Korg PE-1000 - One Weird Beauty!

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tim gueguen
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Re: Korg PE-1000 - One Weird Beauty!

Post by tim gueguen » Sun Feb 22, 2015 2:37 am

madtheory wrote: One of the thing I'd love to see is a demo of the PPG and the other sequencer they were using at the time (it doesn't say what it is in the E&MM article). A lot of people say they were using tape playback but Froese always denied it.
I think some of that is the result of the video footage from the early '80s being poorly edited. There's more than enough variation between pieces in the 1980 and 1981 shows that miming seems extremely unlikely. '82 and later I'm not so sure about. For example the "Logos" on the Tangerine Tree release of the '82 Budapest show sounds pretty much like the official Logos album. But if TD were miming to tape at that point and later you'd think someone with official connections to the band would have spilled the beans by now. A roady, someone connected with their management, Franke or Schmoelling.
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Re: Korg PE-1000 - One Weird Beauty!

Post by HideawayStudio » Sun Feb 22, 2015 11:36 am

rschnier wrote:
Sir Ruff wrote:They are weird, great machines, but my biggest complaint (and the reason Jon S. now owns his :lol: ) is the lack of envelope modulation on the filter. I know you can sweep with the foot pedal, but you would think that true env. or LFO modulation would be de rigueur on a synth that contains such a funky filter.
Agreed, but since each note/key has its own EG, which one would modulate the filter? I suspect that's the problem the designers ran into.

P.S. Thanks Dan for the interior p**n shots :lol:
I think I need to clear up some confusion about the PE-1000 regarding the filters that has found its way around the internet. The PE-1000 shares something in common with the Polymoog in that although both instruments do indeed have overall filters at the end of their audio paths they also have a simple dedicated voltage controlled low pass filter (without resonance) with an independent envelope generator on every key. In the case of the PE-1000 this is a very basic 6dB/oct Low Pass Filter which, in a very similar manner to the PS-3100, is tied to the same envelope generator as the VCA within the tone generator for each key. In both Korgs the "Expand" control acts as the envelope amount for the VCF for each independent key. The key difference between the two instruments is that the PE-1000 is only 6dB/oct and the PS-3100 features an MS-20 Rev.1 style KORG35 filter with resonance per key (yes - its a monster!).

I have annotated the PE-1000 tone generator circuit found in every key to illustrate this:

Image

I am still in amazement that the single transistor VCA used in the Korg PE-1000, PS-3100, MS-20, Micro-Preset and Sigma works so well without incurring massive amounts of CV bleedthru!

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Re: Korg PE-1000 - One Weird Beauty!

Post by Sir Ruff » Sun Feb 22, 2015 6:56 pm

HideawayStudio wrote:I think I need to clear up some confusion about the PE-1000 regarding the filters that has found its way around the internet. The PE-1000 shares something in common with the Polymoog in that although both instruments do indeed have overall filters at the end of their audio paths they also have a simple dedicated voltage controlled low pass filter (without resonance) with an independent envelope generator on every key. In the case of the PE-1000 this is a very basic 6dB/oct Low Pass Filter which, in a very similar manner to the PS-3100, is tied to the same envelope generator as the VCA within the tone generator for each key. In both Korgs the "Expand" control acts as the envelope amount for the VCF for each independent key. The key difference between the two instruments is that the PE-1000 is only 6dB/oct and the PS-3100 features an MS-20 Rev.1 style KORG35 filter with resonance per key (yes - its a monster!).
thanks for posting. I managed to figure this out eventually, but it's really not well documented on the net. I suspect most people (understandably) don't realize what is actually going on with the expand function.

Can you clarify on the PS-3100 envelopes? Are you saying that there's only one envelope for both the VCF/VCA for each voice (which just happens to be tied to a beefier filter)? I take it the 2nd envelope on the PS is just a single, utility envelope then? The SOS review alludes to this, but not clearly.
Do you even post on vse bro?

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Re: Korg PE-1000 - One Weird Beauty!

