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Not possible to blow amps/speakers.

Discussion in 'Amps and Cabs [BG]' started by Zolbol, Oct 22, 2010.


  1. Zolbol

    Zolbol

    Jan 26, 2008
    South Africa
    Hiya TB.

    Before i start it must be known that i am not qualified in any way to offer any technical support to my question. I do have some electrical knowledge and i understand the concept of moving power/signals/whatever in an electrical circuit.

    So.... dont flame me:help:

    How is it possible to blow an amp or a speaker. Why is there not a protection device of some sort at all / any points where overloading / overpowering may cause system failure. I know some / all amps have fuses but then so should speakers. It just baffles me how in this day and age one can still blow a speaker or an amp from a cause that is surely protectable?

    Please if i got the concept completely wrong help me out?? :ninja:

    And another thing - My volume knob goes to 10 so surely playing it at 10 should not damage anything. If it was designed to go to 10 and the knob says 10 then frankly i dont see why there should be a problem. Honestly never played my amp that loud but you always hear someone go "you cant crank it all the way, it'll blow"

    WHY?

    If someone wont mind seperating myth from fact for me, It would be most appreciated.

    Btw in my 33yrs i have never blown any piece of electronic equipment... but then again I never play at 10 :D:D:D

    Again if I'm an ignoramus enlighten me please:)

    Rock it!!:bassist::bassist::bassist:
     
  2. BrBss

    BrBss

    Jul 9, 2010
    Albuquerque NM
    Some speakers, especially PA speakers, do have fuses built in to limit the current that can flow through them. Also, many amps are designed to shut down if they overheat or are driving too low of an impedance.
    This is much like always driving a car with the gas pedal pressed firmly to the floor. It can do it, but it adds a lot of wear and tear.
     
  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Amps have parts. Parts can fail. Where speakers are concerned they will fail when overpowered. Overpowering can be prevented with the use of a limiter, but bass amps don't have limiters built into them.
     
  4. You can turn your amp up all the way- it won't blow, but it probably won't sound good. But it might. Why have it be able to go so high? So it will work with a variety of input levels.

    Speakers can't be effectively protected by fuses. The fuse would have to be a high enough value that it wouldn't blow on high-current peaks, which are generally harmless to speakers. But if it were this high a value, it also wouldn't blow during continuous high-current use, which is harmful to speakers if too high. Hard for a fuse to know the difference.

    Tweeters, by the way, are often protected by 'fuses' comprised of low voltage light bulbs. These work by getting hot during overload events(sometimes even lighting up), and this increases resistance to current. Self-limiting this way.
     
  5. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    i think most musicians would rather have amps and cabs that allow for blowing rather than have them limited and squashed. so to meet the needs of the marketplace, they often don't have protections built in. of course the catch is some end up blowing them.
     
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    When well done limiting is inaudible, right up to the point that it keeps your speakers from getting toasted. Amps don't have limiters because that would bump the price.
     
  7. Jazz Ad

    Jazz Ad Mi la ré sol

    Many amps at least claim to have limiters. Are they not efficient?
     
  8. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    A true brickwall limiter can be adjusted to allow the amp to produce a specific output voltage swing and no more. AFAIK no electric bass amp has a limiter with that capability.
     
  9. Zolbol

    Zolbol

    Jan 26, 2008
    South Africa
    Thanks for the replies guys - making a bit more sense now.

    Then they should all come with some sort of limiter lol.

    Ok that makes sense thank you:D

    Even more sense lol..

    Ok i get it - limiting is basically the only way then.. I think my limited knowlege of signals and all is whats hampering me a bit though.. Ok guys I'm going to talk layman here alright

    Lets just say that speaker X blows at 7 bubbles a second :D, surely a limiter then set at 6.8 bubbles a second will suffice and is not going to squash or affect tone cos its only going to kill the signal when its at 6.8, never before. So i spose if you keep hitting the limiter its time for a bigger amp. I dont know that sounds flawed too hahahaah

    I'm in over my head lol :help:
     
  10. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    a lot of amps do have built in compressors, and in the vast majority of them, they suck. i don't expect any better for limiters.
     
