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Monday, 5 May 2014

JHS Little Black Buffer

Traced from gutshots on the blog forum posted by hahafender, thanks for the pics buddy :o).  Some of the traces on the unused side of the opamp weren't visible but the left hand side is a generic opamp buffer and that's the important bit.  I think the resistors used on the other side we're just used as suggested by the IC manufacturers to do to unused channels.  Not sure why he didn't just use a TL071 and so not require the 2 additional resistors, but I suppose that does make it at least appear further removed from the common opamp circuit that we've seen lots of times before.

Info about the original:
This may be the greatest weapon you didn’t know you needed.

For those of us who are a little “pedal happy” there can be some downfall to our tone. When running a pedal board with more than one or two effects, something called “capacitance” happens. This natural problem happens due to the amount of cable or line that your signal has to travel through, not to mention bad switching systems in certain pedals. The result is a very audible amount of high-end loss, weak signal, flabby bass and uncharacteristic pickup behavior in guitars. Another problem is the assumption that all “true bypass” is good. This isn’t true and actually can be worse than imagined.

This is where the “Little Black Buffer” steps in providing the perfect input impedance to your rig and giving you the final result of clear, natural tone that sounds like you're plugged straight into your amp no matter how many pedals you use.







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71 comments:

  1. drdFX5 May 2014 at 20:22

    Hm... What's the purpose of the rightmost two 2M2 resistors? As I see the complete right side of the opamp is doing nothing.

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    1. IvIark5 May 2014 at 20:55

      The manufacturers recommend that to avoid noise from unused channels you should connect the non inverting input to a reference voltage, and link the inverting input and output. A much easier way to avoid noise from an unused channel is to use a single channel opamp :o)

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    2. Unknown25 July 2014 at 02:06

      help me .. i made the modded version and there is no signal..help me with the wiring

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    3. Unknown25 July 2014 at 02:29

      do you have some images where i can see how to wiring the modded version??.. thankkss

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    4. IvIark25 July 2014 at 11:33

      There was an error on the modded one which is why I removed it. I think you should be able to fix it by putting a cut between pins 3 & 6 where there is currently a gap, and then taking a 1M resistor over the top of the IC horizontally on the 4th row of the vero from the far left hand hole to the far right hand hole (and so connecting pins 3 and 6 with a 1M resistor. Give that a try and see if it fires up.

      I couldn't show the wiring in any way that would be easier than the way you see it now. Wire the input jack to the input connection shown on the board, output jack to output connection, ground to ground, 9V to 9V. And that's it.

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    5. Unknown31 July 2014 at 03:53

      hello its me again i just made the original version and there is no signal too..help about the resistors..there are 1/4, 1/2 and 1 watt. and also i put a cap 10u to 63V ....help me how can i to make this works..thanks..

      Delete
  2. Unknown5 May 2014 at 20:35

    Where is the best place to use this buffer at? In front of all my pedals or I assume at the very end of my pedals?

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    1. Unknown5 May 2014 at 20:48

      first pedal in your chain

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    2. dbat695 May 2014 at 21:43

      Unless you have a fuzz or wha pedal that doesn't respond well to a buffered signal - these pedals should be first in the chain. In such cases place the buffer after these pedals.

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  3. Ross6 May 2014 at 13:07

    Perhaps the other half of the opamp is for a buffered reference voltage?

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    1. IvIark6 May 2014 at 13:30

      That would definitely have made better use of it, but if that were the case then the two 2M2 resistors on the input side of the board wouldn't have been required.

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    2. IvIark6 May 2014 at 13:59

      I've added an "improved" modded version to the post. That is the way I would prefer to build it I reckon.

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    3. Unknown6 May 2014 at 16:06

      i'll be building the first one... i'd give the second a shot but i don't have 47uf caps lying around anywhere. but maybe i'll get to it soon. would be cool if someone built the second version to see how it sounds!

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    4. IvIark6 May 2014 at 16:17

      They will almost certainly sound identical. Buffering vref makes better use of the second channel but it isn't going to make an audible difference IMO. The extra filter caps means the second should be less noisy, but I've never heard a noisy opamp buffer anyway so again I can't see it making too much difference. Basically the second method is something I would prefer to do with the unused channel, but the main difference is two less resistors :o)

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    5. Unknown6 May 2014 at 16:45

      ahhhh okay cool. good to know

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  4. Dave9 May 2014 at 08:50

    Hi Mark,
    I tried to build this (the second version) last night without success. I noticed you are missing a cut under the IC which I added to my build, this gave me a very quiet signal, much less volume than unity . I also replaced the chip several times with no improvement. Looking at the klon buffer, it seems the resistor values are very different for what seems to be a similar circuit. How sure are we of the resistor values in particular?
    Cheers
    Dave

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    1. IvIark9 May 2014 at 10:34

      Hi Dave. No the cut shouldn't be there. That connects the non inverting input of the buffer to the vbias voltage divider as it should. Make a solder bridge over the cut and post the voltages you're getting.

