Saturday, 10 March 2012

Dr Boogie

ElectricTabs emulation of a Mesa Boogie Dual Recitifer Solo Head.  I haven't even attempted to keep this one down in size (width) because with 6 pots no one is going to be putting this in anything smaller than a 1590BB, so you should have plenty of room in there with this being a relatively shallow layout (in height):




And V2 of the layout based on gaussmarkov's improvements:





Video of Geiri's build:



58 comments:

  1. I couldn't access this a couple of hours ago mate, has there been a few tweaks?

    ReplyDelete
    Replies
    1. Hi mate. I noticed I had a resistor near the input in the wrong position so made the post draft while I checked through it. Should be good now, it was just the 1M resistor near the input that I altered, no link or cut changes or anything.

      Delete
  2. What kind of caps are the 1u? In general do you recommend building with metal, mylar or plastic box caps for the Xn values? I've built about 5 pedals from your layouts with plastic box caps and they all sound like the originals as far as I can tell. Even put ceramics in some places and they work fine.

    Now if only I could get my hands on a bunch of j201s sooner.

    ReplyDelete
    Replies
    1. I've got some 1u tantalum axial caps that are exactly that size, so I'd use them here because the layout is more suited to axial caps. I have a good stash of box caps which I do use and I also use Panasonic ECQ-B polyester film. These are all good quality, easily available and cheap enough and so I'd recommend using them for those reasons alone. I'd always prefer to use a film cap than an electrolytic in any situation, even if someone can't hear any audible differences I'd still prefer to use film because they will be working for a very long time, whereas electrolytics have a much shorter life expectancy.

      Delete
  3. This is verified to an extent but I just can't get it to sound right. I've been tweaking the Jfets for ages and I just can't find a sweet spot.. just when you think you have it, you increase the gain and noise enters. So it seems you have to constantly keep tweaking them to compensate. Shame really as this had the potential for being brilliant :(

    ReplyDelete
    Replies
    1. Right ok think I have it now ;o) with the help of this video it seem to be pretty close to the demo... very nice fat distortion.


      Biasing the Jfets;
      http://www.youtube.com/watch?v=X4-UUDoSCPg

      Delete
    2. Nice one mate. I think I'll do a post about biasing at some point and include that vid.

      Delete
    3. "FAQs and Guides" page next to the "Requests and Suggestions" :)
      +m

      Delete
    4. I think I had 'trouble' with because there are so many demos that seem to sound different and with a little tweak with the Fets you can get a wide range of sound so It's difficult to find the 'correct' bias but then I suppose it's all down to ear anyway.

      But it does mimic a Dual rectifier pretty well!

      Delete
  4. My 'Dr Boogie'..... or 'Surgical Rectifier' ;o)

    http://img15.imageshack.us/img15/6062/dsc00303yt.jpg

    ReplyDelete
    Replies
    1. Awesome. How do you like it then after playing it for a while?

      Delete
    2. I like it, It sounds a lot bigger than all the distortions I've tried.. on lower gain settings it stay quite tight but as the gain is increased it gets very mushy but I quite like that. A huge wall of thick distortion. the middle and treble help it stop getting too mushy. I tried a Boss ds-1 in front of it and that tightened it right up for razor sharp riffing.. I suppose is like an amp in a box. I've never played a real dual rectifier but this pedal sounds like all the 'simulation' settings on POD's a etc so it' must be doing something right.

      I really don't see the need for any switches on this one!!
      Or maybe a stompable 'tight' boost?? hmmmm ;o)

      Delete
  5. Is it possible to sub 2n7000's for the j201's? j201's are hard to find here in aus...

    ReplyDelete
    Replies
    1. 2N7000 is a mosfet, J201 is a JFET. Have a look at dpi4parts on eBay, he sells J201s at very good prices and they're all authentic Fairchilds

      Delete
  6. Hi,

    Have built this pedal. All fine, no problems, it worked at first try. Biased from q1 to q4 with no problem at 4,5v, but q5 is impsible to bias, it's always at 7,45v.

    The effect works heavenly with this bias, but not sure if the q4 trimmer should bias the q5 too.

    Hope to hear from any of you :P

    ReplyDelete
    Replies
    1. Q5's drain is sat directly on the supply row so that doesn't need biasing. 7.45V seems low though, are you using an old battery?

      Delete
    2. Yes, it was an old battery. Well, tomorrow or on Friday, when I have the box ready, i'll do a final bias with the Spot 1 switched to get the voltage I'll use nearly always.

      Best regards and thank you once more!

      Delete
  7. Hi again,

    Finally here you have another one for your collection:

    http://guitarrasimportacion.foroactivo.com/t502-capinc-effects-11-beast-inside-dr-boogie-emulador-mesa-boogie-dual-rectifier-solo-head#7021

    Next stop: Klon Centaur in a week or so.

    Best regards!

    ReplyDelete
    Replies
    1. Excellent, glad you're liking it!

