Bass pedal in/out stage

[il_mix]

Hi, everyone!

I would like to better understand how to "optimize" my custom pedals for bass guitar.
Although I can (and will!) do some "use-your-ears" tests, I would like to know your hints on the topic.

Tipically, the input stage of a pedal have a series capacitor, than a resistor that goes to ground.
My first thought is to change the pedal default capacitor (i.e. the one on the schematic found on the web) using a lower value (e.g. use a 10nF instead of the default 100nF one), to have a lower frequency cut.
Any other hint about this?

The output stage tipically have some sort of RC filter, too. I'm not sure if it is a good idea to play with there values, since they are set given the overall circuit response. Letting some more high/low frequencies goes out can let some wild noise escape the circuit.
What's your opinion on the matter?

Thanks!
MIX

[antonis]

My first thought is to change the pedal default capacitor (i.e. the one on the schematic found on the web) using a lower value (e.g. use a 10nF instead of the default 100nF one), to have a lower frequency cut.

You have to "reverse" your thought..

The cutoff frequency is reverse propotional to the size of the cap (or resistor) in a RC filter..

f (Hz)= 0.16 / R(Ohms)*C(Farads) (0.16 is close enough to the irrational 1/2π..)

(for bass guitar a value of 4.7μF metal film should be a good starting point..)

[anotherjim]

You'll need to read up on RC filters if you want to get scientific.

But, yes, doubling the cap value chosen for a guitar effect will take it down enough for bass.

However, sometimes the original  cap value isn't chosen without much thought, it's just one that happens to be large enough - and that may be far too large in the first place, so you won't need to change it.

Sometimes the low end response of the input has been chosen high (over 100Hz) to help reject AC mains hum, especially with a high gain circuit - you could be walking right into a trap if you lower it too much.

Then there's the nature of the Bass instrument, it's not always going to be a straight-forward case of dropping the frequency  response an octave down. A smooth fuzz on guitar can just turn to mush when pushed by a bass. It can actually be better to keep the guitar response and mix in some of the clean sound at the output - so there's still a solid defining thump of true bass under it all.

[il_mix]

uuups...
I was thinking in a deviated-low-pass-filter-way (smallest capacitors will move fc to higher frequencies, giving me "more low frequencies"... ->smashing head on the wall).
Well, forget that.

Basically the answer about how to play with ini/out filters is "it depends on the effect".

Chit-chatting a little more, without going too technically (given the result of the first post  ), are there some other (typical) things that can be changed to get a more bass-oriented pedal? In other words, if I change the input filter, it is the only thing needed to have more basses (this doesn't mean a better sound, of course) or, since more bass frequencies run through the circuit, I need to change something else in the effect core?
I suppose the answar will be again "it depends on the effect"...

[PBE6]

Unfortunately, it does depend on the pedal and what effect you're trying to achieve.

I agree with anotherjim that a blend knob is a welcome addition to most bass pedals, distortion/fuzz pedals especially. Even gnarly sounding fuzz pedals can get lost on-stage without a bit of the original signal mixed in to provide a foundation.

I also prefer cutting back on the input lows in a bass distortion pedal and using higher headroom diode schemes for clipping in order to avoid brittle sounding buzziness at the output.

A fun experiment would be to build/get your hands on a Tubescreamer/SD-1 and a Big Muff (and maybe a Rat or a Dist+), and compare sounds.