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Radio Interference Beano/ Sunface

Discussion in 'Effects, Pedals, Strings & Things' started by roquero, Feb 22, 2009.

  1. roquero

    roquero Bold Supporting Member Silver Supporting Member

    Feb 15, 2009
    I love my Analogman Beano Boost and Sunface NKT 275 but I had to take them off my pedalboard and relegate them to studio use only, due to radio interference.
    I suspect it's due to the germanium transistors, tube amps, plus living in Miami where we not only have the local radio stations, but also pirate hiphop stations and radio waves drifting in from Cuba at night.
    The Beano Boost is a worse offender than the Sunface.
    I have tried different amps and cables but same result [amps: Sovtek MIG 60 w/ Avatar 2/12 Celestion Vintage 30s. Mesa Boogie Mark IIB combo, guitar: Fender EC sig strat, cables: Mogami and Stompin Grounds]
    It got so bad at an outdoor gig I did a few months ago that the radio stations overpowered the music coming out of the amp, which was hilarious to the audience but not so much to me. :(
    Anyone else overcome this problem?
    If so, tips would be appreciated!
  2. analogmike

    analogmike Gold Supporting Member Vendor

    Mar 17, 2004
    A little cap tacked on the switch should help the beano, the clean trimpot could be all that's needed to kill the noise on the sunface.

    Radio Frequency Interference (RF IF) is a tough one, most> gain pedals like Fuzzes and even some wahs have a lot of RF problems.
    Since we cannot duplicate the problem here (it has no noise here) it's not something we can fix at our shop.
    Gain is amplifying the RF from the air like a radio, it is tuned to the local station. Sometimes shortening wires or adding ferrite beads will help but since we don't have the problem here we would only be guessing. If you have a good tech he can try shortening the internal wires one by one and test to see if that helps, or he can try adding more and more ferrite beads and see if that stops the noise.
    Also you can try to add a small capacitor on the input of the board or the input jack to ground, that often kills the noise. Try something small like 100pF then go bigger up to .01uF if needed. We often put a small cap right on the switch from the TO BOARD wire connection (gets connected to input jack when ON) to the GROUND connection.
    Also dirty jacks can cause RF interference, try cleaning them with a swab and some contact cleaner.
    A customer wrote :
    "One thing I did was to uncoil all the power leads in the back of the rack. I had them coiled up pretty tight and then cable tied. This immediately helped, but I wasn't completely satisfied.
    At this point, I noticed that to make the radio signal be it's worst, touching the audio plugs on the back of the power amp (Metal sleeves) would do it. So next I soldered some 4.7pf capacitors across the DC connectors on my pedals. "
    another customer with RF problems with a sunface wrote:
    "Thanks for the note, Mike. After applying an, ahem, no-to-low-tech technique it seems that the RF IF problem is gone. Get this: after reading your reply I got to fiddling with the guitar cables in the chain, which includes a Framptone Amp Switcher in front of two amps. Anyway, I just swung the guitar-out cable from the Strat around from the front and behind my body and presto/change-o, the RF IF disappeared. No contact cleaner, no screwdriver, no solder. No BS."
    Here is another who found a simple fix for RF noise on a sunface:
    "Thanks for your detailed response to my question. I was able to solve
    the problem. I got a ferrite clamp from Radio Shack and tried clipping it onto my guitar cable. It eliminated some of the RF noise, but not all of it. I also noticed some loss of clarity from my guitar signal so I decided to ditch the ferrite and try adjusting the internal trim pot. I set my guitar volume to the most offending spot and adjusted the trimmer until the noise went away. I only ended up turning it down a bit. I would guess it's somewhere around 85%. Now I can use my guitar's volume knob to get that sweet spot w/o the RF interference."

    Hope that helps, good luck!
  3. earthtonesaudio

    earthtonesaudio Member

    May 16, 2008
    The problem is caused by a combination of two things: gain and half-wave rectification. In common emitter gain stages (like the input stage of a Fuzz Face), the emitter-base junction is essentially a diode to ground, which will half-wave rectify an AM radio signal, turning it into an audio signal. The gain just makes it worse (i.e. you can hear it).

    Adding a capacitor only will sometimes help, but sometimes actually make it worse, by tuning in the specific station! The proper way to deal with this is a R-C or L-C lowpass filter at the input (tuned to radio frequencies, won't affect the audio signal at all), or alternatively some emitter degenerative feedback.
  4. zenfreud

    zenfreud Member

    Mar 20, 2002
    Portland OR
    Every germanium pedal I've had has picked up radio stations when the guitar's volume is rolled back, it's part of the charm. Nothing like fading down the guitar and having two radio stations that sound like they're from the 1960-1970's simultaneously play through the delay. I think downtown types call this performance art.
  5. Franklin

    Franklin Supporting Member

    Jul 1, 2005
    My Sunlion only gets one Salsa station and one Christian station depending on where I am. It doesn't bother me too much....

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