Friday, 20 May 2016

LM13700 Janglebox

   I seem to have gotten a bad CA3080 and noticed another poster did as well, so I decided to modify Mark's Janglebox layout to accommodate the cheaper and easier to find LM13700. I have built this and it works, but I moved a few things around. So I'll call this unverified for now but it should be good to go.





23 comments:

  1. nice. i made a dyna comp and its a bit noisy. I then made a ross compressor but used all tantalums thinking that might make it quieter. i subbed 10uf for the 100uf like on the keeley. its actually a bit noisier with the hiss. Are the lm17000 any qiueter than the ca3080? does the circuit still get squishy like the dyna and ross compressors?Thanks for themlayout

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    1. I was wondering whether the tantalums used in the Keeley might make the Janglebox a bit quieter - but it seems likely, from what you've experienced that it won't. Thanks! But yes, loving that jangle!

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  2. With the "Attack" set high and the tone switch in the bright setting it is a bit noisy but I have it wired to my breadboard right meow.

    The less intense settings are less noisy and very nice. It gets lots of smooth, clear sustain

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  3. One of the most compressy compressors for that compressory sound HELL YEAH EVERYTHING SOUNDS LIKE THE BYRDS.

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  4. Thanks for the layout Travis, I've built a couple of the originals, so I'll be using this layout next time.

    Yeah, it's far from the quietest compressor around, but it's got giant steaming sackloads of character, which more than make up for the hiss.
    As Charles says, EVERYTHING sounds like The Byrds, and in my book, you can't get a better recomendation than that.

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    1. Exactly! It's fun as hell. Definitely a recommended project.

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  5. You legend! I was in the process of doing the exact same thing. Couldn't have come at a better time. Thanks Travis!

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  6. Where's a good place to buy the LM13700. The cheap ones on Ebay are all from China. And the US sellers are pretty pricey. So these can be subbed in for a CA3080, maybe on a daughter-board?

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    1. This comment has been removed by the author.

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    2. There are a few options for substituting CA3080 with LM13700 since they are not pin for pin equivalents.

      You could do the "dead bug" method, where the IC is flipped upside down with the pins facing out away from the board. Then you would solder a wire from the IC pins to their corresponding location on the board.

      Or you could make a perf or stripboard daughter board, which would need to be wired to the appropriate locations on the main board

      Or you could make a PCB which you could solder DIP-8 header pins to which could be inserted directly into the main board with no wires

      Or you could redesign the layout to accomodate the LM13700 as I have done here

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  7. No Dr. Iggy, the LM13700 is not a direct drop-in substitute for a CA3080. Travis has completely redrawn this layout from the original (compare them and you will see), to use this IC instead.
    You won't be able to use this chip as a replacement in the original layout, or in any other circuit that uses a CA3080 without a considerable amount of surgery.

    You should (in theory) be good with the Chinese ones, but the usual caveats apply.

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  8. BTW Travis, would the LM13600 work in this layout? I have a couple of those already.

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    1. Hey Beaker. Looking at the datasheets they say that the difference between the LM13700 and LM13600 is the way the buffers are set up. Since this circuit doesn't use the buffers, and the pinouts are equal, I don't think you should have any issue substituting the LM13600 :)

      I've read some info online saying that I should connect the amp bias input of the unused channel to ground to shut it down. Apparently leaving it "floating" will consume more current, and could contribute to noise or premature failure of the IC.

      I added a wire from pin 16 of the IC to ground on my board and there is no difference in noise whatsoever. I may revise the layout with a link from pin 16 to ground just to be safer about avoiding premature component failure. If you've already started building this layout and you are concerned about this, you can simply take a wire from IC pin 16 to ground. I think when I add the link to the layout it will have to be one column bigger

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    2. You could ...

      Swap the bottom 10K with the 470pf
      Swap the 22u with the GND link to its left
      Move the cut at pin 16 to the left
      Double link pin 16 to the newly positioned GND link.

      I built Marks 3080 layout but used a daughter board 13700 with fly wires to the 3080 pin positions. Worked fine with no more/less noise than expected. I'll definitely use this layout in future though. Just makes everything easier.

      Cheers Travis

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    3. Ciaran,

      That's what I was thinking about. I wanted to try building some of the other compressors, like the Ross and others. But finding good CA3080 at a reasonable price seems to be long gone. A LM13700 on a daughter board sounds like the way to go.

      Any thing that the second circuit on the lm13700 could be used for in the same pedal? The pedals in one design. Or is that device strictly for compressor circuits?


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    4. I never bothered with 3080's as I started too late for reliable sources. The daughter board works well, although a bit fiddly. I now modify layouts to suit where I can.

      You find LM13700s in lots of filter designs, phasers, LFOs etc. I'm not sure what benefit you would get adding these designs to a compressor.

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    5. Ciaran, yeah I know I could do that but I don't like double links. I have a big roll of solid wire that I use for links and I can't fit two in one hole. The legs from the Tayda resistors will work but they are often not long enough. So it's a thing I personally avoid

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  9. Good question Dr Iggy. I've read about a trick where you can have two OTAs "mirroring" each other for "better performance" but I'm not sure what all this entails. Most likely it will make the layout huge.

    The coolest thing you could so would be make a noise gate with the other OTA which follows the compressor to eliminate that pesky noise altogether. But.. That's not gonna be easy to make that work properly along side the compressor IMO.

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  10. Ok, thanks for the ideas. Hate to waste that second circuit if it can be used for something cool. But doesn't sound like there's much that can be done easily. I've just never worked with that type of circuit before. So always learning. I'll build this one as is then.

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    1. How about a tone stack+makeup stage?

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  11. One thing that I thought of is to just make another compressor on the same board. It could be cool for a dual compressor build. But I don't see using both at once as particularly useful. And people might want two totally different compressors like one OTA and one optical instead of two OTA comps

    I dunno maybe a Janglebox and Dyna Comp together in one box would be badass? Janglebox + Keeley Comp would be cool. We're talking about a pretty huge board either way.

    You could also do something that isn't a comp with it. Like an OTA based overdrive

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  12. OTA Overdrive? Hmmm, Now thats what I was wondering about. Boost, OD, fuzz. anything useful, I don't see two compressors being of great use.

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  13. I think this is verified, but if not, I've built it and it works. I didn't yet ground Pin 16, though.

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