Thursday, 28 June 2012

Mad Professor Blueberry

Requested by a few people now and I do want to keep the bassists happy too.  In tomorrows blog I'm going to show you how to make pizza boxes, especially for drummers.  Just kidding! :o)

Although the hand built BJF and Mad Professor effects can hurt your wallet, with the new PCB range out they've made them a lot more accessible to the masses.  And as these are great sounding effects and certainly more than Tubescreamers with different input caps, this is another builder that we want to keep making pedals.  Plus Bjorn's a good guy and plays AC/DC and Iron Maiden so I like him! :o)

A few notes: This is small enough to fit in a 1590B with a bit of careful measuring.  Some people have said this is a bass Honey Bee, but doing the layout I found it more similar to the Model H but with diode instead of JFET clipping.  If anyone has trouble with biasing, consider swapping the 30K and 5K6 resistors for appropriate trimmers and aim for around 5 to 5.5V on the JFET drains. 

Info about the original:

BJF design dynamic bass overdrive.

Mad Professor BlueBerry Bass Overdrive (BBBOD) is a high quality dynamic overdrive pedal for electric bass.

It was designed to get light to medium overdrive, reminiscent of vintage tube bass amplifiers.

With the Drive control, you can get natural dynamically controlled overdrive like on those old tube bass amplifiers, or more compressed thick distortion.

At lower drive settings the BBBOD distorts more the harder you strike the strings, and there is no definite clipping point, but rather different shades of distortion as the amplitude changes. Higher settings will give more compressed sounds.

With the clever Nature adjustment one can adjust the tone, and also control what register distorts. From really big and fat with low register distortion to cutting upper midrage solo bass tone.

There is enough volume to use the pedal also as a booster.

While mainly designed for bass guitar, the BBBO can also be used with other instruments for low, dynamically controlled distortion.

Controls:

VOLUME : controls output

DRIVE: sets the amount of distortion and sustain, as well as the type of distortion.

Lower settings give dynamically controlled overdrive, the unit distorts more the harder you strike the strings and there is no definite clipping point, but rather different shades of distortion as the amplitude changes.

Higher settings will give more compressed sounds.
A good starting point with most basses is fully CCW, turn the knob until you find the overdrive level that suits your playing.

Lower settings are good for old school tube amplifier tone, while higher settings gives denser distortion.

NATURE: is a tonecontrol for filtering and to control what register distorts.
Turning CCW gives more lowend and also distortion in the lower registers.

Turning CW gives an emphasis in the upper midrange for more protruding solo bass tone.









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58 comments:

  1. Wow, that was quick! Missing a few parts for this but will try and get it verified ASAP.

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  2. What alternative can I use instead of BF244a? D1,D2,D3 are 1N4001 and D4,D5 are green led?

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    1. I don't know because the circuit may need tweaking to bias an alternative. Try anything with the DGS pinout but bear in mind that you may have to tweak resistors a bit.

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    2. I found 2n5457 maybe, right? D1,D2,D3 are 1N4001 and D4,D5 are green led?

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    3. Yes give it a try and measure the voltage at the drain, you want to aim for around 5 - 5.5V. Yes D1 to D5 is exactly as shown on the diagram.

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  3. This is what i meant earlier with MP/BJF using non-standard components. It's not just the odd E192 resistors, but it's always with the BF-fets and CA-opamps. I'm hoarding these, since i know a lot of bassists :)

    Off topic. I really wondered why i always seems to be out of 3PDT stomp switches, boxes and jacks. I've checked. I've built 17 boxes in june. So no mystery there.. :)
    +m

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    1. When I started hoarding the BJF/MP schematics in my to do list I started ordering all the unusual jfets etc. So I stocked up in advance on the 2N5952, 2N5458, BF244A, BF245A, BF245C, 2SK170 etc. OK I may not have needed 50 or 100 of each but my OCD kicked in! :o) Check out dpi4parts on eBay, he has most of the BJF fets in bags of 25, 50 or 100 and he's really reasonable with cheap postage as well. I was fine for the resistors because I got a lot of more unusual E96 values myself in a bulk lot from a closing shop. I ended up with 3 big cardboard boxes full and there must be at least a quarter of a million resistors there, so I don't suspect I'm going to need to buy any ever again! :o) In fact the reason why Bjorn uses some odd resistors values is because he did exactly the same thing a few years ago, bought a big bulk lot, and has engineered them into his effects.

