switch, even the rhythm instruments can be altered this way. Also keyboard presses get interpreted as FM synthesis data while DIP switches are open, though key combinations also change the sounds, but in this case the behaviour is only deterministic so far the instrument is switched off and on again before creating a sound this way. I conclude that otherwise the currently selected sound channel number from the previous key press gets misinterpreted as sound data too, which causes semi- random results. Also the effect of pressing drumpads or the vibrato button after synthesizing a sound (i.e. when the new sound is active and all DIP switches are closed again) often drastically modifies the new sound (e.g. shortens the envelope a lot, but further presses on the same buttons don't change it further).

I guess that activating a drumpad or vibrato transfers some new register data from the CPU to the sound chip, those in the case of synthesized sounds don't match the alliterated settings in the soundchip and thus change the sound. But what you want?! This mod gives you a synthesizer function for only a few euro of additional hardware, and if you just intend to sample the stuff, its anyway not that important how deterministic or logical the thing behaves. It's fun to get lots of messy sounds by pressing keys with DIP switches open, and since this instrument contains no sequencer RAM (unlike your possibly precious Yamaha PSS...), you don't need to fear to erase its settings. Switch it off and on again and it does always the same.

So far no keys are pressed and no rhythm is running while DIP switches are open, the behaviour of the synthesizer is even so well reproducible that you can write down your own library of synthesized sound by noting the initially selected preset sound, the DIP switch setting, the 2nd selected sound and possible vibrato/ drumpad presses after closing the DIP switches. (You can also select more than 1 new preset sound in sequence to synthesize a new sound.)

Sounds like a winner to me! There are many more home keyboards that feature hidden synthetic depths, tell us your favourites below!

Posted by MagicalSynthAdventure an expert in synthesis technology from last Century and Amiga enthusiast.

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