1. Register NOW and become part of this fantastic knowledge base forum! This message will go away once you have registered.

My mixer magically picks up radio! HELP

Discussion in 'Computing' started by DasV, Aug 12, 2009.

  1. DasV

    DasV Guest

    i have a tapco mix 120. cheap mixer but decent for what im doing.
    i have a XLR in from my line 6 HD 100, and a L and R out to my laptop's mic in. cheap setup but so far its been working great and sounding pretty good as well after EQ.

    UNFORTUNATELY 20 minutes ago i started getting the RADIO in my tracks! its not loud enough to make out, but its definately noticable over the guitar, loud enough to know that you're hearing something other than the instrument.

    i recorded without the amp plugged in, then boosted the track way up and listened. ITS THE RADIO! idk what station but i recorded like half a song and a few commercials n stuff. i have NO idea how its possible but thats whats happening. turning the master volume up or down turns the radio up and down, so its definately the mixer.

    has anybody heard of anything like this? it hasnt always happened, it just started. how do i fix it!
     
  2. dvdhawk

    dvdhawk Well-Known Member

    I wouldn't say it's impossible that it's the mixer, but it is much more likely one of your cables that's acting as an antenna. It was either an unshielded cable to begin with, or a shielded cable that may have broken. (especially check the lines between the mixer and the laptop)

    Try disconnecting everything from the mixer, including the laptop, and plugging headphones into the mixer and see if you hear anything on the mains.

    Listen long enough to get the station's call letters (usually they have to announce their station ID around the top of the hour). Look them up online and see how far away they are, and what kind of station they are AM, FM, other.
     
  3. jg49

    jg49 Well-Known Member

    DVDHawk "Listen long enough to get the station's call letters"

    That way you can know when to tune in to listen to your favorite DJ.

    I experienced this once and I replaced the cables and it disappeared. I have heard that this can sometimes be eliminated by rerouting existing cables, avoiding looping and/or isolating them from power cords/cables.
     
  4. DasV

    DasV Guest

    Yeah i figured the same thing, "must be some cable issue!" so i switched them out, 3 different times, ran them all over, changed outlets, changed outputs, etc. still getting radio. then i though of what DVDhawk said, just unplug it and check with headphones. ill be damned if it isnt still there! i swear its weirdest thing ive ever seen in my life. the weirdest thing is, without a change in my setup for weeks this JUST started happening. Ill try calling the manu company maybe and seeing if they know whatsup? thanks guys.
     
  5. TheJackAttack

    TheJackAttack Distinguished Member

    Could be there is a loose ground wire or chassis wire inside the Tapco. Unplug it before opening it up....
     
  6. Person57

    Person57 Guest

    Radio in the recording - Me too!

    I had the same problem. I was using two identical microphones, using cables that were XLR to (um,... either TRS or TS - Now I come to think of it, maybe that was the problem!), to plug into two inputs of a digital Roland VS-880EX recorder. The mics were about 4 metres apart, but only ONE picked up the radio station!
     
  7. dvdhawk

    dvdhawk Well-Known Member

    Person57,

    Do you have the means to check the XLR cables to make sure they're wired correctly?

    I was troubleshooting a church system someone else had installed last week. One of the wireless systems was injecting all kinds of crap into the sound system. The other identical systems were dead quiet. With an ohm-meter it took 10 seconds to find this gremlin they'd been trying to track down for months. The XLR cable between the wireless receiver and the mixer had pins 1 & 2 reversed on one end. It still passed the out-of-phase signal via pin-3, but wired incorrectly as it was, all the true (in-phase) part of the signal was being run off to ground. And the hash picked up by the shield was now being amplified by the mixer as if it were the primary (in-phase) part of the signal - hence the static and noise. This was a very rural church, so if there was a transmitter anywhere near the shield I would expect it to be picking up radio in that situation.

    Check your cables again.

    Food for thought.



    Soapbox time again - everyone who lurks in audio forums should own and know how to operate a simple multi-meter.

