Dr. Boogey |
This is electrictab’s pedal emulation of the Mesa Boogie Dual Rectifier Solo Head. See his schematic at http://geocities.com/electrictabs/dr.boogey.png. It is a very popular build on Aron’s forum. This layout is a substantial revision of previous ones. It is the product of contributions by many members of the forum.
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ubersam said:
I noticed in the schematic that the value of the capacitor in the presence control of the scaled down tone stack is indicated as 3nF. Is it supposed to be 30nF (or the next common value, 33nF)? I used the closest value that I have, 33nF, to what John listed in my DR thread. I might try a 27nF for more presence, although the circuit seems to have plenty already.
Posted 19.06.2007 at 1:43 pm
gaussmarkov said:
Thanks! I have corrected this (… and it was correct on my computer … no idea what happened …)
Posted 19.06.2007 at 1:48 pm
candley said:
So you’re happy with the J201 in all sockets?
Posted 08.01.2008 at 11:38 am
gaussmarkov said:
I have to admit that I have not experimented with other transistors.
Posted 08.01.2008 at 1:03 pm
Will said:
Hi Gauss. I built the Dr. B a couple of weeks ago and this little beast screams like hell!! I’m really pleased with the sound and very satisfied with the results. Your layout seems to be the best for Dr B.
One out-of-topic question: how do you export the eagle layout to a pdf or Corel Draw vector format?
Cheers!
Posted 27.01.2008 at 3:06 pm
gaussmarkov said:
re pdf: the quick answer is that you use the CAM Processor listed under the File menu. this will work for either schematics or boards. first, select the Device for output and then a file for output. second, select the layers you want to include. third, choose any style features (like Fill Pads). fourth, specify image dimensions (if you like). finally, select Process Job.
i output encapsulated postscript and go from there to pdf.
i hope this is enough info to get you started!
Posted 28.01.2008 at 11:42 am
Will said:
Just did it and it works!! Thanks so much Gauss!
Posted 28.01.2008 at 8:02 pm
Seherezka said:
Is it possible to use other transistors? J201 seems to be unavailable at my local store. Thanks
Posted 30.01.2008 at 12:09 pm
gaussmarkov said:
no, you cannot just substitute in other n-channel jfets. the J201 is special in that it has a low pinch-off voltage and parts of this circuit take that into account.
Posted 31.01.2008 at 4:16 pm
Mark said:
I had just built this project,and this thing really rocks! i still have some humming though. How can i fix this? one more thing. How can i add more bass and tame the highs? Thanks!!!
Posted 04.03.2008 at 2:41 pm
andre said:
My dr boogey has great distortion (pot is with 500k), and even when excessive bass pot 1, voltages of q1 the q5 all 4.5v, which would be ideal for voltages less severe (bass) in the sound.
Q1 =?
Q2 =?
Q3 =?
Q4 =?
Q5 =?
Posted 10.03.2008 at 5:09 am
Norbert said:
Hi
I was wondering……..would this project benefit by using the bi-polar 9v power supply instead of it normal 9v supply……and if so……How would it be added to the schematic?
Posted 19.04.2008 at 4:52 pm
gaussmarkov said:
Norbert:
the jfets are all biased according to the single supply. i think it would take a little redesign to switch to a +/-9V supply.
Posted 19.04.2008 at 5:36 pm
gaussmarkov said:
Mark,
are you using a really clean power supply?
Posted 19.04.2008 at 5:37 pm
gaussmarkov said:
andre,
for the JFETs with output from the drain (Q1, Q2, Q3, and Q4) biasing the drain at least to 5V, preferably 5.5V, as a rule of thumb.
Q5 has its drain tied to the power supply, so that should not be near 4.5V. it is serving as a voltage follower and that’s why it doesn’t need a trimmer for adjusting the bias.
hope this helps, paul
Posted 19.04.2008 at 5:41 pm
sadrew said:
Hi paul, thanks for your great layout.
I built succesfully my dr.boogey, with zero noise and great distortion tones.
What i don’t like too much is the tonestack, and i want to replace it with a more versatile tonemender from runoffgroove.com.
How can i eliminate the tonestack from the dr.boogey schematic to have only gain and volume knob?
Thanks and greetings from italy
Giacomo
Posted 17.05.2008 at 4:15 am
gaussmarkov said:
Giacomo,
that’s good news that your dr. boogey is working well. you are most welcome.
to remove the tonestack, eliminate Q5, R13, R14, C11, and C12. also run a jumper from the pad of Q5 that connects to Q4 and another jumper from the pad next to C10 that connects to terminal 2 of the treble pot to terminal 3 of the volume pot.
you may find that you would like to insert a low pass filter between C10 and the volume pot. let me know, if you do.
and also consider increasing the value of C10.
all the best, paul
Posted 17.05.2008 at 2:28 pm
sadrew said:
I founded a schematic on aron site of the db without tonestack (thanks martymart).
Now i like my boogey even more!
Next step will be trying the tonemender eq, but i want to have only one volume control. Should i eliminate the volume pot from the dr.boogey or from the tonemender?
Posted 18.05.2008 at 1:19 pm
gaussmarkov said:
i would put replace everything from Q5 on with the tonemender. let us know what you do and how it works out!
