Thursday, 3 March 2016

FYA Scream Queen Overdrive

I guess this should be posted here as well. My take on the TS clipping amp with some changes. Brief description and some discussion at FSB.. Due to nature of relatively high gain and the input buffer design, i recommend using a switching jack that'll ground the input jack tip when plug is not present. Currently, the squeel when nothing in the input jack is the only downside to this circuit i'm aware of. And yes. It sounds pretty damn good. Sort of like a sleekier bastard son of Clark Gainster and vintage TS808.

This also utilizes the SIP opamps some of you may already have laying around.


...and here's another version of the same circuit that uses way more common DIP opamp. While the chip initally was 4558, you should try on what you want. I bet it'll sound good with LF353, OPA2604, AD712, NE5532, etc. DIP layout is currently unverfied... verified too.



21 comments:

  1. Do you think i could use the Hitachi HA1457W opamp instead? I have loads of these kicking about which i bought for a preamp i built a while back.

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    1. Forget that just found the datasheets for HA1457W and 4558BL and they look quite different.

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  2. I don't have any SIPs but this looks pretty cool so I'll be trying it out. Thanks for the share!

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  3. sorry to be dense guys, but I can't locate a BL version of the 4558. Is an L close enough? http://www.mouser.com/ProductDetail/NJR/NJM4558L/?qs=sGAEpiMZZMtCHixnSjNA6DRIUwv2n8oLQMzy9WBo0Bo%3d

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  4. Any SIP dual opamp should be just fine.
    +m

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  5. You can also get the JRC4558L SIP chip from Smallbear Electronics:

    http://smallbear-electronics.mybigcommerce.com/ic-jrc4558l/

    Thanks for the layout, Mirosol - very cool. Using SIP chips like this makes for a compact vero layout, and has the wheels turning in my brain (e.g. an MXR OD-808 layout with two SIPs, or a mini-Klon :).

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  6. Miro ....

    Could you educate us in how to do this?

    "Due to nature of relatively high gain and the input buffer design, i recommend using a switching jack that'll ground the input jack tip when plug is not present."

    I have this problem on a few pedals. I have a hunch on how to do it but I would rather know for certain. Thanks in adcance.

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    1. Use a switched jack. Tie the tip lever to the input of the input wire to the switch, and the tip closed lug to ground. So when a jack is inserted, the level is lifted and signal passes. But when removed the lever springs closed and connects to ground. Have a look at the Cliffs switched jacks. They are the open ones where it's easy to see whats going on.

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    2. http://www.switchcraft.com/Drawings/13B_CD.pdf
      Lug named "shunt" to ground. This way the terminal called shunt is completely disconnected when the plug is in place. Once the plug is removed, the shunt connects to the tip and grounds it.
      +m

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    3. Thank you - that is what I figured, but I had never noticed such a part on sale before. Now I know what it is called.

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  7. blue dots in your layouts - is this just a position where two different links meet up?

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    1. Two links connected in single hole. Yes.
      +m

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  8. Verified the DIP version. Used 1N4001s for D4 & 5.

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    1. Great! How does it sound to you?
      +m

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  9. Its very bassy with not a lot of highs coming through. It also rumbles a deep bassy sound when not playing. Don't think this will get boxed. Did use an MLCC from tayda for the 1uf cap and i have heard these can be quite noisy. Might change for a large poly cap to see if it makes much difference.

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    1. Hmmmm... Not quite sure if your build is correct. Here's a clip of mine: http://mirosol.kapsi.fi/varasto/circuit_demos/fya/FYA-SQOD-CLIP.mp3

      The oscillation also points to a short or some other error.

      Cap type doesn't matter. And MLCCs have not been noisy in low voltage audio applications.
      +m

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    2. Just built the DIP version myself. No low pitch oscillation and the tone is very close to my SIP board, maybe just a hint of more crunch. I think that may be due to the chip. I also used all MLCCs for non-polar caps - no audible noise.
      +m

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  10. Thanks Mirosol for sharing this original design. It was a really quick and easy build and it sounds great. Gotta box it and play it through a real amp instead of this practice crappy pedal testing thing, but what I get so far is a nice smooth gain, even when maxed out. I really like the tone control too. It doesn't feel like there is only one setting that works, which is what I often find.

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  11. Miro! I finally got this built up and tested, it sounds great!! I will absolutely box this one. I will probably use it on mid-gain setting and it has a really nice high end with my Tele and great balance overall. Nice job!

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