Sunday, 9 April 2017

Electro Harmonix Knockout Attack Equalizer

"The Knockout is a powerful two-filter combination that can make your Les Paul sound like a Strat and your Strat sound like a Tele. Its secret...the Knockout has a 7 pole filter for sculpting the low end of your mids and a 6 pole filter to shape the top end of the mids. This provides incredible tone shaping. Use after distortion to bring out the heavy weight punch of the metal masters. The Knockout is also truly amazing on Bass."
Original FSB thread and schematic available here.




... and a layout with added Input & Output caps. (Will remove the one above later)

19 comments:

  1. Hi!
    What is a CLR resistor and "LED+"?
    I did not find it in the schematic...

    Thanks!

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    Replies
    1. CLR stands for current limiting resistor and is just a resistor making sure that your status LED gets the right amount of current. There's lots of online calculators to get the numbers for whatever color your using, but if you're unsure 2200 ohm usually works well. LED+ is just the positive side of your status LED(usually the longer leg), the negative going to the switch as in the offboard guide that you can find in the tabs on this site.

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    2. Thank you Voidvessel!
      This one was a bit different from other vero, in that matter.
      Thanks!

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  2. Curious about this. May give it a go

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  3. yesterday I saw the layout ehx equalizer by johnk.
    nice layout Alex. I want to try this

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  4. Could an LT1054 be used in place of the 7660s?

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    Replies
    1. Not on this layout.
      If you give me your email address I'll send you a modified layout for it.

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  5. This comment has been removed by the author.

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  6. i use bc558. cool my humbucker sound like single pickup.. and pot bass so powerfull . damn great must try on bass. tq Alex

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  7. Will it work with a MAX1044 as replacement for the 7660S?

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  8. Anyone know what hFE on the BC309: A, B,or C?

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  9. I built this and used bc558s. Works as advertised, really nails a strat sound with humbuckers. My only issue is a nasty switch pop. Tried adding 1M pulldown on input and output, but still get some DC on the output. I also checked continuity between strips and across cuts—all good. Any other ideas of how to get rid of the DC?

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    Replies
    1. Dear god. Just noticed that the circuit does not have in/out caps at all - the schematic has it without them too. As it is, there will be DC voltage in both, always.

      You definitely want to add something like 1u cap in series with both input and output. And take the pulldows on the outer side of those caps.

      Wonder if Alex would be interested in adding 1u input cap + 1M pulldown and 1u output cap + 220K pulldown to the layout...
      +m

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    2. Cool. Wondered about that. Thanks for the fast reply!

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  10. Do the 1 Uf input and output caps need to be polarised electrolytics - or can they poly box caps?
    If polarised, which way round do they go?

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    Replies
    1. Either will perform the same. Positive to circuit, negative to input and output.
      +m

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  11. Thanks for that both of you - luckily I hadn't quite finished building the board.

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