[sdiy] Roland System-500 Filter pcbs

Dakota Melin dksynth at gmail.com
Fri Jul 30 18:57:59 CEST 2021


The large number of transistors .... these are probably OTAs built out of
transistors along the lines of the Open Music Labs BA662

On Fri, Jul 30, 2021 at 12:45 PM Florian Anwander <fanwander at mnet-online.de>
wrote:

> Hello,
>
> Inspired by the Alex Ball Video mentioned over at analogue heaven I wanted
> to update my page about roland filters with the information on the System
> 500.
> I checked th thomann.de pages for the pictures of the module and got a
> little worried
>
> This is the pcb of the 510 (should be one four stage OTA filter and a VCA)
> https://bdbo2.thomann.de/thumb/bdb3000/pics/bdbo/13948871.jpg
>
> This is the pcb of the 521 (should be two four state OTA filters)
> https://images.static-thomann.de/pics/bdb/379516/10742587_800.jpg
>
> This is the pcb of the 505 (it should be a tranistor ladder filter)
> https://bdbo2.thomann.de/thumb/bdb3000/pics/bdbo/13948906.jpg
>
>
>
> The pcb of the 505 is full of LM37000, while there is no OTA in the
> original Circuit.
> The pcbs of the 510 and 521 show not a single OTA, but many parts which
> seem to be double transistors - which I would expect for the 505.
>
> After a first comparison of the 510 and 505 I thought Thomann mismatched
> the pictures, but the 521-pcb looks too similar to the 501-pcb
>
>
> Can you identify what are 6 pin parts on the pcbs for the 521/510?
>
> Florian
>
>
> -- http://www.florian-anwander.de/
>
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