<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">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">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">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">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">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">http://www.florian-anwander.de/</a></pre>
</div>
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