Post by HideawayStudio » Sun Feb 22, 2015 8:35 pm

Sir Ruff wrote:
HideawayStudio wrote:I think I need to clear up some confusion about the PE-1000 regarding the filters that has found its way around the internet. The PE-1000 shares something in common with the Polymoog in that although both instruments do indeed have overall filters at the end of their audio paths they also have a simple dedicated voltage controlled low pass filter (without resonance) with an independent envelope generator on every key. In the case of the PE-1000 this is a very basic 6dB/oct Low Pass Filter which, in a very similar manner to the PS-3100, is tied to the same envelope generator as the VCA within the tone generator for each key. In both Korgs the "Expand" control acts as the envelope amount for the VCF for each independent key. The key difference between the two instruments is that the PE-1000 is only 6dB/oct and the PS-3100 features an MS-20 Rev.1 style KORG35 filter with resonance per key (yes - its a monster!).
thanks for posting. I managed to figure this out eventually, but it's really not well documented on the net. I suspect most people (understandably) don't realize what is actually going on with the expand function.

Can you clarify on the PS-3100 envelopes? Are you saying that there's only one envelope for both the VCF/VCA for each voice (which just happens to be tied to a beefier filter)? I take it the 2nd envelope on the PS is just a single, utility envelope then? The SOS review alludes to this, but not clearly.
Yes - correct. The PS-3100 VCA and Filter are indeed tied to the same envelope generator - but this is actually a centralised control to a full keyboard of independent polyphonic envelope generators just like the 1939 Novachord and PE-1000. All of these instruments make this possible by the charge transfer method of which the Novachord may well be the first incarnation in a polyphonic electronic instrument.

The expand control determines how the filter on each key responds to the VCA envelope. The general envelope generator on the PS-3100 is, on the other hand, paraphonic and is not dedicated in the same way and can be used for a number of purposes such as adding a trill or slide to the oscillator attack or to implement a delayed vibrato as well as many other more esoteric tasks through the patch bay.

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Re: Korg PE-1000 - One Weird Beauty!

Post by rschnier » Sun Feb 22, 2015 8:45 pm

HideawayStudio wrote:The PE-1000 shares something in common with the Polymoog in that although both instruments do indeed have overall filters at the end of their audio paths they also have a simple dedicated voltage controlled low pass filter (without resonance) with an independent envelope generator on every key. In the case of the PE-1000 this is a very basic 6dB/oct Low Pass Filter which, in a very similar manner to the PS-3100, is tied to the same envelope generator as the VCA within the tone generator for each key.
Thanks for the clarification, and the schematic. There are indeed some very creative, interesting designs in these synth-per-key units.
-- R.

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Re: Korg PE-1000 - One Weird Beauty!

Post by ppg_wavecomputer » Mon Feb 23, 2015 10:42 am

Micke wrote:Other famous users of the PE-1000 include Vangelis (eg on "Albedo"), Space (if I recall correctly both the PE-1000 and PE-2000 were featured on their first album) and Wally Badarou (M's first album, including the song "Pop Muzik", some early Level 42 songs, as well as on Janic Prévost's "J'veux d'la tendresse").
Yes, Vangelis used the 1000 a lot for mainly brass-type sounds or bass (i. e. "Albedo 0.39", the title track) before he switched to the CS80. Space also used a 3300 for at least one album.

The PE series was amazingly popular in France (probably due to JMJ being such an avid endorser of all the Korg stuff of that era).

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Re: Korg PE-1000 - One Weird Beauty!

Post by Automatic Gainsay » Wed Feb 25, 2015 5:34 pm

Fantastic information as usual, Dan!

I only recently found out that this device has an oscillator-per-key, and I am kicking myself for never having bought one. I will be on the lookout, though. This is real polyphony.
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Re: Korg PE-1000 - One Weird Beauty!

Post by Dr. Phibes » Thu Feb 26, 2015 11:12 am

Is that a UJT based oscillator?

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Re: Korg PE-1000 - One Weird Beauty!

Post by HideawayStudio » Thu Feb 26, 2015 11:51 am

Dr. Phibes wrote:Is that a UJT based oscillator?
Not quite... and if I'm honest, I've learnt something here...

The PE-1000 oscillators are technically not a UJT or SCR based but in fact utilise PUTs (Programmable Unijunction Transistor).

It seems that although UJTs have been long obsolete, PUTs are still in manufacture to this day as they serve a specific purpose and, as this case, can be used to implement relaxation oscillators (sawtooth generators) with minimal components ie. just perfect for a crazy old synth with 5 octaves worth of independent oscillators 8-)

Just found this explanation - the second section nicely describes PUTs:

http://www.allaboutcircuits.com/vol_3/chpt_7/8.html

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