Monday, 1 September 2014

Effdub Flapjack OD

Stumbled on to an older Effdub design. This one's based loosely on the Hot Cake and should deliver similar overdrive sounds. Could even solve the oscillation issues a few folks experienced with our original Hot Cake layout.




15 comments:

  1. youtube vid: https://www.youtube.com/watch?v=XhqLfQYAU7M

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    1. Cheers boratto. It was already morning hours and i just simply didn't eve look for one. Embedded this to the post.
      +m

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  2. i just checked out the video. sounds great. definitely similar sounding to the hotcake, but there's something different, it can't put my finger on it, but i definitely dig this one.

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  3. So I was minding my own business on a Sunday night when this great OD circuit shows up on tagboardeffects! I knew I just HAD to build it, so...I started at 10 PM and finished my final tests at 1 AM. The vero layout works great, so you can tag this one (it even fired up for me the first time with no debugging :). I didn't have two C50K pots so I used a B50K temporarily for the volume, which works fine.

    In my tests, the Flapjack sounded much better than I had expected, given such a simple circuit. The Crowther Hotcake had been on my radar for a while, so this gave me an excuse to try out this type of LM741-based OD. It can go from a cleanish boost to massive (almost fuzzy) gain, and the presence does a nice job of adding back some treble especially at low gain. And no squealing at any gain or volume setting! It seems to get the massive gain towards the very end of the gain pot rotation, but that didn't bother me (you can potentially play around with the gain pot arrangement if you prefer different sweep).

    Anyways, thanks for the layout Mirosol!

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    1. Now that was fast! Cheers Frank! I'll tag it right away.
      +m

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  4. Replies
    1. Hmm.. You'd need a compensation cap between pins 1 & 8.
      +m

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  5. Yes, the LM741 is the one to use, and is available in the states at good ol' Radio Shack :)

    I should note that this circuit makes use of op amp clipping - no diodes in either the op amp feedback loop or after the op amp output. It sounds good too, and I wonder if this has to do with the LM741 itself.

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    1. Usually opamp clipping sound does depend greatly on the opamp used. I suppose 741 clips a lot more gracefully when compared to TL071. One could of course socket the IC and try on various single opamps (NE5534, TL0*1, etc.). Any opamp with the same pinout should work.
      +m

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    2. I always socket my transistors and ICs to avoid damaging them in the build process. I'll try out some different ICs for sound quality (I have a bunch of single op amp chips).

      By the way, you can reduce the max gain a little (if it's too fuzzy for you) by changing the 220 ohm resistor on the left side to 470 ohm. I'll probably leave mine as is.

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  6. Hi everyone, at first, thank you Mirosol for publishing that project. I built this pedal in substitute the Hotcake and I used the 8.2V zener diode instead 1N5817, worked great. Maybe later, I'll put a switch to select between 220 Ohm resistor and 470 Ohm, I liked the fuzzy way and the "normal" too, so why not have both?

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  7. If you're looking for a quickie, this should do the trick.

    Put it together in one sitting, although I already had the drilled enclosure. Nice addition to my 741 collection.

    https://lh4.googleusercontent.com/-JwY8BbwXxPM/VCTCk0xQ_hI/AAAAAAAAAQg/KcfCOwDGjww/w346-h642/2014-09-25.jpg

    https://lh4.googleusercontent.com/-_bb9z2a_G8s/VCTC6ISPBvI/AAAAAAAAAQc/ZZlMzHuKnks/w346-h649/2014-09-25.jpg

    May make a triple 741 pedal with my Flapjack, Wampler Modified Distorion+ and DOD250 in a single 1590xx. Then reuse the 3 125Bs for something else.

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  8. Hello,
    I 'm doing mounting on bench éssai and me go from 220 ohms to 470 ohms gives very little difference.

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  9. Would a 1N5819 work instead of 1N5817?

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    1. I built it anyway and it seems to work. This thing sounds pimp on my humbucker equipped guitar.

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