<div dir="auto">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.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri., Jul. 30, 2021, 1:00 p.m. Dakota Melin via Synth-diy, <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">The large number of transistors .... these are probably OTAs built out of transistors along the lines of the Open Music Labs BA662 <br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jul 30, 2021 at 12:45 PM Florian Anwander <<a href="mailto:fanwander@mnet-online.de" target="_blank" rel="noreferrer">fanwander@mnet-online.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div>Hello,<br>
<br>
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.<br>
I checked th <a href="http://thomann.de" target="_blank" rel="noreferrer">thomann.de</a> pages
for the pictures of the module and got a little worried<br>
<br>
This is the pcb of the 510 (should be one four stage OTA filter
and a VCA)<br>
<a href="https://bdbo2.thomann.de/thumb/bdb3000/pics/bdbo/13948871.jpg" target="_blank" rel="noreferrer">https://bdbo2.thomann.de/thumb/bdb3000/pics/bdbo/13948871.jpg</a><br>
<br>
This is the pcb of the 521 (should be two four state OTA filters)<br>
<a href="https://images.static-thomann.de/pics/bdb/379516/10742587_800.jpg" target="_blank" rel="noreferrer">https://images.static-thomann.de/pics/bdb/379516/10742587_800.jpg</a><br>
<br>
This is the pcb of the 505 (it should be a tranistor ladder
filter)<br>
<a href="https://bdbo2.thomann.de/thumb/bdb3000/pics/bdbo/13948906.jpg" target="_blank" rel="noreferrer">https://bdbo2.thomann.de/thumb/bdb3000/pics/bdbo/13948906.jpg</a><br>
<br>
<br>
<br>
The pcb of the 505 is full of LM37000, while there is no OTA in
the original Circuit.<br>
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.<br>
<br>
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<br>
<br>
<br>
Can you identify what are 6 pin parts on the pcbs for the 521/510?<br>
<br>
Florian</div>
<div><br>
<br>
</div>
<pre cols="72">--
<a href="http://www.florian-anwander.de/" target="_blank" rel="noreferrer">http://www.florian-anwander.de/</a></pre>
</div>
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