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looking to build a loop pedal with blend knob

Discussion in 'Effects [BG]' started by DaS HaaS, Mar 16, 2008.


  1. DaS HaaS

    DaS HaaS

    Feb 11, 2004
    Sunrise, Florida
    Endorsing Artist - Ampeg, Ernie Ball
    I have been searching for a few hours and I was unable to find a schematic for a true bypass loop pedal with a blend knob. I only need one FX loop so i'm hoping it will be fairly simple. any help will be greatly appreciated:bassist:
     
  2. Nick Kay

    Nick Kay

    Jul 26, 2007
    Toronto, Ontario
    Both components are really simple designs. The loop is just straight wires with a DPDT or 3PDT switch, since it's true bypass. The blend pot is simply a pot with the hot signal from the dry line on one outside lug, the hot signal from the wet line on the other outside lug, and the middle lug going to the output. You just have to find a way to finagle those two concepts together so the blend pot is only in the circuit when the loop is active. Try it, it'll be good practice.
     
  3. Hookus

    Hookus

    Oct 2, 2005
    Austin, TX
    That won't really work well for a blender. You need a blend circuit. Look for a paralooper, that is exactly what you are describing. There is also the B. Blender, and I have schematics for one more, but cannot recall the name right now.
     
  4. Higgie

    Higgie

    May 31, 2005
    London, England
  5. DaS HaaS

    DaS HaaS

    Feb 11, 2004
    Sunrise, Florida
    Endorsing Artist - Ampeg, Ernie Ball
  6. DaS HaaS

    DaS HaaS

    Feb 11, 2004
    Sunrise, Florida
    Endorsing Artist - Ampeg, Ernie Ball
    I was hoping to find a basic schematic, can anyone help decipher this? Im not very good with electronic schematics

    [​IMG]
     
  7. rob2966

    rob2966

    Oct 19, 2006
    Vancouver, BC
    Hmmm, that is a pretty simple schematic. If you need deciphering you may be better to purchase something (or find a buddy with electronics experience).

    Just IMHO.

    However, all it is is 4 1/4" jacks (IN, OUT, SEND, RETURN), 1 quad op-amp, a bunch of discretes (resistors, caps, trim pot), and a 9V power source (9V battery). See if there is any recommendations with the circuit for type of op-amp and also type of 10uF caps (electrolytic, tantalum, etc). Also confirm the type of potentiometer (I assume it is linear since it is a blend).

    Later
    Rob
     
  8. gibsualdo

    gibsualdo

    Jun 19, 2006
    London, England
    If anyone knows a place that sells a PCB for a loop blender, I'd love to know.
     
  9. Hookus

    Hookus

    Oct 2, 2005
    Austin, TX

    +1

    Knowing how to read a schematic is only about 10% of the battle. You still need to know how to solder well (notice I said WELL), and translate the schematic to a perfboard.

    Now, on that circuit, I think pretty much any opamp will work (there is even a way to simulate an opamp with discrete components, but it is WAY more work), I bet the caps are radial electrolytic, and agree that only a linear pot would make sense. An audio taper would make it an awfully strange blender.
     
  10. Hookus

    Hookus

    Oct 2, 2005
    Austin, TX
    You can download the layout for a Paralooper. Etching boards is really not as hard as you would think, in fact, it is VERY easy. Small Bear Electronics has a tutorial/FAQ on etching boards.
     
  11. joelc1319

    joelc1319

    Sep 12, 2007
    I have all the parts for this, with intention to build it, but other things took priority...However I have spoken extensively with the creator, Sean M.

    The unit uses two opamps, pretty much any ones as was stated. TL072 is a logical choice. The capacitors are radial electrolytic as was stated. And pretty much everything else Hookus said is correct :p
     
  12. gibsualdo

    gibsualdo

    Jun 19, 2006
    London, England
    Thanks for the suggestion, I'll check them out. I haven't actually built any pedals yet, I want to get a few successful kit builds done before I try my hand at making a board. It's something I definitely hope to try eventually though, if the kit building goes well first.
     
  13. Hookus

    Hookus

    Oct 2, 2005
    Austin, TX
    If you can press print on a copier, you can make a board. All you do is iron on the transfer, and drop it in a tub of etchant until the copper is gone. It really is that easy, and it makes it MUCH easier to assemble a board smaller, and with a better layout. I wish I had never used perfboard once I saw how easy it was.
     
  14. DaS HaaS

    DaS HaaS

    Feb 11, 2004
    Sunrise, Florida
    Endorsing Artist - Ampeg, Ernie Ball
    I think im just gonna stick to a simple loop pedal with no blender. Im pretty good at soldering
     
  15. joelc1319

    joelc1319

    Sep 12, 2007
    Sounds good; they're very useful too. Just be sure to wire the switches properly to keep "popping" to a minimal. Are you going to use LEDs?
     
  16. DaS HaaS

    DaS HaaS

    Feb 11, 2004
    Sunrise, Florida
    Endorsing Artist - Ampeg, Ernie Ball
    yeah, I have a simple schematic for a 3 loop version with LED's. I am purchasing the mats today.
     

  17. +1

    I love My VB-jr Blender. Great Pedal
     
  18. Hookus

    Hookus

    Oct 2, 2005
    Austin, TX
    Nothing wrong with that either. Just wire the switches correctly, and place big resistor (like 1.5 or 2 Meg) across the jack lugs to control popping. Or, you can use a millenium bypass to power the LED and control popping at the same time.
     
  19. I've been wanting to build one of these two, since I have a couple boxes that I made for fun at work (I'm a welder) and I wanted something simple to make out of them. I found this today; lots of good info here.

    http://moosapotamus.net/THINGS/paraloop.htm

    I'm not too familiar with op-amps either, can someone point me in the right direction to where I'd get one and what type?
     

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