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

[cheater cheater]

Ah, duh. Figures why I couldn't make sense out of it.

On Sun, Jul 25, 2010 at 23:17, Richard Atkinson <rga24 at cantab.net> wrote:
> On Jul 25 2010, cheater cheater wrote:
>
>> 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.
>
> Try this one.
>
> http://www.youtube.com/watch?v=_p7Ub1NDTVg
>
>>>
>>>  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.
>
> That's not an expo convertor. That's a hold circuit to pass the CV through
> to the oscillator while the Gate is enabled. When the Gate is released, the
> circuit holds the value at that point. The control voltage is in linear form
> (Hz/V) going into the circuit and in linear form coming out of it.
>
>