    Back to the OP: I'd have to suspect DasV's mixer (shielding/grounding) if he's still picking up radio with nothing else plugged in but headphones.
     
  8. dvdhawk

    dvdhawk Well-Known Member

    To expound on my question:

    "Do you have the means to check the XLR cables to make sure they're wired correctly?"


    Plugging in a mic "to see if it makes sound", is not enough to test correct polarity, and will not always indicate a broken conductor or reversed shield.

    In my example, signal passed. It was just bad signal.

    If phantom power is involved all sorts of mayhem can result from one incorrectly wired XLR cable.


    You need a cable tester or ohm meter/continuity tester for a meaningful test.
     
  9. Codemonkey

    Codemonkey Well-Known Member

    "everyone who lurks in audio forums should own and know how to operate a simple multi-meter."

    Alright ALRIGHT dammit! I'll go get one. It'd be easy to get them from a shop in town but their site is fubar ATM. Won't load the extended product descriptions :/
    No idea what I actually need to get. Are something like these for about £10 OK or do I need to take out a loan?
     
  10. TheJackAttack

    TheJackAttack Distinguished Member

    UZ82D

    or

    N19BW

    I have both a digital multimeter and an analog. The analog version is useful for checking capacitors and such.
     
  11. dvdhawk

    dvdhawk Well-Known Member

    Their site really is a wreck right now isn't it?


    You can easily get what you need for under £10 from Maplin.

    You will want one that can handle Voltage up to 1000v AC or DC
    One that can measure Resistance is a must
    A Continuity Checker that beeps is very nice. It saves a lot of eyestrain and looking back and forth
    A Diode Checker can be handy
    Transistor Tester & Capacitance Meter would be a bonus
    I would recommend one with detachable test leads, those with permanently attached leads will eventually fail
    Make sure the batteries are easy to access and replace - I've seen some inexpensive $10 meters use weird batteries that cost you $5 to replace
    Oh .... an instruction booklet!!

    I don't know what some of the meter descriptions mean by "Battery Checker", but pass/fail battery testers are almost useless, if you've got a meter you can get an exact voltage.


    A hearty thumbs up for either of Jack's picks.

    Both digital and analog have their strengths. Digital takes a few seconds to stabilize and display the reading. So it isn't very good for voltages that are blipping all over the place. In contrast analog is very responsive, but you lose the accuracy to 2 decimal points.

    I know it's too much to ask that you spring for both right away, so you might get the most use out of a digital as your first meter.
    Othes may disagree. Personally, my digitals get much more use. Analog comes out for finding voltage dips, spikes and other momentary fluctuations.

    Anyway, rock on brother monkey ... we're proud of ya !
     
  12. Codemonkey

    Codemonkey Well-Known Member

    To be fair I could probably spend a bit more, but I was considering other things. I'd hate to splash then find my CPU fan burns out or something.
    At least I'd be able to tell it was actually broken...

    I shall try and get in at some point soon. I have to register for uni, and with no luck trying to log in from home, I'll probably head in today or tomorrow. 2 birds 1 stone sort of thing.
     
  13. soapfloats

    soapfloats Well-Known Member

    Thanks for expounding dvdhawk.
    I've fished here a couple of times for info on electrical engineering tools before, w/ little success.
    Things like multimeters, SPL meters, soldering kits, gaffers tape, etc never get a second (or first) thought from a lot of new "engineers". I know it's one of my weaker suits.

    Ever consider a topic on "must haves for any REAL engineer"?

    Finally, to the OP - I used to live less than a mile from the main transmitters for Voice of America and WLW. Though their signals have been cut back (WLW is *only* 50kW now, and the VOA station is gone), I used to get interference from those transmitters on all sorts of things - gui amps, telephones, radios, etc.
    Sometimes changing their location/direction helped. I don't know if you have anything like these stations in your area, but they *could* be a culprit.
     
  14. IIRs

    IIRs Well-Known Member

    I can recommend one of these

    Maybe not instead of a multi-meter. But a dedicated cable tester will be much quicker if you ever have a large pile of suspect cables to work through.
     

Share This Page