Analog effects and bass adaption

[CalamitY]

Hey guys, great resource you have here. Just a couple of questions.......

1) What do the components do to the sound in a circuit and why?

What i mean by this is, if i ran the input signal through a diode/resistor/capacitor/**Insert Component Here** or combinations thereof, what changes would i hear in the sound? (this could be really useful for designing custom sounding stompboxes or something)

and finally

2) What chages would i need to make (if any) to adapt these stompboxes for use with a bass guitar and why?

Being a bass player,although the schematics listed here are valid and will do something, would i need to make any modifications to get a better/more effective sound from the stopbox.

any light you can possibly throw on this will be greatly appreciated

Thanks in advance

[Ashurbanipal]

1. Pages and pages could be written on that. I'm a relative newbie, and my advice would be find a few simple effects you want to have, build them, and read as much as you can about how the circuits you're building work.

2. I play bass and guitar. Generally when a circuit needs modded for bass you have to increase the size of one or more capacitors. They often act as high pass filters and can cut bass response in circuits that are not bass friendly. Some of the effects I've built work fine for either bass or guitar and then some needed bigger capacitors for bass. The capacitor nearest the input for example is often .01 or .047, but if you're unhappy with bass response you would increase that to .1 or .22. This is not the only example of how to increase bass response; it depends on the circuit. I would say decide what you want to build and then ask here if any mods would be needed for bass.

[Bernardduur]

Enlarging the caps can do the trick, but in a lot of cases I found the pedal to overload (as you put in too much signal). Sometimes a dual loop pedal (with one loop clean) is more usefull for bass and just leave the components unaltered.

[CalamitY]

Thanks guys,i heard enlarging the caps would help the bass response from a mate of mine. WRT the 1st point, just some basics/links/anything would be good,am just looking for some background before i start messing around (as i find thats the best way to learn about stuff). Thanks for the quick reply

[zpyder]

Ashburb's right... pages and pages... Also, it's not usually so much that a circuit component alters sound in a specific way, more like a network of components systematically changing certain characteristics of the tone.  It is a "circuit" after all... I'm also a relative newbie and I think one of the simplest circuits to understand when starting out is a hipass/lowpass filter.  A "high pass" filter allows higher frequencies to PASS through while killing lower ones.  and a "low pass", well you can guess that one.  It is based on a couple principles:

Electrons flow through a circuit along the PATH OF LEAST RESISTANCE.
Capacitors apply different RESISTANCE (which I believe in this case is actually called "reactance") to different FREQUENCIES of an AC signal (your bass signal)
Therefore, using one capacitor and one resistor, you can make certains frequencies go one way through a circuit, while others go another way.

Basically give the signal a fork in the road - down one way is a capacitor (with a certain resistance depending on the signal's frequency), and down the other is a resistor (which is always the same resistance, let's say 10k).  If the frequency of the signal deems that the resistance over the capacitor is higher than 10k, the signal will go the easier way, through the 10k resistor.  If the capacitor's resistance for the frequency is below 10k, the signal will go through the capacitor, because it's easier.  got it?  electrons goes the easy way...  A capacitors' resistance is higher at lower frequencies, and vice-versa.  A simple highpass filter consists of a signal path in, that has a capacitor going to the signal out, and resistor BEFORE the capacitor, going to ground.  Any frequency below the threshold will find that going through the resistor to ground is easier than through through the capacitor to out, and therefore evaporates into ground, we don't hear it.  To test this out, use a .1uF (.1 microfarad) Poly Film or Mylar or Ceramic capactor and a 1.5k resistor.  Frequencies above about 1000Hz will go through just fine, while frequencies below will be lost to ground.  Get some protoboard, plug it in, and listen for yourself!  Switch the position of the capacitor and resistor and you've got a LOW pass filter... try that out too.

The equation for a capacitor's resistance for a given frequency is:

              1
R =  --------------
        2pi * f * C

Where f = Frequency in Hertz
          C = capacitance in Farads (1uF [microfarad] = .000001 Farads)
          R = resistance in ohms

If you do the calculations with a 1500 ohm R and a .0000001 farad C, you'll find that the cutoff is actually right around 1061 Hz

Get a protoboard and a book!

cheers!
zpyder

[moosapotamus]

...just some basics/links/anything would be good...

Well... there's a bunch of links at the top of this page. Have at it!

~ Charlie

[CalamitY]

Thanks guys, thats precisely the stuff

Cheers

[zpyder]

CalamitY-

Hey... I wanted to correct myself ...:

A simple highpass filter consists of a signal path in, that has a capacitor going to the signal out, and resistor BEFORE the capacitor, going to ground.

This is incorrect... the BEFORE really should be AFTER.  I don't want to leave to totally backasswards so I wanted to correct myself.  If anyone can confirm or deny this, please chime in.

In my understanding, placing the resister to ground after the capacitor is logically backwards.  But keep in mind that electrons actually flow from negative to positive, not the other way as we may have been led to believe.  I think that's why this circuit works but may seem counter-intuitive at first

best of luck!
zpyder

[CalamitY]

Thanks zpyder,appreciate the correction. i haven't had an opportunity to get and havea go yet, so thanks for the heads up