Wednesday, 7 May 2014

Madbean Spackler

Another discontinued Madbean PCB, this time for his modded Demeter Fat Control.

Info about the project:
The Spackler is a modified version of the Demeter® Fat Control™. The effect is a midrange boost that will push the front end of an amplifier while boosting the lower-mid frequency range resulting in what some might call added “warmth” and “depth” to a guitar signal. The Fat Control™ works well as a standalone effect, or before another effect like a dirt box. The Spackler adds one extra control for the total gain amount available for the boost.

The stock design has a buffered bypass. While some may find this useful, the Spackler allows you to also wire in a hard bypass.

The controls are as follows
GAIN: This control allows you to vary the overall gain produced by the circuit. At fully counterclockwise the gain will be approximately that of the bypassed signal. At fully clockwise gain will increase for added volume and midrange boost.
FAT: This control blends between the “buffered” and mid boosted signals. Note that the first stage of the opamp is not a true buffer, but it will sound just like one if you hook the Spackler up using the buffered bypass wiring diagram below.



I can't find a vid of the Spackler, but just imagine this with a gain control :o)






26 comments:

  1. Replies
    1. Haha, oops.

      No it was a test really!! :o)

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    2. Ahah!
      Another good thing would be the possibility to wire up as buffered bypass. As I can see from Madbean's project, we need a switch control in parallel with Fat 1 and 1uF capacitor's cathode...

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  2. Hey Mark, is this straight from the Madbean project file schematic? Some of the values look different. New goal is to just build everything you post, for the hell of it.

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    Replies
    1. It's essentially the same. I increased the size of the filter caps so they were a more appropriate value (IMO) and added a current limiting resistor in series with the supply, but the important bits are the same.

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  3. I'd like to build this with a rotary switch changing cap values so you could change the frequency of the mid boost. Where should I install that ? Which cap is involved there?
    Thanks!

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    1. It's either going to be the 220n or 10n but I'm not sure which will give you better results. Personally I'd build it and socket those two caps and then just try a few different values to see how it affects the mid point.

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  4. Just built this one up and it works great, thanks!

    A note about the gain control for potential builders, it's tied very much to the fat control. So if the fat is at "zero", then the gain essentially does nothing. As the Fat is turned up, the amount of available boost also increases. Perhaps it's obvious, but it does mean you can't use it as a mostly clean boost (which is fine, you wouldn't build this if you wanted a clean boost!)

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    1. That's excellent, thanks for our 700th verification Simon! :o)

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  5. Awesome, I didn't realise at the time :) This is the site that got me in to the whole pedal thing just 6 months ago, so it's nice to be able to give back at least a little.

    Thanks again for all the work, and congrats on such a successful site!

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  6. 700 verified. wow, congratulations and thanks for the great work guys.

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  7. Is there by any chance a way to exchange the gain control for a bass control?

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  8. Hi everyone! I made it and its ok, BUT is there POPPING SOUND over switching. Its too much :(. Switch is ok (i change it), led too and diagram also ok too. Do you know a similar cause please? What could it be? Thx Jan.

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    1. Hey Jan, add a 1M - 4.7M (anything in that range I think is usually fine) resistor going from where the input is, going to ground. You'll probably have a little trouble fitting it in, so you may have to jiggle things around a bit.

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    2. hi mate. i think that there is a 1M resistor already in the board for that.
      is your supply regulated?
      what type you use? also google "guitar fx popping" and you'll find
      http://www.geofex.com/Article_Folders/box_pop.htm
      and
      http://www.mercyseateffects.com/pop-goes-the-effects-pedal-how-to-fix-that-annoying-sound/

      and much more...

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    3. Doesn't the pulldown need to go to ground? The 1M after the 47n is just going to Vb? I'm not that smart, so pls explain if you can! :)

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    4. Nope. That 1M from the input strip is definitely going to ground, not VRef.

      I've battled some with popping switches too, and for some circuits, it just is there no matter what you do. If it's LED related:
      http://www.muzique.com/lab/led.htm

      If removing the LED temporarily doesn't change anything, then:
      http://www.geofex.com/Article_Folders/box_pop.htm
      or in other words:
      http://www.muzique.com/news/noisy-3pdt-switches/

      Sometimes some faults in a pedal are just features. Some are bad and some not so bad.
      +m

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    5. Hi All... Found fault in schema :)... here is picture https://photos.google.com/photo/AF1QipOQ5z71wwO1UsvrKzlJESBm-yDHrUKTMELyUKJq

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    6. if you're talking about this
      http://www.madbeanpedals.com/projects/Spackler/docs/Spackler.pdf
      then i think you're right man...
      there is a problem with the components around pins1&2
      they should end to vb. not to ground.
      strange thing is that it works as it is, cause i've build it.
      i've also build demeter fat control but those 2 aren't that similar at all.

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    7. and yes it pops really bad. i'll try to fix mine right now and report back

      now i see why i've never boxed it...

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  9. hi Mark.
    you should check this out.
    as Jan Černý said there is a mistake here.
    i've fixed mine and now it work as it should.
    100nf, 10nf and 220k should go to vb. in your layout those 3 are going to ground. somehow that was working but not properly.
    yesterday i forgot to change 220k's place and that was why "fixed it but still popping."
    today i've changed that too and it works perfect.
    thanks

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    Replies
    1. Yes thanks for the heads up mate, and Jan of course for spotting it. I'll fix this and post tonight

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    2. I just checked the scheme and the 220K does go to ground, but I've got it going to vb. Is that what you meant?

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    3. yes mate.that was what i meant. i was in hurry
      after those changes, this one works really great.i have fat control inside my guitar, and really liked it. that was why i wanted to build sparkle too.
      thanks

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    4. It was the 220K that would have been causing the popping problem, the two caps to vb probably doesn't make too much of a difference. I've added the fixed layout. Unfortunately it has grown a column and row in order to get a vb row at the top, but it was a fairly small layout anyway and will still fit easily in a 1590B.

      If anyone has one built and would like to fix it, first I'd just remove the 220K and add another one going to one of the ground rails somewhere. I think that will probably do the trick

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