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brock
Joined: May 26, 2011 Posts: 112 Location: Canada
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Posted: Mon Sep 05, 2011 11:23 am Post subject:
12 Bar Blues Thing - my Lunetta Challenge design |
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I don't know when I'm going to get my Lunetta Challenge design finished so I figured I should post a preview of what I've been working on. My design entry is a 12 Bar Blues Thing (TBBT). This might not be considered a Lunetta by some, perhaps it's more budget synthesis, but I happened to get the parts to do it and it's really cheap to make, probably less than $20, so I chose to make a tunable instrument even if that might be a bit heretical.
The main building block of the TBBT is the Diatonic Noodler which is basically an eight step digital sequencer built around a 4040 or 4020 counter and a 4512 decoder. It works on the same principal as a top octave generator with a high frequency oscillator driving a counter that is decoded and reset at audio rate. This TOG concept was previously presented by AnalogCustom here http://electro-music.com/forum/topic-45583-0.html&postdays=0&postorder=asc&highlight=top+octave as recently pointed out by richardc64 here http://electro-music.com/forum/topic-48268.html
The Diatonic Noodler only puts out one note out at a time rather than a twelve note octave, and in this implementation it's more like a bottom note generator as I divide the high frequency clock first to get the I-IV-V progression common in 12 bar blues, so I can use the same decode logic for all keys. One thing to note about this design is that the tone outputs come from the highest order bit that is decoded from the counter. I've used a 4019 configured as an OR to get the outputs from two bits, one of which must be the highest bit decoded. This gives a range of just under two octaves but results in a varying pulse width for the output depending on frequency. If you want square wave outputs or more range you can clock a flip-flop or counter with the 4512 output.
I was kind of gate poor in my parts kit with only 2-4001s, 2-4011s and 3-4019s so I decided to cheat a bit and use diode ANDs to get the wide input decode gates necessary just as AnalogCustom did with his TOG. My first thought was to use DIP switches for the decode selection, kind of like what Les has done with his boolean sequencer, but I didn't have 32 or 40, 10 wide switches kicking around and the thought of changing up to 400 switches for a sequence seemed kind of crazy. I might have been wrong about that as what I chose to do, use 0.1 inch dual row headers with hard wired plug-in modules, is proving time consuming and cumbersome to make although once done is kind of nice as it's like having presets.
I use three Diatonic Noodler sequncers in the TBBT, two of them can be 16 step or alternate 8 step with different patterns, the Bass Thing is an 8 or 16 step version of the Diatonic Noodler and the schematic is attached.
I keep telling myself I'll finish this thing "this weekend" but this weekend keeps turning into next weekend. I hope to get the full schemtics, pics and recordings posted soon, meanwhile, he is the the basic Diatonic Noodler circuit, a possible decode circuit and the Bass Thing schematic.
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Paradigm X
Joined: Feb 15, 2011 Posts: 363 Location: Null and void
Audio files: 2
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Posted: Tue Sep 06, 2011 3:16 am Post subject:
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awesome. So clever what people are coming up with from the cmos bags.
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sndbyte
Joined: Jun 26, 2009 Posts: 119 Location: sf
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Posted: Tue Sep 06, 2011 9:42 pm Post subject:
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That is pretty interesting, I hope you are able to post a video... it would be great to see/hear it in action. |
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Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Wed Sep 07, 2011 12:10 am Post subject:
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Absolutely fascinating! I particularly enjoy the naming of things here, but the circuit is equally interesting and should be well worth the time and effort involved.
May I make mention of it on my radio show?
Les _________________ "Let's make noise for peace." - Kijjaz |
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brock
Joined: May 26, 2011 Posts: 112 Location: Canada
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Posted: Wed Sep 07, 2011 4:23 pm Post subject:
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Les, I'm not sure there's anything worth mentioning so far but go ahead if you want.
Glad you enjoy the naming. I think that's part of the fun of creating things. The overall concept came to me when I was looking at my list of seemingly non-Lunetta-ish parts while listening to Green Onions and I wondered if I could make something that could play Green Onions. After a bit of work the Green Onion Machine became the 12 Bar Blues Thing which is simpler and more generic. The Diatonic Noodler was originally called the Chromatic Noodler but while messing around with it I realized it did at most eight distinct notes so diatonic seemed more appropriate. I guess I should make a diatonic module to justify the name. |
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Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Wed Sep 07, 2011 7:50 pm Post subject:
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brock, that reminds me of another thing that I really like about your project. You are applying actual music theory, conventional formal musical training, to a Lunetta. This is a step in the right direction I feel as far as expanding the territory and usefulness of Lunettas in general.
If we can do "real" musical "stuff" with our crude little chips, and of course we can, then the widespread acceptance of Lunettas as more than noisemakers but real musical instruments opens up like a new road before us.
Keep at it, you are pushing the Lunetta frontier limits, and I really like that!
Les _________________ "Let's make noise for peace." - Kijjaz |
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brock
Joined: May 26, 2011 Posts: 112 Location: Canada
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Posted: Thu Sep 08, 2011 10:29 pm Post subject:
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I think you could state the opposite with equal validity, that making "real" musical "stuff" with a Lunetta is horribly limiting and misses the point of these instruments. I'd make that argument myself and I'm building this thing, but fortunately it has more potential than just producing conventional tones, that just happened to be my starting point. |
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