[sdiy] [AH] KORG 700S CV Hz/V / gate retrofit

[cheater cheater]

On Sun, Jul 25, 2010 at 21:15, David Bulog <d2ba at xtra.co.nz> wrote:
> Korg 700S was used entirely for this classic track
> http://www.youtube.com/watch?v=S5QErPDNcj4

This demo... is not especially encouraging the purchase of a Korg 700S.

> Hi there has anyone done CV Hz/V / gate retrofit to e Korg 700S
> I have two ways to go--Kenton which would ensure a good match for any of
> there midi -cv interfaces
> http://www.kentonuk.com/products/items/sockets/korg/700s.shtml
>
> or DIY
> full mod diag
> http://www.cykong.com/Synths/Korg%20700S/Images/Korg700-CVGateInModFull-Schmo.gif

What you're looking for is an exponential converter. Those can be had
in many forms and most VCOs with linear FM input have an exponential
converter. You might want to look at a 2164 based one, they're
extremely stable. I think David Dixon had some boards for his VCO, but
not sure. You'd take the VCO and stuff just the exponential converter,
basically, and maybe or maybe not you'd need to add a current->voltage
converter with gain but that's not a big thing if it's needed at all.

The DIY one you have posted doesn't seem to have any temperature
compensation and does not use precision voltage references, so it'll
be quite crap I think. That doesn't mean the Kenton's much better,
it's probably just as bad. SSM 2164 based exponential converters are
currently the best ones you can get, and the chips aren't expensive at
all.

Cheers,
D.


> part 1
> http://www.cykong.com/Synths/Korg%20700S/Korg700S-Mods1..htm#Proper%20External%20CV/Gate%20In
> part 2
> http://www.cykong.com/Synths/Korg%20700S/ElabJapan/ElabKorg700CVGateMod.htm
>
> thanks in advance
> David
> To: analogue at hyperreal.org,
> From: Zane Whitaker zanewh2000 at yahoo.com,
> cc:
> Subject: [AH] MiniKorg Mod Woes
> Date: Tue, 2 Dec 2008 17:38:38 -0800 (PST)
>
> ________________________________
> Hello AH'ers.
>
> Long time archives lurker here. I have posted once or twice since around
> 2002, usually when one of my synths breaks, and this is no exception.
>
> A little background first:
> This site:
> "http://www.cykong.com/Synths/Korg%20700S/Korg700S.htm"rg700S.htm" is the
> most common source of information for Minikorg mods. I previously did the
> 'basic' CV/Gate and Audio Filter-In mods with no problems. By basic, I mean
> I didn't need to build the buffer/tuner circuit, as you get everything but
> the repeat function without it, and you don't even need to hold down a key
> to use the external Gate, at least not on mine.
> is the most common source of information for Minikorg mods. I previously did
> the 'basic' CV/Gate and Audio Filter-In mods with no problems. By basic, I
> mean I didn't need to build the buffer/tuner circuit, as you get everything
> but the repeat function without it, and you don't even need to hold down a
> key to use the external Gate, at least not on mine.
>
>
> BTW
>