      Delete
    2. You're welcome :) Just add that the final bias has been 5,2 volts on every Jfet. The Spot 1 power supply gives 9,25, so q5 shows this voltage too.

      Sweet and powerful point between 5-5,5volts to my ear at the expense of a little more noise tan at 4.5v.

      Delete
    3. i just built this one today. man it has a TON of gain! it sounds just like a boogie amp to me, as in too much mids! ;-)

      i may mod it for a bit less gain and try and scoop some of the upper mids in the tone circuit. either that or make the bass lower and more active.

      Delete
    4. BTW, mine sounds best with all of the transistors biased at 4.5V. at 5V or more, there's a slightly gated (and fizzy) decay on the sustained notes, but it's perfect at 4.5.

      Delete
    5. since i use miy pedals for bass, i revoiced the coupling caps and tone stack and this pedal rocks with a bass now. it can go from dark to scooped, and from middy to bright all the way from a low overdrive, to a ridiculous amount of distortion. here's a couple of pics of my build:

      http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DrBoogie/DrBoogie-01.jpg

      http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DrBoogie/DrBoogie-02.jpg

      thanks again Mark!

      Delete
    6. Great looking build John

      Delete
  8. Hi guys, can you please indicate what are exactly the 4 yellow rounded signs n the top of the board layout, marked as 100K?
    Thanks in advance and congrats for amazing layouts!

    Best regards,
    Pier

    ReplyDelete
  9. Thanks for the quick answer!

    Best regards,
    Pier

    ReplyDelete
  10. I have a stupider question: what are the values of the trimmers? Thanks, Greetz M

    ReplyDelete
    Replies
    1. It shows the value above them in the layout, they're all 100K

      Delete
  11. they're listed above the vero. all of them are 100K.

    ReplyDelete
  12. Yes sorry I asked it the wrong way. I meant what should be the voltage value of them? Or that's not defined? Sorry I'm very unexperienced.

    ReplyDelete
    Replies
    1. You should get all the JFET Drains at ~4.5V.
      +m

      Delete
  13. Hi Mark,
    I am preparing to attempt this build and have been studying the schematics readily available on the internet (guassmarkov & chunk chunk - which are both very similar) on which I presume your layout was based. I notice that in the schematics there are two 100u electrolytic caps in the power section of the circuit, yet you only laid out one. As I am sure this is not a mistake, I was hoping you could share your reasoning as to why the second 100u cap is not required. Thank you.

    ReplyDelete
    Replies
    1. One of the schematics I used had just a 100u cap, one had 2, one on either side of the 100R. As far a filter caps are concerned I often don't use what has been suggested in the scheme because often it simple isn't necessary, and so with this one I just put a single 100u in both layouts which has been ample for me in any of my builds. If you're not getting unwanted noise then adding an additional cap is unnecessary, but if you are then you could add an additional 100u cap to the left hand side of the 100R resistor on the top row of the V2 layout. I left it out because I didn't think it was worth the additional columns that would be required.

      Delete
    2. Thanks a lot for the explanation - it definitely helps in my understanding.

      Delete
  14. Here's my observation when I built it yesterday. Biasing is a piece of cake. Use 47k trimmers instead of 100k. You will get much greater accuracy and it will be easy to bias.

    I used a 2k pot for mids and it works fine, any higher will offer too much mids (in my opinion) and when you max out the mids knob, the other EQ knobs don't do very much. When you scoop the mids, the rest of the EQ comes alive. Just keep that in mind because I was trying to figure out for a while why only the mid knob was working. I was always tweaking the others when I had the mids all the way up (or at least past 12 o'clock.

    It's a really good circuit and I like it! Recommended for anyone wanting a serious distortion tone.

    ReplyDelete
  15. I'm currently building this circuit, and have questions about the JFETs. I've read a lot in different places about how using "matched JFET pairs" is beneficial. Usually one reads about these matched pairs in phaser circuits where the JFETs are working together. But in the Dr Boogie circuit, where there are discreet gain stages in series, would using matched pairs make any sense? I bought and measured the Vgs of 80 J201s. They vary quite a bit. Should I use similarly rated ones, or is it possible to use ones that are quite dissimilar from each other in each separate stage. So that is question one.

    Second question -
    There are some distortion circuits, like the BSIAB2 and the Wampler Pinnacle, in which a mu-amp configuration is used - i.e., two JFETs together in a block configuration. Would using matched pairs make sense here within each block? If so, would value differences matter from matched pair to matched pair? I believe those circuits use different types of Jfets, i.e., a pair of J201s, then a pair of 2N5457s. So if I used a matched pair of J201s, their values might be very different than the matched pairs of the 2N5457s which have a different spec. I guess that's unavoidable. Comments?

    Hope these questions are clearly stated. It seems to me if someone could offer some insights into how/when matched pairs are used, it might help lots of us build better sounding circuits. (BTW - the Jfet tester I used was one I made from a schematic on this site, so thanks for that!)

