Wednesday, 20 March 2013

Bearfoot Baby Pink Booster

Info about the Bjorn designed original:

The Baby Pink Booster is a booster with clean transparent boost and very fine Line Driver in bypass position. It sports adjustable and switchable boosts ranging from unity to approximately 8 times or +18 dB, which is the practical limit with the signal levels and supply voltage range used in conventional effects-empirically derived.

Baby Pink Booster was designed to do just the transparent natural clean boost, there is no overdrive or distortion options, to include an overdrive with Clean Boost one would have to compromise one or the other, we recommend Baby Blue OD or Dyna Red Dist for distortion. The unit doesn't have even Tone knob because it doesn't alter your tone, it just boost your signal and doesn't color your tone at all.

And with it's 180 degree phase bend you can even use it to connect the two channels of your vintage Fender amps (more about this later).

Baby Pink Booster doesn't have a True By Pass but a very well designed Line Driver (buffered output).
It is good to have one pedal with buffered output or you would loose some signal and high end even with best cables if you drive two cables and few short one between pedals.






Original version:




True Bypass with Boost/Buffer toggle switch:



31 comments:

  1. Hey IvIark - thanks for posting this, seems to be good timing. I've been looking at building an ABY pedal - but after a lot of research it all seems very daunting and confusing, with a lot of conflicting information and discussions (ground loops, buffered/active passive wiring, buffered/not buffered, phase reversal, potential amp issues/shocks if not done properly) and am about to give up on the idea.

    i'm very interested in the "more about this later" comment in the write up - as it seems that this boost could articulate well into being an ABY. Would you (or Miro) provide some insight into this at all?

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    1. I'm not too sure about technical requirements for ABY switching or the amps he mentions, although if you point me in the direction of something I'll have a read up. But I think what Bjorn (or Donner, not sure which) must mean here is that because this booster is a common source amplifier it means the output is 180º out of phase with the input, and I'm assuming this must be an issue that needs resolving when connecting the channels of some Fender amps.

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  2. Mark- i built this, and i'm guessing that the switch is a bypass/boost switch? sounds real nice and clean on boost. just like the demo. when i toggle the spdt switch, it seems to be at unity volume, and does sound somewhat buffered, but the boost pot has no effect at all. so is this the fine line driver that is mentioned above? is this how its supposed to behave? if so, than you can tag this one.

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    1. Ha ha, top man! It's funny I look at schematics every day and get an idea in my head about what everything is doing and I completely took that as a buffer/boost switch. But you're right, the original says it isn't true bypass and so that's a buffer/boost stomp isn't it.

      That's why I love this place. I do my bit and it may be wrong, but then someone like you puts your perspective on it and everything suddenly dawns on me! :D

      Not sure how to do this one now, do you think a true bypass with boost/buffer switch and another version as per the original? I think that would keep most people happy.

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  3. i think two versions would keep most people happy indeed. it is a really nice sounding clean boost. i didnt play with it too much as just the buffer, but i'd have to guess its pretty good just because its Bjorn. then again, i am rather attached to the cornish buffer, so being able to use it just as a true bypass boost sounds appealing as well.

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  4. Two versions done and I think that makes it verified after what you said, so that's excellent. Thanks for verifying.

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  5. What would be good substitutes for the 2N5952?

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  6. Hey, built this up today, but realized as I was wiring everything together that most pedals only have a 9v+ rail not come of those and an LED+ rail, so I was wondering if I had to connect the two because I'm assuming the LED needs 9v to light up. Also do I need an LED limiting resistor or is that what that 2.2k is for?

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    1. LED+ goes to the LED anode and includes a CLR from the supply. The cathode then just needs grounding by the switch.

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  7. Are there special considerations when putting this in an enclosure with another pedal? I wired this up with the em drive schematic, in accordance with your two in one schematic, but I get no sound and the em drive's led lights up for a second when the 3pdt switch is pressed, while the booster has no led action whatsoever, so I'm assuming it's some sort of power issue.

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    1. You really want to test the boards individually before wiring up the switches. Soldering up the switches first gives another potential point of failure. Once you know the boards are ok, then you can worry about all the offboard. Measure voltages at the transistor pins and we can see if that gives any clues.

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  8. Hi Mark,
    I have built a clone based on your layout (the original version), thanks for sharing it.
    I have an issue, though: the voltage at the drain is 3.6V, when I have read (at http://revolutiondeux.blogspot.fr/) it should be 4.5V. Effectively, the signal, when I plug the pedal between my guitar and my amp, is weaker than when the pedal is out.
    Also, the gain pot is not working at all... Not sure if it's a cause or a symptom...
    I am guessing the first thing to do is to try and bias the jfet correctly, so I was thinking switching the 14K7 resistor after D1 for a smaller value. Would that be the right way to go? If so, should I switch the other 14K7 resistor, to keep both resistor values equal?
    Thanks

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    1. PS: The voltage is measured with the circuit powered by a Boss 9V DC adapter. :)

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    2. Yes, alter the 14K7 or even put in a trimmer so you have more control. And no, just the drain resistor.

