Sunday, 31 March 2013

Runoffgroove Azabache

As requested. A long time ago. Size of the board tells you why it wasn't drawn up earlier....

From ROG:
More than a year ago we set out to revise and improve the Professor Tweed. Several approaches were pursued, but we were unsatisfied with the results. One of the downfalls was the high level of interaction between the tone and gain controls. Just as in the original Princeton amp, the tone control became ineffective when gain was set close to maximum. In addition, this arrangement was adequate only for a very specific type of sound.

We decided to step away from the inspiring amp's circuit and concentrate on developing a solution superior both in tone and usability. Builders may notice that the design does not correspond to any particular existing amp or pedal circuit. Though the use of a modified "Big Muff Pi" style tonestack is apparent, it is placed before the overdrive sections as opposed to its common location as a final tone shaping device.

The result is a circuit that is much more flexible and refined than its predecessor, and in our opinion it captures a wider variety of Fender-like tones. We have named this new circuit Azabache, which is the Spanish word for "black amber". The duality of its name recalls the Blackface and Tweed aesthetics.

This pedal has a very effective and flexible Tone control that varies the sound from fat and warm when set fully counterclockwise, to full at the center, to thin and bright at the clockwise end. In addition, two switches further expand the tonal possibilities: a Bright switch adds a glassy character to the sound, while a Scoop switch reduces the midrange around 400Hz to achieve more clarity. The different switch combinations produce several sounds which we have loosely named as follows: 

Bright OFF / Scoop OFF: Blonde mode
Bright ON / Scoop OFF: Brown mode
Bright OFF / Scoop ON: Silver mode
Bright ON / Scoop ON: Black mode

As for the Gain knob, it can adjust the sound from almost clean, to a warmed-up light overdrive, to a medium overdrive, to a quite gainy overdrive. Each stage is set up to produce a moderate amount of gain while avoiding hard clipping in the JFET itself. The result is a refined overdrive with a natural note decay that reacts very well to the guitar's volume knob.

Finally, the tone shaping that takes place at the end is essentially modeled after the distinct frequency response of a Jensen P10R speaker, with its bright tone and deep 400 Hz notch. We think of this part of the circuit as a mini-Condor Cab Sim because the frequency response is akin to the Condor, however adapted to take into account that another amp and guitar speaker will follow afterwards.

Overall tone was optimized for solid-state amps that are moderately bright. If using a very bright guitar and/or amp it may be desirable to tame overall brightness a bit by changing the 1n capacitor between Q4 and Q5 to 1n5. Conversely, a bit more brightness could be achieved by replacing said capacitor with 680p. For best noise performance, it is recommended to use metal film resistors and replace the drain trimpots with fixed resistors once the necessary value is determined. Good wiring and shielding techniques are also encouraged.






Video of Geiri's build:



And according to discussion below (and the ROG post on DIYSB), the excessive treble content on the tone control can be cured by just lowering or shorting the 47K resistor at tone pot lug 1 connection. So here's a "fixed" version of the layout. I used 4K7 for this resistor, which should be  low enough to achieve better tone control. But you can go even lower or replace that resistor with a link if you want to.



37 comments:

  1. thanks, indeed. Really want to build this but i'm still afraid from large boards :)

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    1. You guys should probably wait until it's verified. Although i'm fairly certain about it, i'm known to get blind when looking at something long enough...
      +m

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  2. Man, I'm SO building this!!! I've been wanting to build this for months fron the original rog documentation, now I don't have to! :)
    I even have most of the components on hand...

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  3. To get the target voltage at the Drain, do you hold the DMM black lead at ground and DMM red lead at Drain, then turn the relevant trimmer until you see the desired voltage?

