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I think I killed my cab

Discussion in 'Amps [BG]' started by Crypt Ghast, Dec 2, 2013.


  1. Crypt Ghast

    Crypt Ghast

    Dec 2, 2013
    Vancouver
    Yesterday I was jamming and all of the sudden, my cab stopped working. I have a 4x10 SWR Goliath and a SWR WorkingPro 700W head. From what I could tell, I hadn't done anything that I hadn't done with the amp before. All of the sudden, it distorted my sounds for a second, then cut out. Then it started smoking from the port in the back (not much smoke though). All of the sound cut out at once, so I don't think I blew the speakers(? Maybe? I don't know, but blowing all of them at the same time seems unlikely). I figure it's either the crossover or the voice coils. The distorted sound i think was it clipping.
    Can anyone help me out with this?
    (And I would add pictures of the crossover but it's not letting me :/ )
     
  2. Have you ever smelled a burnt out speaker of that size? It's a sickly sweet kind of smell. If you've smelled it before you would know. The smoke is not a good sign.

    Is it possible that you blew out just one speaker and it's wired so that the others cut out, but are not damaged? I'm not an expert on this, nor do I know much about your rig. Hopefully someone does.

    Now, distortion can come from cold solder points in your head. Is it old? Seen abuse? Temperature fluctuations? I had a head (preamp) repaired due to this. It was an easy, cheap fix. The thing was over 10 years old, and sat in the corner as a backup, or was in storage, so it made sense.

    However, distortion and smoke sound speaker-related to me. I hope I'm wrong, but, well, where there's smoke, there's at least a problem (thankfully no fire though!).

    I hope that will help you narrow down the problem; help you isolate it and fix it. Cheap. Hopefully... Good luck!
     
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  4. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Disclosures:
    Endorsing: Ampeg Amps
    You have to use an outside site like Photobucket to post pics unless you reformat your pics to be much smaller than they likely are. Anyway, it's possible you just blew the crossover or tweeter. Pretty sure it uses a light bulb as a fuse. Not enough info to tell for sure, though.
     
  5. Do you have the tweeter attenuator wound on heavily? Quite likely it's that or the crossover fried and a relatively cheap fix.

    Assuming woofers are ok you can get get going again quickly by unhooking the crossover and hooking the woofer wires direct to the cab input.
     
  6. Crypt Ghast

    Crypt Ghast

    Dec 2, 2013
    Vancouver
    [​IMG]
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    Maybe these pictures will help. Something is broken inside the bulb. And to be honest I don't know anything about electronics and anything related to it.
     
  7. BawanaRik

    BawanaRik Supporting Member

    Mar 6, 2012
    New Jersey
    Take it apart and follw your nose. Take pictures and use a marker. Take notes so it goes back the same way it came apart.

    This might be an easy fix.

    I've never had a speaker flame on so it might be something else.
     
  8. Blown bulb, symptom of a blown bulb. I very much doubt that's the end of it.
     
  9. Crypt Ghast

    Crypt Ghast

    Dec 2, 2013
    Vancouver
    So if the bulb is blown, does that mean it's a crossover issue? Or does the blown bulb at least mean that it's not a speaker issue?
     
  10. Fawkes007

    Fawkes007

    Sep 13, 2005
    SF Bay Area
  11. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    The bulb is a protection circuit for the tweeter. If you smelled burning you make have done more damage than just the bulb. You can check the speakers physically or with a meter. If you push on the speaker cone and it doesn't more or if it feels like it's grinding/rubbing you may have blown that/those speakers. You could also check the speaker impedance with a volt meter. If you can't get a reading then the speaker coil has failed.
     
  12. Blown bulb should only affect the tweeter. It could have been already blown, you need to dig deeper.
     
  13. I suspect the crossover will be toasted, mucking up any testing with a meter until it's removed.
     
  14. paparoof

    paparoof Supporting Member

    Apr 27, 2011
    Minneapolis
    Disclosures:
    fEARful koolaid drinker
    Obviously the bulb/fuse is pooched. Was it a lotta smoke? Maybe the smoke was just that melty wire that's sitting on the bulb (move the wires to better locations, and replace the melty one).

    Do the 9v battery test on each speaker, one at a time. If they jump from the battery, then run some low level signal through them (one at a time) to see which ones make sound and which ones dont.
     
  15. I think you'd be jumping the gun testing woofers individually, that's a lot of work unbolting that is unnecessary at this stage.
     
  16. No way all four woofers blew, unless there was a catastrophic amp failure. Which is possible. Proceed with care.
     
  17. Mr. Foxen

    Mr. Foxen

    Jul 24, 2009
    Bristol, UK
    Disclosures:
    Amp tinkerer at Ampstack
    Have you checked the amp works with something else, might have done that, and then that took out the bulb. Also possible the bulb has been blown for ages and you've just been going without a tweeter.
     
  18. B-string

    B-string Gold Supporting Member

    Just to be sure, you are using a SPEAKER cable and not an instrument cable?
     
  19. Crypt Ghast

    Crypt Ghast

    Dec 2, 2013
    Vancouver
    I'm not quite sure how to access the speakers. I don't know how to take off the grill. And it's a speaker cable.
     
  20. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    Disclosures:
    GreenBoy fEARful kool-aid dispensing, AFM 72-147 union card-carrying, liberal, academic, musician
    Test amp. I bet the x-over bulb has been dead for >25 years. This is a goliath II (or maybe a goliath I). They are wired in a series parallel circuit. If one driver is disconnected, there is a fair amount of distortion from it's mate. There is a wiring diagram somewhere around here...

    Here is a "Product Description":

    The first upgrade to our original 4x10, featuring a redesigned crossover, input panel, and 10" driver, greater power handling capacity (500 Watts RMS), and upgraded construction techniques and materials. The Goliath II was upgraded again in 1996 to the Goliath III.

Impedance: 8 ohms @ 600 Hz
Power Handling Capacity: 500 Watts RMS
Sensitivity: 103 dB SPL @ 1W1M
Frequency Response: -6dB @ 40 Hz and 12KHz
Safe Excursion Limits: 400 Watts continuous sine wave @ 40 Hz, 56V in @ 8 ohms.
Size: 23" W x 23" H x 18 1/2" D
Weight: 90 lbs.
    Production Period: 1990 to 1996

    4x10" - Impedance: 8 ohms @ 600 Hz - Power Handling Capacity: 700 Watts Continuous Program, 500 Watts RMS continuous pink noise, 40 Hz to 10K Hz, 8 hours - sensitivity: 103 dB SPL @ 1W1M - Frequency Response: -6dB @ 40 Hz and 12KHz
     
  21. BawanaRik

    BawanaRik Supporting Member

    Mar 6, 2012
    New Jersey
    That's pretty good advice. It's easy to get distracted from the basics.
     



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