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[Tony Mamoh]

I always  previously assumed that damages to a loudspeaker HF driver was likely to be caused by a mismatched power amp. I recently dry rented an active JBL EON 612 monitor pair to a third party.  I (wrongly??) assumed that since there was no issue of matching a power amp with a speaker, there would be no issues. Alas, one HF driver was damaged....and I promptly ordered the damaged  part, replaced it and all was well!

Considering the fact that the particular powered  speaker has an internal power amp that was specifically matched , what could have caused a HF driver get damaged? I am thinking that perhaps if a sustained clipped signal is fed , then perhaps that may be a likely cause  of the damage.

I'm just trying to know what else could be done in future to avoid a repeat scenario. Maybe someone needs to be over the shoulders of whoever was handling the mixer to make sure it doesn't persistently display a clipped output?

[Robert Healey]

Here is an old article from EV about loudspeaker failures that is still highly relevant:

https://www.electrovoice.com/binary/EV_PABible-03-Add02-Power_Handling_Cap-1979.pdf

[Matthew Knischewsky]

The damaged voice coil will tell the tale of what happened to it. If the coil is black or looks burned all over, that would be long term damage. If the coil is open (no continuity) but has no visible damage or a very small burn mark that would be something more short term, like feedback. If the diaphragm is shattered or has holes in it that could be debris between the diaphragm and the phase plug. If there's one deep scratch in the coil that would be debris in the gap. If there's a wider area of scratches that could indicate the driver was dropped, or wasn't well centred upon installation. If there's scratches all the way around that could indicate long term overheating.

Less frequently it could be a manufacturing defect. I've also seen bad solder joint between the terminal and the voice coil lead, which may be repaired.

[Bob Faulkner]

I always  previously assumed that damages to a loudspeaker HF driver was likely to be caused by a mismatched power amp. I recently dry rented an active JBL EON 612 monitor pair to a third party.  I (wrongly??) assumed that since there was no issue of matching a power amp with a speaker, there would be no issues. Alas, one HF driver was damaged....and I promptly ordered the damaged  part, replaced it and all was well!

Considering the fact that the particular powered  speaker has an internal power amp that was specifically matched , what could have caused a HF driver get damaged? I am thinking that perhaps if a sustained clipped signal is fed , then perhaps that may be a likely cause  of the damage.

I'm just trying to know what else could be done in future to avoid a repeat scenario. Maybe someone needs to be over the shoulders of whoever was handling the mixer to make sure it doesn't persistently display a clipped output?

Too much power over a long period of time (relatively speaking).  Too much power equates to overheating, which results in failure to the speaker.  As referenced before, if the speaker windings are black, this is the result of long term overheating.  Basically, overheating is caused by running a speaker (the individual driver) with the speaker's RMS rated power... not its continuous-rated power.  A speaker's RMS rated power is usually 3db more than its continuous-rated power.

[Luke Geis]

Ultimately there are three main causes of failure. Overheating, rubbing/shorting coils ( in, or on the gap ), or mechanical failures.

Overheating is self-explanatory.  The coil simply gets so hot that is cooks and burns possibly warping it and delaminating the coil till it shorts the gap or breaks the coil.

A rubbing or shorting coil is typically caused by debris in the gap or a warped and or offset coil. Gigs at the beach can be really mean to drivers. Over-excursion is also not helpful in this regard. Over-excursion is caused by literally powering the speaker to the point where it nearly or actually jumps out of the gap. As it does so it can warp the coil/speaker cone and cause it to nick the gap as it goes back down. Think mic drops and pops from unplugging things.

Other failure possibilities are more environmental or mechanically based. Moisture getting into the coil/gap area will corrode the coil or short the coil to the gap. I have seen delamination of the coil from the diaphragm, where the coil simply separates from the coil former, or the coil former and coil from the cone. There have been instances where HF drivers have literally disintegrated too. If you can imagine the metal diaphragm simply shattering or breaking apart. These are more isolated and rare incidents but do happen.

[Don T. Williams]

What causes loudspeaker failures?  Renting or letting other people use your equipment!  Seriously!  I'm to the point where there are only a couple of brands and models of speakers that I will rent.  That model is not one of them, but the SRX8XXP's have held up for me.  My six (eight before two were stolen when a rental was not returned - it was a felony) QSC K12's have been golden, and the KW181's have only failed due to being handled roughly - causing the magnet to mis-center.  The DB Tech DVA series has also held up 100%.  I'm looking to add IG4T's after reading the positive comments on these in the forums.

Full disclosure - I am a dealer for these brands and others.  I'm not trying to sell anything (I don't sell online or over the phone). I just relating my experiences renting gear for 25+ years.

[Paul G. OBrien]

Considering the fact that the particular powered  speaker has an internal power amp that was specifically matched , what could have caused a HF driver get damaged? 