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    1. Exactly. I recall there was a nice tutorial video on the Dr. Boogie comments.. Yup. There it was: http://www.youtube.com/watch?v=X4-UUDoSCPg

      Also, i didn't include the "correct" voltages on the layout, but they should be reading:
      Q1, 2N5457, drain at 6V
      Q2-Q4, J201s, drains at 5V
      +m

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  4. Just ordered some bits for this one, i must say i'm a bit intimidated by the big board/component count but hey we only learn by facing our fears LOL

    Thanks for this one Miro

    James

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  5. This is such a great pedal. Built this instead of the Catalinbread Formula No.5 and other Fender-like pedals and I don't regret it even for a minute.
    A keeper on my pedal board. Works great with fuzz pedals and with any pickup. Highly recommended once the board layout is verified

    http://fuzzquest.blogspot.com/2013/03/well-im-really-excited-about-posting.html

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  6. Ok, built this as per layout and i got a very hissy pedal with a gated signal and seemingly no response from the switches. I`ve scoured the schematis for over an hour and finaly noticed that the 1n cap doesn`t go directly from emitter to base on the 5088, it goes to the base via the 39k resistor, took the 1n cap out and put a new one in from emitter to 39k ( the row above volume 1), i had to sit the body of the cap on the link to make sure not to short anything, fired it up and it works great, EXCEPT..... the tone doesnt work, after another quick look it seems to me that the cut under the trimmer at tone 3 needs to be left out, will have another go tomorrow, i need to try and get the imprint of the schem outta my head :-)

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    1. Thanks for the notes man. I'll check those parts right away and commit a fix.
      +m

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    2. Yup. Massive f-up on my part. To get that board working, take tone 3 to under that 220n right from the Q2 trimmer. That'll need some jigging to fix..

      You're correct about the 1n too.

      I'm working on a fix right now...
      +m

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    3. Ok. Took me an hour.. Both of those mistakes were inexcuseble. Sorry for those. Like i said above, you should get your board to work by taking Tone 3 to where 10n and 22K meet on that same row.

      I seem to do this one mistake over and over - i reserve a row for something, maybe even connect a wire to it. The 15 minutes later i hog that same strip for something else - and forget that it's been reserved already. This is the exact thing that happened here too. I'm calling this "the layout blindness".

      This current layout *should* be safe to build.
      +m

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    4. On the positive side, i got one row off the size and slightly fewer links/cuts...
      +m

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  7. Tone 3 goes to the 10n, not the 220n.

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    1. Yup. I meant under it :) As there's no room to put it neatly anywhere...
      +m

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  8. Yeah that looks good, old layout works fine with the tweaks so this should be good to go too. I must have gone over the schem 15-20 times before I spotted it, guess I suffer from schematic blindness too :-)

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    1. Quite happy with it now - and i'm fairly certain that this fixes it. But somehow i don't trust my judgement too much at the moment...
      +m

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    2. I trust your judgement! We do the layouts, it's everyone elses job to verify them and tell us what we cocked up on :o)

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    3. Heehee.. :) Bigger the schematic, more chances to get it wrong. Almost wish we wouldn't have all the fuzz faces done already :)
      +m

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  9. Painting by numbers is easy, but when someone leaves out the numbers or mixes them up, that's when we improvise and when we improvise we learn. As much as I detest debugging, I hate building something that doesnt work more. Mark's right, we had a poll to see if we wanted only verified layouts published and the vast majority said no, verifying the layouts is a chance for us to contribute to the blog.

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    1. And we're very lucky to have a bunch of guys like you who help us massively by spending your time verifying the layouts that we really don't have time to verify ourselves because of the amount of or free time we spend doing layouts. Catch 22! :o) I always said that without you guys I'd have only verified about 20 of my own layouts so big thank you always to all of you.

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  10. I'm gonna have a go at this now..

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    1. Also, there are 27 cuts, not 26 =)

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    2. I'm assuming if those bottom 10K are placed correctly then there needs to be a cut underneath them.

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    3. Fixed all those and added labels for transistors. Thanks for the heads up Geiri!
      +m

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  11. Built it, worked right away. This pedal sounds fucking great! I've got an Orange Dual Terror which sounds alright but running this pedal just brings it to life. I feel like I've got a proper Fender amp.

    Highly recommended!

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    1. Build this too, and it worked right away. This pedal is maybe the best sounding "Fender" like circuit out there, only the Wampler Black 65 might beat it.... A bit too bright for my ears, so i took a 2n2 instead of the 1n cap!

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  12. Been wanting to build this since I started building for the first time, and now finally I have earned the skills and experience enough for such a large circuit, and I have a couple of days ago I managed to put it together, and got it up and running straight away.

