Tuesday, 5 August 2014

Buffers

Following a couple of threads in the forum where people had oscillation problems with certain effects that disappeared when a buffered pedal was placed before them, I said I'd do a post on here with a few different compact buffers that people could try tucked away in the box to place in series before the effect board.

So we have:
IC vero using TL071
IC perf using TL071
JFET basic buffer
JFET buffer with voltage divider for increased headroom.

Looking at the differences in sizes I'd be tempted to try the basic JFET buffer first, because if that does the job well enough it's so small that it should be easy to fit in any effect's box with the minimum fuss.



41 comments:

  1. Looks like I'll be trying out the basic JFET in my volume pedal. Any thoughts on how to incorporate it in?

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  2. Thanks! I'll try out the fourth one to see if it cures my squealing OCD build. For those who want more information on these (and other) buffers by Jack Orman, here is a link:

    http://www.muzique.com/lab/buffers.htm

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  3. I built buffer number one and buffer number four last night and they both work fine (how could they not being simple circuits?). However, they didn't cure the OCD squealing.

    In my tests, I discovered that the BOSS TU-2's buffer seemed to tame the squealing. There is a schematic of the TU-2 online, and it looks like the buffered bypass is an FET buffer at the input followed by a BJT buffer at the output. Maybe that's the magic? I may try building the Klon buffer eventually and see if that does the trick.

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  4. Very interesting. I knew a version with two resistors, 1M or 2M both, but it wasn't impressive.
    Must try this one.
    Is there possibility to have a vero with gain and/or tone control?
    Thanks

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    Replies
    1. BTW: verified TL071 is verified and sound very good and transparent ;)

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    2. Hi Guys, I put #3 in a guitar after the PU select switch and before the vol pot. The middle PU has a coil select switch that pops when switching coils. I like the sound- I used a J201 instead of the 2n5457 for this one as it sounds brighter to me. Where should I put a pull down resistor to silence the popping? 10k, 1m?

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  5. Replies
    1. If it has a gain control it isn't a unity gain buffer

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  6. The IC perf TL071 seems weird to me... maybe I wrong, but the 1M resistance is not connected properly on the 3rd PIN?

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    Replies
    1. It's just two different configurations, check out the top two opamp buffers shown on the AMZ buffer page: http://www.muzique.com/lab/buffers.htm

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  7. I built Buffer#3 for its compact layout and put it on board my guitar after the pu selector switch and before the vol pot. It sounds great, and is so tiny I just stuck it to the battery w/ double sided tape. Thanks for helping me improve my tone!

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  8. Is there an alternative for the 2n5457 in the third layout?
    Thanks!

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    Replies
    1. Pretty much any JFET should be ok in a simple unity gain buffer. Just watch the pinouts

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    2. Thank you, is a J201 the same pinout?

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    3. not sure, but if you search google for "j201 datasheet" and "2n5457 datasheet" you should find the data sheet for each on the first or second page. just compare to see if they are the same or not. if not you may need to twist the pins or flip the transistor 180 (backwards from how it's shown on the layout) to get it in the right orientation. always consult the datasheet, it's one of the best things that can help you out.

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  9. For the jfet buffers, can I replace the resistor between the Source and Ground with a trimpot to create a boost?

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    Replies
    1. No. That would be the case, if you took the signal out of Drain, but from Source - that won't work.
      +m

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  10. hi, i had a couple of 2n5457's laying around so i built the third layout (verified).
    the tone of my guitar is back!
    i am housing all my pedals under a single box at the cost of low-volume-and-less-treble sound, but not any more.
    however my fuzzes are not the same any more, they sound way too harsh than before.
    the buffer is placed before the fuzz.
    is there a way to control the impedance and make it more fuzz-safe ?
    like this guy suggests?
    http://screaminfx.com/tech/why-and-when-to-use-a-guitar-buffer-pedal.htm

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  11. Hi Guys, I put #3 in a guitar after the PU selector switch and before the vol pot. I like the sound, but there is a pop when I toggle the coil cut selector switch. where should I put a pull down resistor to silence the pop? What value resistor 10k,1m ? Thanks, and always thank you so much for all your time and info

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  12. spent the last 3-4 days and got nothign ..finally got frustrated and just wired the few reamining ic chips up p2p , and they worked, just to make sue I am nt crazy ,..no I dea why these wouldnt turn out ..

