Sunday, 14 February 2010

MI Audio Boost & Buff

Original version:



Modified with TB-Buffer selector switch:

17 comments:

  1. Dude. I didn't have any particularly high hopes for this, but it is just great. Simple <30 minute builb and the boost is nice and almost clean. Maybe a bit more harmonic/musical than LPB2.And the boost comes in like sneak attack with 1:1 unity when pot is CCW. There is enough boost in CW. I used liner pot and that makes the control feel really good.

    By just testing this for 15 minutes, i can say that this is recommended build.

    (Personally i don't see the point in wiring that optional true bypass as the buffer is really good too.)

    So. This here. Tag.
    +m

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    Replies
    1. Great stuff. I must admit I've been really impressed with everything by MI Audio, with the exception of the Tube Zone which just didn't sound good with my amp.

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  2. I can't find C25K anywhere.


    Would this trick work in this circuit??
    ""For 25K RevLog you need 5x25K=125K Lin Pot and 25Kx1.25=31.25K resistor soldered on lugs 2 and 3""

    Or would it modify the total load impedance of the circuit??

    ReplyDelete
    Replies
    1. http://www.ebay.com/itm/PEC-KB253S28-25K-reverse-audio-anti-log-pot-2-units-/160941808056?pt=Vintage_Electronics_R2&hash=item2578e119b8

      ka-ching... I know.

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    2. Or use these, for that all important MOJO factor;
      http://www.studioelectronics.biz/sunshop/index.php?l=product_detail&p=1157
      They're a little less than the eBay ones...

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    3. You could go with 25K lin. Or even with 20K lin...
      +m

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  3. Thanks for all the replies!
    I suppose from your answers it's not a good idea to use a paralel resistor with a bigger pot so as to change its tap point?

    I just found this dealer a bit cheaper, and ships to Europe:
    http://www.ebay.es/itm/Mono-Mixer-Potentiometer-16mm-Reverse-Log-C-Pot-/120746208325?pt=UK_BOI_Electrical_Components_Supplies_ET&var=&hash=item61ce930d5d

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  4. hi,
    please sorry my english in advance. i am not a native speaker.
    This is one of my first builds, and my experience in electronics is limited.

    just built this booster. Sounds clean, musical and very quiet with a battery. But as soon as i use the ac adapter for power, there appears a low frequency buzz noise that is as high as the guitar level. I use this same ac adapte powr supply with other commercial pedals, and there is no problem with any of them.

    is there any easy fix for this? like filtering the output with a capacitor to mass or something?

    Another problem i,ve noticed is a pop noise when swithching bypass. I tried a 1M resistor to mass at the input, but it still does the same pop noise.

    I suppose these has to be typical problems in pedal building, but didn,t find any concrete information on my forum searches.

    thanks again
    best fx blog ever!

    ReplyDelete
    Replies
    1. oh, i forgot to also ask about polarity protection. Maybe a diode in series of +v?

      i know these are a lot of questions...

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  5. hi, i just found a series of psu related articles about filtering and polar protection.

    http://diyeffects.com/blog/archives/category/building-effects/power-supplies

    Anyway it would be great if you have something to add that is related to the boost,n,buff pedal.

    kind regards

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  6. Hi there, how would I add a volume control to this? Having both level and gain controls.

    Thanks

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  7. This pedal sounds terrible; I hate it. I don't like the 5M input impedance, it thins out any guitar into a cartoony mess, and you can't turn it off! Because it's always on as a buffer! >:-{ I would recommend building almost any other booster instead: Fulltone Fat Boost, Colorsound Power Boost, MXR Micro Amp, Landgraff Boost, etc. This one is firmly in last place for me. This is one of the worst pedals I've ever built. I threw it in the trash can today.

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    Replies
    1. The buffer mode should have no effect on the fidelity of the signal.

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    2. Then you built it wrong or had it horribly placed in your chain dude. This is a great, versatile pedal that can be used in many different ways depending on placement and setup. Of course if you already have an overly bright setup to begin with, a buffer is the opposite of what you need. The way I built mine, it works as a buffer or clean boost at low settings, a treble boost and mid-high settings, and a really good overdrive at high settings (notice I said overdrive...as in pushing the front end of a tube amp...not a distortion box), and the way I did mine it's also true bypass, buffer bypass, or a kill switch.

      Delete
  8. Hi, how do I include a Led on this circuit?

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  9. Hi All, Love both my v3 and v5 versions of this pedal on RigA and RigB (as my first pedal on the pre-amp side).

    I'm now interested in building up a couple of cheap boosts to even out the levels on the return path of the effects loop (and to allow RigA / RigB FX loops to be easily level matched when using different amps).

    Am I correct in assuming that the 8M2 resistor is key to achieving the high impedance input? How low could this value go before it starts to effect the circuits overall behaviour? i.e. could I substitute for say a 5M1 or even down to a 1M? I'm really after the gain as a clean-boost, so dont expect it to be dimed.

    Thoughts are very much appreciated?

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  10. Just built this pedal, and it works great, thanks! Didn't have vero, so just used breadboard. I added a Panasonic 100uF electro on the power in for filtering, and used Panasonic stacked metal film instead of electros. Kept the 220pF Silver Mica 5%. Only had 5% carbon film resistors to use. Also didn't have an 8.2M, so subbed a few resistors in series for 7.5M, worked great. Installed everything in a Hammond 1590B. Works great at 9V or 18V (I like 18V better). I built the version with the DPDT true bypass toggle, but I used an On-Off-On. With the toggle in the middle position, this allows you to cut the signal completely when "bypassed" but still functions normally as an "always on" boost/buffer/overdrive when turned on - works great as a quick kill switch (tuning, guitar changes, breaks, etc), but can still use normally in buffered or true bypass mode with a quick flip of the toggle. Super versatile pedal - buffer, clean boost, treble boost, overdrive, kill switch, all true bypass-able if necessary. Love it!

    ReplyDelete