# Cobalt Drive



## Chas Grant (Oct 4, 2020)

Just finished up a Cobalt Drive pedal, it sounds GREAT! It's a stock build per the doc since this is the first time I built this one. I'll give it a few months and then look up some mods on it and see how they sound. The pedal went together with no problems, The PedalPCB layout is awesome and easy to work with! First time I tried this finish and I'm pretty happy with it. A water slide decal straight on a sanded box then 5 thin coats of lacquer gives it a nice look with a small bit of depth.


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## Chuck D. Bones (Oct 4, 2020)

Nice!


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## Barry (Oct 4, 2020)

Very nice


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## Chas Grant (Oct 4, 2020)

Thank You Chuck, Thank You Barry!


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## cooder (Oct 4, 2020)

Great looks and build!


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## Chas Grant (Oct 4, 2020)

cooder said:


> Great looks and build!


Thanks!! It sounds great too! For some unknown reason I’m a sucker for Boss pedals and this one has that classic Boss sound. This one goes right up with my OD1 and DS1 clones!


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## bzdunowski (Apr 8, 2021)

What did you use for the a250K dual pot? I cant find one anywhere


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## fig (Apr 8, 2021)

Found this;

https://www.taydaelectronics.com/250k-ohm-logarithmic-dual-taper-potentiometer.html


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## Chuck D. Bones (Apr 8, 2021)

Tayda has some that you'd have to hard-wire to the board.  Small Bear has B250K dual, which will work fine, the bottom-end of the range will be a little more sensitive.  Or you can use an A500K dual and either enjoy the extra 12dB of gain at the top end or add a 470K resistor from pin 1 to pin 3 (two places).


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## bzdunowski (Apr 8, 2021)

fig said:


> Found this;
> 
> https://www.taydaelectronics.com/250k-ohm-logarithmic-dual-taper-potentiometer.html


Thanks but the pins arent going down and thats a 6mm shaft not a standard 6.35mm aka 1/4". Someone pointed me to the one i need on lovemyswitches.com


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## fig (Apr 8, 2021)

Perfect! I should have thought of Larry first!


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## fig (Apr 8, 2021)

wow...an hour later...this arrives in the mail


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## Kroars (Apr 19, 2021)

Chas Grant said:


> Thank You Chuck, Thank You Barry!


I see what you did there . Nice build! Love the color scheme and graphics.


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## Urshurak776 (Apr 19, 2021)

Looks great.  I'm building one also (waiting on parts.)  I can't find that dual pot anywhere (right angle pins.)  Tayda doesn't carry them.  Bought one with solder lugs, hopefully I can wire it.  Worried about clearance issues.  I'm doing the Keeley MOD also.


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## Chuck D. Bones (Apr 19, 2021)

By Keeley Mod, you mean replacing two of the clipping diodes with 1N4002 and retuning the TONE control, right?  Are you thinking PHAT mod too?


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## Urshurak776 (Apr 19, 2021)

Yes, the PHAT mod. Maybe saying Keeley isn’t the right description.  Not sure.

Oh, R24 in diagram should be 10K.  The guy that did it made a typo.


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## Chuck D. Bones (Apr 19, 2021)

Sort of.  My read of the Keeley mod as applied to the PedalPCB board is: 

Change C20 to 10uF 16V Tantalum.
Replace C14 with 33nF.  For Keeley PHAT mod, add a switch that connects a 68nF in parallel with C14. 
Jumper D2, replace D1 with 1N4002.  *OR *remove D1 & D2, connect 1N4001 from D1-A to D2-K.
Change D3 to 1N4002.  This makes no sense to me because D5 & D6 should never conduct.  The original BD-2 used a different opamp and it might have made a difference then.  But who am I to 2nd guess Robert Keeley?
Replace ceramic caps with SM (or film).
R24's value is not critical.  2M would have been a problem with aluminum for C20.  With tantalum, it doesn't matter.


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## Urshurak776 (Apr 21, 2021)

Chuck D. Bones said:


> Sort of.  My read of the Keeley mod as applied to the PedalPCB board is:
> 
> Change C20 to 10uF 16V Tantalum.
> Replace C14 with 33nF.  For Keeley PHAT mod, add a switch that connects a 68nF in parallel with C14.
> ...


Wow, that's different from the diagram I posted from the Tone Geek.  Now I'm not sure?  Also, I got a 500K log dual gang pot from Small Bear.  Going to just put 470K resistors across pins 1 and 3 of each "gang."

Thanks Chuck.


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## Urshurak776 (Apr 21, 2021)

Chas Grant said:


> Just finished up a Cobalt Drive pedal, it sounds GREAT! It's a stock build per the doc since this is the first time I built this one. I'll give it a few months and then look up some mods on it and see how they sound. The pedal went together with no problems, The PedalPCB layout is awesome and easy to work with! First time I tried this finish and I'm pretty happy with it. A water slide decal straight on a sanded box then 5 thin coats of lacquer gives it a nice look with a small bit of depth.



Looks awesome!  How do you do your pedal artwork?  I would like to make mine look nice but have no idea how to do this?


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## Chuck D. Bones (Apr 22, 2021)

Urshurak776 said:


> Wow, that's different from the diagram I posted from the Tone Geek.  Now I'm not sure?  Also, I got a 500K log dual gang pot from Small Bear.  Going to just put 470K resistors across pins 1 and 3 of each "gang."
> 
> Thanks Chuck.


Not all that different, just more clear and more accurate.

U r welcome.


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## uranium_jones (Apr 22, 2021)

Chuck D. Bones said:


> Replace C14 with 33nF.  For Keeley PHAT mod, add a switch that connects a 68nF in parallel with C14.



So, you're switching the value between 33nF stock and 101nF Phat?  If so, could I do the same by wiring a 33nF and a 100nF to a spdt switch and connecting the two ends of the switch to the holes for C14? I'd have to think of how to make a switch that adds a capacitor in parallel but is an open circuit otherwise.


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## fig (Apr 22, 2021)

maybe think of the poles sideways? not sure...brain must work more


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## uranium_jones (Apr 22, 2021)

Wait I think I figured it out... Does this look right? This assembly replaces C14 via the two leads on the right.


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## Chuck D. Bones (Apr 22, 2021)

You got it right!


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## Urshurak776 (Apr 22, 2021)

Not sure I understand this.  If it’s open circuited, nothing would go through the tone pot?


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## uranium_jones (Apr 23, 2021)

Urshurak776 said:


> Not sure I understand this.  If it’s open circuited, nothing would go through the tone pot?


If you're talking about the figure I just drew as replacing C14, then if the switch is open, the whole thing looks like 33nF between the two right leads. If the switch is closed, the two capacitors are in parallel so it's 101nF.


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## Urshurak776 (Apr 24, 2021)

quality_jones said:


> If you're talking about the figure I just drew as replacing C14, then if the switch is open, the whole thing looks like 33nF between the two right leads. If the switch is closed, the two capacitors are in parallel so it's 101nF.


Got it!  Thanks!


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