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    3. Hi,
      OK... I have tried biasing the jfet, and even after taking everything apart and starting over with a new vero, just in case, still no luck. I can get a louder signal reducing the resistor value to the drain, but it is still much fainter than the original signal. :(
      I have ordered a couple of new jfets, maybe I have broken this one down, pulling the legs apart to fit it on my vero, or overheating it during the soldering. :-\
      Keeping my fingers crossed, else I'll just go for the AMZ mosfet booster option. I know I can get this one working alright, I just wanted to try something different. :-S
      Thanks

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    4. Hi Mark,
      Got it to work: this was my first vero build, and what I learned was that the copper strips were not capable of letting the signal through. Once I linked all components and wires with solder, it worked like a charm. ^^
      Here's a pic of my build, fitted in a 1590A. Because it will always be on, I went for a toggle rather than a footswitch, and I used a dual colour led that switches from blue in buffer mode, to red in boost mode.
      http://imageshack.us/photo/my-images/90/kecq.jpg/
      Thanks again for the help.

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  9. Hey, I did like you said with the boards individually, and I got the one side working perfectly (your compact Em Drive schematic). This booster however, when bypassed is fine, but when engaged has a volume drop and it sounds really fuzzy/buzzy/farty.

    The drain measures about 0
    S measures 0
    Drain is 9.15

    The diode has 9.2 on the negative side and 9.45 on the positive side

    LED lights up fine as well.

    Thanks for any insight!

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    1. I used the second layout btw if that makes a difference.

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  10. Thanks for all you post! This sounds very nice--lots of headroom with little coloring.

    I am getting a split second pop and drop in volume/stutter when toggling it, though. I tried swapping transistors and a pulldown resistor. No change with the swap, and the pulldown helped with the pop, but the signal still cuts out. I also tried another switch with no luck. Fwiw, it seems better if the pedal is engaged/disengaged a few times, but it eventually gets worse once the pedal sits for a bit.

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  11. What's a good sub for the 1N4002? Seems to be the only diode I don't have on hand right now..

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    1. 1N4001, 1N5817. Pretty much any diode would be fine really

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  12. I built this pedal with the True Bypass with Boost/Buffer toggle switch and it is a really nice addition to my board. It is a easy build and fired right up. Thank you again for this awesome layout.

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  13. I have a newbee question. Why is there a switch as there is not one on the original Pink Booster. It is my understanding that it always buffers whether you are engaging the boost or not. Is the switch to bypass the buffer if you want to do so? Is there a way to do away with the switch to make it closer to the original?

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  14. Hey! I've got the same issue as Frederic Beraud mentioned above. I have drain voltages of about 4.4 which should be fine. The signal is always lower than without the pedal, in buffered and in boosted mode. AND the pedal is letting signal through even if its not powered. This is strange isnt it? What do you think I did wrong? Thx a lot! cheers

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    1. I forgot to tell: I use 2n5457s and a linear 50k pot, but I guess the latter shouldn't be any problem at all.

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  15. Okay...sigh. I had the transistor in the wrong direction. My 2n5457s seem to have another pinout than the original ones. Now I have a drain voltage of 4.7 and everything sounds very nice, except the signal with the pedal is louder even in buffered mode. Reducing drain voltage don't solves this problem. What can I do to lower the bypass-signal (so it won't be louder than the original signal without the pedal)? Which resistor is capable of helping with this? I tried higher values for R2 (14k7) but I'm not sure if this would affect the sound? Thx!

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    1. Decrease the 150K next to the link. It may be a good idea to socket it so you can try a few values until it's perfect

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  16. thx a lot! I'll give it a try!

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    1. I've still got trouble with this device. I ordered some 2n5952 transistors and tried those after I had a very buzzy sound with the 5457. But its still the same problem. I adjusted a drain voltage of about 4.3 volts (~34k drain-resistor) and tried both higher and lower voltages by changing drain-resistors. Lower voltages lead to a buzzy sound especially when the pedal is engaged and higher voltages lead to low volume-levels, especially when the boost is engaged. At the moment I've got a 15k resistor installed for the Gate, because I didn't have a 14k7. Could this be the problem? Will this cause the problems mentioned?
      Maybe somebody who built this one could tell some voltages and resistor-values for a working build...? This would be great. Thanks very much!

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