PLLs, digital pattern generators, etc

sdcurtin · Joined: Dec 15, 2007 Posts: 18 Location: Detroit, MI

Hi All,

Here comes another core dump, sorry for the long post...

It's great to see this discussion. Being on the synthDIY list for a couple of years generated a ton of ideas I'm still chasing. My synth building started 20 years go, and had a lapse like many during the MIDI craze but restarted in '95. in '04 I needed a bunch more oscillators and took a board had by Romeo Fahl which is a clone of Grant Richter's Wooglebug (a Lunetta by any definition). This is mainly to get at the PLLs, which are great VCOs all by themselves, although they have a very slow voltage response.

The digital stuff is inspired by my mentor, the late great Salvatore Martirano, who I studied with at Illinois in the mid 80s. His Sal-Mar Construction is a bunch of shift register random generators that can be constrained by gates and is controlled by a large touch-switch panel. For more information check this out:
http://ems.music.uiuc.edu/~martiran/HTdocs/salmar.html

I do like the small circuits approach advocated by Lunetta, and this is how I've worked, adding little circuits to the modular, these days without benefit from front panel, just "hot rod" on a breadboard which then goes out to banana patch points. My myspace site has some pics and sounds.

One circuit I keep making over and over again, in software and hardware, is variations on the "digital pattern generator" by John Blacet, as described in an article in Synapse magazine in the 80's- there's a PDF of the article at blacet.com. The idea is very simple- attach the outputs of a counter to pots, add them up and then twiddle the pots as the counter counts up. I added XORs to this so each bit can be inverted. It's essentially a DAC with variable weights for each bits. This is very simple and works very well for me. Adding decoders to this for sequencer type functions adds to the fun.

One more little idea I saw for a cheap "binary VCA" was on the synthDIY list from a Japanese synthesizer. All you do is have your square wave oscillator gating on and off a 4066 or similar analog switch. Feed a varying voltage into the switch and take the output to your favorite filter or processor. The result is a square wave whose height follows this varying voltage. So now for VCAs with the PLLS I just use 4066s.

Steve C
myspace/stevencurtin

loss1234 · Posted: Mon Mar 17, 2008 5:21 am Post subject:

wow

lots of good ideas here

id love some elaboration on how to use PLLS in a modular context and also on the decoder added to the end of blacets circuit for sequencing use...

i am going to build that blacet circuit today.

are there any schematics from the Salvatore Martirano machine??

thanks

loss1234 · Posted: Mon Mar 17, 2008 5:25 am Post subject:

checked out your myspace page and i was wondering what are all the circuits on breadboard? and whats that cool box with the fractal looking artwork and banana jacks called "work in progress"?

i'd love to hear more about the circuits you use in your setup.

thanks

sdcurtin · Joined: Dec 15, 2007 Posts: 18 Location: Detroit, MI

Thanks for checking out the site. I have some schematics somewhere for the SalMar, but will check with Sal's widow about getting some more. It was recently restored, so the person who did that will have some information. Here is a video on YouTube with the restored SalMar in 2004, by my teacher at Mills and Martirano student David Rosenboom, now dean of Music at Cal Arts:

http://www.youtube.com/watch?v=v1vkotuORWE

The box with the fractal on the panel etc is a microcontroller based synthesizer sequencer/pattern generator. There's some more details about it on one of the blogs. It's based on a version of the Motorola 68HC12 running Max-Forth. The four sets of eight banana jacks will be analog and digital input and output. It is patiently waiting to me to be done with my papers in grad school and get some attention, maybe over the upcoming break between trimesters. I'll be at Analog Heaven Midwest on April 12 in Indiana, that's some motivation to get something working to show...

CJ Miller · Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1

Thanks for the links to these and the SalMar video. Rosenboom has a good ear, I would like to have been there for the performance. What needed restoring in The Construction?

