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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: Thu Sep 03, 2009 1:56 pm Post subject:
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You know, it's funny, those thoughts of yours were the last thoughts I had before deciding to post the diagram as it was. So we're all thinking alike. In my case, my lack of modular synth knowledge led me to question whether the average synth could form appropriate signals, but I guess it can.
If we can eliminate the noise chip and the transmission gate chip, that reduces our chip count from 9 to 7, which is a step in the right direction. I also think I went a bit overboard on all the voltage followers, perhaps that can be done simpler.
Thanks for the suggestions guys, I'll update the diagram and post it for your review.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Thu Sep 03, 2009 4:17 pm Post subject:
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OK folks, I put in your changes and did some simplifying. The burst is simply an input now, so a modular user could use any desired signal for it. The voltage followers scattered about have been reduced from 8 to 4, removing one quad opamp. They have been replaced by appropriate bias networks. The VCF and VCD inputs now have a bias control such that one need not hook up inputs to them, and can work them from two front panel pots if desired.
This reduces the circuit to just five chips, one of which is just a three-terminal regulator, so only four big chips. The discrete count goes up though. I hope this will fit on the tiny boards proposed, because we just can't get any better than $51 for a set of prototype boards as far as I know.
Please let me know what you think, then I'll start working on a schematic.
Les
p.s. maybe we can add a switch to the Burst input, that way one could produce music using this module alone and no inputs would be required (though highly desired).
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Revised Karplus-Strong Block Diagram |
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_________________ "Let's make noise for peace." - Kijjaz |
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Dan Lavin
Joined: Nov 09, 2006 Posts: 649 Location: Spring Lake, Mi, USA
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Posted: Thu Sep 03, 2009 7:23 pm Post subject:
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Les, If you can stay with that low of a chip count, i can definitely use the Expresspcb $51 for 3 boards deal. Even with supporting passives, I don't see a problem. -Dan |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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DGTom
Joined: Dec 08, 2008 Posts: 211 Location: Adelaide
Audio files: 3
G2 patch files: 1
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Posted: Fri Sep 04, 2009 7:06 am Post subject:
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Wow!! I get distracted by other things & look what happens! I will need to go back & read thru again but this is looking amazing!
As a modular guy, the seperate boards is a massive bonus, I would be looking at 2-4 K-S modules minimum & a pair of boolean sequencers dueling it out would be a dream come true
Love the addition of CV & external excitation (if I understand correctally?) can't wait to see this project develop, sign me up for the first run of boards! |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Sep 04, 2009 10:15 am Post subject:
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Why, that's great news, DGTom! Thanks to everyone's help this project is starting to shape up. Should be a pair of nifty little boards, I hope. Of course we don't have a working prototype of KS yet, so please be advised that there is plenty of work to do.
At the present time, the latest is that this morning I began the schematic capture and layout. I made a part for the 1/8" audio jacks and we need five of them. Well, don't you know it they are too big and won't fit on the prototype board. So the lesson learned is that for cost and software reasons we will have to at least do the prototype with Jacks and Pots and Switch on a panel-mount thingie. I'm open to suggestions on how to proceed with that.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Sat Sep 05, 2009 12:37 pm Post subject:
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Since my last post I have completed a schematic and board placement for the Karplus-Strong board. Please see below for screenshots. Oh, i forgot to put a copyright on the schematic: schematic is copyright 2009 Les Hall.
I just have one question at this time: What is the pinout on the three pin Molex power connector?
Since the prototypes will be only $51, I feel no need to breadboard the circuit. Please let me know of any issues or questions you may have. Thanks.
Les
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Karplus-Strong Board Placement |
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wmonk
Joined: Sep 15, 2008 Posts: 528 Location: Enschede, the Netherlands
Audio files: 15
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Posted: Sat Sep 05, 2009 1:16 pm Post subject:
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Why a 3-pin and not a 4-pin? Most modular guys here use the 4-pin molex 0.156" spacing. Layout: +/0/0/-.
I think it's a better practice to breadboard the circuit before ordering a prototype board. You can easily adjust resistor and capacitors to get the best results. And there is no need to spend the money twice (if there is something wrong with the circuit) |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Sat Sep 05, 2009 1:25 pm Post subject:
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Sure, I'm easy going. What you say makes good sense wmonk, thanks for the suggestion and the information. Next I need to work out the component values...
Les _________________ "Let's make noise for peace." - Kijjaz |
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DGTom
Joined: Dec 08, 2008 Posts: 211 Location: Adelaide
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Posted: Sun Sep 06, 2009 8:15 pm Post subject:
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if there is room for a 4 pin .156 I'd go with that... but tbh I'm moving away from them, IMO they are a massive PITA. They are big & 9 times out of 10 a struggle to wrestle with, especially on dense boards, even on Blacet PCBs you are almost always trying to turn your wrist at wierd angles in an attempt not to bend decoupling caps.
making a .156 -> .100 cable to hook up to your existing power distro is trivial & .100 hardware is soooo cheap. All my DIY / perf boards use .100 so I'm just making .100 distro boards that hang off the .156 distros.
.100 are stilled keyed, I just don't see the sense in using these bulky 'legacy' connectors on smaller & denser boards.
