Modifying a Korg EX8000

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MisterE
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Modifying a Korg EX8000

Post by MisterE » Wed Sep 12, 2007 4:32 am

I just got this unit not too long ago, and I'm loving it. The filters and delay are awesome. It didn't take long for me to wonder if anyone out there had thought about modifying the unit to allow audio inputs to use the analog filters and possibly even the delay. The original sound source is digital waveforms, and the filters are analog, but the delay is digital. I would assume that the delay comes after the analog filters, which would mean that the sound is converted from digital to analog, goes through the filters, then for the delay is converted back to digital...

So it seems to me like at the point before the filters that you could have an audio input line come in. Granted I don't know anything about electronics much, and wouldn't just try to figure something like this out on my own unless I had time to read some basic books and practise on other things. But the filters in this unit seem pretty nice sounding to me, and so does the delay, so I just wondered if anyone out there ever modified one of these (or knows of anyone who has) to use it as an effects processor on other audio?
In particular I think it would be cool because I would think it would still be possible to use the keytracking on the filter while running audio through it, with the synths output being switched 'off'.

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Post by MisterE » Wed Sep 12, 2007 4:40 am

Also, I'm interested enough in this and learning a little electronics/getting into doing some small projects of my own, that, even if nobody knows of anyone having actually done this, if anyone is familiar with the schematics of this thing and has any thoughts on the possibility/difficulty of it, I would be interested in hearing.

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Post by Sealed » Wed Sep 12, 2007 5:06 am

According to Synrise site, there seems to have been the updated version called DW-8000 ACTION series. They had an external input for the digital delay.

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Post by gs » Wed Sep 12, 2007 8:14 pm

On the DSS-1 (a sampling DW/EX-8000 on steroids), you can use the sampling input to treat an exernal audio source with the twin digital delays (same DDL as in EX8000 but two of them!). Unfortunately, you can't treat that external signal with the filter. :cry: that is, without modification.
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Re: Modifying a Korg EX8000

Post by gs » Wed Sep 12, 2007 8:19 pm

MisterE wrote:I would assume that the delay comes after the analog filters, which would mean that the sound is converted from digital to analog, goes through the filters, then for the delay is converted back to digital...
The DDL in the EX8000 is not of the modern all-DSP variety; it's more like the old DDLs of the 80s (like the Roland SDE-1000) which actually bounces a digitized copy of the original sound in analog form (it is a DDL with an analog signal path). And often in factory patches, the original sound is mixed in with the delayed signal.

The result is it sounds better and "less digital" than modern all-DSP based delays.
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meatballfulton
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Re: Modifying a Korg EX8000

Post by meatballfulton » Wed Sep 12, 2007 8:44 pm

gs wrote:The DDL in the EX8000 is not of the modern all-DSP variety; it's more like the old DDLs of the 80s (like the Roland SDE-1000) which actually bounces a digitized copy of the original sound in analog form (it is a DDL with an analog signal path).
????? WTF ?????

Trying to make some sense out of that...
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Post by micahjonhughes » Wed Sep 12, 2007 10:28 pm

It would be somewhat difficult to get a signal through the filter as there are 8 filters, one for each voice.

You would have a much easier time doing what you want to do with a poly-800 mkII. It has a single filter and a digital delay. I would think you could tap the signal path before the filter and then use the filter, VCA and delay to process an external signal.

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Re: Modifying a Korg EX8000

Post by Sir Ruff » Wed Sep 12, 2007 11:18 pm

meatballfulton wrote:
gs wrote:The DDL in the EX8000 is not of the modern all-DSP variety; it's more like the old DDLs of the 80s (like the Roland SDE-1000) which actually bounces a digitized copy of the original sound in analog form (it is a DDL with an analog signal path).
????? WTF ?????

Trying to make some sense out of that...
80s DDL=bucket brigade type device. someone else will have to explain the technicalities, but the sound is passed along individual analogue chips rather than replicated just digitally as 1s and 0s in one single chip (is that right? :?)

I believe however, the dw8000/dss-1 delay while digital, is actually 12-bit, hence it sounds warmer, and more like an analogue delay.
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Post by carbon111 » Thu Sep 13, 2007 12:28 am

Bucket Brigades (like the old SAD chips) are pure analog, not digital.

Digital Delays are RAM or DSP based.
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Post by solderguy » Thu Sep 13, 2007 12:37 am

Looking at the EX-8000 service manual, the digital delay is most certainly analog-in, analog-out. It includes an 571 compander chip for noise reduction, same as used in many analog (BBD) delays. However, the delay itself is digital, based on a custom gate array chip, with A/D D/A conversion on the board. Regeneration is done in the analog domain. It could certainly be modified for external inputs. BTW this is the same digital delay circuit as used in the DW-8000.

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Post by carbon111 » Thu Sep 13, 2007 12:55 am

A gate array as memory? Sweet! What was the bit-depth of the delay? IIRC, it sounded pretty good for its time :D

A friend had a DW8000 some years ago (when they were new!) and I remember the combination of the filter, arp and delay being a blast.
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Post by Sir Ruff » Thu Sep 13, 2007 2:28 am

carbon111 wrote:A gate array as memory? Sweet! What was the bit-depth of the delay? IIRC, it sounded pretty good for its time :D

A friend had a DW8000 some years ago (when they were new!) and I remember the combination of the filter, arp and delay being a blast.
Sir Ruff wrote: I believe however, the dw8000/dss-1 delay while digital, is actually 12-bit, hence it sounds warmer, and more like an analogue delay.
Do you even post on vse bro?

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Post by carbon111 » Thu Sep 13, 2007 2:40 am

My main point was to clarify a misconception:
Bucket Brigades (like the old SAD chips) are pure analog, not digital.
Differences between the two are readily heard, especially with digital...The lower the bit rate the rougher the sound - plus you get aliasing, decidedly not analog. at all ;)

Thats not to say old digital delays don't have a lot of character of their own!

Analog delays and digital delays have quite different characters. Both are very useful which is the reason why Moog issued a nice creamy analogue delay and why Eventide reissued a revamped Princeton Digital unit.

Also why something like the old Ursa Major digital delays are still sought after...i think they were eight bit - very "granular" sounding :shock:
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Post by 30h5 » Thu Sep 13, 2007 3:42 am

Did you buy my EX? :D

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Post by solderguy » Thu Sep 13, 2007 4:20 am

The delay memory actually consists of two M5M4416 dynamic RAM chips connected to the gate array. These are probably each 16K x 1 (not a very big memory). There are 12 data out lines from the gate array, these go to a resistor pack which serves as a D/A converter, the output is sent to the expander part of the 571 compander, the D/A also does double-duty in the A/D conversion.

Haven't tried a DW-8000 or EX-8000 yet, just got a DW-6000, already one of my favorites. The DW-synths seem to be very rare in Canada for some reason, altho there are a lot of ESQ-1 floating around.

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