  11. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Agreed.
    Spend some time with a good FOH engineer.
     
  12. Zolbol

    Zolbol

    Jan 26, 2008
    South Africa
    My point!

    Ok so on another thread recently posted, bass going through the desk,the singer says
    bass too soft and whacks the fader - basser smells smoke and now got some wild fuzz coming out of the monitors. Voice coil blown it sounds like, according to replies.

    I cry foul - shouldn't happen, not in 2010.

    Lol - does anyone at least half agree with me??

    Thats all
     
  13. Zolbol

    Zolbol

    Jan 26, 2008
    South Africa
    Would it be correct to say that a compressor works on the input signal and a limiter on the output signal??
     
  14. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Pigs should fly too. Who's with me? ;)

    Vote with your wallet. Not enough other players are doing that, or it would be closer to what you want.
     
  15. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    i'm talking about built in amp limiters, not limiters in general. a good one will work great and sound very musical. i'm not expecting that in bass amps.
     
  16. JohnMCA72

    JohnMCA72

    Feb 4, 2009
    Numbers on a volume knob don't mean anything. I've blown speakers with the vol. on '2'.

    BillF: I think Jimmy's comment about not expecting better from a limiter was a reflection of amp manufacturers, not sound engineers, i.e. those who would install a crappy compressor are just as likely to install a crappy limiter.
     
  17. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    Problem with fuses is that if one blows and you're driving one with a tube amp, the impedance seen by the output transformer will suddenly go to infinity, and all the energy of the output stage will be reflected back into the primary winding. If it's only for a few seconds, maybe no harm done, but still... :eek:

    Also, a fuse properly sized for safe power margin may be way oversized to protect against overexcursion, especially where you've got a reflex cab that rolls off (unloads) early and [DEL]and[/DEL] an ill-informed operator's trying to make up for that [DEL]will[/DEL] with heavy use of bass boost -- either in the amp or in his active bass or both.
     
  18. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    And before someone jams me up on that, I was assuming one cab and one fuse. If there were two of each, and only one blew, the "seen" impedance would only double, assuming a parallel connection. Bit of a cushion there, comparatively, but still not the best way to do things.
     
  19. Singers should never be allowed to touch any audio equipment except the microphone. Ever.

    Speakers are not always sold with the amp that's powering them. Lots of mix and match. There's an enormous variety of different speakers and different amplifiers. The amplifier may be capable of putting out far more power than the speaker can handle.

    It's up to the user to learn how not to abuse equipment.

    Who would you blame if you had a car with a manual transmission, and the same singer screwed it up by driving down the highway with it floored in first gear? Would you blame the manufacturer for making a car that can be screwed up this way, or would you blame the dude who burned it up by using it in a way it was never intended to be used?

    Even cabinets designed to be used with a certain amplifier can often be broken by said amplifier, if you do something really stupid like turn it all the way up and boost the lows all the way up. That's a great way of blowing speakers, and unless you know for sure your gear can take it, it's a pretty idiotic thing to do.

    Speakers especially are vulnerable to this, but like cars, they often make unpleasant noises when you're damaging them. Speaker farting is as unpleasant to the ears as it sounds. The assumption is that most people will not do idiotic things to their gear, and even if they do, will pay enough attention to hear when it sounds awful.

    Amplifiers have parts, lots of them. They're not exactly the most simple of machines. Many of these parts, just by the amplifier doing its job, are repeatedly subjected to very large amounts of electrical power, and in being used are also subjected to somewhat high heat, depending on the type of amplifier.

    Doesn't just about every car need to go to the shop once in a while, even if it's a good car? Why expect amplifiers to magically never have parts wear out, when that happens to basically everything that has parts?
     
  20. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Me neither, as it would bump the price by $100, and no one would pony up. Perhaps when DSPs show up in bass amps.
     

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