      Ha ha, 17?! You'd better buy your missus a bunch of flowers mate to stay on her good side! :o)

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  4. Should be able to get this finished now that the parts I was missing have arrived. Had to sub in 15k for those 14.7k resistors and used a 360k and 30k in series for that 390k. Hopefully it will still work ok.

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  5. Finished this one this afternoon. You can tag it now, the layout is correct. Sweet build, easily one of the best bass overdrives I have tried!

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  6. Made a few substitutions for some of the resistors that I didn't have and couldn't find but it still sounds good.

    15k for 14k7
    150k for 147k
    2k7 for 2k6

    Bass players looking for an medium overdrive will like this one. The nature pot is quite interesting as it seems to control how dark or light the tone is rather than cutting lows or highs out.

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  7. Just to check, the drive pot is wired as rheostat?
    +m

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  8. Just put this together and it's cool. Just like in the posted demo. Now i need to box this up, as it is going our bassist for the next rehearsals...

    This has one kind of funny aspect to it.. The "Nature" pot controls which clipping stage (Shcottkys or green LEDs) is the dominant one. I never thought that diode clipping would be "natural" :D

    I'm really liking the schottky clipping. Gotta use more of those in the future.
    +m

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    1. http://mirosol.kapsi.fi/varasto/boxes/mustikka.JPG

      :)
      +m

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  9. I've just read the manual of the original (http://www.mpamp.com/bjf/BBBOD_Owner.pdf) and found this description:

    VOL. sets the balance between processed signal and non-processed. A good starting point for this control is center (twelve o’clock) or a bit lower.

    To me it sounds more like a mix than a volume knob
    What is the beaviour of the orignal device?

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    1. They may have changed it of course, but the schematic I did this from definitely shows a conventional voltage divider to ground attenuator as the volume control.

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  10. Sorry for maybe stupid beginners question, but where is output and on/off/bypass switch?

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    1. Here :)
      http://tagboardeffects.blogspot.fi/2012/02/offboard-wiring.html
      +m

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  11. This comment has been removed by the author.

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    1. Thanks mirosol ;)

      One more - does the Drive 3 goes to ground?

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  12. Got this up and running and it sounds like the demos on youtube, but with less volume. When my volume knob is at max the signal has the same volume as when bypassed. Should it be like this or is something wrong? I usually want load dirt devices...

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    1. Check for any bridges and other usual suspects. Mine is pretty damn loud..
      +m

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    2. Yes! Found some weird values and replaced the 2k and 30k resistors and now its loud! Sounds great, thanks for the design and help!

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  13. I ve recently built this, however it seems that the drive and nature pots are not working properly, as in the pedal goes silent when turned more than a quarter of the turn. I couldnt find BF244A so i use BF244B which was available. Could that be the issue, or anything else? I ve triple checked all the usual suspects with no luck so far...

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    1. Judging by the symptoms, i'm fairly certain you have either a short or misplaced component around those pots.
      +m

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    2. Thank you Miro, pretty certain myself about that, since the BF244B is not the issue. I keep looking at the board over and over, i m sure its right there but my brain is not responding to it. I ll get back to it fresh in a bit, again thank you so much

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    3. Probe and voltages could also reveal something.. But usually the part of the sweep should tell something too.
      +m

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  14. Hi, I will build this pedals in few days, but i've got some questions,
    have you got an equivalent for the BF244A or not ? (hard to find it excepted ebay)

    Why there are 2 green led ? one for use and one for power ?
    Is the 360K be replaced by a 390K ? Do i make arrangement ?

    Thanks for answers, the website is awesome !!! ;)
    Gael from France

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  15. the diodes are for sound shaping (diode clipping). They will only glow while playing.

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  16. okay but why 2 ? (for example on my ebs compressor i've juste got one led which glow while playing and while powered)

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    1. It's an overdrive pedal, not a compressor and they're used to clip the signal. They're in an anti-parallel arrangement, and so one LED clips one half of the waveform, and the other clips the other half.

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    2. Thank you IvIark, i understand. I will contact you if I got building problems

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    3. I've just finished to weld the circuit (except BF244A, that I haven't received yet) so i've got some questions about offboard wiring (I have ever read all your wonderful documents).

