Wednesday, 11 August 2010

MXR Micro Amp


This one was done specifically for some components I wanted to use and it's sized appropriately, so if you're using smaller components you may be able to shift things round a bit to save some space.

17 comments:

  1. way cool!! this is the pedal when you want a clean as possible flat even boost of all frequencies with as little tonal shift as possible. Super Hard On is always brighter, and Fat Boost is always on the thick and low-middy side...this one's right down the line

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  2. is this a dual or single op amp?

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  3. Oops, missed it off. It's a single and I think MXR currently use a TL061

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  4. you've got your pot wired in backwards: pot lugs 1 and 2 should go to the 2K7 resistor, and pot lug 3 should go to op amp pin 2

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    1. Sorry I missed your heads up Dan. I'll correct the layout and post the new one. Thanks very much.

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  5. Hi IvIark,

    Shouldn't be there a 1N40001 diode in the Microamp circuit?

    thanks so much
    giulio

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  6. Yes there was, but it was used for reverse polarity protection as per this diagram and so won't have an audible effect on the circuit (other than whatever is cause by dropping the supply voltage by 0.5V or so):

    http://generalguitargadgets.com/diagrams/microamp_sc.gif

    I'm not too bothered about that in any of my layouts because I use a regulated negative ground daisy chained supply so there's no chance of me reversing the polarity. Anyone who does want to include one just needs to put it in series with the 9V supply as shown in the schematic.

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  7. Tag this one too. Just built it. Sounds good. Opinion zone starts here :) I like it better than EHX LPB2. Say what you will. It's a little grittier and as loud as anything. Might even like it more than SHO..

    Couple of deviations; didn't have 15µF axial, so i used 22µF instead. As there was space for it, i swapped that 1µF cap also for axial electrolytic.

    Thanks Mark for this mojo version.
    +m

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  8. Hi guys. I am hoping you can give me some direction. (I won't go into all the details unless you're interested). Basically, I want to build a Micro Amp and have the option of having a balanced XLR output in addition to the normal 1/4" output we normally use for guitar. Do you have a circuit layout somewhere that converts normal stomp box output to XLR balanced that I could add on to the Micro Amp circuit? If not, could you give me any leads or point me somewhere I could do some further research? Thanks.

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  9. Hey guys! Question. Built this and it sounds great, but... my build pops. I am using 1M pulldowns on the in and output of the circuit (omitted the 2,2M on the board) AND Led Depopping as described here:

    http://www.muzique.com/lab/led.htm

    Even with a 47uF value it still pops. The tubescreamer in the same box is dead quiet with a 10uf as cap for the led depopping. Any ideas?

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    1. Have you tried another switch? Sometimes you get one that just pops no matter what preventative methods you try.

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    2. Thanks! I'll yank it out and try another one tomorrow. Thanks for the layout Mark! Love the mojo components and the Microamp completely kills the SHO for me

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  10. It wasn't the switch. After adding power filtering (a friendly forum member pointed out that it's missing in the mxr microamp) the led depopping worked!

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    1. Hi, mine pops too. Can you explain what kind of power filtering did you use? I suppose an electrolytic but it would help to know the exact value to save time, thanks

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  11. This comment has been removed by the author.

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