Sunday, 20 January 2013

AMZ Mini-Booster

Jack Orman's DIY classic that has been inspiring many builders and businessmen alike over the years. Simple as Fuzz Face, but very big, strong, lively sound. There must be tens or even hundreds of variations around, just as there must be tens or even hundreds layouts around. Still we didn't have this one covered yet. Now we do.




And Geiri's demo! Sounds great doesn't it!


21 comments:

  1. Verified. I'm really getting into these booster circuits and it's nice to be reminded that I'm playing guitar and enjoying the beautiful clear chime that instrument has. Nice simple one, too. Cheers!

    Mark

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  2. Hi Miro. What's the orientation on the 3.3uf cap? Thanks.

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    1. All the schematics i've seen state that it's non-polar...
      +m

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  3. I've actually got a 3.3 polarized (but no non-polar) and wanted to make sure I oriented it properly.

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    1. Build it to that point and measure which side has the bigger dc voltage.
      +m

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    2. You would usually expect the source of Q2 to be at a lower voltage than the gate, but I'm not sure if that is still the case with muamp configurations like this. But that's the way I would try it first, with the positive lead on the bottom row.

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    3. The schematic here: http://www.muzique.com/amz/miniboo.gif indicates that the negative pin on the cap goes to the bottom rail, to connect to the 1M R3 that goes to ground. The positive goes to S of Q1 and D of Q2.

      Having said that, I've just built this layout and gotten nothing (and tried the 3.3 polarised cap both ways)- I've used a 500k pot instead of 100k, and 2n5459s but that shouldn't make a difference as they're the same pinout. Oh well, back to troubleshooting.

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  4. If anyone doesn't have 3.3uf non-polarised, try using 1uf. I do it and I like it. I haven't tried using the correct value so I'm not sure how big of a difference there is. Oh and I don't have a 10pf so I use a 15pf. Other than that, the components are right.

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  5. 1u (non-polar) for that position and 5p for the ceramic seems to work fine. 3n3 chiclet :-o was ear bleeding-bumblebee-transistor radio-esque....and not in a good way

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  6. Verified(+). Sounds very profesional. A clean boost, it adds clarity and definition. It would be a must, 20% or 30% more output volume.

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  7. It 's normal that if the volume control is set to 0 will not come out any sound, and if the pot set to the 100% is lower than the input volume?

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    1. Yes in virtually all these layouts, when the volume control is fully counter clockwise all the signal is dumped to ground and so it is silent. Fully clockwise should be much louder than the bypassed signal so you must have an error somewhere.

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  8. AMZ Mini Booster: is there a mod to increase the overall volume a bit?

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    1. Try J201 instead of the 2N5457.
      That should give you quite a bit more volume and a slightly dirtier tone.
      Mine is insanly loud and unity level is about 10 o'clock, and it is capable of pushing my amp beyond overdrive and into fuzz territory.
      I actuall has never dared to turn it all way up, being afraid that it might be too much for my amp to handle...

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  9. Thank you Neil, good idea.. maybe i try change one 2n5457 for J201, and see what happens.

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  10. I finished this today and my attempt is definitely not a clean boost, even at unity to the bypassed sound. It has more of a mild overdrive sound. I have 2N5457's in it at the moment. I tried J201's but those are even dirtier. It's almost there, it just adds a little hair to the sound. Any suggestions as to make the circuit cleaner? I know I could try it at 18v, but that is not the best option for me.

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    Replies
    1. Try to change 1k resistor for another with a higher value (10k)

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    2. Thank you, Boratto. That totally worked!

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  11. Perhaps there is a mistake in the vero. According to GGG, 22n should be 220n (0.22 uF): http://www.generalguitargadgets.com/pdf/ggg_joam_a_bom.pdf

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Should all layouts be verified before publishing? This would mean less layouts but more peace of mind?