Dr.Boogie Build Questions.

[steveyraff]

As the title says, I'm finding it very hard to track down a 20p Cap, but I have found some little ceramic 22pf caps, will this be ok?

I'm doing a Dr. Boogie build as seen below...

http://3.bp.blogspot.com/-vIcjUbcqnHE/T1vk4VB3bbI/AAAAAAAAA_Y/G_KnEiTXHEM/s1600/Dr+Boogie+V2.png

[Kipper4]

They should be fine.
Normally I work around a +/- 10 per cent which is what I've seen other forumites say here.
Keens second law!!!!!!!!!!!!!

[steveyraff]

They should be fine.
Normally I work around a +/- 10 per cent which is what I've seen other forumites say here.
Keens second law!!!!!!!!!!!!!

Ok cool, because I'm finding a few hard to find - 30n, 20p, 5n.   

[MrStab]

^good point, i didn't even consider tolerance. it looks like a low-pass filter (though maybe it has another function i don't understand).
in an ideal world of 0% tolerance, the original 20pF filter rolls off frequencies above 16931Hz, while 22pF does 15392Hz. it's probably meant to get rid of RF interference (and/or oscillation?), in which case 22pF just cuts off a little lower without harming the guitar range.

...as far as i know.

[steveyraff]

^good point, i didn't even consider tolerance. it looks like a low-pass filter (though maybe it has another function i don't understand).
in an ideal world of 0% tolerance, the original 20pF filter rolls off frequencies above 16931Hz, while 22pF does 15392Hz. it's probably meant to get rid of RF interference (and/or oscillation?), in which case 22pF just cuts off a little lower without harming the guitar range.

...as far as i know.

Thanks guys, this helps a lot. I wouldn't mind very slight differences in sound - I'd be more worried about doing something that'll cause the finished product to just not work! 

[MrStab]

so long as you're cautious with wiring, with the Dr. Boogie's notoriously-high gain and oscillation potential in mind, it should work a charm. good luck!

[Brisance]

Speaking of tolerances, I wonder if resistor manufacturers just measure their product and when it passes the 1% it gets painted blue, else that brownish color.

[steveyraff]

so long as you're cautious with wiring, with the Dr. Boogie's notoriously-high gain and oscillation potential in mind, it should work a charm. good luck!

I'll keep that in mind - thanks.

An unrelated question, but one of you guys might see it here and prevent me making another thread.

Another thing on my shopping list for this build is a 2.5k LOG pot. I can't find one of those. Whats the nearest closest common valued pot I could use instead?

(The original version of this build asks for a 22k log, but I am doing an updated slightly differing version that asked for the 2.5k)

[MrStab]

when it passes the 1% it gets painted blue, else that brownish color.

i wouldn't be surprised if some seedy companies did that, though it'd probably be infeasible to test em all. aren't the brownish ones carbon composition, though? in that case, they'd probably have to declare what's in it, in line with RoHS etc.

Another thing on my shopping list for this build is a 2.5k LOG pot. I can't find one of those. Whats the nearest closest common valued pot I could use instead?

hmm... this post here: http://www.diystompboxes.com/smfforum/index.php?topic=70732.msg923722#msg923722 goes into detail about making REVERSE log pots out of linear ones, but maybe you could reverse the equations or live with having the pot backwards.

[Brisance]

Check, what they have, but you could also make one: http://www.geofex.com/article_folders/potsecrets/potscret.htm

[steveyraff]

Check, what they have, but you could also make one: http://www.geofex.com/article_folders/potsecrets/potscret.htm

Hmm, I was hoping something like a 2k log wouldn't make much difference? Isn't that pretty close, no?

I found the missing caps I was looking for on ebay, they are indeed painted blue actually. Well, 4.7nf and 33nf.

[MrStab]

gah... ofc you can make regular log pots out of linear. i spent 15 hours on pedals yesterday, i'm allowed to be dumb. lol

[MrStab]

i think a 2k log would be fine, worth trying before trying to bridge pots with resistors

[steveyraff]

i think a 2k log would be fine, worth trying before trying to bridge pots with resistors

Thanks - I'll go for a 2k, but I'll still look into the other methods you mentioned - just for future reference. Thanks a lot man.

[MrStab]

no probs dude, hope either solution works out

[Kipper4]

I think my Dr B has the Gus Markov layout without any problems. although without looking I cant remember if I used a shielded input and out put wiring.

[J0K3RX]

You can actually leave the 20p cap out and you probably won't hear much of a difference. You might get a better result if try 200p instead.

[steveyraff]

Thanks guys, all useful info for this build.

Kipper, I'd read others had shielded the input and output wires, so I was planning on doing the same. Every little helps!

[Govmnt_Lacky]

Don't buy any 2K pots....

Take a 5K linear pot (5KB) and put a 5.1K resistor between Lug 1 and Lug3...... VIOLA.... its now a 2.5KB pot 

I've done this with all of my Boogie builds. Works great.

You might even be able to use a 4.7K resistor but it will be a little more "off" than the 5.1K

[J0K3RX]

Most of the values can be subbed with values in either direction as long as you do it with a bit of intelligence...

I have never really been a big fan of the scaled down tone stack on the Dr.Boogie, It's alright but 'to me' it sounds like it thins the actual tone out too much, like it's narrowing the tonal range.  I like to use the original values with a 50k or 100k "sweep" pot in place of the 47k. If you turn the sweep pot it changes the entire tone stack and gives you a whole different stack each time... Not to mention also boosts the mids like crazy or scoops the mids like crazy, depending on which way you turn it.  If you haven't tried it, take 1 minute and throw a pot on there. It makes a big difference! I haven't tried it with the scaled down stack but it it will probably be an improvement as well, just use a 10k pot instead. Another thing that I like is the way they sound with +18v