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, February 19, 2019

Inverting Phase Buffer

Got a request for a dual buffer that inverted the phase of the signal. Found this post from Parasit Studio and used it for the basis of this design. I added polarity protection, power filter cap, and output caps. You can use either dedicated jacks for the in phase and inverted phase outputs, or use a SPDT toggle connected to a single jack and use it to select between the two outputs. (In phase output pad to lug 1, output jack to lug 2, inverted phase output pad to lug 3.) Should prove to be a handy utility. Single and dual versions below.


27 comments:

  1. I'm curious... Why you want invert the phase?

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    1. Lots of effects invert phase which can sometimes cause some issues with other pedals in your effects chain. This corrects that. In Freppo's post on the Parasit Studio blog, this was originally designed to be put inside an existing pedal that inverts phase.

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  2. When phase get inverted, especially lower frequency area
    of sound get withdrawn, precisely saying, offset by other instruments which share same frequency range as yours.You won't be aware of it when you play alone in your bedroom, but in ensemble phase really matters.Built-in bass preamps like Bartolini or some guitar pedals/amps often invert your signal. If you play in a band, better build and set it in your pedalboard just in case.

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    1. Never Notice that.. I don't understand how it sounds in a real situación... I'll investigate this. Thanks for the kindness.

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  3. Hello!
    Can I request this latest Baja device from fsb forum ?
    http://www.freestompboxes.org/viewtopic.php?f=13&t=29467&hilit=baja&start=20

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  4. Great. I put all together at my breadboard but I noticed that the inverted output clips, the non-inverted output doesn’t do that.
    do you have an idea why?

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    1. You could try putting something like a 470Ω resistor after the output cap and a 100k to ground after that, ala the Klon buffer. You could also lower the value of the 10k resistor in the feedback loop, but I think you'd need to also adjust the value of the 10k between the two opamp stages.

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  5. Nice compact layout. Definitely building the dual version.

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  6. So, will this be the same as a balanced output to a xlr3?

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  7. shouldn't the dual version have caps on the in phase outputs?

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    1. Good catch. I guess I am just going to wire the output 10uF cap off board. Thanks for the heads up.

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    2. Doh. I think I got so happy with how symmetrical it turned out I forgot to add them. haha Will update.

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  8. Nice!

    One more suggestion: http://www.freestompboxes.org/viewtopic.php?f=1&t=23189&hilit=mesa+throttle+box

    your layouts are the best!

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  9. is it possible to make a simple inverted dual fet version? would be great.

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  10. I can verify the dual version. Thanks for the layout.

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  11. A nice addition to these would be a splitter buffer that inverts one channel. A split-n-blend for out of phase circuits.
    I stacked the inverting half of the parasite on top of Paul in the labs splitter and it works. My layout is not the greatest though.
    https://www.diystompboxes.com/smfforum/index.php?topic=112303.0 I change r 1 an2 to 1M.

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  12. Is it possible to use this buffer (tl074) with 10 Mohm resistor for higher input impedance?

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  13. or maybe with 3 Mohm. which resistors i have to change?

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    1. The 2, 1M resistors on the left and right edges of the board.

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    2. so for 3 Mohm input impedance i have to change the two 1M on the left and right side to 3Mohm (each) or to 6Mohm?

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  14. Awesome,This is a mini Balance or Di-box XLR Pin
    GND = PIN 1
    Inverter > Inverter Phase = HOT = PIN 2
    Non Inverter > In Phase = Cold = PIN 3

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  15. Inverting phase op amp maybe can be utilize after feeding guitar signal into non inverting op amp. ,, to minimize hum and unwanted buzz???maybe?jun fr Philippines

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  16. It works i just build it dis morning. I place it in front before my compressor and i noticed that helps reducing hum and noise coming fr my strat. Well tnx and its very verified!jun fr Philippines

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  17. BOA NOITE. ALGUEM TEM ALGUM ESQUEMA PARA IVERTER A ORDEM DOS EFEITOS DE UM DUAL DRIVE (PCB'S SEPARADOS)?
    GRATO.

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