The digital delay in 1980s Korg polysynths

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RhythmDroid
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The digital delay in 1980s Korg polysynths

Post by RhythmDroid » Mon Dec 02, 2019 1:17 am

I've owned a DW8000 as a teenager and currently have a DS-8 (Korg's wimpy but loveable answer to the DX7...but it's more like a DX100 with "tone control" sliders)

The built-in digital delay on both these is, to me, lusicous. Evocative..icy and warm at the same time...like an October evening when the village burns the leaves and the smoke covers the orange sky.

Does anyone know for certain if these built-in delays were the same as in Korg's 80s rackmount delays or was it a different thing entirely?
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commodorejohn
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Post by commodorejohn » Mon Dec 02, 2019 3:30 am

I dunno, but it's beautiful dark magic, whatever it is...between that and the SSM filters, just...man.
Computers: Amiga 1200, DEC VAXStation 4000/60, DEC MicroPDP-11/73
Synthesizers: Roland JX-10/SH-09/MT-32/D-50, Yamaha DX7/V50/TX7/TG33/FB-01, Korg MS-20 Mini/ARP Odyssey/DW-8000, Ensoniq SQ-80

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Post by marcn » Mon Dec 02, 2019 3:54 am

Quick look at the Korg DW8000 schematics show the Delay block labeled as KLM-775 , probably a module Korg used in other devices.
As for the whole delay, apart from some 3rd party IC's it seems to use some proprietary ICs or at least google doesn't return anything on them.
I think it's safe to say though if you look through any service manuals from Korg and find a delay block labeled KLM-775 it is essentialy the same as in the DW8000.

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Post by RhythmDroid » Mon Dec 02, 2019 1:45 pm

Thanks for looking that up! I found this...

https://syntaur.com/Items.php?Item=4380

THAT'S THE BOARD.

Damn, there is a lot of stuff going on there.

It'd be fun to turn that into a tabletop module, ahah. Kinda boutique...too boutique??
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Post by DMR » Mon Dec 02, 2019 4:34 pm

RhythmDroid wrote:
THAT'S THE BOARD.
I have a DW8000 I've been trying to fix, I've thought about using the delay stand-alone as well, if the synth as a whole isn't salvageable. I believe the delay parameters enter the board from the DW8000 CPU as analog control voltages.

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Post by Mungo » Mon Dec 02, 2019 5:11 pm

marcn wrote:Quick look at the Korg DW8000 schematics show the Delay block labeled as KLM-775 , probably a module Korg used in other devices.
As for the whole delay, apart from some 3rd party IC's it seems to use some proprietary ICs or at least google doesn't return anything on them.
I think it's safe to say though if you look through any service manuals from Korg and find a delay block labeled KLM-775 it is essentialy the same as in the DW8000.
The DW8000 schematics I looked at have the entire delay circuitry, which is a simplified version of the SDD2000 effects unit (that manual explains the operation of the circuitry).

Its a digital implementation of a BBD running from a VCO. Some of the magic sound will come from their compressor/expander before/after the delay, and some from the mismatch of the filtering and sampling (aliasing).
DMR wrote:I believe the delay parameters enter the board from the DW8000 CPU as analog control voltages.
The feedback level is set with a digital control word, which would need some reverse engineering and a micro controller to drive it.

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Post by The Real MC » Mon Dec 02, 2019 6:59 pm

I do know that the digital delay in the Korg DSS-1 is the same as their SDD-1200 dual digital delay.
I haz a wrench, to fix da synth.
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