1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Tweeter damage

Discussion in 'Home Cinema Speakers' started by higenbs1, Mar 17, 2003.

  1. higenbs1

    higenbs1
    Active Member

    Joined:
    Aug 16, 2002
    Messages:
    460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Ratings:
    +11
    I know it's a strict no-no, but does anyone know if it's possible to damage your speakers tweeters by having the treble up to high.
     
  2. Mark Ward

    Mark Ward
    Member

    Joined:
    Sep 12, 2001
    Messages:
    1,796
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    41
    Location:
    Kent
    Ratings:
    +18
    Does anyone use Bass and Treble controls? As far as damaging your Tweeter, I wouldn't imagine adjusting the "Treble" control would be the cause of any problem, maybe the sheer volume you played at?

    What speakers and what amp is powering them?

    I blew a tweeter in one of my Celestion A1s, I'm pretty sure that it was during a stupidly loud (+0) session demoing "Mission Impossible 2". I cut to the start of the scene where Mr. Cruise is climbing the rocks near the start. The scene starts with the end of an explosion from the previous scene. Even at lower volumes the initial sound from that chapter seems like it wouldn't be kind to a tweeter going from 0 output to intense volume instantly.

    It wasn't very expensive to replace BTW, and very easy.

    Can I add a sub-question. Can source material harm speakers?

    Mark.
     
  3. higenbs1

    higenbs1
    Active Member

    Joined:
    Aug 16, 2002
    Messages:
    460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Ratings:
    +11
    It was using a Denon 1602 and a pair of Eltax Liberty 5's. I don't think it was played a high volume, but I noticed that the amp treble was turned up to full.
     
  4. dts_boy

    dts_boy
    Well-known Member

    Joined:
    Nov 26, 2001
    Messages:
    2,512
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    86
    Location:
    Manchester suburbs...
    Ratings:
    +141
    i'm guessing from cold any speaker is more vunerable to damage, saying that i have never blown any of my tweeters thankfully - i try to raise the volume after 5 mins and then watch a film:smoke:
     
  5. NicolasB

    NicolasB
    Well-known Member

    Joined:
    Oct 3, 2002
    Messages:
    5,804
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Emily's Shop
    Ratings:
    +520
    Try playing a CD-ROM data disc in your CD player and find out.
    :devil:

    As often observed before, most speaker damage problems are caused by having an amplifier that isn't powerful enough. But if you want to shove a high-amplitude 22kHz square wave through your speakers then that certainly isn't going to help.
     
  6. snelly

    snelly
    Standard Member

    Joined:
    May 24, 2002
    Messages:
    227
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    Berkshire
    Ratings:
    +3
    Treble / bass controls damaging a tweeter eh...

    Well if you think about it when you use a treble control you are basically asking the amplifier to exaggerate those tones - this it does by calling on more amplification and hence more power. If you had the amplifier at listening levels where the amp was running cleanly and then demand a 10db increase in treble (requiring a ten fold increase in power) you can easily push the amp into clipping (do a search if you are not sure what this is as there are many good descriptions) where basically the amp runs out of power before it should, and you end up sending DC (or squarewaves) to your speakers instead of nice treble frequencies.

    The tweeters normally die before the woofers anyway as they heat / burn quicker.

    At least thats my take on the situation...

    HTH

    Tim
     
  7. Sunday Ironfoot

    Sunday Ironfoot
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Can playing ultra ultra low frequency sounds, to the point where you can actually see the bass/mid speaker cone move in and out at a good 2-3cm at say 2-5 times per second, damage this speaker cone?
     
  8. NicolasB

    NicolasB
    Well-known Member

    Joined:
    Oct 3, 2002
    Messages:
    5,804
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Emily's Shop
    Ratings:
    +520
    Not if it's a smooth (e.g. sinusoidal) wave. The problem with bass is that the ear becomes much less sensitive as the frequency drops off, so what sounds the same loudness as a higher frequency sound actually requires hugely much more energy to sustain.
     
  9. snelly

    snelly
    Standard Member

    Joined:
    May 24, 2002
    Messages:
    227
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    Berkshire
    Ratings:
    +3
    I would agree with NicolasB but make this slight addition.

    In normal operation the heat is dissipated from the speaker fast enough to prevent any damage occuring. This process is helped by the fast movement of air around the voice coil. If the speaker 'stalls' in clipping i.e. it is just hanging without movement ath the top of a square wave damage can occur. Additionally if a very powerful amp is driving it cleanly past the point of normal operation then the surround of the cone can be taken past its point of normal linear excursion. In effect the cone will nto be moving as far as the signal dictates it should because the surround is restraining it. In this case I can imagine that you could either overheat the coils *or* damage the surrounds.