    ReplyDelete
  16. Hello! I knew Dr. Boogie can be powered with 9V, 12V and 18V. Will it need some modification in the circuit for this?

    ReplyDelete
    Replies
    1. Basically, you need the 100uf electrolytic to be at say 35V rating

      Then, you bias the transistors with half the input voltage

      With 9V, 4.4-4.6V each, with 12v, 5.8-6.2V each , with 18V, 8.9-9.2V each

      Delete
    2. Thank you for the clarification! I noticed a better sound with higher power.

      Delete
  17. This comment has been removed by the author.

    ReplyDelete
  18. This comment has been removed by the author.

    ReplyDelete
  19. This comment has been removed by the author.

    ReplyDelete
  20. I was thinking about putting this together and have a dpdt switch to change the bass response I was looking online and mods for this and people say which cap to change to allow more bass through, which also changes the treble response and such, but I'm not sure where on the layout that cap is.

    http://www.madbeanpedals.com/forum/index.php?topic=3632.15

    "
    I just finished my chunk chunk, and with the stock build I felt that I also wanted a bit more low end. I noticed that when engaged, my build seemed to really strip out alot of lows that had to be put back in with the amp because my bass pot didnt give me quite enough... I also noticed that my treble knob seemed to get aggressively bright once past 3 oclock... I have my fets biased more towards 5v rather than 4.5 because it seems to tighten up my sound a bit and does away with a bit of fizz... probably also could be making it a bit thinner also which could be contributing to my low end issue.

    anyway...

    I saw this thread and decided to socket my C12... i replaced the stock value with a 47n. and it really made a nice difference...

    I now have a full range of lows which adds all the versatility that i want..

    However, this swap also made my treble knob become usuable all the way to max with no harsh unusable sound... i dont know if this is even possible from the swap or its just my mind tricking me.. but my treble is much more usable now all the way around."

    I was looking on the schematic here, http://gaussmarkov.net/layouts/drboo/drboo-schem.png, but I dont see that cap and size. Any is this the wrong schematic, or am I missing something.

    ReplyDelete
  21. It sound really good but I don't know why the volume is lower than the amp volume also if set at maximum. I need help

    ReplyDelete
    Replies
    1. I have the same issue...did you fix it?

      Delete
    2. Same here, any ideas? Full pedal volume lower than no pedal volume.

      Delete
  22. Ok, it works!!!! how can I increase bass!

    ReplyDelete
  23. Another question: It's an amazing pedal its really an hi gain tube distortion but it seems that there are too many high, and too gain, its very hissy

    ReplyDelete
  24. This comment has been removed by the author.

    ReplyDelete
  25. I built the Gauss Markov version. Etched the board. The tone controls don't make a lot of difference but I think I need to play with the amp settings. I'm running it into the distortion channel of a Carvin V3.

    I like it but I think I need to also play with the J201 biasing. Set them to about 4.5. I'll see what happens.

    ReplyDelete
  26. Took some samples back when I did it, although i couldn't get rid of the squeal/oscillation that appeared at a high gain setting (but the gain was NOT usable in that position anyway)

    http://forums.rgc.ro/index.php?app=core&module=attach&section=attach&attach_id=165260

    ReplyDelete
  27. Hello, I am wondering about the grey boxes marked 1u I. I am thinking they are axial 1uf caps, and that the I is for the tolerance. Can someone please confirm, or correct?

    Much appreciated!

    ReplyDelete
    Replies
    1. The dash after "1u" denotes the negative end of the electrolytic cap. Tolerance for caps should be at least 10V, though they're usually 16 or 25V.

      Delete
  28. Perfect, thank you for the response, so electrolytic is what I am after then.

    Another thought just occurred. Are the variable resistors log or linear?

    Again, than

    ReplyDelete
  29. First off - Great work. Secondly - I found the gain control a little un-usable after 8 or 9 o'clock (after spending 2,000,000 hours biasing to my preferences) so I started messing around with an additional resistor on the gain pot between the wiper and ground. 10k gave me a very "Carry On My Wayward Son"-ish type of sound. I'm thinking about adding a switch that toggles between a few different resistor values, similar to the Vintage, Raw, and Modern settings on some of the current Rec's. Thoughts?

    ReplyDelete
  30. Before build this pedal take a look at the mods that i've done.
    Link on topic - TechniGuitare
    http://techniguitare.com/forum/post248752.html?hilit=Miss%20woogey#p248752
    Link on Schematic
    http://www.bo-blues.fr/depot/miss_woogey.pdf

    Mods Are:
    -Correct bug on source resistor of 3rd stage (R12) > 39k
    -Two caps, C15 C16, on tone stack for great palm mute
    -An output bass boost stage for 7 and 8 strings
    -A charge pump for 18v on board

    About R20(120k), a strap will be better!

    A new name "Miss Woogey"


    ReplyDelete
  31. May I have a stupid question. Where are the bias points to configure the JFETs?

    ReplyDelete