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  13. I have been using the above vero TL071 buffer for some time, but it never felt really transparent to me. I was wondering if it might be worth adding soulsonic's stupidly awesome buffer to the above list: http://www.freestompboxes.org/viewtopic.php?f=13&t=26102 It's a more complex circuit but the difference in transparency is night and day. I posted a somewhat crude but verified vero layout in that thread.

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  14. I know this is over a year old, but thought you might be interested in just How small I've managed to make 2 of these buffers using PCB and SMD technologies...

    The Opamp one is based on the perf, while the JFET one is just the simple version.

    http://imgur.com/TDScpqu.png

    Fender Medium pick for scale.

    -Ryan

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    Replies
    1. Crikey! That IS small. Well done. You get them done at OSH Park? They must have been like, $3 haha.

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    2. Not even! $1.70 for the Opamp buffer PCB, and $0.60 for the JFET one. And that's for THREE OF EACH. And yeah, got them done at OSH Park.

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    3. Maaaaan! Genius. Cheap. I'm impressed. SMD is a little daunting but it's doable huh...

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    4. Nice job Ryan. SMD isn't as bad as many people may expect, as long as the board isn't designed around anything daft like the 0603 or 0402 packages. For 0805 or 1206 it's actually really easy. Just tin the pad slightly then line up the components and touch the legs with your iron. That usually give you enough heat to secure it in place and then you can add more solder if you feel the need.

      For DIY I really couldn't understand why some people ever consider using the smaller (0402 or 0603) packages. There is never a reason to. You could easily fit a Klon or I bet even a huge flanger circuit in a 1590A using the larger 0805 or 1206 size components so what is the point in ever doing it smaller?

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  15. Hi, All!
    Will these circuits reverse the phase of the signal?

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    Replies
    1. The JFET circuit is a source follower and the IC circuit is non-inverting, so in both cases the input and output will be in phase

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  16. Thanks for these curcuits!
    #4 in 6x5 http://oi61.tinypic.com/sf9yxw.jpg

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  17. Got a Question regarding the JFET version with voltage divider... Shouldn't there be one more 10uf within the voltage divider? E.g. from 7/5 to 6/5 ? Its done like this in http://www.muzique.com/lab/buffers.htm for Vr, which is basically the same...

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  18. Hi,

    will this cure HM-2 clone from this site? I have build one and it starts to squeal on 85% of treble when gain is at max. Is this a issue that will buffer cure?

    Thanks,

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  19. Hello, can anyone tell me what the 'red squares' indicate on the diagrams? (Red square filled with white and a red dot in center) Please pardon my ignorance, I'm new to electronics. Thanks for the info!

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    Replies
    1. It indicates a place where you have to make a cut on your vero board. Left side has no connection to the right side any more. Can be done by using a simple drill bit.

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    2. Thanks Peter, much appreciated!

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  20. Ok, so I'd like to build one IC and one jfet buffer from this post (the topmost layout and the bottom layout) just to hear the difference. I'm using these as a 'piezo buffer', and I've noticed that a lot of the buffers specifically for use with a piezo pickup use a 10m resistor... Can I build the layouts above and just substitute a 10m in place of the 1m?

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    1. This comment has been removed by the author.

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  22. (Thanks for the quick reply lvlark) Ok, so I've got the topmost buffer built, (tl071) and I get no sound at all :( I've double checked my layout and it's correct, no visible shorts or anything. I used a 0.1uF 100v capacitor (little grey flat box) for the part marked '100n' and my ic has the #1 leg in the top left corner... I used a 4.7m instead of the 1m shown. I've got the 9v+ wired to the pad marked 9v, and everything grounded to the ground pad. It should work just as is right, I don't need to ground the ground to a metal box? This is my first circuit, thanks for your patience and incredibly cool help.

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