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<B>
Moog Micromoog/Multimoog DIY Modifications
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<B>
VCF Modification
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<B>
Written by: Michael Caloroso
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Micromoogs and Multimoogs have always been adequate for lead lines and noise
FX, but they have a "fault" that restricts their ability to deliver bass
timbres a'la the classic Minimoog bass.  The VCF has a cap on the audio input
that provides DC isolation, but it also forms a high pass filter; on the
Micro/Multi, the cap is not large enough to allow low frequency components to
pass through.  This is evident when you observe the change of the pulse
waveform on a scope, as you switch the VCO octave from 8' to 32'.
</FONT>
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This "fault" is easily fixed.  Just parallel C506 with a 100uf 50v electrolytic
cap.  Refer to the attached pics for the location of the cap on the main board;
it is located smack in the middle (Micromoog and Multimoog use the same main
board).  Make sure you observe the polarity of the cap and that you have
sufficient clearance. I tack-soldered it on the underside on the PC board and
</FONT>
</P>
<P>
<FONT SIZE="3">
This lowers the cutoff frequency of the composite high pass filter formed by
the input cap and associated impedances, and thus results in better bass
response.  I compared the modified Micromoog to the Minimoog, and the Micro can
easily compete (on a one oscillator level, of course).
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<IMG SRC="manuals/moog/micromoog/vcf_fix1.jpg">
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Image 1
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<P>
<IMG SRC="manuals/moog/micromoog/vcf_fix2.jpg">
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Image 2
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<A NAME="links">LINKS</A>
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Thanks go out to the following people for their contributions to this page:
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         <LI>Michael Caloroso
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All images and text are copyright by their respective owners where
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The Archive is always in search of more material.  If you have anything
that you feel would make a great addition, please feel free to contact
the curator!  He is always on the lookout for schematics of synths,
drum machines, sequencers, effects, and about anything else you can think
of!
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Have any comments or suggestions?  Send E-Mail to:
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<A HREF="mailto:tom@sdiy.org" ONMOUSEOVER="window.status='Mail the curator!'; return true;" ONMOUSEOUT="window.status=''; return true;">tom@sdiy.org</A>
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<I>
Last Updated 2-28-00
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Copyright&copy;2000 Tony Clark - No use without permission
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