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Test a horn/tweeter?

Discussion in 'Amps and Cabs [BG]' started by DiabolusInMusic, Oct 5, 2013.


  1. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    I think I have narrowed an issue down to my horn, I get a static sound that goes away when I turn the horn off. I know how to make a sub dance and test a speaker but is there a special way to test a horn? My friend has a tone generator (9 volt, alligator clips and a button to make it beep) I can use to test speaker lines, I am thinking this is the only way to test a midrange. Is there a better method or easier method so I do not have to drive over to buddy's shop.

    I am trying to find out if the static is coming from the mid range or if it is an issue in the crossover, the cross over is fairly simple though so I am thinking it is the mid range.

    I already opened the cabinet and checked all the connections, the spades were all secure, I reset a couple of them. The tweeter control is soldered on; the joints are all shiny.

    Thanks in advance!
     
  2. If the tone generator is the typical 1000 Hz test tone it should work just fine directly to the horn and then through the crossover. A sweep test would be more precise.
     
  3. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Go on about this sweep test...

    I do not know what frequency the tone generator is, he uses it for car stereos but we have tested in wall speakers with it before as well.
     
  4. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    the tone generator makes "a noise"; typically one set frequency, you say his is 100 hz
    tone generator with sweep with make a range of tone, from say 2000 hz to 20,000 hz.

    be careful how much voltage you put to the horn, they generally can't take a lot.
    a repair video I watched yesterday sad "about 1 volt is proper."
     
  5. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Beauty. Thanks again you guys. I just called my preferred tech and it does have a generator to do a sweep test. I might have to wait until Tuesday but it isn't my main cab so that is fine by me My friend's tone generator definitely only does 1 pitch, I have used it enough to know it.
     
  6. Visual Analyser 2011 is a free program that has a sweep generator output from a PC or laptop. If you have a speaker output (will drive non powered speakers) it will usually have a safe output level. Horns are between 15 and 50 watt input max usually, 1 volt is sufficient for testing if you are unsure about the low frequency limit of the horn. ~ 2.83 volts at 8 ohms is 1 watt which can damage even a 100 watt mid-range horn with a cut off of 800 HZ if you push 60 Hz into it, so set the range of frequency sweep (set the limits) to a known frequency response of the horn if possible. Once you set and run the generator it will"sweep" from lowest to highest set frequency and you can listen for abnormal sounds.
     
  7. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    Good news and bad news, I took the midrange to L&M (Canadian GC) yesterday and had the tech run some noise through it and it seemed just fine.

    So I think my issue lies with the crossover. I will start a new thread so I can elicit more answers.
     
  8. Doug Parent

    Doug Parent Supporting Member

    May 31, 2004
    San Diego, Ca.
    Dealer Nordstrand Pickups.
    Can you be more specific what you mean by static sound? Hiss? Random noise? Irregular? If its irregular and crackly it could be the tweeter level control. Not enough data here to diagnose.
     
  9. Doug Parent

    Doug Parent Supporting Member

    May 31, 2004
    San Diego, Ca.
    Dealer Nordstrand Pickups.
    What kind of cab?
     
  10. Crossovers can cause random crackles, pops, HF distortion. But they will also pass what an amplifier is sending them to the mid or HF drivers, no matter if it is from the amp itself, effects or bass. ;)
     
  11. Doug Parent

    Doug Parent Supporting Member

    May 31, 2004
    San Diego, Ca.
    Dealer Nordstrand Pickups.
    Exactly. If a tweeter makes any noise whatsoever it usually indicates the problem is elsewhere.
     
  12. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    The cab in question is a MarkBass 104-HF-4. The issue does not arise from any bass, cable, or amplifier, the issue lies exclusively within the cabinet. I would describe the static as somewhat similar to dust on a record. It is somewhat irregular, but is present when playing loud and seems to vanish when the tweeter is turned down. I suppose it could be the control.
     
  13. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    Could also be dust in the diaphragm
    Disassemble and clean may fix it
     
  14. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    The midrange is fine (thankfully because I do not want to disassemble it).

    I am bumping this thread instead of the other one in hopes of some more assistance.
     
  15. Most likely to be defective in a crossover are caps or L-pads, followed by resistors with inductors being extremely unlikely. I have even seen protection lamps cause cutting out but not a static noise without also cutting out.
     
  16. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    How can I test an L-pad? (That is a tweeter control, right?) Just hook up the multi meter and test the resistance?
     
  17. Yes that is the tweeter control. The best reliable way to test is with an oscilloscope with the cab IN OPERATION. Other than that, sub in a new L-Pad.
     
  18. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    An easy way to test a tweeter is to connect it to a small headphone amp, like in an iPhone, and play recorded music through it. It should sound like the music but very very thin and sharp.
     

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