The Karplus Strong eChucK DIY Project

Inventor · Posted: Sat Apr 10, 2010 10:50 am Post subject:

I fixed the few areas of overlapping silkscreen, so that's no longer an issue. Thanks to wmonk for pointing that out.

Les

fluxmonkey · Joined: Jun 24, 2005 Posts: 708 Location: cleve

will there be some boards from this second batch available for sale? who should i follow up w/, les or jeff?

b

Inventor · Posted: Sat Apr 10, 2010 11:07 am Post subject:

jeff-o · Joined: Jul 19, 2009 Posts: 97 Location: Ontario, Canada

Hmmm, I'm not sure what would be easier. I suppose I can "sell" this round of boards.

How big is the board (length x width)? I can't tell from the PDFs that are posted. Just to get an estimate for cost and whatnot.

Inventor · Posted: Sun Apr 11, 2010 2:24 am Post subject:

Inventor · Posted: Mon Apr 12, 2010 1:06 am Post subject:

Good news folks, I prototyped the expo converter and it works just fine, at least at first glance. I still have to make detailed measurements and I might need to change the tempco value for 9V battery operation plus tweak the output resistor for the three supply voltages, but none of that will change the layout of the board.

In building this prototype I epoxied the two transistors to a small piece of metal, and also epoxied the two 1kOhm 3300PPM tempco resistors underneath the piece of metal to simulate the actual on-board condition. The Digikey part number for the tempco resistors is P1.0KCHCT-ND. You'll want to buy several of them because they are 0805 and so it's easy to lose them or mess them up.

I guess this means that I'm ready to generate output files and send them to jeff-o, but I'll wait a day or two for anyone to make any comments they might notice about the design. So please let me know of any gotchas you might notice, thanks.

Les

ExpoProtoPhoto.jpg

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Expo Converter Prototype

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wmonk · Posted: Mon Apr 12, 2010 1:37 am Post subject:

Can you give us a recording with the different octaves? Very Happy

Inventor · Posted: Mon Apr 12, 2010 1:50 am Post subject:

jeff-o · Joined: Jul 19, 2009 Posts: 97 Location: Ontario, Canada

Great work, Les!

OK, I'll get these boards made up once the designs are checked and re-checked! I'm looking forward to playing around with it.

Inventor · Posted: Tue Apr 13, 2010 7:02 am Post subject:

jeff-o · Joined: Jul 19, 2009 Posts: 97 Location: Ontario, Canada

I can get 12 boards for $100. Volume pricing takes effect after that (though to what extent, I haven't found out yet). With the CAD files I can ask for a quote on a larger number. How many are we talking here? I'm happy to order as many boards as people want, but I'm not prepared to maintain an inventory.

But, I have a solution to that.

Batch PCB currently offers a Marketplace where you can submit your design for anyone to order through their service. In return, the owner of the design gets a small payback. If/when this design catches on, it could be a great way to produce boards for anyone who wants them "on demand," while allowing someone else to act as the seller.

Inventor · Posted: Tue Apr 13, 2010 8:52 am Post subject:

dang that's cheap! 12 boards for $100 is nice. That might take care of our needs just fine.

The marketplace will be electro-music.com, where we will sell the boards.

Les

Inventor · Posted: Tue Apr 13, 2010 9:03 am Post subject:

Folks we've been talking KS for a long time, and my thoughts turn to BS on occasion. My previous designs involved LEDIL and sum of products logic with only positive input terms. However I have found through practice that XOR logic is way cooler in terms of musical quality in a BS.

For this reason I've changed my design thoughts from DIP switches to rotary switches. Put a rotary switch on each input of an XOR gate and connect the counter outputs to the switch inputs. That will make a nice song encoder.

Just the latest thoughts for you.

Les

jeff-o · Joined: Jul 19, 2009 Posts: 97 Location: Ontario, Canada

Yeah, that's a pretty good price IMO.

So now we just have to decide how many to get.

