Holy crap! WTF happened to my IDMAX ?????

[95Prober 10+ year member]

It's possible the basket was bent and that the surround landing, spider landing, and voice coil gap weren't perfectly alined linearly and the voice coil just rubbed itself to death. I would try and figure out exactly what caused the issue before dropping more cash on a recone if it may do the same thing again. The sub very may well have been dropped during shipping and bent the basket just slightly.
If you're sure that the basket is good and want to recone it. Then I suggest taking compressed air or a vacuum and getting all large particles out of the voice coil gap. Then take a business card and put some tape over it with the sticky side out and slide it in the voice coil gap and run it around a few times to pick up any smaller particulates. Lastly, take some acetone or some kind of alcohol based cleaner and wipe it in the gap with a paper towel wrapped over another business card. Let it dry, and make sure the new recone kit is installed and the voice coil is perfectly centered in the gap. Once the recone is installed, press on the sub and listen for any rubbing or any noise for that matter. If you hear anything....ANYTHING, don't bother powering it up because you're just going to throw more money down the drain by cooking another recone.

Hope this helps.

Nick

Helps a lot, thanks!!!!!!

 

[skittlesRgood 10+ year member]

only way to cook coils is to apply too much power, or throw them into a fire with some seasoning

wrong. you can underpower them and still cook them if you clip the hell out of the signal.

op, were you bumping hard when they died? how much power and what hu? (not sure if its the same setup as your sig)

 

[Kyle_Keating 10+ year member]

wrong. you can underpower them and still cook them if you clip the hell out of the signal.

Sorry, this is not correct.

A clipped single is simply a square wave (or a wave with the peak voltage cut off because the amplifier can not supply any higher voltage), in fact you can think of it like this: the clipping actually protects the driver because otherwise it might indeed be too much power! The amount of RMS power across the coil is really independent of the shape of the AC voltage signal. What kills drivers is the long term power which heats up aluminum and melts the glue onthe voiec coil.

VVV *not directed at skittles anymore* VVV

One of the things that always comes up with subwoofers is how much power can this driver ("woofer") take. Take it from me, this is the wrong question to ask, you need to ask how much SPL will driver make given this much power.

 

[SSS 18734 5,000+ posts]

Honestly, I lol'ed when I saw that picture. It literally looks like your IDMax exploded.

 

[ciaonzo 5,000+ posts]

Sorry, this is not correct.
A clipped single is simply a square wave (or a wave with the peak voltage cut off because the amplifier can not supply any higher voltage), in fact you can think of it like this: the clipping actually protects the driver because otherwise it might indeed be too much power! The amount of RMS power across the coil is really independent of the shape of the AC voltage signal. What kills drivers is the long term power which heats up aluminum and melts the glue onthe voiec coil.

VVV *not directed at skittles anymore* VVV

One of the things that always comes up with subwoofers is how much power can this driver ("woofer") take. Take it from me, this is the wrong question to ask, you need to ask how much SPL will driver make given this much power.

An AC voltage signal with the peaks "clipped" off are sending DC voltage to the coil. At frequencies near the stall mode of the driver where the movement is such that it cannot force enough air over the coil relative to the input power, AC is dangerous enough, let alone DC from clipped output. If the power being applied is below the thermal rating of the coil but very near it, sending DC to the coil from very low frequency waveforms that are clipped for an extended amount of time will indeed cause the coil to reach it's thermal limits. You can have driver failure due to clipping.

Clipping is one of the reasons some people end up baking the tweeter so easily. When the waveform going to the tweeter is severely clipped and harmonics begin to reach the the maximum output potential of the amplifier, it begins to resemble a square wave. Or if you will, AC with portions of DC. The tweeter's coil cannot dissipate the heat being generated by the DC voltage from clipped input, not only because the mass of the coil is tiny but also because it's not moving or forcing air over it to cool it. Thus the implementation of Ferrofluid.

It's worth mentioning that complex musical waveforms blending together can also cause DC current to be applied to the coil while operating well within the unclipped power range of the amplifier. DC is the killer.

 

[95Prober 10+ year member]

Honestly, I lol'ed when I saw that picture. It literally looks like your IDMax exploded.

but I wasnt laughing, haha

it was destroyed pretty good though

i have a Pioneer DEH-P780MP and and 2 subs were wired together were on a 2200 watt mono amp but the settings were turned down

 

[audioholic 5,000+ posts]

I can see where this thread is leading... the same old argument over whether or not squared AC waves can be called Direct Current or not.

