Wednesday, 20 July 2016

BYOC 27V Boost

Taken directly from BYOC.

Possibly the World's cleanest, most transparent boost. It utilizes the 7660S charge pump's ability to take a standard 9v power supply and output both +18v and -9v. The op-amp based boost circuit takes advantage of the whopping 27v differential to produce 20dB with an amazing amount of headroom. It doesn't matter if you're using active pickups - you will not get any clipping from this boost. Slam it with another boost, it still won't clip! The treble control allows you to cut/boost frequencies above 3k3Hz by 6dB.

To be honest, it's not as small neat as I would like it due to the three different power connections, but here she is. 



On the site it says it uses a 7660s for the charge pump, but the schematic shows a MAX1044, remember the two are interchangeable. 

22 comments:

  1. Replies
    1. Correct. I forgot to put that in the build notes. I'll fix that when I get home.

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  2. hi zach
    its 17/16 and not 18/16
    is there a mistake?
    thanks

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  3. Yeah, first verification of mine incoming :D
    You can tag it, nice Boost. I made it for Bass and its really transparent and stays pretty clean. It even boosts my active 6 String Bass without to much clipping.
    Great stuff, thanks for that.

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    Replies
    1. Can I ask what you did to change it for bass? Increase the input cap?

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    2. you shouldn't need to do anything, it was designed for bass.

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    3. I just upped the Input cap to 22nF I think, but thats it :D

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  4. Got this one working with a MAX1044, thought with the treble controls up high, there is a very high pitched tone that is constant. Still a very nice, usable boost that takes signal from other pedals with ease.

    I experimented with a 7660s and got a pretty nasty whine from it.

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    1. i think i found the source of the whine. if you look at the 10uF cap that goes from pin 4 to ground, right next to the 3.3M is reversed. the negative should be on ground and the positive at pin 4.

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    2. Thanks!! Flipping the polarity of the 10uF you described cleared up the whine on the MAXX1044. Sounds great(er)! I still have a nasty oscillation with 7660s, but then again, I might have a few bad 7660s'.

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    3. Well glad the cap was the issue. I can't believe I had it reversed, probably happened when I was moving stuff around and didn't realize it was flipped. Also, really happy it sounds good, since there's no videos samples to hear I wasn't sure if this was a worthwhile build.

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    4. So. I build it. It works. And it works very powerful. Thanks Zach!
      But I have that constant noise, that Brandon describes (and other too).
      Zach, did you manage to correct the layout or I must connect the 10uF cap reversed? I am now connecting the negative of the cap to Ground, but still have that noise.
      It goes off when I turn the Treble full ccw (at zero I think). But it comes again if I start to lower the volume of the bass guitar.
      The noise is present event before I connect the bass.
      I play on active bass if that matters.
      The same is with the lead guitar, though.

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    5. I accidentally touched the board under the MAX1044, somewhere between 7 and 8 leg, and the noise gone. Where I go wrong? What to add to compensate my finger?
      p.s. Excuse my English

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    6. Note sure what's going one, maybe a bad chip. The layout was fixed. Your finger is acting as ground. Form what I see in the schematic pin 7 & 6 are not connected. Maybe adding a ground to pin 7? And your English is fine.

      If you add the ground to pin 7 and the noise goes away let me know and I'll add it to the layout.

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    7. I don't see any logic, but putting a jumper between legs 6 and 7 solved the problem (for me). No noise. Works perfect.
      Before that I test it with second chip and the noise was still there.
      Thank you!

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  5. I have just finished 27 v boost. It works, but i have noise sound when i turn the treble pot.

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  6. I'm trying to build this one. I have several 10uF 35v bipolar (non polarized) electrolitic caps lying around, can I use them as well?

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  7. Ok, it works! There's a lot of volume output, but it's not clean. It starts clipping with volume at 9 o'clock and it gets more crunch and loudness until full scale. The clipping is fine but again it's not clean at all, it sounds more like an overdrive than a booster....

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  8. Hi, I am building my own preamp for a marshall combo which preamp is dead (luckily the power amp is alive). I tried with a ready made preamp delivering a nice amount of gain though I would like to get still a bit more power from it. Would you recommend to use this booster to send a bit more input to the preamp stage? Would it boost all the frequencies? Thanks in advance!!!

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  9. Does the MAX1044 need to be an 's' model like the 7660 or will a mx1044CPA work without whine?

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