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th0mas
Joined: Feb 27, 2010 Posts: 12 Location: Ottawa
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Posted: Tue Dec 14, 2010 11:28 am Post subject:
My MFOS Soundlab Subject description: some pics, questions |
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Here's some pics of my MFOS soundlab. Sorry for the blurry pics, cell phone camera, the usual..
AND the obligatory "holy rats nest" pic:
Problems I'm dealing with:
It's kind of hard to read but there's a "sub" pot in the mixer section. My plan was to take the squarewave output of VCO2, feed it to a 4024 binary counter to generate sub octaves (schematic). It, uh, doesn't work. I'm guessing the 4024 doesn't like my squarewave that goes -ve? I'm waiting on new oscillator probes to be shipped and hopefully I can track down the issue once they arrive.
The other issue seems tied together. My LFO doesn't seem to generate squarewaves although ramp/saw works, but at the LFO frequency it shorts the noise output. Hard to explain. There's been a few other posts on the forum about noise output being influenced by VCO2, this seems to be similar. I'm guessing it may have to do with the fact that I made my own panel wiring since my panel is obviously not the same as the stock Ray Wilson one.
Regardless most of the synth works and plays great. I'll record some demos. I have a MIDI->CV converter so it's pretty fun to play.
Oh and I missed the LFO and ENV modulations of the VCA on my panel so they're unlabelled. Doh! |
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RF
Joined: Mar 23, 2007 Posts: 1502 Location: Northern Minnesota, USA
Audio files: 28
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Posted: Tue Dec 14, 2010 12:12 pm Post subject:
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That looks very nice - congrats on the nice build.
I've seen worse rats nests
bruce _________________ www.sdiy.org/rfeng
"I want to make these sounds that go wooo-wooo-ah-woo-woo.”
(Herb Deutsch to Bob Moog ~1963) |
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frotje
Joined: Feb 26, 2008 Posts: 18 Location: Netherlands - Nuenen
Audio files: 5
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Posted: Wed Dec 15, 2010 2:16 pm Post subject:
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nice synth spagetti ! |
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th0mas
Joined: Feb 27, 2010 Posts: 12 Location: Ottawa
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Posted: Thu Dec 16, 2010 8:39 pm Post subject:
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I think I figured out one of my problems (LFO does not output squarewave)
Using my oscilloscope I found that while the ramp signal is going to the non-inverting op-amp IC7-B, that op-amp is outputting absolutely nothing.
Bad LM444 I guess? I had another problem which was my noise circuit was intermittent at the same rate as the LFO, so I'm thinking the comparator opamp in IC7 for noise was also bad. I'm hoping anyways.
I've desoldered it (note to self: not socketing chips was a good idea until something went wrong :/ ) and await a replacement. _________________ -=facebook-twitter-soundcloud-blog=- |
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