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.

Wednesday, September 23, 2015

BearFoot FX Sea Blue EQ

Here's a cool EQ/booster from Bjorn Juhl. If pushed hard, it will break up much like a tube EQ would, and adds warmth and clarity to your tone. It uses 2 JFETs and a James style tone stack.



18 comments:

  1. Hello Friend! For some reason is not working, I used all the components in the exact values and the transistors used were the 2n5458's. I tested all the components individually before assembling and everyone is ok. Have any suggestions of what can be? Because I followed everything to the letter and did not really work ... Congratulations for the site and for the initiative and thank you!

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    1. if what you meant by "did not really work" is the kranked sound, then you are not alone. I face the same matter, the sound is too kranked / over driven.

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    2. I've gone over the layout again and it follows the schematic correctly. Sounds like the JFETs might be biased incorrectly. Check out this schematic and note the voltages given by Q1 and Q2. Then adjust the resistors going into the drains accordingly.

      http://3.bp.blogspot.com/-NAazBanhoPQ/TxLdN6cEJJI/AAAAAAAAAi4/cm4d9kxR9hI/s1600/sbeqv.png

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    3. Wish me luck, I'm rebuilding this one. I'm assuming my previous build sounds bad because I use 15k resistor to replace all 14.k ones. so wish me luck.

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  2. okay man, you can now label this one VERIFIED!
    how does it sound? just like the original one. awesome!

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  3. Is there any chance to run this at 24v? I know I should use 25v caps but how about Q resistors?.

    Tried with increased Drain resistors (330kOhm gave half of supply at Drain, about 12v) but it distorted hard.. Any ideas?

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    Replies
    1. Biasing JFETs isn't always an exact science. I would recommend socketing those resistors or using trimmers to dial in the right voltage. Half the supply is usually the starting point, then adjust until it sounds good from there. That's how I do it anyway. Hope that helps.

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  4. This comment has been removed by the author.

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  5. Friend: the 1uf to Volume 3 is the other way round . Now it works perfect! Thank you for your work. Greetings from Argentina

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  6. Hi. Can i use it as a tone stack? I would like to put it before a fuzz and omit volume control of eq. Should i link volume 1 to ground and link volume 3 to in of another circuit? Thanks and sorry my poor english.

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    Replies
    1. It's more of a preamp than a tone stack, but I think it would work ok the way you have in mind. You can ignore the vol. 1 pad (as long as you ground the board from the ground pad) and the vol. 3 pad would be the output.

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    2. Thanks, man. I want to try build an algal bloom with sea eq. I am thinking put a filter too or blender. Any suggestion? Maybe Comet Filter or 70 Funk box.

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    3. this is interesting. i'll try to stack it with dod 250

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  7. Verified, with extra mids pot control (Jhon Kallas mod).
    I removed the 1K resistor to ground on bass lug 1, then connected that to an A50K pot lug 1 (new mids control)and connected lugs 2&3 on the mid pot to ground. then I just added a 47n cap between lugs 1&2 on the bass pot.

    So transparent and like it so much...thanks brother...your the man

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  8. Pedal incredible, but putting the pass by the poping and horrible... Some Suggestion?
    Thank you!!!

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    Replies
    1. Have you tried increasing the value of the input pulldown resistor?

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  9. I tried to work with 2M2 but the poping still persists, I'll try 4M7 Thanks

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