COT50 mod

SebC

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Hi all,

I recently got a hand-wired cot50 (foldey box) that I really like, except that it's just a bit too bright for my setup. Doing some research I came across this post on TGP by Sean Michael for someone in my same situation:

"If you have soldering skills.. take a .001-.01 small poly cap or ceramic cap from the output lug on the switch to the middle lug on the switch.."

I'm confident about my soldering skills but just wanted to ask a couple of things. 1st, from .001 to .1 how much darker are we talking about? I just want to take off a little bit of the edge. And also, which one is the output lug? is it the one labeled "to PCB input" in this image from the AMZ-FX blog?

3PDT_3.jpg

Any help would be much appreciated!
 

owlexifry

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Feb 10, 2021
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Adelaide, Australia
Hi all,

I recently got a hand-wired cot50 (foldey box) that I really like, except that it's just a bit too bright for my setup. Doing some research I came across this post on TGP by Sean Michael for someone in my same situation:

"If you have soldering skills.. take a .001-.01 small poly cap or ceramic cap from the output lug on the switch to the middle lug on the switch.."

I'm confident about my soldering skills but just wanted to ask a couple of things. 1st, from .001 to .1 how much darker are we talking about? I just want to take off a little bit of the edge. And also, which one is the output lug? is it the one labeled "to PCB input" in this image from the AMZ-FX blog?

View attachment 984086

Any help would be much appreciated!
any help based on this reference image may be misleading..
we need to know exactly how your COT50 is wired up to the switch.
photos would be good.

for this purpose, i wouldn’t recommend larger than .001 (1nf), try that value first...

assuming your COT50 is wired exactly as the image above, this is what you need to do (per the advice you have referenced, he's talking about running a cap from output to ground):
1652744191385.png


another option, if you're game, is to retrofit a tone control....
you could do this with a trimpot and leave it inside the enclosure:
1652746889864.png


alternatively, another way to do this without touching the switch, is to use the output jack instead....
(may be a better idea, and avoids the risk of overheating and damaging the switch):
1652747523282.png

"fixed" tone control...
this is probably the simplest way to do it.
you can just change the cap value til it sounds how you like it (and no risk of overheating anything)

if you find 1nf is shaving off too much high end, try something between 470pf-1000pf.
if 1nf isn't enough, try 4.7nf, then 10nf, 22nf, 47nf etc.

(note: 0.001uf = 1nf = 1000pf)


1652747836106.png

variable tone control option

(edit note: tone mods on the output jack will affect both bypass mode and with effect on)
 
Last edited:

owlexifry

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Thanks a lot, @owlexifry. The trimpot sounds interesting! Thanks so much for your illustrations. Here are pics...
View attachment 984169 View attachment 984170
no worries :)

this is how your switch is wired:
1652749025870.png



could also use the output jack, like this:
1652749321863.png

but there is a catch: this will also effect the guitar tone when in bypass mode.
high end will be cut in bypass mode and with the effect on (i should have mentioned this above)

if you don't want this to happen, then you will need to add the cap as per the switch illustration above...

(perhaps for the experimental stage, you could initially use the output jack to determine the cap value that works for you, and then once all is decided, you can add the preferred cap value on the switch)
 
Last edited:

pi

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bay area, CA
I built a COT50 clone, and used 47nf. I breadboarded it with and without before building, and I found it was subtle difference but liked it better with.

There's multiple ways to wire a switch, so don't assume your diagram matches the pedal--check with a continuity tester. I would also wire between ground and the "from PCB output" lug (not to "output jack" lug), otherwise the cap will be in the bypass path as well, which you don't want.
 




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