Friday, 29 April 2016

Brunetti Mercuri Box

Here is a layout for the Brunetti Mercury (should fit in a 1590B size box).
Frank_NH has uploaded another verified, slightly modded version in the Forum section a while back.

This is the best video I could find (in Thai language):


Start biasing JFETs at 9V.

29 comments:

  1. Whoa, what a great layout, turned out pretty compact. I've made one of those using the layout Frank posted at the forums and gawd, it's my favourite gain box, I've using it in my pedalboard as my main od/distortion pedal since then. Guess I'll build one more

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  2. Nice layout, Alex! This is really good overdrive/distortion, and I hope others will give it a try with this more compact layout. I should note that the 3.3nF cap next to Vol 3 rolled off too much treble for me, so I replaced it with a 390 pF cap. Also, you can use other JFETs in place of the J201s (e.g. 2N5457), which will lower the gain some.

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  3. I went ahead and built 2 from your layout, Frank! I subbed the 3.3nF with 1nF in mine

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  4. I built mine with 2n5457 . nor as wooly as the demo but more than enough gain for my taste. Maybe ill make this one with the j201 since its not verified yet just to compare.

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  5. Thanks for the layout, looks like an interesting distortion. Went through your layout and seems to be ok to me comparing to the schematics on FSB, except for the resistor from Body2,3 to ground. In your layout it is 4k7, while on the schematics available it is 10k. Could you please doublecheck? Or do you have a different source for the schematic?

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    1. 4K7 is the corrected value.
      http://www.freestompboxes.org/viewtopic.php?f=7&t=9846&p=253908&hilit=brunetti#p253908

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    2. Oops... I missed this one, thx.

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  6. I'm currently buildind it but I realise I don't have any BAT85 diode.
    Would any 1N58XX be a good replacement ? I also have a few BAT46...
    Thanks

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    1. you can use anything, the 1N58xx will be as good as the BAT85, is just for the charge pump section

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    2. I forgot to write the type of diodes!
      I've added it.
      As Guilherme said, they are 1n5817 but any 1n58XX would work.

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    3. Thanks Alex I'll report back on friday

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  7. I used a 50kA pot instead of the 1M for 'Body'. I noticed that the 1M maxxed out when increased about 10%. The 50k pot gives a great range of tone.

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  8. Ok it's verified, you just need to swap volume & gain leads 1&3, and probably also bite (as you get more treble CCW but maybe it's like that on the original).
    I will replace the gain pot with a lin tapper as I get almost immediatly full gain.
    I also socketed that 3n3 cap and like it better with 1n
    Very nice sounding distortion

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    1. Good Job. Its cool isnt it. I realluy like this pedal. I made mine with the 2n5457. I didnt have a trimmer but i did match the jfets to .01 volts. Did you use the j201 or the 2n5457? Did you match them? Is it as wooly as the demo. With the 2n5457 its not quite as wooly but plenty of gain.

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    2. I tried both and like it better with J201, a bit smoother. I biased the drains at 8.2V as I get 16.4V out from the TL071 with my power supply.
      100k lin for the gain, 500k lin for body and 100k log for the volume are the pot values I ended with

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    3. interesting . ill play with those pot values. thanks for the response. Ill make one of these soon. I just got a bunch of j201 but the voltages test low probably factory rejects but ill give them a shot. Did you match them at all?

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    4. interesting . ill play with those pot values. thanks for the response. Ill make one of these soon. I just got a bunch of j201 but the voltages test low probably factory rejects but ill give them a shot. Did you match them at all?

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    5. Thank for verifying it!
      Are you sure you need to swap legs 1 & 3?
      If lug 3 would go to ground the volume would work in the opposite direction.

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    6. That's right vol 1 should go to ground but OTOH I really had to swap the leads. Maybe I confused the legs on the pot, you should wait for a 2nd advice before modifying the layout.
      Pics of my build :
      http://www.casimages.com/img.php?i=16050803593614005914208817.jpg
      http://www.casimages.com/img.php?i=16050803594114005914208818.jpg
      strassercaster no I didn't match the J201, I picked the 2 first that came to my hand from the box

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  9. Like this one. Used J201s. Didn't match my J201s as i used smds.

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  10. Really cool sound pedal.
    just a low gain to my taste.
    is there a way to increase the gain(i build it with j201)?
    thanks

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    1. mine has tons of gain did you bias the Jfets to 9v?

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  11. This comment has been removed by the author.

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    1. ep strassecaster i did bias them to around 9.5v
      everything works just fine.
      sound like a medium overdrive.

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  12. Would the 2N5458 also work for this project? I am buying parts from TAYDA and they don't have the J201 or 2N5457.

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    1. I strongly advise you to get SMD J201 with adapter board they are much much more reliable and sound way better in these kind of circuits
      http://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&cPath=6&products_id=52

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