Radio Interference ?

Forum dedicated to helping people debug and troubleshoot non-functional pedals or builds. Please use an clear and informative title, indicating circuit and basic problem. Don't forget to mark the issue as fixed if this is the case.
Post Reply
User avatar
travsbluz
Breadboard Brother
Information
Posts: 55
Joined: 15 Mar 2009, 20:57
Has thanked: 17 times
Been thanked: 1 time

Post by travsbluz »

Hello, I use both Single coil guitars and Humbucker guitars. With humbuckers the radio interference isn't noticable. But when I switch to my strat etc. it is real bad. (mainly with fuzz/distortion circuits)

I'm looking into properly sheilding my single coil guitars, but I was wondering if there is something to tame the radio down in your pedal builds, or do you just try to ignore it?

I really would like a couple of my fuzz style builds if I could just get rid of the radio interference.

Thanks for your time,
Travis

User avatar
RnFR
Old Solderhand
Information
Posts: 4879
Joined: 09 Jan 2008, 06:02
my favorite amplifier: Traynor YBA-III, Fender Super Six
Completed builds: custom fuzz.
Location: Inner Earth
Has thanked: 139 times
Been thanked: 133 times
Contact:

Post by RnFR »

the basic radio interference protection configuration that i've seen is a small, say 220pF, cap to ground at the beginning of your circuit. this should take care of any RF interference you might have. if this doesn't work, i'm not sure. anyone else have anything to add?
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

Blog-APOCALYPSE AUDIO

User avatar
Scruffie
Opamp Operator
Information
Posts: 1739
Joined: 13 Mar 2009, 17:59
Location: UK
Has thanked: 28 times
Been thanked: 170 times

Post by Scruffie »

Can only add the way i shielded my strat from this site http://www.guitarnuts.com/wiring/shielding/shield3.php which worked a treat for hum and im sure alot of noise protection (my fuzz factory occasionaly gets mild noise/radio interference, seems greatly reduced if at all with the strat thats been shielded)

Scruff.

User avatar
rrhoads33
Breadboard Brother
Information
Posts: 51
Joined: 09 Apr 2009, 19:58
Location: Austria

Post by rrhoads33 »

To block RF and other noise, Gus Smalley suggests a 10k resistor in series with the input and incorporating a power supply bypass cap.
http://www.runoffgroove.com/sili-face.html

Just to be sure: Your distortions are in a metal enclosure, which is connected to ground (via the jacks). I had already the pleasure to listen to Radio Moscow, when I tried out my distortion+ clone without enclosure. Some Wah and Volume pedals can be not adequate shielded.

If the hum of the singlecoils doesn't annoy you so much, you don't need to shield them. Too much shielded area in a Strat affects like a capacitor towards ground, which means that some high frequencies get lost. It's often described, that shielded guitars lost their "liveliness".

Edit: Ahh, just read, that you've already shielded your guitar; Maybe this post will someday help someone else...
There are 10 kinds of people in the world: Those who understand binary and those, who don't.

User avatar
Scruffie
Opamp Operator
Information
Posts: 1739
Joined: 13 Mar 2009, 17:59
Location: UK
Has thanked: 28 times
Been thanked: 170 times

Post by Scruffie »

Hmm i'm not sure that always applies, probably have to do it on a guitar to guitar basis. My strat is actually too bright for me even after shielding it and i've got a 0.47 Cap so Average Warmth But that's just my strat. And alot of the shielding process is also good wiring process with removing all the ground loops n' Such But maybe it's just my preference.

Scruff.

User avatar
rrhoads33
Breadboard Brother
Information
Posts: 51
Joined: 09 Apr 2009, 19:58
Location: Austria

Post by rrhoads33 »

Hmm, yours is too bright? The sound of singlecoils is brighter than that of humbuckers of course. What Potentiometers are used? 250k? With a lower value you'll get a less bright sound.
There are 10 kinds of people in the world: Those who understand binary and those, who don't.

User avatar
Scruffie
Opamp Operator
Information
Posts: 1739
Joined: 13 Mar 2009, 17:59
Location: UK
Has thanked: 28 times
Been thanked: 170 times

Post by Scruffie »

Yea 250k CTS Pots, it is a rather bright guitar though, i built it to be pretty bright (just needs that edge taken off), Ebony Board, Maple Neck & American Ash Body, I'm not bothered by it, it's just the single coils im using at the moment which are too lower output which shall soon be bareknuckle Singles, I was just saying that shielding some guitars is ok for brightness and had to be done on a guitar for guitar basis.

User avatar
earthtonesaudio
Transistor Tuner
Information
Posts: 1244
Joined: 28 Jan 2008, 04:00
Completed builds: Metal Simplex, Fuzz Factory, two Fab Echos-modded, Noisy Cricket, Earth & Space Wah, TS-7-modded, passive xover/splitter box, opamp fuzz
Location: Bloomington, Indiana
Has thanked: 11 times
Been thanked: 75 times

Post by earthtonesaudio »

Hearing radio stations requires gain and rectification. Half-wave rectifying the signal can occur with a BJT base-emitter junction, so that bit is hard to eliminate, but you can reduce gain at radio frequencies pretty easily. Just a cap to ground can actually tune in certain frequencies and make it worse. Better to use a R-C lowpass filter or negative feedback at radio frequencies. Shielding the guitar will probably help too.
rocklander wrote:hairsplitting and semantics aren't exactly the same thing though.. we may need two contests for that.

User avatar
RnFR
Old Solderhand
Information
Posts: 4879
Joined: 09 Jan 2008, 06:02
my favorite amplifier: Traynor YBA-III, Fender Super Six
Completed builds: custom fuzz.
Location: Inner Earth
Has thanked: 139 times
Been thanked: 133 times
Contact:

Post by RnFR »

earthtonesaudio wrote:Hearing radio stations requires gain and rectification. Half-wave rectifying the signal can occur with a BJT base-emitter junction, so that bit is hard to eliminate, but you can reduce gain at radio frequencies pretty easily. Just a cap to ground can actually tune in certain frequencies and make it worse. Better to use a R-C lowpass filter or negative feedback at radio frequencies. Shielding the guitar will probably help too.
ok, so say a 10K series resistor, and a 220pF cap at the beginning of the circuit, along with the large(>10uF) cap from 9v to gr that gus recomends. or some sort of neg feedback through a small cap to filter highs. give that a shot.
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

Blog-APOCALYPSE AUDIO

User avatar
Fuzzer
Diode Debunker
Information
Posts: 982
Joined: 16 Sep 2007, 15:17
Been thanked: 21 times

Post by Fuzzer »

Add a Cap (0.1 non electrolytic) in parallel to the >10 [uF]. :thumbsup
The Freestompboxes Forum search function is soo great, use the search function..., the S E A R C H function.

User avatar
travsbluz
Breadboard Brother
Information
Posts: 55
Joined: 15 Mar 2009, 20:57
Has thanked: 17 times
Been thanked: 1 time

Post by travsbluz »

Thanks for all the replies. I will try these out today when I get the chance.


Travis

Post Reply