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Discussion in 'Archived Threads 2001-2004' started by Haris Ellahi, Jan 23, 2003.
When woofers/drivers of main speakers (not subwoofers) "pop" or "fart," what does that mean?
You are overdriving them and they are showing audible signs of distress. Permanent damage is imminent at this point.
Any magnet driven cone has a maximum throw (excursion)-- the max distance the woofer can be pusted outward. When it hits this point, it will often make an unpleasent noise (because it is trying to vibrate a full cycle to complete a wave- and insead it hits its max and clacks).
So, it just means the full travel of the driver has been exploited, and you are overdriving it.
Maybe it had a big bowl of chili for dinner...
Nice thread "fart" Patrick!
Aaron James Garman
Treating your connections with "Beano" may prevent that though
When my Woofer (A Female Doberman Pinsher) Farts we usually
vacate the room! (Quickly!)
If a Driver Bottoms out (the motor structure pulls the
driver down past it's mechanical suspension travel) it will
make a loud *CLACK* sound as the Voice Coil Former
physicaly touches the T-Yoke (Magnet Backing Plate). This
can cause the Voice Coil Former to bend or warp from the
blunt force (The Former is usually Kapton or some sort of
Pressed Paper Material) If the Voice Coil Former is bent
then the voice coils will also be bent which can cause them
to drag inside the Magnetic Gap and will ultimately lead to
a short circuit as the Voice Coil repeatedly rubs against
the Magnet and rubs the Shelacking off of the Voice Coil
Wire and ultimately shorts out.
When the driver is overextended the opposite way (outwards)
the Surround will often make a very loud *POP* sound
as it is traveling further than it was designed to do. Over
Extending the driver this was is slightly "safer" because
the surround usually won't let the driver go any further.
But if the surround is not strong enough to stop the force
of the moving cone it can cause the surround to tear, or
seperate from the cone (it would most likely tear first as
the glue they use to bond a surround to a cone is fairly
strong stuff). And if the Motor Structure is strong enough
it is also possible to dislocate the whole Voice Coil/Former
assembly from the underside of the cone.
Either way, Pushing a driver past it's linear suspension
travel is BAD and if you hear that sound then it's time to
quickly turn the volume down and figure out why it is that
you care causing this to happen.
Lets say that this is due to amplifier clipping. Will this cause more damage to the speaker or the amplifier?
When an Amplifier clips it sends out square waves (imagine
an ocean wave.. Nice and rounded crests.. Now lop off the
top and you have a rounded slope with a flat top) Square
waves will fry tweeters instantly if they do not have
protection circuits (and still even with protection it could
still fry it..)
Clipping the Amp it's self can ultimately lead to failure
from just driving them amp too hard but it doesn't happen
as "instantly" as speaker damage will.
If you are getting Popping sounds from a Mid Range or a
Sub Woofer and the cone is moving a good deal, chances are
you have too much power, rather than not enough.. When you
tend to clip and amp is when the speaker can barely be driven
with the amplifier at full gain (the speaker is hardly moving)
but it's being sent a clipped signal because the amp is
trying to work too hard.. The speaker tries to reproduce
the square waves and will ultimately fail from heat damage
to the voice coil..
For how long would I have to keep "playing" the speaker like that to damage the woofers/drivers?
Brett, take a look at this link regarding clipping...thoughts?
Very GOOD read!
The problem is as the article states, today even the cheapest
of amplification units are far better dynamicaly then they
were 10 20 years ago. Clipping is not easily heard by a
novice or a pro when you have amps capeable of wide dynamic
ranges from practicaly zero cycles clean up to 100 thousand
I stick by the rule that too much power is never bad but
not enough power is a very bad thing. It's better to have
way more head room than you will ever need, and run the gains
low.. Then to have too little power, run gain full and cause
the amp to be overdriven and start sending out clipped
Some tweeters are a little more "stable" with square waves
than others, Ribbons can handle somewhat square waves but
Dome's can't do it they just give up the ghost in no time.
When the day comes that a speaker can faithfully reproduce
a Square Wave, that is the day that all of this clipping
talk becomes a thing of the past.
never hurts to have more power...ask California
Ohh don't even go there... California is the reason the
company I work for is on the verge of Bankrupcy! (I work
for a Power company and Cali screwed us big time!)