Posted 19.05.2008 at 4:34 pm
Roger Yu said:
Paul, Hi my q1=5.42v q2=5.40v q3=5.38v q4 = 4.50v so my q5 g= 4.50v and s=5.08v and d=9.23 . My question is do I need to make the q5 gate more higher let say make it 4.75v or more ? Vg 4.50v -VS5.08 = -0.58 isn’t it? I’m using al J201 and my regulated adaptor power supply is 9.37v
Posted 22.05.2008 at 4:05 am
Matt McQueen said:
Mark,
I have watched some videos of this pedal on youtube. Love the way it sounds. I would love to find some pictures of this pedal’s guts and maybe even get a few pointers on building it. Thanks a bunch in advance.
Posted 28.05.2008 at 8:13 pm
gaussmarkov said:
you will probably find some gut shots in the Pictures! post on diystompboxes.com. also there are quite a few build reports on that forum as well.
i hope this helps!
Posted 28.05.2008 at 9:43 pm
gaussmarkov said:
Roger Yu,
If you like the sound at 4.5V for Q4’s source (and Q5’s gate), then don’t raise the voltage. I suppose you have experimented with higher values? What do you hear?
Paul
Posted 28.05.2008 at 9:56 pm
Roger Yu said:
Feedback even volume setting is minimum. I change Q5 into MPF102 and Source resistor into 1.2k and retain Q4 voltage at 4.5v now it’s tame. I can dial the volume up to 3 0′clock before it squeal. I tried MPF102 at Q1 but not aggressive compared to all j201 that’s why I experimented MPF to Q5. Now I’m very satisfy. One more question Paul, Is it true that I should not use Mil Bypass on this circuit co’z it may affects the circuit or causes more feedback or squeal? Thanks in advance.
Roger
Posted 29.05.2008 at 9:08 pm
gaussmarkov said:
Roger,
That’s good news. I’m pleased that you worked it out.
It has been so long since I looked at R.G.’s Millenium bypass that I do not know without looking. It surprises me to hear that. I will try to remember to look.
Cheers, Paul
Posted 29.05.2008 at 9:32 pm
Roger Yu said:
Thanks Paul, There’s one question still I like to verify… Electrictabs used 1uf polarized on Q1,Q2 and Q4 fet source but then you used Non-polar, What’s the difference? Is there a theory or just in practice choosing what to use? I may encounter the same circuit in the future so that I’m may know.
Roger
Posted 05.06.2008 at 11:24 pm
gaussmarkov said:
hi Roger,
polar electrolytic caps have large capacitances for their size and have been used for 1uF values for a long time. but now box film caps come in this value, are not too expensive, and are not too big. they are generally a better choice.
the primary reason is that electrolytic caps deteriorate more rapidly over time and have to be replaced more frequently.
electrolytic caps are also leaky and they become more leaky over time. they behave like a box film cap with a resistor across its leads. this can be taken into account in a circuit. all the the source caps you mention already have resistors across their leads in the circuit so it is possible to compensate with the values of these resistors.
with new capacitors, i doubt we would notice the difference in the sound of the dr. boogey, unless the inherent variation of the capacitances caused us to accidentally put in very different values.
i hope this helps, paul
Posted 06.06.2008 at 5:22 am
Roger Yu said:
Paul thanks,
At first, I used non-polar electro on the three Q’s but feedback sometimes occur when idle even though I tame it a little by using MPF102 at q5. So I when look on electrictabs schmo which indicates polarized and I only got one 1uf tantalum then I used it on Q4. Suddenly the feedback has stop. I don’t know if this help more the MPF102 to permanently control the feedback. I never bother to change the NP electro on Q1 and Q2 anymore.
Again, thank you so much.
Roger
Posted 06.06.2008 at 5:15 pm
gaussmarkov said:
hi Roger,
perhaps the actual values of the capacitors are quite different? did you measure their capacitances with a DMM?
paul
Posted 07.06.2008 at 8:07 am
tomas said:
gaussmarkov, where is the “out” in this layout? is it in the 2nd pin of the vol. pot?
many thanks.
looking forward to this one!
Posted 08.06.2008 at 1:16 pm
gaussmarkov said:
yes, that’s right.
2nd lug/pin of the volume pot is the output. wire the output jack to that and you are good to go.
all the best, gm
Posted 08.06.2008 at 8:02 pm
Roger Yu said:
Hi Paul,
I used 105 marked on tantalum and I also test it with analog multimeter only. It has a positive symbols on it.
Thanks,
Roger
Posted 11.06.2008 at 4:16 am
Pascal said:
Hello Gaussmarkov,
I’m more tube specialist and I know in that case how to adjust the bias, but here, what is the rule to adjust the FET bias with the trimmer ?
Thx
Posted 23.06.2008 at 12:40 pm
gaussmarkov said:
AFAIK there is no common rule for biasing JFETs with the trimmer. i suggest that you start by setting the trimmers to get 4.5V at the drain (for a 9V supply) and then adjust upward according to what your ear tells you.
Posted 23.06.2008 at 9:21 pm
Audioguy said:
I dont suppose you’ll do a layout for the JCM800 or the Slow Century? They are both really close in design to the Dr. B as they were all essentially done by the same folks. And if you use the original layouts, they all suffer from the same noise issues… Your Dr.B is dead quiet and even seems easier to bias!
Hell I would even pay you for your time!!!
take care!
Posted 05.07.2008 at 8:57 pm