Removing Hum And Hiss

[Saga]

hi anyone who's reading this. I just bought a guitar and a speakerbox (with distortion, reverb, clean sound etc). The guitar have two single coils and a humbucker (in this order, from bridge to neck: H S S). I noticed a small "hiss" and sometimes a "hum" depending on the pickups I'm using. Is there any way to make a circuit that filters these noises and take 'em out? thanx in advance.

[Dugz Ink]

"Hiss" is usually the result of a weak signal that has been greatly amplified.

"Hum" and "buzz" are usually created by RFI or bad grounding.

You can reduce both using EQ, but that also reduces the (identical) frequencies that you want from your guitar. (Unless we're talking about a pure 60Hz tone; you can kill that without ruining the sound of your guitar.)

It's better to identify the source and fix it. In this case, the singles are probably picking up RFI. If the humbucker coils are wired in parallel, it could be that you're not getting a strong enough output from them.

I'm not saying that those ARE the problems; I'm saying the thay COULD BE the problems. Check into it. As soon as you accurately identify the problem, you'll also identify the solution.

D~s

[lovekraft]

I noticed a small "hiss" and sometimes a "hum" depending on the pickups I'm using.

You actually have several separate problems to deal with. 60Hz (50HZ in Europe and other parts of the world) is considered hum, and comes from the AC line, while buzz is 120HZ/100Hz, and is usually generated by DC power supplies - both of these can be reduced greatly by shielding the guitar and eliminating any ground loops (see the Guitar Nuts wiring and shielding site for specifics). Hiss is usually a product of your amplifier, and associated with high gain settings and high treble. There's not a lot you can do about that, other than upgrading your amp.

Is there any way to make a circuit that filters these noises and take 'em out?

Trying to use a filter to eliminate noise is problematic, since any filter sharp enough to eliminate the offending signal without gutting your guitar sound is going to be complex, expensive and sensitive. A well-shielded, correctly-wired guitar and a good quality (but not necessarily really expensive) cable will eliminate most of your problems under normal conditions.

[ansil]

i have to agree with lk here however if you do wish to fry your brain. [been there done that.] you can make a multilple filter bank thats not too overly complex but you will lose some of the freq range.. but if you want to play with single coils its my favorite thing to do. it basically notches out a simple rc filter at 6db per octave in the following freq ranges.

30hz 60hz 120hz 240hz 480hz 960hz 1920hz 3840hz 7680hz 15360hz

thats a total of ten filters. to make. unless you want to make it a double pole filter then its 20 of them.

basically its one unity amplifier to keep from loading down the signal. and then dump all your sound into these filters.

also to be noted to make the correct notch unless you want to do the graphic eq style of filters with the opamp and the capacitor to make the virtual inductance which is simpler but i lost the formula for finding the correct freq of it.

you would need a highpass filter and a low pass filter set up to make a notch in the sound.. similar in fact to the BMP tone control set up.

for the first one. i just use a simple high pass filter and roll off anything under 72hz. and the last one i use a simple lowpass filter and roll off anything past 10k.

there is a free online calculator to get all of this up and running for you here.

http://www.muzique.com/schem/filter.htm where you input the capacitor and resistor and get the frequency.. so basically you need a lopassfilter to notch out around 115hz and then a high pass to get the 125hz so you effectively loose 10hz at 6db per octave. i will draw a flow chart.

I run mine in parallel. i also use a small trim pot like 100K or so instead of the two fixed resistors there i find it lets me balance the circuit in those instances that you have to deal with wide tolerance shifts.

also the first filter parameters would be .068uf capacitor and a 20k resistor to give you a notch of 117.1hz and 12.5k and .1uf for a 127.4hz notch. which way you use it is up to you. and as always have fun .

[unclej]

whatchutalkinboutwillis?

[ansil]

whatchutalkinboutwillis?

sorry was that unseasoningly long i thought i was quite clear i appologize.

[unclej]

ansil, i do hope that you know i was just teasing. it's a bad habbit of mine. but no, your explanation was very clear and concise.

[ansil]

oh no thats fine i was just making sure. no worries.

[Saga]

heh, thanx everybody! I just shielded up the guitar and changed my cable (there's still a small noise due to overdrive saturation and reverb, but no one would hear it while I play ...) thanx!