Sunday, 16 August 2020

Xotic BB Pre Amp

 Two layouts for this one. One stock and one with an additional Mid control. The clipping diodes is placed on the side of the board so you can easily add a diode clipper switch. Just omit the diodes on the board and add wires tat pad 1M and 1N to a DPDT switch where you solder your diodes of choice.

Stock layout

 
Layout with Mid control
 


14 comments:

  1. Hi. I guess that two layouts are both the one with Mid control.

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    1. Yes, I noticed it yesterday, will upload the layout without Mid control when I get back in a few days.

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    2. Layout withiout Mid control uploaded.

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  2. Thank you for the layouts. When they put out the midrange version, (called "MB") they also put out a version with a 3 way clipping switch called "Comp"

    Like you suggest, use an on-off-on switch for 2-diodes/bypass/4-diodes. That will let you get normal and Timmons model sounds.

    To get the midrange version to sound like the stock model, just turn it down almost all the way.

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  3. Built the top layout as shown. I didnt do and switch mods or anything on this one. Tag It. Works and sounds GREAT.

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    1. Thanks! Tagged. Thats verified layout number 600.:-D

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  4. Hi!Thanks for all your work!I wonder if there is a real difference between this new version and the Timmons one other than the clipping.There are the first schematic with a dual gang volume pot that Andy supposedly favoured..
    http://effectslayouts.blogspot.com/2016/02/xotic-bb-preamp.html

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    1. Yeah, the difference is that the volume control has an extra gang which sort of affects the the impedance between the overdrive section and the eq section. Looks interesting but I don't know how much difference it would make versus the more recent version.
      The extra components can be added quite easily but it would require a bit wider board.

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    2. I would like to try it some time..Thanks!!

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  5. Re the diode switch option I’m not sure I get what, “add wires tat pad 1M and 1N to a DPDT switch”, means. Could you elaborate?

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    1. Just hook up one wire from 1M to lug 2 of the switch. Another wire from 1N to lug 5. Remove D1 and D2 from the board and solder them back to back between lug 3 and 6. For lug 1 and 4 you can choose whatever you want like LEDs, just solder them back to back. Then you'll have a switch for two diode settings. Middle off position lifts the diodes from the circuit.

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    2. Thanks very much. I actually realised after you posted how much of an idiot I am. I was looking at 1M and 1N thinking, those parts aren’t on there! Didn’t occur to me it meant the grid 😂.

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  6. Hi!The good folks over at Aionfx have traced the circuit recently (AT,bass etc) They use the dual gang volume pot and some other things.Cheers!!

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  7. Hello everyone, Doe's anyone knows any on line source to find 19k Resistor.?
    Thank you guy's

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