This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Tuesday, January 20, 2015

Lovepedal Purple Plexi 800

Here's another Lovepedal circuit. It's similar to the Black Magic, adding a frequency control, and is supposed to sound like a Marshall amp.


54 comments:

  1. realmente está funcionando?

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    1. Eu não o construí eu mesmo, mas é verific por alguma outra pessoa

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    2. Sim, eu montei.funcionou bem.

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    3. está sim, já construi alguns e fiz modificações.

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  2. https://www.youtube.com/watch?v=z77kbZL2miI

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    1. Hello Maurus.. Have you modified something on the circuit or did you do it like the image?

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  3. work to me also , my mine is https://www.youtube.com/watch?v=tdA4tY_501s

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  4. i use lm386 N-1 but the sound is so damn small..
    if i turn the volume and gain pot to max. not helping to increase the volume
    do u know how to fix it?

    the voltage through ic looks normal..

    pin 1 : 10.7 v
    pin 2 : 9.6 v
    pin 3 : 9.6 v
    pin 4 : 9.6 v
    pin 5 : 11 v
    pin 6 : 11.5 v
    pin 7 : 10.7 v
    pin 8 : 10.7 v

    is this normal ?
    could you please help me ?
    im a starter.. looks like the wiring is ok.

    i replace the 2.2 M resistor
    with 2 piece of 1 M in the same hole..
    also i replace the 370pf capacitor with 390pf ceramic capacitor.


    im pretty confused.. maybe you can help me friend.
    thanks..

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    1. I had a similar problem. It was bad soldering between the opamp terminais.

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  5. comments anybody ? maybe you have tips to me, to check first.
    im on dead end evrybody, could you please help ?

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    1. It could be any number of things. Can you post some pics of your board? Have you tried taking an audio probe to it?

      http://www.diystompboxes.com/pedals/debug.html

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  6. so i need to probe all the legs resistor and the caps ? to check if there is no sound, then it is a cold solder.
    ok i will try that.

    is this also a solution to find out if resistor or caps is dead or not ?

    Thanks Dtgehring.. thanks for replying me..

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    1. Yes, it should work for that as well. It's a good little tool to have on your bench.

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  7. okay i already probe all leg in my circut<, also im using a looper before the love pedal. so i can hear music that i programmed on the looper instead of no sound.

    i found 2 problems, and i already fix it,
    but right now it feel strange since all leg are ok now but except the both BAT46 one side leg that are coming from the Volt input. the other leg of the BAT46 is ok.

    that leg from the 9v input is not showing any sound, but the other leg do.
    is it normal Dtgering ?

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    1. i havent put it in the box, i just want to make sure if things are ok now.
      by not hearing the sound from one of two leg of the BAT46, need to confirm first.

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    2. The main job of a diode is to direct current in one direction. Since those diodes are for polarity protection, their job is allow voltage to only go the direction the cathode (-) is pointing. So it's not surprising you aren't getting any sound anode (+) side. You should be good to go.

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    3. one more last question before i put it on the box,
      i see your off board wiring, and i found that there is two ground in the board.

      one going to 3DPDT , and one going to ground DC jack.

      the question for the love pedal it has only one hole for Ground,
      can i use that one hole for both of going to DC jack and the foot switch ?

      Thanks

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    4. also i see the cable from board ground is going into the sleeve of the output jack first then go to the footswitch ?

      is it correct ?
      and the sleeve of the jack input is not grounded with the sleeve of the output jack
      because the case was metal.

      is this also correct ?
      Thanks dtgehring.

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    5. You might be over thinking this. Things can be grounded to the board, as long as the board is grounded to one of the jacks. Or you can ground everything to the jacks. It's really just a matter of builder preference. And wire order doesn't matter. Since there's just one ground pad on this layout, run a wire from the ground pad to one of the jack sleeves. Run a wire from the DC jack ground to one of the jack sleeves. Same with the 3PDT.

      If you're using an aluminum enclosure, the jacks you're using are plastic, the sleeves will be connected through the enclosure. Check with a multimeter to make sure though.

      Good luck!

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  8. I can't find bat46 diode...
    Is there any substitute for BAT41 which is also difficult to find?

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    1. 1n400X series. It's just for polarity protection

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  9. Great pedal! Built one and love it! Thinking of take off the 470r "gain resistor" to get it less driven and more "plexi" since it's high gain all the "pot" way

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    1. Good tip, i've done it, but now i guess i will need a log pot for the gain

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  10. What I don't understand about this layout is the two bat46 diodes. Why are there two of them facing the same direction. One is not sufficient?

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    1. Yeah, I don't understand that either. I'd just use a single 1N5817.

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    2. Verified with 1N5817. Also I included a switch between legs 1 and 8 to reduce the distortion somewhat. This pedal has more than enough gain.

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  11. What would be easiest way to cut a little out of the bass response? Would reducing the value of the first 4.7nf cap do the trick?

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    1. I'd reduce the right 47uF cap to like 10 or 22uF. Or play with the 100nF cap directly above the IC.

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  12. Which IC should I use N1, N2 or N4 ?.
    I use the N4 and it has too much gain, remove the pin8, it improves but it is still very strong. Thank you

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    1. The original Purple Plexi uses the JRC386D, which I believe is the same as the LM386N1.

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  13. mine worked but the volume is too low

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    1. I think I found the error. Maybe a wrong soldering spot.

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  14. i guess the reversed bottom side doesn't match the component side one

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  15. I've just finished building it, worked the first time pretty well. It acomplishes the job of being a "marshall in a box" but fails providing good range and gain controls.

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  16. I can't find the LM386, would it work with JRC4558, TL072, 741, etc?

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    1. Those won’t work in this circuit–different pinout, different kind of chip.

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  17. It works, the drawing is good. I built a few pedals from the drawings here. Thanks for them.

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  18. works and has great sound. But the inverted perf layout contains 2 errors, please update. use a bat85 only, as always your layouts are very good !!! Greetings from Brazil!!!

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  19. I just fixed the gain problem.
    the new layout on my facebook is my fixed layout. now It's perfect!!!
    below is the link.

    https://www.facebook.com/photo.php?fbid=163432361668447&set=a.163432395001777&type=3&eid=ARBTr1aUnmITMNoGMONx8I8_yDCn0BbkqduOSVZ7-y8RgTEL3I8ZWsiq0S7zSm_dP7EijivaLPhh5ez2

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  20. can another diode be used instead of bat 46?

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    1. Yes, if I were building it, I'd just use a 1N5817 for D1 and a 1N4001 for D2 (or just leave D2 out). They're there for power polarity protection.

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  21. Verified works great although i tried with b100k ill change to a100k though

    Btw can i reduce popping little bit?
    It looks like it pops a little

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    1. I dont think its called popping..when i pic i can hear scratches and little noise...

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  22. I cannot find any log pot in my country.. can i use any linear which will make good match to log 100k???


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    1. I used 100k but if i dial to 1 it becomes full and if i dial 0 it bcome silence.. its not workin quite well

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    2. B100K with 20k resistor between lug 1 and 2 could fake an A100K

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  23. This comment has been removed by the author.

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