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Beginner pedal: Blender

Discussion in 'Burnt Fingers DIY Effects' started by JuneauMike, Mar 1, 2021.

  1. JuneauMike

    JuneauMike Poster Extraordinaire

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    I've never built a pedal before but I've been leaning toward taking finally taking on a project. I've got a couple of utility pedals in mind that I think would be useful. One of them is a simple blender pedal.

    Anyone have a confirmed schematic or know of a kit that will allow me to blend an effects signal with the clean signal? I would want it to have the ability to swap polarity in case there's a phase issue. I don't think it needs a buffer, but I could be wrong about that. I don't know that it needs a footswitch (the blender would take care of that itself, right?) but again, I don't really know.

    Are there any challenges to the blender circuit that a beginner should watch out for?
     
  2. Mark the Moose

    Mark the Moose Tele-Afflicted

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  3. Mark the Moose

    Mark the Moose Tele-Afflicted

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    Mouser is a good supplier but can be overwhelming. Tayda is cheap and usually has what I need. Small Bear is also solid.
     
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  4. JuneauMike

    JuneauMike Poster Extraordinaire

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  5. JuneauMike

    JuneauMike Poster Extraordinaire

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    Just bought the Buff n Blend PCB and some parts. Guess I'm committed now.

    Question for another pedal I'm kinda thinking about. I was interested in a junction box that included one buffered input and a buffered output. Can I wire the same buffer to both, or do they need to be isolated with their own separate buffer circuits? A newbie question, I know.
     
  6. tvas22

    tvas22 Tele-Meister

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    I might be misunderstanding, but what exactly are you wanting to do? If you wanted to go buffer out to a pedal, or a pedal to a buffer, you could do that with just a buffer pedal that you put in the chain before or after a pedal.

    If you wanted a sort of loop situation, where the signal goes in, to the loop with a pedal in it, and back, you could have a switch to easily control whether it goes to the buffer before or after the pedal.

    If you wanted the option to pass signal to both an input and output buffer at the same time, you’d need two buffers, again you could put these on a switch inside your junction box easily enough
     
  7. JuneauMike

    JuneauMike Poster Extraordinaire

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    Ideally, a pedalboard has a buffer at the begining of the chain before the first effect and after the last effect on to the amp. That's what I'm thinking about here. So to cut to the chase, I would need something like this and not something like this. Or would I need two single IC units? Worried about space.

    This would be a junction box with a buffered input and a buffered out.
     
  8. loopfinding

    loopfinding Friend of Leo's

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    there are a few ways to do blending. the caveat with the single pot "crossfader" is that in certain configurations you never get full cancellation on one side, or the middle is lower volume when the two signals are directly in parallel, a number of things. for most scenarios it's not a problem (you’re looking for a blend right?), and you can always add some gain or attenuate elsewhere, but i would be mindful of that.

    Best way is probably with a dual gang pot with each side wired in opposite directions as voltage dividers into a summing amp. But I often use a single gang pot with ground at the center lug and the outside lugs connected to either input of the summing amp, and it gets the job done okay.
     
    Last edited: Mar 2, 2021
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  9. tvas22

    tvas22 Tele-Meister

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    Ah OK, so you would have like a master in/out box that inserts your pedal board between your guitar and the amp, and has a buffer both after the guitar and after the board.

    You could put that in one box no problem, you'd just need 4 jacks (guitar in, board send, board return, amp send) and that IC dual buffer board would be fine. It can be used as two separate buffers, so you basically use it as such http://www.generalguitargadgets.com/pdf/ggg_ic2buf_sc.pdf

    There's lots of flexibility you could add in here, and you could combine it with a blender that you could switch in if you wanted dry/wet blend across the entire board, though phase might get tricky as you switch pedals on/off.

    You could easily add in the option for a dry pass through switch to bypass the board, plus with switches on each buffer you could have the options of:

    Guitar -> buffer -> board -> buffer -> amp
    Guitar -> amp
    Guitar -> buffer -> amp
    Guitar -> board -> buffer -> amp
    Guitar -> buffer -> board -> amp

    Which might be useful for playing with fuzz or other buffer sensitive effects.
     
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  10. Gaz_

    Gaz_ Tele-Meister

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    I think this might be what you need?
    I built it, I love it. I love being able to wet/dry my effects.

    [​IMG]

    https://tagboardeffects.blogspot.com/2012/02/split-n-blend.html

    I know there's a thousand ways to do everything, but I just bought in bulk on ebay, the first pedal probably cost me £50, but since then, everything's cost about the cost of an enclosure.
     
  11. Mr. Lumbergh

    Mr. Lumbergh Poster Extraordinaire

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    Ain't that the truth... There' so much to search through there, whenever I put a list together it takes quite a while to get it all entered.
     
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  12. Mark the Moose

    Mark the Moose Tele-Afflicted

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    Should you get into this, here are a few things I’ve discovered along the way.

    1. Baseball card sheets for three ring binders are good for organizing small parts. Once I discovered this it became way faster to populate a board.

    2. Shipping costs as much as or more than the parts, so buy lots of parts in each order.

    3. 125b enclosures are negligibly larger than a 1590b on the pedal board but way easier to work with.

    4. It only costs a dollar more to get powder coated enclosures. Worth it.

    5. For drilling out enclosures, there are some drill templates to be found in pdf form. Otherwise, masking tape and a ruler for marking holes.

    6. A step bit saves lots of time.
     
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  13. JuneauMike

    JuneauMike Poster Extraordinaire

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    I don't think I would know a summing amp if it bit me, but generally it seems like all the circuits I've seen use an Op-amp and it's in front of all the incoming signals balanced by N value resistors. This is a Jfet that sends a buffered dry signal through the effect and another dry signal to the blend pot. In this instance R5 seems to attenuate the incoming effect signal.

    The gang pot idea sounds intriguing. Would that change the values of R6-R7?

    blend.jpg

    I'm still looking for enough information on this circuit to understand how it works, so my comprehension is limited. Looks like R1 bleeds C1, and R2-R3 sets the bias and sets the input impedance and R4 sets the current the Jfet will operate at. Collectively these are the buffer circuit. How'd I do?

    Although as I look at it, I don't think I understand how the switching works. It's a 3PDT switch and as far as I understand it, there's only one. Is SW1A-SW1C just the three poles? Hmm. Why would there be a switch on each end of the circuit? That would be true bypass, right? No buffer when circuit is off?
     
    Last edited: Mar 2, 2021
  14. JuneauMike

    JuneauMike Poster Extraordinaire

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    Interesting. So it looks like the 1590b is more of EHX or MXR type side-jack pedals. 125b would be JHS pedals, generally. I've got both and I recall thinking the JHS stuff sits a bit taller than my Carbon Copy or Soul Food and Memory Toy.
     
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  15. Mark the Moose

    Mark the Moose Tele-Afflicted

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    I've quit buying 1590b enclosures as it's just so much easier to get everything in the box with a 125b. That little bit of height is almost nothing under the foot, but is a life saver when you're trying to get a circuit board behind pots and switches.
     
  16. tvas22

    tvas22 Tele-Meister

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    You have the switching right, 1A does the input, 1C output, 1B LED, all wired to one 3PDT switch. You just jumper one of the input throws to one of the output throws. The pedal always stays ‘on’, but the LED switches in and off, and when it’s off no audio is passed through. Switching the output prevents oscillation and other weirdness from getting to the output, might not always be necessary?

    As far as I know that’s the ‘standard’ way of wiring a pedal true bypass.
     
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