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Rig shutdown at Gig... any ideas what went wrong?

Discussion in 'Amps and Cabs [BG]' started by ::::BASSIST::::, Oct 15, 2009.

  1. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    They do but I don't know where to get them, plus they really don't protect from the elements. What they do protect from is the occasional whistling and distorted sounds you can get from unused speaker jacks.
  2. +1 on checking the speaker cables (I carry an extra speaker cable as well), you may have a loose connection.
  3. MNAirHead

    MNAirHead Supporting Member

    Many things can cause one to pop off.. some will shut down the amp.. some just parts of it.

    Many things can cause one to heat.

  4. Only one sure answer:


  5. SpamBot


    Dec 25, 2008
    St. Paul, MN
    If your cab worked untilted but didn't tilted, open it up and check the solder connections. It's possible that they are not solid. Check both the jack connections and the speaker connections.
  6. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    The little speaker hole plugs are available both at Lowes and Home Depot, in the section with the drawers of all the little miscellaneous screws and nuts. That's where I got mine. Like twenty cents each.

    Also, my rig once shut down 4 songs into the first set. I use a pre/power setup with a QSC 3002 power amp. Turned out the fan wasn't running. No reason, and it never happened since. It just didn't want to start that day when I powered the amp up, and it went into heat protection in the 4th song. Over a year later it never happened again. Go figure.
  7. I think MarkBass has a protection system for low/wrong voltage that kicks in and stops the whole unit from receiving any electrical power (someone from MarkBass could verify this.) Kind of good for protecting gear, but bad in case you are at a gig and it happens... Then again it is good, anyway.

    I'm always weary of bad AC outlets at venues, humming, power fluctuations, those places are badly wired, anything could happen. I also try to find an unused outlet far away from other equipment in case there's a lonely 10Amp fuse trying to take care of a huge load, blowing up. Find a separate outlet somewhere else minimizes this risk.
  8. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    I was the only one using the outlet and all I had plugged in was my LMII. No effects or anything.

    It *could* be the building as it is fairly old. (The Railway downtown Vancouver). However, the band after us was fairly loud > 2 guitars, bass, keyboards and three vocalists and they had no trouble.
  9. My gut feeling is that it's the amp. My Carvin BX500 suddenly last week decided to go into protect mode twice, where it shuts down totally then comes back on 10-15 seconds later. After checking everything from connections to cabs, I returned the amp to Carvin for a new one. They are sending it in with a notice that a component is going out inside of the amp. Those things happen.

    One side note, what's with the bandleader jumping on your case, it's not like you don't have enough to deal with when your gear is on the blink - Geeesh!!:rollno:
  10. Thor

    Thor Gold Supporting Member In Memoriam

    Is the DI pre Eq or post EQ. If the DI was working wouldn't
    that mean that the preamp was working and the fault
    potentially lies in the power amp?

    Yes, I would definitely open the cab and check the internal
    wiring and the wiring at the connector on the jack plate.
    Though I find it unlikely that moving that back home would
    have fixed that.

    My gut feeeling is thermal overload.
  11. svtb15

    svtb15 Banned

    Mar 22, 2004
    Austin,TX - McKinney,TX - NY,NY, - Nashville,TN
    I play it all. Whatever works for the gig. Q+
    My cop friend who also plays bass has a LM800 tube and the same thing happened to him today.... He said it just shut off.. but after he turned it off then back on his was OK... I think his is a class D though
  12. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Yeah the bandleader was a bit frustrated because he said he could not hear his guitar. (He didnt want to turn up because his amp was mic'd and he thought that would effect FOH).

    What happened is that I asked the sound guy to turn up my monitor so I could hear *some* bass, but I think that added bass into my bandleader's monitor as well. As it was I had to stand on the edge of the stage to play by the FOH, which I could barely hear from my vantage point. I was mainly playing by vibration. Not fun.

    I'm glad it was only a one set / one hour gig.
  13. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    I think I set the internal jumper to post eq, but its been so long I really dont remember.
  14. klyph

    klyph Supporting Member

    Mar 28, 2009
    My digital amp gets "much" hotter when I run a higher impedance (8 ohm ) cab. Even gets pretty warm with a 4 ohm load. It seems to be happiest (cool as a cucumber) with a 2 ohm load, regardless of volume (gets HOT even at low volumes into a single 8 ohm cab). I haven't yet had the pleasure of gigging with an LMII, but maybe trying to get the same spl from a single cab generated enough heat to trigger a themal shutdown. At least you didn't damage anything!

    Isn't the LMII a Class D?
  15. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
  16. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    LMII is AB. F1 is D.
  17. figuredbass

    figuredbass Supporting Member

    Jul 11, 2007
    NYC vicinity
    My first thought was the same as some others had - bad power (usually too low a voltage) that may have set off the power amp section's protection circuitry prematurely. I've been on gigs where some keyboards could not even boot up because of insufficient power, yet all the other amps still worked fine.

    However, when Eric mentioned that his QSC had shut down on a gig because the fan wasn't turning, it suggested to me that if that had somehow happened to your LMII on this isolated gig it would have probably caused the amp to go into thermal shutdown. Due to the nature of the design, class AB power amps like the LMII's still dissipate heat even when there is NO signal going into (or coming out of) the power amp, which could also explain why the amp didn't "recover" in a relatively short time when you stopped playing through it. So if something prevented the fan from turning, either physically or if the internal connection to the fan got loose, that *could* have been the culprit. So you may want to check the fan too. Just another thought..
  18. your idol

    your idol

    Oct 13, 2008
    Murfreesboro TN
    jealous guitarist sabbotage
  19. Ric5

    Ric5 Supporting Member Commercial User

    Jan 29, 2008
    I grow organic carrots and they are not for sale
    Could it be a cold solder joint? That could cause intermittant failure.
  20. John Wentzien

    John Wentzien

    Jun 25, 2007
    Elberta, AL
    Artist:TC Electronic RH450 bass system (original test-pilot)
    The fan might be dusty.
    Blow it out with some "canned-air"

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