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    2. Dave9 May 2014 at 11:53

      Ah ok, I'll stick it back then. That means by build has something else going on then because it didn't work before I made the cut, I got no signal at all. Id love to post voltages but I accidentally left my multimeter on and its now out of battery! ARGH!
      Cheers for the reply
      Dave

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    3. IvIark11 May 2014 at 21:43

      Let us know the voltages when you get a new battery in it. I can tell the layout is good by just looking at it, it's a classic generic buffer, so there must be a problem somewhere. Did you socket the IC?

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    4. Dave15 May 2014 at 08:36

      I did, I think your layout is spot on, I reckon I have a faulty component somewhere. I'll report back when I debug.

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    5. Unknown30 June 2014 at 01:54

      Like Dave above, I couldn't get the modified version to work either. No signal at all. Built the regular version and it worked first try using the same socketed IC as I did on the modified... Not really sure what's going on with the modified...

      Delete
  5. Unknown13 May 2014 at 13:06

    can i retrofit this on a volume pedal? taking the output from this to lug 1 of the pot lug 2 to output of volume pedal and lug 3 to ground? if so what value do you think is best for the pot? 50K? 100K?

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    1. IvIark13 May 2014 at 13:26

      The pot lug numbering would depend on which direction the pedal actuation rotates the pot, but yes there's no problem in doing what you suggest. For a pot value if you opt for 100K log that should let the full range of frequencies through and not filter out any low end.

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    2. Unknown14 May 2014 at 03:55

      I guess the typical wiring for most rocker pedals.. also thinking about 100K log.. Thank you!

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  6. Unknown22 May 2014 at 20:05

    Hi there!
    I found only 2M resistors (closest to 2M2). Will the pedal work with the resistors I have?

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  7. farmereffects29 May 2014 at 17:14

    Built the none modded layout... Worked perfectly! VERIFIED!!

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  8. deancw992 July 2014 at 19:52

    Where is the second/modded version? Or is this it?

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    1. IvIark2 July 2014 at 20:07

      A couple of people have had issues with it, and although I can't see what the problem could be, I decided that the original one was the important one for this thread rather than my take on the circuit. I may add it as another buffer at some point but I'll build it first myself to verify next time I'm sat in front of an iron.

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  9. kirshman1 August 2014 at 04:43

    If you bring the led out of the board like this, do you still need the 2k2 resistor?

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    1. IvIark1 August 2014 at 09:55

      If I have room I will put the LED resistor on the board, so if you see a connection saying LED+ then you don't have to add an additional resistor offboard. That wire goes to the anode, and the cathode goes straight to the stomp switch

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    2. kirshman1 August 2014 at 16:43

      thanks man. sorry if you've answered a hundred times.

      Delete
    3. Looney Tones14 November 2014 at 09:44

      Hi !
      I'm a noob, but I try to understand what's going on.
      If I follow the 9v path on the board, the LED resistor is the 470R, right ?
      Isn't that low ? I usually go with 2K2 for a LED. Does something happen to the 9 volts that I don't understand ? or can I use à 2K2 if I don't have a 470R ?

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  10. Unknown2 August 2014 at 22:41

    i made two times the original version and doesnt work.......

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  11. Unknown8 December 2014 at 07:18

    Also if I am not using a stomp switch and have it on all the time how should it be wired??

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    1. mirosol8 December 2014 at 09:14

      Input jack to input, output jack to to output. Both sleeves to ground.
      +m

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  12. Unknown8 December 2014 at 18:30

    I built one the other day and all i get is a squeal sound , any ideas? i double check my layout and it all looks good. Bad IC chip?

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  13. Unknown4 March 2015 at 05:19

    Would a TL082 be an ok IC replacement?

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  14. Unknown6 April 2015 at 13:29

    Hey guys, how is this schematic? can you guys vouch for it?

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    1. Meek7 April 2015 at 18:37

      yes, it works well.... satisfaction guaranteed just around the corner ;)

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  15. Unknown3 November 2015 at 10:32

    Hey I'm new at this. Do I put the components on the same side as the cuts? I feel like if I make the cuts on the copper side then put everything on the opposite side that the components won't be in the right spot according to the cuts.

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    1. ξεναγός νεκρόπολης3 November 2015 at 11:27

      noooooo!!!!!!

      just read this first!!

      http://tagboardeffects.blogspot.gr/2012/04/vero-build-guide.html

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    2. Unknown3 November 2015 at 16:21

      Ahhh I knew there was something so simple that I was missing!! Thanks!

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  16. Unknown3 November 2015 at 23:58

    Can I use a 100nj cap instead of a 100nf?

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    1. Unknown4 November 2015 at 05:15

      nj? The 'n' is relevant to the actual capacitance of the capacitor - the 'j' is there to denote the tolerance of the cap - in this case 5%. That means it will be within 5% of 100nf.

