Suzuki SX500 / Siel EX80 review

A few weeks ago a friend gave me this curious looking box. A Suzuki synthesizer? Surely not.

A google search turned up very little, except a page at Hollow Sun. Essentially the Suzuki SX500 is a rebadged Siel EX80 which in turn was a copy of the Korg EX800.

Here’s what we know. There are two DCOs offering sawtooth and square waveforms (the square waveform can mix up to 4 octaves of square waves together). There is an analogue 24db Low Pass Filter (SSM Filter IC). Two amp envelopes (yes two!), filter envelope, two LFOs (hardwired to osc pitch and filter frequency), chorus effect and a basic record/playback sequencer.

Unfortunately it’s not a true polyphonic synth. It’s paraphonic, meaning that there is only one filter and amp for all 8 voices (actually there are two amps for a slightly odd ‘double’ mode which gives 2 x 4 voices with an interval setting for detuning the 2nd set of voices).

Here’s a quick demo I knocked up. It’s raw SX500 except for some delay (even the best analogue synths can sound a bit lifeless without effects). I think it sounds rather fine!

Apparently when the unit was shipped, the SSM filter chip was tweaked to tame its resonance. Presumably the engineers believed that extreme resonance settings weren’t good for realistic sounds, which is clearly what this was aimed at (check out the list of preset patches printed on the top of the unit). Luckily there is a pot which can be tweaked inside which will restore the SSM chip to it’s screaming former glory. More details on the pot tweak here.

One of the nice aspects of the unit is that every parameter is controllable via midi cc#. This gives a good opportunity for control via your DAW. I knocked up a controller for Ableton Max For Live, which if nothing else, should give you a good idea of all the parameter the synth has to offer. Download the SX500 / EX80 controller.


Overall the SX500 / EX80 is far from perfect. The envelopes are really slow, the oscillators are limited in waveforms, it’s not truly polyphonic and some of the features are esoteric by todays standards but it has a definite charm. I think if you can find one, they can be had for very reasonable prices. Definitely worth a punt.

5 thoughts on “Suzuki SX500 / Siel EX80 review

  1. I just got one, after my DK-80 died πŸ™

    I like it even though the envelopes are slow and sounds brittle on the low end. How did you make the 2nd and 4th patches? Sounds great!

    Take care.

  2. Hi Hansel,

    Thanks for the kind words. Nothing special about patch 2, just some chords and some automation on the filter cutoff. The 4th patch gets is animation from automating the 4 square wave outputs from the square oscillator. Great little analogue poly for the price!

  3. I see. I haven’t automated any parameters yet, just programmed it from the front panel (which is not as tedious as i’d feared). It does sound kind of static though. I’ll try and feed it some midi CC’s πŸ™‚

    I did calibrate the filter which is a big improvement. Planning to add some pots for the filter, too. Seems like an easy enough job.

    Take care.

  4. Haven’t gotten around to it yet, but it looks like you have to desolder the small cutoff and res trimpots on the pcb and solder the positive, negative and ground to the relevant connections on linear pots.

    You’ll have to go easy on the resonance, because it goes all the way into self-oscillation and beyond. You wouldn’t wanna ruin an expensive pair of monitors with a cheap chunk of plastic like the Suzuki πŸ™‚

    There’s a very similar mod for the Korg Poly 800 called “Moog Slayer”, you can look it up.

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