Collosalus 2015 question resolved

[jimilee]

If I were to get a 12v power supply, would I need to make any modifications or just keep it at the 9v config? Same noise everyone else seems to have. I have it at a minimum after working it for two days, it's usable now with just a little noise and that classic flanger swoosh. I"m thinking a noise gate will get rid of that little bit.

[danfrank]

What kind of noise? Hetrodyning from the BBD clock and charge pump? If so, try putting a 30-50pf cap between pin 7 of the charge pump and ground. This will lower the frequency of the charge pump... Ideally, you want the CP to be at 17-20 kHz. If you have a frequency counter you can get the CP working frequency from pin 2 of CP

[jimilee]

What kind of noise? Hetrodyning from the BBD clock and charge pump? If so, try putting a 30-50pf cap between pin 7 of the charge pump and ground. This will lower the frequency of the charge pump... Ideally, you want the CP to be at 17-20 kHz. If you have a frequency counter you can get the CP working frequency from pin 2 of CP

Maybe so, it's dead quiet with a battery.


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[danfrank]

Hmm... A battery will also use the charge pump so maybe it's not hetrodyning... Are you using a switching wall wart like a One Spot? Some of those switching supplies are noisy. Try finding a linear wall wart supply to power it, one that has an actual step down transformer in it.

[jimilee]

Hmm... A battery will also use the charge pump so maybe it's not heterodyning... Are you using a switching wall wart like a One Spot? Some of those switching supplies are noisy. Try finding a linear wall wart supply to power it, one that has an actual step down transformer in it.

Yeah, I looked up heterodyning sounds, definitely power supply noise. I use a Dunlop power brick most of the time. I've tried 2 boss power supplies and a boss wall wart. Now, I live in an apartment, do you think that has anything to do with it? How can I calibrate it with a frequency counter? I have a decent DMM I can use.

[danfrank]

Well the frequency counter is to see what frequency the charge pump is operating at. LT1054 CPs are typically rated at 25kHz operating frequency but that is not a frequency set in stone... The last batch of 1054s I bought from Mouser all operated at 35kHz and they definitely caused hetrodyning issues in flangers and chorus circuits. This is where a small cap from pin 7 of CP to ground helps to lower the CP frequency to where it won't cause noise issues with clock circuits. This probably won't help in your case as it definitely sounds like a power supply issue.
What I would do is add a 2200-4700uf electrolytic cap at the DC power jack, inside your Collosalus pedal box. Whatever will fit inside. This should fix any 60Hz power supply noise. If you're using a switching power supply, try some 1uf MLCC caps in the same place along with a 1000uf electrolytic.

Or buy a bunch of batteries!

[jimilee]

Hey man, I really appreciate your help.


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[jimilee]

I bought a 12v power supply and removed the charge pump and diodes and all is right with the world. This resolved all of the issues and sounds amazing.


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