In this case with a powered speaker the "cause" of failure is a barely adequate driver and insufficient driver protection, there is no other explanation for it. The compression driver used in this box (2414h) has a meager 35w rating while the amp powering it is rated at 150w continuous 300w peak, that is more than enough juice to smoke the driver in a second with mic feedback for example if there isn't sufficient protection. Clearly JBL has not put enough engineering into this box, it is an entry level product but other manufacturers(EV) manage to produce entry level powered speakers(ZLX) that can handle mic feedback without blowing drivers.

[Dave Pluke]

Moisture getting into the coil/gap area will corrode the coil or short the coil to the gap.

Often the case with Monitor wedges.  Sweat, colas, beer, you name it  .

Back in the day, we traveled with giant, multicell horns - which our crew would store in the "driver down" orientation.  Transitioning from cold to hot or vice versa created enough condensation to destroy several diaphragms, before we instructed the crew to store "horn down".

Dave

[John Roberts {JR}]

I'm shocked this has never come up before?

JR

[Tony Mamoh]

I'm shocked this has never come up before?

JR

Most of the responses appear to be relevant to passive speakers. My specific scenario was for a self powered/active speaker. But I certainly note the multiple possible causes. Including the fact that you get what you pay for!!

[Bob Faulkner]

I'm shocked this has never come up before?

JR

LOL

[Brian Jojade]

In this case with a powered speaker the "cause" of failure is a barely adequate driver and insufficient driver protection, there is no other explanation for it. The compression driver used in this box (2414h) has a meager 35w rating while the amp powering it is rated at 150w continuous 300w peak, that is more than enough juice to smoke the driver in a second with mic feedback for example if there isn't sufficient protection. Clearly JBL has not put enough engineering into this box, it is an entry level product but other manufacturers(EV) manage to produce entry level powered speakers(ZLX) that can handle mic feedback without blowing drivers.

This exactly.  The fact that a speaker is powered or passive doesn't change the rules on what burns out a speaker.  Too much power over too long of a time, or physical over exertion of the driver or external physical damage (such as drops, liquid spills, etc) are the 3 things that cause speakers to fail.  Just because the speaker is in a powered box doesn't change those rules.

Manufacturers of powered boxes typically will put in components that make it difficult for you to overdrive the speakers. This is done by either using speakers rated at higher power ratings than the amp inside, or by adding protection circuits to keep a valve on the potential current supplied to the speaker.  In the case of the eon 612, the JBL marketing team wanted to have a bigger watt number to plaster on the side of the speaker, so they put in bigger power amps but neglected to put in an HF driver that could actually handle that kind of power.  So, if you crank the box up to 11, the net result is the HF driver goes up in smoke.

Now, to be fair, it does take quite a bit for this to happen. You have to overdrive the cabinet quite a bit before there is a problem.  Any competent user shouldn't ever run into an issue.  However, if you let the speaker go into feedback for an extended period or are just an idiot and crank it up to an obviously too loud because it now sounds like crap before it blows level and don't notice it, you'll be replacing a lot of drivers.

[Tony Mamoh]

When you say 'crank up to 11'; do you mean crank the gain to the 11o'clock position? Pls clarify......

This exactly.  The fact that a speaker is powered or passive doesn't change the rules on what burns out a speaker.  Too much power over too long of a time, or physical over exertion of the driver or external physical damage (such as drops, liquid spills, etc) are the 3 things that cause speakers to fail.  Just because the speaker is in a powered box doesn't change those rules.

Manufacturers of powered boxes typically will put in components that make it difficult for you to overdrive the speakers. This is done by either using speakers rated at higher power ratings than the amp inside, or by adding protection circuits to keep a valve on the potential current supplied to the speaker.  In the case of the eon 612, the JBL marketing team wanted to have a bigger watt number to plaster on the side of the speaker, so they put in bigger power amps but neglected to put in an HF driver that could actually handle that kind of power.  So, if you crank the box up to 11, the net result is the HF driver goes up in smoke.

Now, to be fair, it does take quite a bit for this to happen. You have to overdrive the cabinet quite a bit before there is a problem.  Any competent user shouldn't ever run into an issue.  However, if you let the speaker go into feedback for an extended period or are just an idiot and crank it up to an obviously too loud because it now sounds like crap before it blows level and don't notice it, you'll be replacing a lot of drivers.

[Tim McCulloch]

When you say 'crank up to 11'; do you mean crank the gain to the 11o'clock position? Pls clarify......

It's a Spinal Tap reference.

https://www.youtube.com/watch?v=4xgx4k83zzc

[Tony Mamoh]

It's a Spinal Tap reference.

https://www.youtube.com/watch?v=4xgx4k83zzc

👏👍😀😇

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