I think I destroyed a speaker

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by 56_Special, Jun 15, 2008.

  1. 56_Special

    56_Special Member

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    I have an Eminence Cooperhead that I wanted to break in. So I get a frequency generator on my computer and I set it for 60hz. I come out of my soundcard into a Crown XS500 power amp. From the Crown I go into the speaker which I have sitting face up on my desk. I turn on the signal generator and turn up the power amp until I see the speaker working nice and hard. It's loud but by no means deafening. I go take a shower and then go downstairs to do some reading. All the while I hear the speaker humming merrily away. Then I don't. I go upstairs and find that the speaker is still vibrating but not at the low 60hz frequency. I load it into a guitar cab. No bottom end, all treble. I guess I over did it. My question is, what exactly did I do to it? There is no visible damage. Is there any repairing it?
     
  2. solitaire

    solitaire Senior Member

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    There's always a safety measure to have the speaker mounted in an amp or onto a baffle. In an open air situation you don't hear how loud the speaker plays and no resistance to work against the cone excursion will be greater. Still, the Copperhead is good for 75W so it should withstand a great beating out-of-the-box.

    Looking at the specs it's stated its usable frequency range goes from 70Hz and up. This could also be why the speaker gave up; what seems to be small vibrations may have several Watts behind it.

    Breaking in speakers should really be done at certain power levels. Your amp being good for 500W clean just a touch on the volume knob can make or break a speaker.

    It could actually be a manufacturing error. Either way what happened was probably a wire insulation of the coil melt and the magnetic force isn't strong enough to drive lower frequencies that require more power. The speaker should not be very loud either. However if it is as loud it should be, then I would come up blank...
     
  3. 56_Special

    56_Special Member

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    Hey thanks for the info solitaire. No doubt I was over aggressive. Yeah, the volume dropped a bunch. So I fried the coil? I guess it's a lost cause now.
     
  4. phyrexia

    phyrexia Member

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    a lot of speakers are rated for stuff over 100hz. You can fry an EV 12L with 150w if you're playing a bass through it and you hold your mouth right. I bet that's what happened.

    Why didn't you set your frequency generator to something more guitarlike? Even 100 or 150hz seems like it would have been more appropriate.
     
  5. testing1two

    testing1two Gold Supporting Member

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    This is just my opinion, but a sine wave generator is the wrong way to break in a speaker. There are differing opinions about whether to use pink noise or white noise or program material. Personally, I think using program material (some music with decent bass content) will do the trick. Since you have upper frequencies in the mix, you will be able to set the volume more accurately and avoid these kinds of mishaps in the future. FWIW, I would also do this with the speaker in the cabinet to identify any possible rattles or unwanted vibrations.
     
  6. DIXØN

    DIXØN Member

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    I would personally record some guitar jammin' onto my PC, load the speaker into the cabinet, then wire my PC into a basic solid amp, then into the cabinet. That's if I had the time to break in speakers, if not then I would just use it at low level for home practice for a bit before cranking it for full band practice or gigs.
     
  7. 56_Special

    56_Special Member

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    I got the idea of a 60hz sine wave from Ted Weber who uses a filament transformer which generates a 60hz frequency. Of course, he's smart and he measures the amount of voltage that he's putting across the terminals so he knows that he won't blow it up. It don't think that high frequencies would do much to break in a speaker. The thing has move in order to loosen up!
     

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