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How do you blow an amp?

Discussion in 'Amps and Cabs [BG]' started by froglips, Apr 7, 2009.


  1. froglips

    froglips

    Feb 9, 2009
    Arizona
    Stupid question I know ... But is it usually when you turn the volume up too much, or is it when you have the instrument, gain and volume up too high at the same time?

    Or is it just something that happens because it just happens?

    Thanks
     
  2. Sounds like a good title for a porno flick :)

    Seriously, You can blow the speaker by feeding it too much power over an extended period of time causing the voice coil to over heat and burn out. Or cause it to move farther back and forth than it was designed to move causing some sort of mechanical failure. As for the electronics side of things, turning things up too loud can shorten the life of components by making them operate at a higher temp. (jmho)
     
  3. southernrocker

    southernrocker Banned

    Apr 4, 2009
    with a little TNT.
     
  4. chicago_mike

    chicago_mike

    Oct 9, 2007
    Chicago - LA - Rome
    Endorsing Artist : Genz Benz
    if the amp isnt really meant to be turned past 7 or 8 and you still need more volume..yeah you can blow the power transistors easy. Real easy.
     
  5. I'm really no help here.........

    Just find it really really funny that a guy with a screen name of Frog Lips is asking how to blow an amp :)
     
  6. Dark Horse

    Dark Horse Supporting Member

    Jul 31, 2008
    Austin, TX
    Blowing the amp could be a lot of things. Running it too loud, overloading, overheating, voltage spikes or drops, etc., but most of the time has nothing to do with the instrument - unless you are sending voltage into the input jack. Blowing speakers, more often than not, is do to UNDERPOWERING them ! Most people are afraid of having too much power too them, but having too little power means people crank their amps causing the signal to get distorted (bad distortion, not good distortion!) which can damage the speaker.
     
  7. seamonkey

    seamonkey

    Aug 6, 2004
    It's very hard to blow power transistors these days. Power amps have built in protection including short-circuit/over-current protection, and limiters. Any amp that blows transistors is just cheap or poorly designed. That amp manufacturer should get out of the business.
     
  8. You can blow an amp by sending the output signal to a lower resistance speaker enclosure quite easily.
     
  9. BbbyBld

    BbbyBld

    Oct 13, 2005
    Meridian, MS
    When you say "blow" I'm assuming you mean not just stop working, but actually self destruct. The best failures are ones that set up a chain reaction and really BLOW the amp. :D

    Any decent power amp will protect itself against too large of a load and output shorts. If the manufacturer did their job, you should be able to do whatever you want with the knobs and not hurt the amp. If a modern amp randomly blows, then something was probably wrong with it to begin with. For example, one of the power transistors not being clamped down to a heatsink, or a fan may be installed backwards...something like that. If the amp uses MOSFETs, one of them may have been mishandled at the factory, which can make it weak and likely to fail.

    All of these scenarios assume you have a quality, fairly modern amp:

    If you let your amp become really dirty and dusty inside, OR if you don't let an amp get enough ventilation, that can cause it to overheat and self-destruct.

    You can blow an amp by plugging it into the wrong wall outlet voltage. Along the same lines, some amps will blow if you try to power them with crappy portable generators.

    You can plug the speaker outputs of two amps together--that's a good one!

    If you drop an amp, that can cause problems inside that may cause it to blow.

    It's possible to blow an amp with a defective speaker cable. This goes back to built-in protection, but this can still harm a well protected amp in certain cases.

    Speakers are a LOT easier to damage than an amp.
     
  10. PSPookie

    PSPookie

    Aug 13, 2006
    Ocoee, TN
    Lets not forget running it for an extended period of time at the wrong impedance.
     
  11. JTE

    JTE Supporting Member

    Mar 12, 2008
    Central Illinois, USA
    Wrong load impedance, especially running a solid-state amp into a load below its minimum impedance (e.g. running an amp rated at a 4 ohm minimum into a 2 ohm load). Pushing the amp too loud. Not letting the amp warm up enough after it sits in the cold (i.e. 20 below Central Illinois winter) van for two hours before you turn it on. Physical abuse (banging the amp around, slamming it, dropping it, etc.) Not keeping a tube amp maintained, especially letting the power tubes go. Running a tube amp into no load.

    Lots of times the amp's protection circuits will step in and save your posterior, but don't count on it. The stuff I've seen in my tech work includes mis-matched power tubes, broken and/or burnt resistors (those screen resistors that sit right above the 6L6's in Fender amps are notorious for burning up), shorted outputs (why you shouldn't ever plug and unplug amp outputs while the amp is on!), and the ever popular "I only had it turned up to five!" when they had it nailed wide open and running into a 2 ohm load...

    jte
     
  12. kevinjack

    kevinjack

    Oct 3, 2008
    nashville tn
    he is very right i was in a classic rock band and was playing with a little 180 watt behringer combo amp. i would always have it turned up couldn't hear it. sooo i went out and got the svt-4pro and and 8-10E now i can over power both of the guitars if i need to but i dont. the other think is that a lot of the newer amps will have a clipping control on them which makes it hard to blow speakers with it on.

    you could blow it by like having and SVT-4Pro and then just having like 1 -10 inch speaker and just crank every thing and turn off all the safty stuff on the 4pro. that should do it
     
  13. Jaco who?

    Jaco who?

    May 20, 2008
    Oh god, here we go again....... If you could blow speakers by cranked underpowered amplifier distortion, guitarists with 50W Marshall stacks would be constantly replacing woofers. Search the forums and decide who's opinion is the most valid, since mine's usually pretty questionable, but this is a myth that just never seems to go away.
     
  14. jgroh

    jgroh Supporting Member

    Sep 14, 2007
    Pennsylvania
    well first you give it a roofie-collada then tell it "im not going to hurt you, im not going to hurt you..."

    =)

    Ahhh, cmon...that one just wrote itself with that title!
     
  15. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    No bass driver was ever damaged by too little power this is a myth that has to die.
    Square wave or clipped wave forms have no adverse effect on low frequency drivers within their thermal handling.
    Thats why turning on a fuzz pedal at the same apparent volume that the power amp can do clean will not blow the bass driver or amp. however if you use a clipped signal at a level that also clips the output stage of the amp you are vastly overdriving the amp and speaker.
    As the output in watts is measured at maximum clean not maximum dirty. Depending on the design of the power supply this might be as much as twice the amps actual rated power.
    The only proviso to this is where a very hard driven amplifier may start to create an offset or not return the loudspeaker to the at rest cone position in the center line of the original.
    But DC offset is not a problem for well designed amplifiers operating within spec.
    If Under-Powering was an engineering fact your loudspeaker would have blown before it was ever put in a cab or even connected to an
    amplifier. Its not science:spit:
     
    Roadstar likes this.
  16. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Thank you. Please, myth, just die already! [​IMG]
     
  17. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    That was my first thought too. :p
     
  18. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Rochester, NY
    -A bad speaker cable does the trick nicely.
    -A tube amp without a speaker load never ends well.
    -Some amps just aren't a fan of phantom power.
     
  19. PSPookie

    PSPookie

    Aug 13, 2006
    Ocoee, TN
    That's just plain silly. Everybody knows that you need magical bad distortion in order to cook your underpowered speakers . . . duh
     
  20. Phalex

    Phalex Semper Gumby Supporting Member

    Oct 3, 2006
    G.R. MI
    Mine just got old.
     

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