[sdiy] SPV-355 -15V rail issue

[Adam (synthDIY)]

Actually, yes you're right, the Roland BA662 OTA that they used a lot around this time, both for VCAs and VCFs. I've sent you the schematic.

I think they've been cloned successfully in recent years

A

> On 19 Jun 2023, at 1:10 pm, brianw <brianw at audiobanshee.com> wrote:
> 
> Although the VCO is surely bespoke, I was thinking that the VCF and/or VCA might be one of those dedicated chips that perform individual functions. Do you have a link to the schematic? I'd be curious to see how the VCF and VCA are implemented.
> 
> Brian
> 
> 
> On Jun 17, 2023, at 8:54 PM, Adam wrote:
>> I don't think there's any "vintage synth chips" in this, is there? It's basically a pitch to CV converter driving a VCO/VCF/VCA  with envelope control, same era as the SH-09 monosynth.
>> 
>> Actually just looking at the schem now, I'd always assumed they used a Phase Locked Loop in there but I can't see one.
>> 
>> One thing I do see in there that is virtually unobtainium is a Fairchild uA726, IC18
>> 
>> <grab 2023-06-18 at 1.52.50 pm.png>
>> 
>> 
>> 
>> Unless someone has managed to clone that in recent years..?
>> 
>> A
>