With regards to boardmounted jacks / pots / switches, I say leave em off! keep it uber modular so people can have maximum flexbility in how they put these together, a row of headers, 3 pin for pots, 2 pin for I/O would be best - sorry I suck at reading board layouts, you may have done this already
Looking good so far tho! I'm really excited by this project, scraped my plans to purchase a BBD module for K-S & having a total re-think about my VCO plans!! |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Mon Sep 07, 2009 2:41 am Post subject:
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DGTom, that is nice commentary, thanks. I'll stick with the 0.100" connector that I have, though there is actually room on the board for both connectors if need be. I could even double-footprint them if you like.
I'm happy to hear that you are looking at this board from the perspective of equipping your modular with a rockin' Karplus-Strong orchestra. Way cool. I can't wait to hear one of your audio files with these, though there is a monstrous amount of work to be done before that happens. Thanks for the preorder too, that will help get the ball rolling.
I had a conversation with wmonk and Blue_Hell in the chatroom and they offered over half a dozen suggestions for the board which I implemented. Most notably the rebiasing stage from the VCO to the MN3102 chip is replaced by a transistor buffer at Jan's suggestion. Overall I think I'm ready to prototype but I have to wait until payday to order parts.
I've decided to form a compromise on the theme of parts aligned to the panel. The three pots and the switch are positioned along the long edge of the board for direct panel attachment, and the jacks are done with a wiring harness. That way we get the best of both worlds.
So things are on delay until I can order parts but hey, whatcha gonna do? It's only a week or so delay.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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wmonk
Joined: Sep 15, 2008 Posts: 528 Location: Enschede, the Netherlands
Audio files: 15
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Posted: Sun Sep 13, 2009 6:21 am Post subject:
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Where is the 4017 in the schematics? I thought you replaced it with a 4040? |
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Uncle Krunkus
Moderator
Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
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Posted: Sun Sep 13, 2009 6:24 am Post subject:
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Looks good Les.
So does a Karplus-Strong work on the idea of making a BBD howl in a controlled kind of way?
My experiments sure have pumped out some cool howling sounds, and I know about the need to "kick" it into action. _________________ What makes a space ours, is what we put there, and what we do there. |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Sun Sep 13, 2009 6:33 am Post subject:
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Thanks Andy, I've put a lot of work into it already. Karplus Strong is this really simple digital algorithm for making string and percussion sounds. I'm implementing it in analog form. The basis of KS is a summing amp with a delay line and a filter in the feedback loop. Adjust the loop gain properly, set up the filter and delay line characteristics, and hit the stim input to get a guitar or sitar or percussion kind of sound.
Most definitely if you've been playing with flangers using BBD's and such, it would be quite easy to hook up a feedback loop that sets up a KS type oscillation.
By the way, where is the thread on your BBD project, I'd like to read up on it.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Sun Sep 13, 2009 7:00 am Post subject:
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That's weird, I replied to you wmonk, but the post got lost. Either that or i hit the wrong button. Anyway, you're right it's a 4040 not a 4017, thanks. I'd hate to have to place another order so soon.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Sun Sep 13, 2009 1:58 pm Post subject:
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With a little time on my hands I decided to work a bit on the Boolean Sequencing board. It's the new version that does only Boolean Sequencing, nothing else. I'm not too sure if folks will be happy with the way that I'm generating CV, but I think it will be OK. There's not much room on the little 2.5" x 3.8" board. It can be wired up to a Karplus-Strong board directly, all you need is a clock source at 4Hz or so.
Comments welcome as always.
Les
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Counter and LEDIL Sections |
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Output Section with pulse generator |
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wmonk
Joined: Sep 15, 2008 Posts: 528 Location: Enschede, the Netherlands
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Posted: Sun Sep 13, 2009 3:00 pm Post subject:
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Am I wrong or are the LEDs in the LEDILs reversed? |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Sun Sep 13, 2009 3:06 pm Post subject:
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wmonk wrote: | Am I wrong or are the LEDs in the LEDILs reversed? |
I *think* they're OK. There are six AND gates feeding into one OR gate. The AND gates go low if any output is low, so that's good. Then if all inputs are high or open, the AND gate goes high. The diodes are reversed to do the OR function so that if any input is one the output goes to a low value of one. Any more outputs going high drives up this voltage to create a CV. Then a comparator circuit picks up the rising edges and creates a narrow pulse. Am I correct?
Les _________________ "Let's make noise for peace." - Kijjaz |
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loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
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loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Mon Sep 14, 2009 2:47 pm Post subject:
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loss1234, I am quite happy that you plan to breadboard the KS circuit, hopefully together we can get it to work. Below are four close-ups of the schematic which should give you a clear indication of component values. Any questions, just post.
Regarding the eChucK component, I found that the board would not fit so I removed that feature. Now it's strictly a modular or perhaps stackable board. The VCO and VCD inputs can be left unconnected and just set by their potentiometers. The BS and KS boards are designed to work together but you can actually just drive a narrow pulse train into the KS stim input and adjust the pots to get different sounds for test purposes. Also there is a switch on the stim input which is intended to allow stand-alone operation for test, just hit the switch to get a burst of sound from the KS circuit.
Hope that helps.
Les
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upper left detail of KS schematic |
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upper right section of KS schematic |
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lower left section of KS Schematic |
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lower right section of KS schematic |
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loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
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Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
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