Input caps for bass

[RFreeman]

I'm about to take on my first build. It's a Maleficent Mids. I plan on using it on bass guitar.

Is the input/output RC network on this build suitable for bass, or would I have to swap these?

Here's the link to it's schematic.

 

[BuddytheReow]

You should be ok using the stock 4.7uf caps. For future reference you can use this RC filter calculator.

Guitar Pedals: R-C Filter Calculator

Calculate frequency cutoff for guitar effects pedals with vacuum tubes and solid state electronics. FREE calculator.

www.muzique.com

 

[phi1]

I usually rely on a simpler RC calculation. The same equation finds the cut off frequency for HPF and LPF. In this case, the output HPF cutoff is plenty low at about 3Hz and the input is even lower, so no problem.

I would be more concerned about the potential for a pop sound, since electrolytic caps are sometimes leaky, to the point they overwhelm the input and output pull down resistors and cause DC to sit on your input or output. You may get pop, you may not. I’d consider subbing with tantalum or MLCC, since both those types are less likely to significantly leak DC.

 

[RFreeman]

You should be ok using the stock 4.7uf caps. For future reference you can use this RC filter calculator.

Guitar Pedals: R-C Filter Calculator

Calculate frequency cutoff for guitar effects pedals with vacuum tubes and solid state electronics. FREE calculator.

www.muzique.com

Thanks. +1 for the calculator link

 

[RFreeman]

I usually rely on a simpler RC calculation. The same equation finds the cut off frequency for HPF and LPF. In this case, the output HPF cutoff is plenty low at about 3Hz and the input is even lower, so no problem.

I would be more concerned about the potential for a pop sound, since electrolytic caps are sometimes leaky, to the point they overwhelm the input and output pull down resistors and cause DC to sit on your input or output. You may get pop, you may not. I’d consider subbing with tantalum or MLCC, since both those types are less likely to significantly leak DC.

Is the issue with cap leakage a quality issue; ie, cheap vs quality caps. Or just a characteristic of electrolytic capacitors in general?

 

[phi1]

Probably some of both… I think electrolytic is fundamentally more prone to leakage, and then quality comes into play. I don’t have any specific recommendations of electrolytic brands or sources that will have acdeptably low leakage, I usually go the replacement route.

 

[RFreeman]

I usually go the replacement route.

Is this something you would do for most builds? Replace the input/output caps with mlcc or tant if they call for ec?

 

[BuddytheReow]

If you're unsure your best bet is to socket the component and swap it out.

 

[phi1]

Personally yes I usually swap on the input or output cap if it’s electrolytic. Often times you can get by just fine with 1uF on the output, and 100nF input. Depends on the resistors to ground after the caps (follow the calculator above). Others may have had better luck than me or know of a source that consistently has non-leaky caps

 

[RFreeman]

Thanks for taking the time to help me. And a pre-emptive apology for all future noob questions I may have.

 

[RFreeman]

I will be socketing the input/output caps on the first build.

 

[museums]

This depends heavily on the circuit but the old fashioned "make the input and output caps bigger for bass" advice rarely accomplishes the intended result. Often there is no effect because a pedal will already pass all usable bass frequencies on the input as in the case of a Rat where increasing the 22nf input cap makes zero difference in the sound of the pedal. Best bet when tuning a pedal for bass use is to look at every location where there is a high pass filter and do the math to figure out the corner frequency (online calculators are fine) before determining if you can make a change to increase bass without negative consequences.

 

[fig]

+1 on tantalum @ C1 & C6, but source wisely as tantalum is a blood mineral.

 

[giovanni]

This depends heavily on the circuit but the old fashioned "make the input and output caps bigger for bass" advice rarely accomplishes the intended result. Often there is no effect because a pedal will already pass all usable bass frequencies on the input as in the case of a Rat where increasing the 22nf input cap makes zero difference in the sound of the pedal. Best bet when tuning a pedal for bass use is to look at every location where there is a high pass filter and do the math to figure out the corner frequency (online calculators are fine) before determining if you can make a change to increase bass without negative consequences.

I second this. Input and output caps are not enough to determine the overall bandwidth of a pedal. You need to look at each stage individually.

 

[BuddytheReow]

I second this. Input and output caps are not enough to determine the overall bandwidth of a pedal. You need to look at each stage individually.

Agreed, but for the more simpler fuzz or distortion circuits out there the in/out caps will be all you need to tweak.