[sdiy] BA662 (Was Re: SPV-355 -15V rail issue)

Tom Wiltshire tom at electricdruid.net
Mon Jun 19 10:32:48 CEST 2023


Yes, Alfa make a clone - or at least a chip with that number:

https://www.alfarzpp.lv/eng/sc/AS662D.pdf <https://www.alfarzpp.lv/eng/sc/AS662D.pdf>



> On 19 Jun 2023, at 04:41, Adam (synthDIY) <synthdiy at adambaby.com> wrote:
> 
> 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
>> 
> 
> 
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