Vintage Synths: Reminiscing About Poly 800 + Moog Slayer Filter Mod + Poly-800 Meets Octatrack Improv


My First Synth

My very first synth was the Poly-800 which I bought the year it was introduced in 1984. It was the first programmable polyphonic synth for under a thousand bucks (I bought mine for $795 new). It was an incredible value at the time with these features:

  • MIDI  (which had only just been introduced at the 1993 NAMM show)
  • 8 note polyphony
  • Two stable digital oscillators (DCO) but with a 24dB/oct low-pas analog filter
  • Hold, Chord Memory
  • A step Sequencer
  • 49 Full-sized keys (non-velocity sensing)
  • Runs on battery (6 C cells)
  • 3 envelope generators
  • Chorus
  • Noise
  • Strap pegs so you could wear it like a keytar
  • A joystick to control pitch bend and modulation and the filter


Great Starter Synth

It was a fantastic first synth to own because even though you have to program it with two buttons and a 2-digit LED, all the parameters are laid out graphically on the top of the synth. Being able to easily visualize these parameters without having to crack open the manual quickly taught me about subtractive signal flow and architecture.

Photo Nov 23, 8 52 44 AM


It is also a quirky synth in that even though it has MIDI, it didn't have Sysex. This meant that back in the day, you had to save presets to audio cassette :^o. Note, you can find factory presets on the internet in .wav format (see links at bottom of post). BTW – The Poly-800 MKII added Sysex capability along with digital delay effects.

Another quirk that I like is that the filter is shared by all voices. So any time the filter is re-triggered, it's re triggered for all voices. This is actually a pretty unique feature and allows you to get cool strumming type sounds out of the instrument.

What's Old is New Again

I sold it years later to a friend to help fund  another bigger ticket synth – probably an ESQ-1. Even though I sold it, the Poly-800 was one of my favorite synths of all time and I hoped to own one again someday. Well I'm happy to report that my friend Darwin Grosse (Art + Music + Technology Podcast) just sold me a Poly-800 with the added bonus of having the Moog Slayer filter modification.

Moog Slayer Filter Modification

Photo Nov 23, 9 12 28 AM

In a nutshell, this mod adds two physical knobs to the Poly-800 just above the joystick to control filter cuttoff and resonance. Before the mod you countrolled filter via the up/down buttons having only the Photo Nov 23, 8 53 09 AMability to step through a discrete 0-99 range for filter, and a super lame 0-15 range for resonance :^( Pulling the joystick down doesn't sweep the filter but instead turns up the intensity of the filter LFO (called a MG or modulation generator on the parameter index panel). So this mod is really a game changer in that it allows you fine continuous control over these parameter with no zippering effect – woot! Now you can get to take yourself to the ragged edge of self-oscillation and can get all Hendrix with the Poly-800!

Poly-800 Moog Slayer Filter Mod Meets Elektron Octatrack

Photo Nov 23, 9 07 11 AM

These days, most things that make sound in my studio become either Absynth or Octatrack food. Below is my first experiment doing an improv with the Poly-800 Moog Slayer as the only sound source for the Octatrack. It's worth mentioning that when I got the unit all the presets were reset to INIT. Rather than load the factory presets I'm setting out to re-kindle my relationship with the Poly-800 by creating custom presets. This recording uses my first three super gnarly presets :^)

[Link to soundcloud recording]


Before I started my live improv, I created a sonic bed with a mashup of these three sounds using the Octatrack's "Pickup Machine" (which is a looper). I then did an improv in real-time starting with pure Poly-800 where I'm riding those new glorious cutoff and resonance knobs. I then live sample the Poly-800 into a "Flex Machine" and setup some sequencer trigs on the fly to trigger those samples. I fade in the bed I created in the pickup machine. I then play the Poly-800 and manipulate it's signal and signal of the the pickup machine and flex machine with pitch, low pass filters, comb filters, delay, lo-fi bit crushing, and reverb all courtesy of the Octatrack. The piece ends with pure Poly-800 again – bam!

Great to Have My First Synth Love Back in the Studio

I feel fortunate to have started with the Poly-800 in so many ways. Learning to program through the 2-digit display and have to grok the architecture in my head (vs one knob per function) created a way of thinking for me that shortened my learning curve with instruments I would later buy like the Ensoniq Mirage (2-digit hex display). This certainly comes full circle when I consider the interface of the Octatrack. Deep, hard to learn, but the deeper you go, the bigger the reward.

Thanks Korg for making such a groundbreaking synth at a price point I could reach when I was a baby synthesist and to creator of Moog Slayer Filter Mod. And thanks Darwin for reconnecting me with my first synth!

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Hi, this is Mark Mosher. Welcome to my blog. I’m a synthesist, Composer, Producer, and Visualist living in Boulder CO. I’m also the founder of the Rocky Mountain Synth Meet and Synth Patrol.

I’ve been blogging wince 2005 and this blog is a mix of posts on artistic news as well as synth tech & technique posts under the category Modulate This!

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