A squared wave of the same frequency will display more area under the 'curve' than will a normal non-squared wave. This is a visual representation of the extra power passed through a voice coil when a clipped signal is being fed through it.

 

[stangman67 10+ year member]

what amp??

 

[its_bacon12 10+ year member]

i had the same thing happen to me with a r/f p2 took it to a shop they pushed on the sub it would barley move al locked up like they told me i had a low voltage surge.

That makes sense if the constant wattage output is the same. Watts = voltage*current so less voltage = more current.

And we all know why power companies transform to 50,000+ volts to increase efficiency. Higher amperage on a coil will cause it to burn up/melt, like your coil looks in some places.

 

[will3 10+ year member]

The tolerances are real tight on those subs , if someone had the cone out , and didn't reinstall it correctly this could be the result.

What amp did you have on them?

 

[ciaonzo 5,000+ posts]

I can see where this thread is leading... the same old argument over whether or not squared AC waves can be called Direct Current or not.
A squared wave of the same frequency will display more area under the 'curve' than will a normal non-squared wave. This is a visual representation of the extra power passed through a voice coil when a clipped signal is being fed through it.

I like the way you put that, I've never considered that to be debatable until now. I've always viewed non-sinusoidal behavior as doing the same sorts of damage that DC is responsible for but this might be one hair worth splitting. Thank you for a new perspective on that.

If you apply DC to a coil, it pushes out and remains there until you remove it. That's what we expect. When these AC waveforms have their tops lopped off they're doing essentially the same thing. Whether it's AC holding the coil in place for an extended period of time with each cycle or DC being applied, the damage is the same.

This is from BCAE:

* If your speakers are capable of handling significantly more than your amplifier can produce, driving them with a clipped signal will not likely hurt them.

* If the speakers can handle 3 or 4 times the power that your amplifier can produce, there's virtually no way to damage your speakers (no matter how clipped the signal is).

* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a clipped signal for extended periods of time may cause speaker damage and/or premature failure.

* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a square wave signal for extended periods of time will likely cause speaker damage.

 

[na_rsx 10+ year member]

looks like that coil is having a bad hair day

 

[ciaonzo 5,000+ posts]

looks like that coil is having a bad hair day

That was actually pretty funny. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[audioholic 5,000+ posts]

I like the way you put that, I've never considered that to be debatable until now. I've always viewed non-sinusoidal behavior as doing the same sorts of damage that DC is responsible for but this might be one hair worth splitting. Thank you for a new perspective on that.

The key is the duration of time in which you are looking at the supplied power, when debating if its truly alternating or direct current. For a portion of each wave cycle, the power is direct/constant. But when viewing the entire waveform, the signal is clearly alternating. Does this squared portion of each wave actually make the speaker cone stop moving? No. The speaker will have an 'overhang' period where it is transitioning from moving one direction, to stopping, to starting to move the other directon again. The speaker suspension will translate this into continual motion, but with a non-fluid tendency to transition from one direction to the other. This is what is sometimes known as 'cone fapping'. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

True Direct Current, applied over time, would as you said simply push the cone one direction and hold it there. But due to the signal actually being alternating current with flats at each wave crest, the cone doesn't actually stop moving. Cone motion IS impeded however, and does diminish cooling. Not saying I disagree, just clarifying your point a bit.

 

[ciaonzo 5,000+ posts]

The key is the duration of time in which you are looking at the supplied power, when debating if its truly alternating or direct current. For a portion of each wave cycle, the power is direct/constant. But when viewing the entire waveform, the signal is clearly alternating. Does this squared portion of each wave actually make the speaker cone stop moving? No. The speaker will have an 'overhang' period where it is transitioning from moving one direction, to stopping, to starting to move the other directon again. The speaker suspension will translate this into continual motion, but with a non-fluid tendency to transition from one direction to the other. This is what is sometimes known as 'cone fapping'. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif
True Direct Current, applied over time, would as you said simply push the cone one direction and hold it there. But due to the signal actually being alternating current with flats at each wave crest, the cone doesn't actually stop moving. Cone motion IS impeded however, and does diminish cooling. Not saying I disagree, just clarifying your point a bit.

Very well done. That was the missing ingredient from my point of view.

So while the BCAE info shows that clipping can destroy a coil when the circumstances are such that amplifier output is closely matched to the coil's thermal dissipation abilities and a clipped signal is present, I can no longer attribute this to DC as my mind was trying to rationalize.

For the record, I don't believe clipping is the reason behind most driver failure. Indeed I think it's very rare. I just wanted play devil's advocate to address the absolute statement that clipping cannot cause driver failure.

"Today was a good day."