      So technically that cap you have should read 100nf j. NF denoting the nanofarad range, and j denoting the tolerance.

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    2. Unknown4 November 2015 at 05:16

      Check this out http://www.sentex.ca/~mec1995/gadgets/caps/capcodes.gif

      Delete
  17. Unknown30 November 2015 at 16:33

    Does anyone have a picture of this circuit completed that I can look at?

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  18. Unknown3 December 2015 at 00:21

    I'm having a hard time completing this. I can't figure out how everything connects as far as the led, jacks, and power jack. It would be awesome to see a pic so I can see exactly how everything connects.

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  19. Anonymous3 December 2015 at 05:13

    jason go to site links and read the off board wiring

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  20. Unknown6 December 2015 at 07:58

    Anybody else got a pop when this buffer is in a loop ? .. ok .. what I mean is... when testing I put this buffer in a tbp loop pedal , to hear if there was an audible difference vs the unbuffered signal. I got the "common" pop of the 3pdt. Tried pull down on input and no dice, the pop was still there. And in another test... I built a blues breaker, all wired up with it's own 3pdt... all is good.. but with this buffer before the bb (as is, in line before the bb, no on/off of any kind) I got the pop again. With the bb I tried lowering the input pull down from 2M2 to 1M and in a seperate test put a 100K pulldown on the output. The pop kinda reduced, but never really go away. Is this a common thing with this or any other buffer ? Can this be fixed or should I try an other buffer ?

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  21. Tronc.the.cube4 March 2016 at 05:02

    This has made the pedals after it pop loudly. I didn't add the led. any ideas?

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    1. mirosol4 March 2016 at 05:50

      Try adding 220K resistor from output to ground.
      +m

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  22. ZackHeil7 March 2016 at 15:59

    So if I attach the input to the unused opamp, and have it setup the exact same as the other opamp, do I essentially have their buffered splitter?

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  23. Unknown15 August 2016 at 01:15

    the led i used (ultrabright 8000mcd)was very bright with the 470R resistor, used a 4,7 k instead.

    anyways nice & easy build, Thx for the layout

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  24. Unknown9 April 2017 at 04:17

    Hi, I'm a bit late to the party on this one but I wanted to try a buffer pedal in my chain and this looked like a pretty straight forward first project.

    The build seems to be working in that the LED comes on and the instrument sound gets though the build out to the amp, I'm pretty happy with that result for a first go.

    The output seems very quiet though. If I plug the either an active bass or passive guitar directly in to the amp it is a lot louder than when I go through the effect.

    Is that normal? Is there something I should look at in the circuit that might be causing this?

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    1. Unknown23 April 2017 at 20:36

      Turns out low output is not normal :-) I had done one bad solder point (on the resistor after pin 3). All works perfectly.

      Delete
  25. Brent Rusinow9 July 2017 at 08:59

    Hey all, so I just built this thing and really like it, but I've noticed a really odd issue that I can't figure out. When I power up my amplifier after the powered pedalboard (with buffer included), I get noticeable white noise. If I turn down the amp volume and power cycle JUST the buffer, the noise goes away. I've tried power supply as well as battery with the same results. Any suggestions?

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  26. Unknown14 August 2017 at 05:23

    When I use a battery to power this the led comes on but when I use a power supply it doesn't come on and I get this burning smell

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  27. Unknown11 November 2017 at 02:02

    I made this to put it inside a Patch bay, and made it switchable with a millenium bypass. The thing is I'm getting radio frequency when I turn it on. Can you help me figuring out a solution, please?

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    1. mirosol11 November 2017 at 22:07

      470p (or lower) cap from input to ground should cure it.
      +m

      Delete
  28. Unknown8 December 2017 at 14:22

    Hey guys, thanks for the schematic! I have an issue though. So I built this board exactly to the schematic, and I've quadruple checked it but it has a constant buzzing and popping. Any help is greatly appreciated!

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  29. Blackwing7 October 2018 at 18:20

    Can this be a simple volume pedal? If so, how would you wire? Also, if not any suggestions? Thank you!

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  30. Gaëtan25 April 2019 at 22:06

    Hi Guys, I've built this one today as my first build ever, works like a charm. Thanks a lot for your work and for keeping this site up !

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  31. DC28 April 2020 at 02:12

    Built last week. Substituted a 4558D as I am out of TL072s. It works great, dead quiet but brings back some sparkle that was robbed by my cheap cables and growing pedalboard.

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  32. Anonymous22 July 2020 at 03:46

    This was my first stripboard project. I've completed two of them now, both work and sound great. It's really nice to have a couple loose buffers around to handle long cable runs, especially when recording.

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  33. mesquil23 March 2024 at 22:59

    Hi, I ran out of 100n caps, would this also work with 150n ones? I couldn't find information about the input cap selection for TL072 buffers, only some schematics, always showing 100n caps. I need to throw one of those together pretty quickly... Thanks for your help

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