[sdiy] Roland System-500 Filter pcbs

Jacob Watters jacobwatters at gmail.com
Fri Jul 30 19:36:44 CEST 2021


This is what I was thinking too. I did talk to Josh about the filters, and
he said that his goal wasn't exact clones of the circuits, but to create
something that captures the same essence of the original 100m and 700
filters. He said that the capacitors were an important part of getting that
sound.

On Fri., Jul. 30, 2021, 1:00 p.m. Dakota Melin via Synth-diy, <
synth-diy at synth-diy.org> wrote:

> 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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