      On the circuit, there is no output point except on the Volume 2(on Volume pot) ? So may I link right my footswitch to the Volume pot ? It is normal or it is a forgetting ?

      Thanks ;)

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    4. Volume 2 is output. So you are right, simply connect Volume 2 with your footswitch.

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    5. Yes but i think it is weird, because Volume 1 is on the ground, Volume 2 as output so, and Volume 3 is connected.

      So if i've well understood, we get the output signal only with the Volume 3 pot ?

      Thanks

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  17. Great pedal I have two questions ...The gain of the pedal seems quite high is there a simple way to lower it? and the Nature control is WAY TO PHAT on the bottom end ..any simple way to change the low pass filter?

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  18. can i replace the green led to red or yellow?

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  20. Hi, thanks for the layout. I've built the pedal And it only works when the gain pot is on low. At other settings I get loud oscillations like a tone generator . One of the green leds flashes a lot. Any help would be appreciated! Gary

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  21. Finished this yesterday, could only try it with guitar yet. Even for that it is quite nice :) For the jfets I only had one BF244A at home, so I had to play a bit. The BF244Bs did not work well, probably after some tweaking with the biasing they would be ok as well. Found the same with BF245Bs. Then I tried a 2n3819 and that was it. BF244A at the beginning and 2n3819 at the end, and you are good to go. Also the opamp can be changed, I tried LM308, OP07, they both resulted in a rat-like distortion, just not that high gain. Absolutely not bad, maybe a tad too dark. TL071 can be used too, that gives you a somewhat cleaner and brighter sound.

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  22. Hey guys just built this up... yeah im late to the party on this one, just hoping to get some help.

    All the pots seem to be working correctly but the overall output is too quiet. With drive and vol at 100% its right at unity. I used BF244As and biased right at 5ish volts on both drains. Also checked all the cuts, component placement, and metered for bridges... all the normal stuff and still no luck! If anyone has any suggestions i would appreciate it!

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    1. Same thing here, checked the whole board like 10x, and have the same issue :/

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    2. JFET and IC voltages will give us the best clue where the problem may be

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  23. Hi Guys,

    I'm new to making pedals and chose this for my first build :D

    It was quite challenging for a newbie to get this into my 1590B but managed it after a couple of false starts and extra holes in the box :)

    Thanks for all the info and layouts on this site, great stuff!

    Pictures are on my flickr if you want to take a look: https://www.flickr.com/photos/drofmij/sets/72157650530443205/

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  24. I am about to build this and wanted some clarification on the led orientation. Is the darker shaded area the cathode

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    1. you are correct. but since they are used as clipping diodes, it doesn't matter as long as you place them anti-parallel. also, you may want to check out the bearfoot blueberry and/or the bjfe blueberry. not as much gain as the mad professor version, and in mine and a lot of the bassists here prefer them over this. this one seems kinda lifeless when you play, but that's just MHO. i've made, posted, and verified layouts for the bearfoot and bjfe and they're posted in the contributions section.

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    2. johns,
      i ended up using your layout of the bearfoot. It was exactly what I was looking for, thanks for the suggestion and the layout

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    3. no problem buddy. glad you built it, it was successful, and you like it.

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  25. Thanks for the reply, ill check out the other pedals

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  26. Just built this and sounds really great. Although I HIGHLY recommend lowering the gain pot value (50k maybe? I used 10k and the drive range is fully usable. The original 1Meg pot does nothing past about 9 o'clock and has ridiculously high gain)

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  27. I built the Blueberry Bass Overdrive and it sounds awesome. I have attached a link to my build picture and hope that it can help someone else. Thanks and Great Layout.

    http://s1383.photobucket.com/user/denfox1/media/Blueberry_zpss2cpxcim.jpg.html?sort=3&o=0

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  28. hi , i got a question: what exactly is the first transistor stage of the OD for? the schematic is over at fred briggs revolution deux blog.

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  29. Currently have it build on breadboard
    Using the default resistor values, my drains are nowhere near 5V.
    They are about 0.4v Q1 and 1.4V Q2.
    However, the pedal sounds pretty much like it should. The only thing is, it is a little 'noisy', but i guess that is because it is on breadboard without proper shielding en the occasional 'antenna-effect' happening.

    I tried biasing the first BF244A to 5V but at 4V it was already completely shut.
    Somewhere during measuring it also started to oscillate from time to time...

    I'm curious about your experiences

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