The "fractal box" finally persuaded me to register a MySpace account so I could see it. Reminds me of some forks off of my projects which I've never persued. Like the 68HC12 evaluation board which is in an envelope around here somewhere, which I've never done anything with. I've always wondered about Forth, it seems like a really versatile, elegant language. Microcontroller stack machines? But like a lot of things which are really general and open, I don't know where to start. I met Larry Polansky briefly in Boston years ago, he was playing with Richard Boulanger and the Dr. Nerve quartet. They were very encouraging with regards to my wide-eyed haplessness, showing that it can be done. Also I obtained HMSL about a year ago, but have no idea where to start with it. I am gradually putting together a "new" old mac for ancient software and a solid RS422 MIDI interface, so maybe I can explore it sometime. When I'm not trying to finish dozens of PCBs and kits!

23isgood · Posted: Mon Mar 24, 2008 11:14 pm Post subject:

I built the, "digital pattern generator". It is very cool. At the moment it needs a panel so its kinda messy but you can get some cool little sequences out of it. It is kinda wacky and unusual. Each pot sets a "range", so the next pot after the first step covers another range of pitches. The patterns seem random but not quite random. Its great for wacky fills, where you trigger it every once in a while, with another sequencer like the MFB drum sequencer. I will try to get an audio demo on here when I get a min.

pete

sdcurtin · Joined: Dec 15, 2007 Posts: 18 Location: Detroit, MI

Cool, it will be interesting to see/hear how someone else uses it. Warren Burt also used the algorithm for a series of pieces in the late 90s, inspired by my use of it. Don't forget to throw in invert switches on the outputs, it multiplies the possibilities. There is a new version put out by Blacet called Binary Zone.

Steve C

Inventor

loss1234 · Posted: Wed Mar 26, 2008 1:49 pm Post subject:

wow
that sounds really neat. you said its up on your site for download? is chuck a free enviroment or is it something like pluggo that you have to buy?

thanks
i love this site!

Inventor · Posted: Wed Mar 26, 2008 3:24 pm Post subject:

ChucK is freeware under the GNU General Public License, so anyone with Mac, PC, or Linux can download it and use it with no issues. It's from Princeton University and those folks really did a thoughtful and thorough job of making everything work together very effectively. I've probably learned and forgotten about 20 programming languages in my years and ChucK has got to be the easiest and most fun to use one of them all. You can link to ChucK from my ChucK music page which is here (there's a link in the introductory paragraph):

http://www.freedomodds.com/music/

That link takes you to the command-line version of ChucK which does not support graphics. The other link which is on the Synth Lab page is for the miniAudicle, which is the graphic-ready version of ChucK. I repeat, however, graphics only work on the Mac for now. They are porting to PC/Linux currently. We all grumble at that limitation.

You can reach the Guitar Lab page and the Synth Lab page from the above link, you 'll see the sections describing them just below the introductory paragraph. But remember: ChucK is very powerful so you must use it for good, not evil or we'll all be in trouble!

23isgood · Posted: Tue Apr 01, 2008 8:15 am Post subject:

Here is a demo of the "digital pattern generator". I recorded it the other day. I used an Oakley VCO, and I just played with the pot settings while it was playing. The audio is kinda irritating, but keep in mind that you can get some nice melodies if you have patience and dial them in just right, though it is kinda tricky.

pete

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loss1234 · Posted: Tue Apr 01, 2008 9:50 am Post subject:

so you just built that on a bread/perfboard from the synapse schematic? man i wish someone would do a press n peel layout. maybe i will try this on perfboard tonight.

where do you get that nice wire?

thanks

loss1234 · Posted: Tue Apr 01, 2008 9:51 am Post subject:

btw,those build instructions for the pattern gen, they look different!! never seen those before. where did you get em?

thanks for the sample!

23isgood · Posted: Tue Apr 01, 2008 12:00 pm Post subject:

The docs you see underneath are for the JH kraut rock phaser. I think thats the pcb you can see in the upper right. I built this on to a protoboard from the synapse schematics. It wasn't too difficult. Though I was pleasantly surprised that it worked right away after plugging everything up. I got the wire from Halted. Its from a 1000 foot spool, that I paid only $15.00! Frikin excellent deal on that fer sure! I should have wire to last me for a while. I have used a ton of it already.

pete

Coriolis · Joined: Apr 11, 2005 Posts: 616 Location: Stilling, Denmark

Hey Dan, there's a Chuck subforum right here in the diy hardware & software forum! Exclamation

C