lol…
“that vibration becomes distorted” please, explain furhter.
excessive distortion from an overdriven amp has ZILCH to do with underpowering.
Excessive distortion is not “vibration”
Excessive distortion IS SQUARE WAVE.
You know, an amplifier outputs AC. Alternating Current. When the current is beyond the limits of the PCB, then the tops of the frequency waves are “clipped off”, or it’s a clipped waveform. This is distortion.
When the over current is so severe that You’re effectivly outputing Direct current, You end up clipping off nearly the entire transitional portion of the wave form. Ending up with “square wave”.
Square wave will pop a coil in a matter of moments, enclosure dependant.
Clipped wave will also pop a coil, but not nearly as fast.
Neither of these two things will cause a coil to “vibrate” to death.
The reason that overcurrent pops coils is this: The fact that the coil will “hang” excurted for 1/8 cycle or so, causes it to lose some cooling effect. In a passband of 30-120 cycles, losing an 1/8 cycle on EVERY wave will cause ALOT of overheating if done continuously. Consequently the coil binding -or- glue, overheats and breaksdown. At this point any coil wire can break loose of the former. When this happens, the wire shorts against the ferrite, causing a DC short into the motor. No more boom boom.
What YOU are referencing is a mechanical failure. Not electrical. Mechanical failures only happen when a driver is poorly designed -or- the enclosure is poorly designed.
What is a poorly designed driver? One that has more Xmag then Xsus.
You do know those two terms, right?
Xmag is a reference for the “Power” or BL of the motor.
Xsus is a reference to the abilities of the suspension (primarily the spiders, but also to include the surround & tinsel leads)
The commonly overabused TS parameter of Xmax is derived from these specs. More importantly, most beter motors are rated for Xmax where the BL falls below 70% (iirc). Or, the lesser of the two (xsus & xmag)
Now, in the case of a severly limited suspensoin, or greatly overpowered motor - You will easily reach mechanical limits in any application with with recommended power.
Or, in the case of a poorly designed or built enclosure, You will hit mechanical limits of a suspension quite easily. If You’re running an Adire Brahma 12" in a 2.0ft 4th order ported with a resonance of 80hz… but feeding it 35hz @ 800wrms (actual wrms with a clamp & ammeter), then the suspension is going to unload and the “bottomless” driver will bottom out with enough abuse. The coil former can either flat out “bottom” on the backplate of the motor. OR the SPIDER can reach it’s physical (mechanical) limits. At these limits, the spider cannot maintain linear control. Therefore it (it IS the main centering force) cannot keep the coil centered on the pole piece. The whole soft assembly will rock and short the coi against the pole piece or ferrite, causing coil rub, and eventually a short (coil to ferrite).
But these kinds of failures are mainly due to ignorance. A decent (or better) enclosure can be made for $40 - $80, but if no one takes the least bit of time to make sure that the dampening & tuning is right, then they are wasting alot of driver capability. In other words, they would REALLY have to fuck it up to reach xsus under anything less the Mecca / dBDrag usage.
In anycase, underpowering a driver WILL NOT break it.
If you still dont get that, think about this: If Underpowering a driver is bad for it, what happens EVERYTIME you turn the volume down from the Gain Pot set point?
Answer: The coil gets less current & voltage. EVERYTIME. Boy, better never turn that knon down.
Oh, and forgive me any typos / omissions, this is what I remember from my heavyier audio & competing dayzzzzz.
No offense Dirty, but You should absolutely do some reading. Then, get Your hands on a few different motors and see what they can do. And, If You havent yet, disassemble a well built driver, then rebuild / recone it.
Feel free to hit me up, I have a feeling that I could learn You a few things. Ask Your boi Jim @ Underground.
-Nick