    It sounds quite nice, but I only have one BIG issue with it:
    This is the harshest and most extreme high frequency shrieking pedal I have ever heard.
    Yes! It sounds like a Fender, but with only when the amp's highs are cranked all the way up to full, and with the bass and mids rolled off almost all the way.
    This circuit is splitting my ears, even with the muddy old Humbucker on my 77 Custom Telecaster.
    It only sounds good if I roll off the tone (on the pedal) almost completely (but then it sounds really nice)
    Is this normal? Is this really how this effect sounds? Is it supposed to be that extreme in the highs?
    None of my other pedals are this extreme, not even the treble boosters I've tried when set at the most extreme settings.

    I replaced the 1nf cap with a 2.2nf as Heiko suggested, but it is still way too extreme in the higher frequencies, (which renders the tone control almost useless as it only sounds nice when it's in the lower 5-10% part of the pot, and that section is quite bunched up and difficult to precisely dial it in at the sweet spot).
    I will try to increase the cap one more time, but I would like to hear someone's opinion about this pedal and the amount of high frequency being pushed out. Anyone feeling the same as I do here?

    I will give the Wampler Black 65 a go as well, as I really do like the Fender sound (but only when the highs are rolled of a bit. Otherwise they sounds like shit, as they are way too trebly and ear-splitting for my taste, and it is never as extreme in the highs, as what this pedal is putting out)

    But: I love the sound of the pedal, and I am determined to find a way to tweak it to my liking.
    Hopefully a 2nd cap swap will do it.
    If someone knows a different way of reducing the highs and make the tone control more useful (any other caps worth replacing in order to tame the highs?), I would very happy to hear about it. - Cheers!

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    1. Hi Neil,

      Glad you built this super fender pedal. I have had great results with this one and it became a favorite in my rig.
      There is obviously something fishy about your build as it sounds really good at every configuration. Try to find the problem. If not, try the Formula 5 by catalinbread, should be better than the Wampler.

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  13. Hey Neil,
    i think those ROG geeks tend to use their pedals with cab simulators (recording), so it makes a huge difference if you use them with "real" guitar amps. I built a lot of their circuits, and all of them felt sort of *icepicky* to me, so.... (except one: the tonemender, great pedal to "simulate" amp responses). You could try using a 100K *Audio* tone pot, might give a better response (i did so). However, the Black 65 could be your pedal..;-)

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  14. Hi everyone,
    Has someone tried it under 18v?
    Since it's an amp sim, a charge pump could be useful, or am I wrong?

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  15. I have this on breadboard now, with charge pump. IMO it sound more detailed. Will build it this way.

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  16. I just finished building the Azabache, but using a TH Custom FX's PCB. I'll make Neil's words mine: this pedal is VERY bright. I'm using all the specified parts and stuff and I'm totally sure there's nothing wrong about my build. I think I'll change the tone pot to 100K A or even 50K A, because, just as the previous poster described, my build is sounding best with the tone knob on "0". The bright switch itself makes the circuit already plenty bright, also.

    Having the super-bright tones dialed out, the circuit sounds phenomenal. I just can't believe the '65 would sound better than this. The tones are killer, and the pedal can also be quite gainy, as ROG said.

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  17. I've found a really nice, simple mod to tame the treble of this pedal and make the tone control more useful, courtesy of the ROG guys themselves (from a thread on DIYSB): just substitute the 47K resistor going to TONE 1 for a link (or a smaller value resistor). Now, I find that the tone control really works as it should, with a nice balance between bass and treble on the noon position and more bass and treble-cut to the left, bass-cut and more treble to the right- like a Big Muff, not just trebly-er than my clean tone on "zero" and various degrees of ear-piecing treble on the rest.

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    1. Great mod. Will definitely try this one out, although the only problem I have with the trebleness of the pedal is that it adds a lot of hiss with the volume pot above unity.

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    2. Damn it. Just recently built one of these for a friend to try out as a "slow bubbling" Neil Young tweed simulator. I felt it was rather sluggish on the lows, but deemed it as a feature. Needless to say the friend didn't like it as it just cut the lows too much. I'll add a modified layout to the post...
      +m

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