Sunday, 19 June 2016

Mad Professor Amber Overdrive

Direct from the source:

One of the most sought after guitar tones is a combination of a great overdrive or fuzz pedal into overdriven tube amplifier. Amber Overdrive produces this sound even when running though a clean amplifier. It produces a very thick sound whether playing chords or single notes – fat and juicy with just a hint of fuzz.

Though highly saturated, this dynamic overdrive can be cleaned up with the volume control of your guitar. As with all Mad Professor pedals, it offers a wide range of dynamics and expressive touch sensitivity.

When you plug it into a clean amplifier, Amber Overdrive can give you the massive sound of a saturated amplifier running wide open. It can also be used as a slightly distorted boost to increase saturation on slightly overdriven amplifiers.

NOTICE: Amber Overdrive is a medium input impedance device that places a light load on your guitar pickups to produce a smoother tone. it will work best as the first pedal in the chain. if you run a buffered pedal ahead of Amber Overdrive you will get an increase in treble and upper midrange.





37 comments:

  1. Its verified and sounds awesome.

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  2. Rockett. thanks for posting this one up. Can't wait to build this.

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  3. So do you connect gate pins of the 2N3819s as well?

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    1. I'm pretty sure you cut off the Gate leg (the middle one) and use the Drain and Source as if it were the anode and cathode of a diode.

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    2. No. You connect the drain and source, as stated in the notes, leave the gate intact. You then use the gate as one point of the diode and the connect drain and source as the other.

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    3. I only asked because I did read the notes and wondered what you connected the drain and source to!

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    4. The drain and source are connected, i.e. Take the leg of the drain and physically connect it to the source leg and solder it together. I don't know why you're getting so angry about it, when I explain it say it's in the notes.

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  4. Any substitutes for Q4 and D1-D2?

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    1. For D1-D2 use just about any diodes or transistors you want. If you want to be more or less true to the original use any jfet transistors. Q4 could also be replaces with another jfet, but proper biasing will be needed, so you might need to tweak the 14.7k resistor going from drain to +9V. Place here a trimmer or pot, and find your value, then use the correct value resistor. I would try the common J201, 2N5457, etc., but mind the pinout (as usual).

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  5. Hi all, just to confirm that with the 3819's you just cut off the middle leg? does the orientation matter? thanks

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    1. No, with the 3819 the middle leg is the gate. Either use the gate and source or the gate and drain or (as on the schematic) connect the drain and source and use that with the gate. But there won't be a big difference compared to Si diodes. The forward voltage is 0.7V, so you could simply use any Si diodes instead, and that would also save you from wasting two of the quite expensive jfets.

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    2. ahh I see, thanks for the reply. So put the drain and source through the same hole and the gate through the other, orientation shouldn't be an issue? I have 1N4148's will these do the trick? or I have 1N4001's what's the best substitute? thanks again

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    3. If you want it to sound the same as the original you need to use MOSFET clipping for D1 & D2. The orientation does not matter as long as the two are reversed. You don't put the drain and source in the same hole, physically connect the two legs together and use one leg to go into the hole.

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    4. @Matt,
      That's correct. Or you can go the way Zach mentioned if the holes are too small for two legs (god, I can't help, but with conjuntion of "muff" I have some very nasty thoughts writing the above :D). As for diodes: both the 1N4148 and the 1N4001 should be ok. Try to put sockets there and see what fits you best (my all time advice when it comes to clipping diodes)

      @Zach,
      Are you sure about the MOSFETs? The good folks at FSB mention only 2n3819 in that position and that is definitely a JFET. Also Mad Professor is known to use JFETs, more precisely 2N3819s in several designs as clipping diodes (the Fire Red Fuzz - which is almost identical to this one except for the tone stack and the Sky Blue OD as well). Nevertheless I'm still true to my statement that using simple Si diodes will yield almost the same (if not totally the same) sound as using JFETs - for way less money.

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    5. you're right, they're JFETs. i assumed they were MOSFETs cause i honestly never heard of JFETs as clipping diodes. honestly, never been a real fan of the mad professor stuff, the BBD being the one major exception. good to know.

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  6. Oh god, a Muff under a "false flag". Watch out.

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    1. It is a modified big muff, but doesn't really sound like one. It's more of s medium to higher gain overdrive. Plus, since when is a big muff s bad thing? Show me a man with too many muffs and I'll show you a man who has yet to live.

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    2. Absolutely agree: one can never have enough muffs.

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  7. Hi all. I've built a lot off M's sight but the treatment of D1 and D2 is knew to me. If I understand it. I take a 2N3819 transistors, twist the drain and source legs together and put them on as shown for D1 and D2? Asked above but what about the orientation. It matters a lot with diodes I think..?.?.? Can someone explain D1 and 2 to this idiot please? WITHOUT telling me how to earn xtra $$ at home....!!!

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    1. Hi Jeff. What you mean by, you need to know about orientation? Just like two diodes, one oposed to the other, after you have drain and source legs together as you are mentioning. Like in the schematic of any muff variant.
      O<---O
      O--->O
      or
      O-DS-G-O
      O-G-DS-O

      basicaly you have drain and source of D1 with Gate of D2 in the same point, and Gate of D1 with drain and source of D2 in the other.

      Or, just forget the fets and put there two of silicon diodes. :D

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    2. Thanks very much RD.
      I will just socket the 2 parts and play with the sounds. Starting with the diodes.
      I guess it is a dumb q, but if I were to use 2 legged fet's would the flat sides be back to back?
      I think I need transistor theory regarding polarity.

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  8. This comment has been removed by the author.

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  9. It does still sound like a muff. Its just a different flavor.

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  10. This comment has been removed by the author.

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  11. sorry, where is the 5th link??? i just see 4 o them
    or the longest one has a double link?

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    1. nope, it was left over when i was messing around making the layout. just fixed and reupped the layout. thanks and nice catch.

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  12. Is there any schematic the tonestack available?

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  13. What software do you use to design your schematics, veroboards and other drawings such as offboard wiring (switches, jacks, etc??)

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  14. Hi, guys. Really basic question here, and not necessarily particular to this layout (though it happens here too). I see on a lot of the layouts that a lead from a pot comes back to hit the ground rail on the board (like Vol 1 does on this layout). Is there a reason for this, other than just convention? It seems to me that it would make for a cleaner build if that lead went straight to a common ground in the enclosure. Am I all wrong here?

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    1. Personal preference just. Bringing them back to the board means less wiring flying loose in the enclosure making for a neater look. I admit that I keep it all neat inside when building for a customer...but for my own I just bring every ground to a "point in the sky," twist, solder and heat shrink. It's faster, but awful looking.

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  15. Sounds great this. Used BF245As for D1 & 2. Its nice and loud.

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  16. Isn't this close to a Skreddy P19?

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    1. It's a big muff with fet clipping in stage 2, so since they're both muff variants you can say they're similar.

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    2. Cheers, there are some differences in transistors and component values but overall they are indeed similar.

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