Inventor · Posted: Tue Apr 13, 2010 9:20 am Post subject:

Well jeff-o, the board is new enough that i'd like to spin it one more time before all is said and done, so no need to make a lot of them. Gosh, $100 is practically free. I'd go for that.

My pal kkisinger wanted one and I think bbob wants one and wmonk and a few others plus I'd like at least two (will paypal you), so yeah we will probably fill a dozen order.

My only concern is that wmonk tells me that we can get like 50 boards for only a small extra charge. That may not be true with your pricing model though. Please find out and let us know.

Les

jeff-o · Joined: Jul 19, 2009 Posts: 97 Location: Ontario, Canada

OK, I'll find out pricing for 50 boards. I will need the gerber files to do that, though.

There's also the option for different colour boards, like blue, red, yellow, white or black. That's another $20 for the whole order - but it sure looks cool!

Dan Lavin · Posted: Tue Apr 13, 2010 3:24 pm Post subject:

I'm up for a new K-S board too! I still need to get my old board going!

Les:

Maybe you should break this into 2 threads: one for the K-S instrument and one for the Boolean sequencer.

Inventor · Posted: Wed Apr 14, 2010 10:47 pm Post subject:

Dan Lavin · Posted: Thu Apr 15, 2010 8:32 am Post subject:

Les, I wouldn't start 2 new threads because people will keep replying to this one regardless. I would make this the K-S thread and start a new Boolean sequencer thread since the bulk here in the K-S stuff.

Nice show Tuesday. I had my normal Tuesday evening meeting moved to wednesday so I could join. It wasn't as big a train wreck as you made it out. The K-S demonstrations were well worth the wait, particularly the chaining of 2 K-S devices. It sounded well beyond my expectations. Some really nice organic sounds there,(a biological , not in a B3/pipe sense of organ) .

Inventor · Posted: Fri Apr 16, 2010 11:58 am Post subject:

Inventor · Posted: Tue May 04, 2010 9:04 pm Post subject:

Here's an update on the KS status. I am waiting on two other people at the moment. Jeff is getting a quote for 50 boards for the second run, and Doug is testing the KS board that I sent him.

We have added a dotcom power connector and AMP connectors for the jacks, removed all battery power, battery switch, and power indicator, and spaced the pots at 1.6 inches apart on the front panel. Had to move the mounting holes off of the front edge to do that.

Also, I'd like to mention that Doug and I have opened discussions about his including the KS board in his line of unusual modular synthesizer products. Doug plans to sell built and tested modules with panels, but not kits or bare boards. The arrangement with Doug does not change the plan of splitting half of the board profits with electro-music.com and half with myself (to fund future projects).

Les

rosch · Joined: Oct 03, 2009 Posts: 165 Location: germany

hi Les! cool project the KS. i've just begun listening through your shows, very impressing.

Inventor · Posted: Thu May 13, 2010 9:49 am Post subject:

Inventor · Posted: Fri May 14, 2010 4:05 pm Post subject:

Good news: I've been talking with Doug about offering built KS boards for the second run, and it looks like we're going to be able to do that. So you will be able to get either bare boards or built and tested boards (no panel).

We still are not sure of exactly what the cost for built boards will be. Given that a bareboard KS build will cost about $60 US in parts plus all the shipping from multiple sources and the need to buy certain parts in multiples, I feel that it would be worthwhile to buy built boards as long as the cost is reasonable. For a ballpark figure, just to pull a number out of the air, I'd guess that $120 would be a fair price for a built board. I say that just to put a number on it, not sure if it should be higher or lower.

So my question to you is: "With $120 as a ballpark figure, would you pay that much for a built and tested board (without panel or jacks)?"

Les

jeff-o · Joined: Jul 19, 2009 Posts: 97 Location: Ontario, Canada

How about a kit with all the parts but not soldered together? That cuts out most of the labor for whoever would be building these, but you still get the benefits of buying parts in larger quantities.