    Tim
     
  10. NicolasB

    NicolasB
    Well-known Member

    Joined:
    Oct 3, 2002
    Messages:
    5,804
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Emily's Shop
    Ratings:
    +520
    It's not so much the fact that the cone is motionless during the flat section of a square wave, it's the fact that it has to make the transition from moving extremely fast to being absolutely stationary (or vice versa) in almost no time at all. If you imagine yourself pushing something heavy to and fro at varying speeds, it's relatively easy to do if you've got lots of time to speed up and slow down. It's hard if you have to make it start or stop immediately.

    It's certainly true that you can damage speakers by driving them too hard and pushing the cone beyond its intended limits, but this is actually quite difficult to do in practice. You could probably drive the speaker to the point of distortion by using an amp that's too powerful and turning the volume up, but actually damaging it would be hard. By contrast it's really quite easy to damage a speaker by using an amp that isn't powerful enough and turning the volume up loud.

    It is certainly the case that if you ever hear the sound of your system beginning to distort at high volumes you should immediately turn it down. Doesn't matter whether it's the amplifier clipping or the speaker being driven into a non-linear response, either one is bad news! :eek:
     
  11. snelly

    snelly
    Standard Member

    Joined:
    May 24, 2002
    Messages:
    227
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    Berkshire
    Ratings:
    +3
    NicolasB,

    I understand that the inertia of the cone and the kinetic energy it has make it difficult to stop but, how does this, in particular, cause damage???

    I mean that as a question, not a challenge! I'd like to know

    Tim
     
  12. Sunday Ironfoot

    Sunday Ironfoot
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Could someone explain how speakers can be damaged by being driven by an amplifier that's not powerful enough. I'm not sure I understand the science behind this. Further-more I've told my flatmate this and he's not convinced. Could someone provide me with a detailed answer so I can tell him.
     
  13. EvilMudge

    EvilMudge
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    When you drive an amplifier to it's maximum voltage (clipping it in audio terms) the voltage remains flat for quite some period of time. This sends a DC voltage through the crossover network, rather than an AC signal. This causes the tweeter to move further than it normally does, and it stays fixed in one place for quite some time, straining the suspension and causing the voice coil to heat up. Eventually the process causes one of the components in the driver to fail, either due to heat or mechanical stress.
    HTH
    Blowing a woofer requires much more skill.:devil:
     
  14. BK Electronics

    BK Electronics
    Active Member AVForums Sponsor

    Joined:
    Aug 10, 2002
    Messages:
    376
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Essex
    Ratings:
    +25

    I would have to disagree slightly to this theory, as Dc should not be able to get through to the tweeter as capacitors will be in the filter blocking it. What does happen with a clipped signal is that it can closely resemble a square wave, the leading edge and falling edge of the wave are at very high frequency and easily passes the crossover network into the tweeter, or under these conditions the FUSE
     
  15. EvilMudge

    EvilMudge
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I stand corrected. However I can't see how the power produced by the edges of the square wave would be enough to kill the tweeter, because it very quickly becomes effectively a DC signal.
    My electronics is a little hazy, because I can't remember what happens to the voltage across the tweeter when the capacitor in the crossover network saturates and then discharges through it. That might be the cause, but I honestly can't remember.
     
  16. NicolasB

    NicolasB
    Well-known Member

    Joined:
    Oct 3, 2002
    Messages:
    5,804
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Emily's Shop
    Ratings:
    +520
    If you want a more mathematical explanation, then think about what happens when you subject a square wave signal to Fourier analysis. There's an enormous amount of energy in high-order harmonics.
     
  17. NicolasB

    NicolasB
    Well-known Member

    Joined:
    Oct 3, 2002
    Messages:
    5,804
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Emily's Shop
    Ratings:
    +520
    Or alternatively, look at it this way: the output signal from the amplifier controls the position of the speaker cone - cone position should (ideally) track the signal exactly.

    The velocity of the speaker cone is therefore the first derivative of the amplifier output; and the acceleration of the speaker cone is the second derivative. What is the second derivative of the signal at the point where there is a sharp corner rather than a smooth curve?
     
  18. Lithian

    Lithian
    Standard Member

    Joined:
    Jan 16, 2003
    Messages:
    38
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    9
    Location:
    Edinburgh 3
    Ratings:
    +0
    'Storm Shadow', a bloke who works at Monster writes a section in Penny Arcade which is called The Hookup

    One of his writings contains a rather interesting description of clipping.

    ahem, i am not sure if all of that will get through the swear filter, but i am sure you get the idea.
     
  19. Sunday Ironfoot

    Sunday Ironfoot
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Thanks Lithian I think I understand now, it's amzing how as soon as you introduce breasts into anything it becomes so much easier to understand :lesson: :D
     

Share This Page

Loading...