This is my take on Rob Hordijk's amazing <a href="http://casperelectronics.com/finished-pieces/benjolin">Benjolin</a> synthesizer. In Early 2010 I started working with Brendan Gaffney of <a href="http://www.burnheartsynth.com/">BurnHeart Synthesis</a>. One of the big projects we've been working on is adapting the Benjolin into a fully modular system.  
<a href="http://casperelectronics.com/wp-content/uploads/Benjolin/ModularBenjolin/IMG_12955.jpg"><img src="http://casperelectronics.com/wp-content/uploads/Benjolin/ModularBenjolin/IMG_12955.jpg" alt="" title="IMG_12955" width="400" height="250" class="alignnone size-full wp-image-644" /></a>

<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1294.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1294.JPG" width="400" height="294" alt="" title=""  /></a>

<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1261.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1261.JPG" width="400" height="250" alt="" title=""  /></a>

<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1273.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1273.JPG" width="400" height="250" alt="" title=""  /></a>

<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1268.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1268.JPG" width="400" height="250" alt="" title=""  /></a>
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Here's a video showing the first prototype of the current modular Benjolin design. You can also see modular benjolin version 1 in the top left corner of the screen. 
<iframe width="450" height="300" src="http://www.youtube.com/embed/O3cgDeXJ7lE" frameborder="0" allowfullscreen></iframe>
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<h2>Makin' it modular:</h2>
It was important to us in adapting the Benjolin to make sure it retained all of the original functionality that Rob designed into it. We also wanted to greatly extend its capacity to interface with other gear, especially other Benjolins. So, while it <em>is</em> completely modular we decided to include the normalized features of the original, like "rungle amount" for the oscillators and filter and put in switches on the rungle section to switch between the original setting or external inputs. 
Here's a list of all the features, old and new.
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<strong>FEATURES:</strong> <em>(** indicates original feature. All others features have been added to the modular version)</em>
<strong>(2) VCOs </strong>
---Coarse tune adjustment**
---Fine tune adjustment
---Rate indication LED
---Rungle amount adjustment**
----- square and triangle output jacks**
----- 2 frequency CV inputs w/ adjustments
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<strong>(1) VCF</strong>
---Cutoff adjustment**
---Resonance adjustment**
---Rungle amount adjustment**
---Internal mix level adjustment
-----2 cuttoff CV inputs w/ adjustments
-----2 audio inputs w/ adjustments
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<strong>(1) Rungler</strong>
-----Clock input jack w/ clock select switch
-----XOR input jack w/ OSC/loop select switch (see Rungle mods below for more details)
-----3 bit output jacks w/ state indication LEDs
-----Rungle output jack **
-----XOR output jack **
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<strong>(2) AR envelope generators</strong>
---Attack rate adjustment
---Decay rate adjustment
---State indication LED
-----Gate input jack
-----Envelope output jack
<hr><hr>
<h2>SCHEMATICS:</h2>
Click the schematics below for more info
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RUNGLE MODS
<a href="http://casperelectronics.com/rungle-mods/"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/BenjClockBuffer2.jpg" width="400" height="200" alt="" title=""  /></a>
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CV AND AUDIO INPUTS
<a href="http://casperelectronics.com/benjolin-cv-and-audio-inputs"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/Benjolinmodularization.jpg" width="400" height="200" alt="" title=""  /></a>
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AR ENVELOPE GENERATOR
<a href="http://casperelectronics.com/ar-envelope-generator/"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/BenjAREnvGen2.jpg" width="400" height="250" alt="" title=""  /></a>
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REVISED SCHEMATIC
<a href="http://casperelectronics.com/images/finishedpieces/benjolin/NewSchematic.jpg"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/NewSchematic.jpg" width="400" height="600" alt="" title=""  /></a>

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Here's three modular Benjolins blippin away
<iframe width="450" height="300" src="http://www.youtube.com/embed/uaFwLh4pHGw" frameborder="0" allowfullscreen></iframe>