Korg Poly 800 II. Owned from about April-August 2000, bought for $135, sold for $200.

This was my first real synth and I was very excited about it. Now it doesn't impress me terribly much but at the time it was great. I didn't have it for very long and it was over 3 years ago so this might not be completely accurate.

The synth is simple enough, light weight plastic case, 49 keys (pretty lousy squishy key action, no velocity), midi in/out (no thru), stereo outputs, tape dump jacks, sustain and patch change pedal inputs, joystick for pitch bends/LFO modulation, stores 64 patches.

The voice architecture works like this: You can have either 1 DCO per voice and 8 voices or 2 DCOs and 4 voices. The oscillators are weird in that there is no actual sawtooth wave. There are 4 octaves of square waves that can either be on or off. For square waves they're all mixed at full amplitude, for saw waves they're mixed to approximate the shape of a saw wave. I've never verified this, it's just what I've heard. At any rate this means that there more possibilities for making waveforms than on other simple analog synths. The oscillators each have a pretty wide range of tuning range and can make some nice low bass (something that the DW-8000 really lacked as it only went down to 16'). Each oscillator has its own 6-stage envelope (attack, decay, break point, slope, sustain, release). There's only one filter for all the voices, and really I think it has a pretty nice arrangement which could give some unusual effects. The filter has its own 6-stage envelope too (shared with noise), and it can be set to retrigger for each new note, or trigger in legato mode. It doesn't self-oscillate but the resonance gets pretty high. Then there's a digital delay. You can set the delay time, feedback, modulation amount, and modulation rate. With these controls it does anything from flanging, chorusing, etc. to delays up to 1024ms. After this there are very simple EQ controls for high/low boost/cut. When editing any of the delay/EQ parameters it resets the delay for a second, which is a minor annoyance. There's one delayed triangle wave LFO (not counting the one in the delay) that can be routed to the oscillators or filter. It doesn't go very fast and there are only 16 steps for the modulation parameters. Also it restarts on each keypress and I found that annoying. There's also a step sequencer. Contrary to what most people say it can be somewhat useful for a simple repetitive bassline or something. But it's just one pattern, one track, difficult to use, and not particularly useful. There's a chord mode too which will transpose any chord across the keyboard monophonically. Since it just moves all the notes around in parallel it isn't very useful either but it's possible to get all the voices stacked on one note. There isn't any portamento, and of course nothing fancy like ring modulation or oscillator sync.

The sound is very nice. Oscillators tend to sound pretty harsh and buzzy (particularly in comparison to the darker DW-8000 waveforms). With the waveform arrangements it's possible to make unexpectedly good bell and organ sounds. The filter is excellent- it sounds warm and the resonance is great but it takes all of the bass away. Also when the resonance is high and there's slow modulation on the filter, stepping can be heard. Internally I think the controls for the filter CV is only 8-bit. Legato triggering can do very nice things to pad sounds with slow filter sweeps. The delay is probably the best part about the synth- it really warms up the sound and adds a lot of depth.

Using the Poly 800 isn't much fun because there's no data entry slider. You enter a 2-digit parameter number and press the up/down buttons until it's the right value. In this respect it's fortunate that a lot of the parameters don't have a very wide range of values.

Inside, the oscillator chip is an MSM5232, which was also used in some arcade games. The filter is an NJM-2069AD, a custom Korg chip similar in architecture to the CEM 3378 (mixer, VCF, and VCA on one chip). Due to the voice architecture, I think the VCF is actually placed after oscillator VCAs, with a gate after that to mute it when there's no sound output. For obvious reasons this makes self-oscillation a bad idea. The delay is on its own separate board and consists of a simple 12-bit VCO-clocked companded arrangement. Actually it's got a custom chip in there but that's the basic idea. On paper it doesn't seem like much but it sounds great. The nice part is that unlike more advanced delays that do everything in DSP, the feedback path goes through the anti-aliasing filters again, which gives a warmer sound. When mixed to the stereo outs one delay output channel is inverted to give a pseudo-stereo effect.

Overall the sound is excellent. It excels mostly at pad sounds, but also does tinkly sounds and bass sounds very well. The independent oscillator envelopes really help with evolving sounds. The filter and delay are a wonderful combination for making lovely sounds. The synth isn't particularly versitile but it sounds nice and is capable of a few unique tricks that would be difficult on other synths, so it's worth buying for a low enough price.

Mine was modified with the typical cutoff, resonance, and noise knobs (it's just a matter of replacing trimpots on the main board with panel-mounted potentiometers), but I also added a knob to control the delay clock. This was really interesting because the sample rate could go really low, making a very strange aliasy sound. At one point (with full feedback) the delay even self-oscillated. These knobs work in a rather unusual way since they're just replacing the trimpots: the values can't be saved and the parameter values still have an effect. But they're useful for tweaking in realtime. It can be modified further: the filter has an unused 2-pole output and it should be easy to make inputs for the filter and delay...

pictures: I didn't have a camera at the time so I put it on my scanner.


links:
There's a page for adding cutoff and resonance knobs that works out much better than the way I did it: Moog Slayer Filter Mod for Korg EX-800 and Poly-800 It's for the original Poly 800 but it works just as well for the Mk. II model.

back to synth index
Hosted by www.Geocities.ws

1