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Topic: OT - Help with radio noise in home studio

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  1. #1

    OT - Help with radio noise in home studio

    Hi,

    I come to the friendly environs of the discussions here knowing that I'll probably find the answer to my question...

    We just recently moved to a new house. I set up my modest home studio in the basement and immediately begain receiving radio signals (audible, talk-radio signals!) through my monitor speakers. When I plug my headphones directly into my laptop...no radio. If my speakers are anywhere in the loop...radio.

    Could it be that these speakers are just susceptible to radio reception? They are M-Audio StudioPro 4 and they work well for me. (I did mentiont the modest part, right?)

    Any thoughts? suggestions?

    Thanks for any help you can give...
    Brad Pearson
    THG Music
    Spokane WA

    MacBook Pro (2.33 GHz Intel Core 2 Duo), 3 gig RAM, OS 10.6.5, Finale 2011b, GPO4 & CMB2

  2. #2

    Re: OT - Help with radio noise in home studio

    I had a similar issue with a set of Altec Lansing speakers. 89.7 FM came in as long as there was juice. They didn't have to be plugged into the computer or even turned on, just plugged into the wall.

    Those monitors are supposed to be magnetically shielded according to spec though. Odd...

  3. #3

    Re: OT - Help with radio noise in home studio

    I could not have said it better myself Stephen.

    Good advice for these folks as usual.
    I always prefer a separate stereo power amp and passive two way speakers myself.
    Dan

  4. #4

    Re: OT - Help with radio noise in home studio

    Quote Originally Posted by Stephen McMahan
    The problem arises because of two things - first the speakers (self-powered) use high impedance inputs and second the inputs are unbalanced. Balanced inputs are lower impedance and also are meant to cancel common mode signals (which is how the radio noise is getting into your speakers - there is no common mode cancellation and the hot lead is acting like a good antenna into a high impedance amplifier.)

    Try finding some toroids (check with any major hifi or pro audio shop) to wrap your input cables around - this should significantly reduce the radio noise. RC or RF choke mods could be made inside the speakers - but this has to be done right and would void your warantee (if that matters to you - personally I have either modded or have had modded most of my gear to get it up-to-snuff as far as quality.)

    In the future - if at all possible - avoid any audio devices with RCA jacks for anything but SPDIF. Try to stay with balanced lines. The only exception would be speaker wires from a power amp. It is getting harder and harder to avoid radio and other electrical/electronic noise these days - and balanced lines are generally immune to this.
    Stephen,

    Thanks so much for your quick reply. I'll be going tomorrow to find some toroids.

    Peace....
    Brad Pearson
    THG Music
    Spokane WA

    MacBook Pro (2.33 GHz Intel Core 2 Duo), 3 gig RAM, OS 10.6.5, Finale 2011b, GPO4 & CMB2

  5. #5

    Re: OT - Help with radio noise in home studio

    OK, Stephen,

    On the Radio Shack site they offer two types of toroids: one is like you mentioned, where you wrap the cord. The other is a snap on type. Which is preferred?

    Do I use it on the cables going to the speakers from the mixer? (That's 1/4" to RCA going into the powered speaker of the pair.) The powered speaker then passes on signal to the other. Would it help to use the toroid on the cable going to the passive speaker as well?

    Thanks for helping with this...
    Brad Pearson
    THG Music
    Spokane WA

    MacBook Pro (2.33 GHz Intel Core 2 Duo), 3 gig RAM, OS 10.6.5, Finale 2011b, GPO4 & CMB2

  6. #6

    Re: OT - Help with radio noise in home studio

    thgmusic,

    Both versions work well. The wrap through version might be marginally better, but the snap on version is often more practical - especially if the connectors are big.

    Put the magnets on the cables that feed your speakers. And place each magnet near the end of the cable - at the end that connects to the speaker. For an extra measure of protection, you can put a magnet at both ends of the cable.

    And Stephen's right about opting for balanced lines where possible. You can run long lengths of balanced cabled without interference.

    Oh, one more thing. Use as short a cable as possible to each speaker, and use cables with good quality. Look for cables that have both a braided (wire) and foil shield. Sometimes they call such a cable "double shielded". Every bit helps!

    And one more, more thing: You can also get RF interference through the power supply. If you're still getting RF interference, a magnet around the power cable near the speaker wouldn't hurt.

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