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Author Topic: What's wrong with my woofers?  (Read 14001 times)

Jordan Wolf

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Re: What's wrong with my woofers?
« Reply #20 on: October 18, 2011, 11:36:39 PM »

The EU level limiter is interesting, didn't know anything like that existed.
Yup...Drawmer makes a similar device that apparently keeps the level from exceeding a set level.  It's meant to be used in parallel between the console outputs and the system processing.  I've never used it myself, but it seems like an interesting device.
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Bill Hornibrook

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Re: What's wrong with my woofers?
« Reply #21 on: October 19, 2011, 02:21:51 PM »

Hello! long time reader, first time poster..

Long time reader and first time poster here as well...

I'm a musician/sound guy who's mostly been a DJ lately because I can now gig 4 and 5 nights a week again.

I'm passively tri-amping, and managing everything with just a Driverack PA. It's unsophisticated but gets the job done. Each band has it's own dedicated limiter with an overeasy setting and a bar meter to visually show you what's going on. In addition to that there's a global compressor which will actually kick the whole signal back when you push against it too hard.

In hindsight it's probably a safe bet that the 600 watts or so that the PLX was throwing at that woofer before it's own limiting engaged was probably too much for the driver to take, and if you keep the same components you need some more help in the signal chain. Used DRPAs are pretty cheap... $250-300. Something to think about anyway.

In defense of DJ's, our jobs often depend on getting bodies on the dance floor and there's no better way of doing that than with nauseating amounts of low end. If you're DJ'ing for young singles there's no such thing as too much bottom. Or too much anything for that matter ;)
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Rob Spence

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Re: What's wrong with my woofers?
« Reply #22 on: October 19, 2011, 06:17:39 PM »


Thanks for the insight, Stuart. You may be right, perhaps they were just driven too hard. The DJ's do abuse them, and maybe this abuse week after week has caused them to die, rather than the normal "blow ups" I am used to seeing in speakers.

snip

Interesting thought about the compressor but probably wouldn't be good for my situation. I work closely with the DJ's and am friends with them, so they'd probably ask me to "fix it".. I wouldn't want to explain "well it's a punishment until you learn to behave!"  .. If this weren't the situation I'd definitely implement that compressor.. great idea!


Ah, speakers blowing up isn't normal. It is simply their way of telling you that you are exceeding what they were designed to do :-)

I sure wouldn't tell the DJ he was being "punished". I would instead tell him that is the indicator of the maximum capacity of the rig. If he thinks he needs it louder he should talk to management about upgrading the rig. It is a business decision for them. Heck, how loud is it after the speakers blow?

I expect that either the Aphix or some other device to put the brakes on is going to be cheaper than even one set of recones let alone multiples. Again, put it to management. Do they want to keep buying repairs or fix it? Also, how does having the system fail improve their bottom line. If I want to dance and the system blows up every so often, perhaps I will find another venue to spend my cash.

I have only had one woofer destroyed in 20 years... and that was when a crew member powered off FOH before the amps (twice - even after being warned not to...).

Just a thought...

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Todd Rasmussen

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Re: What's wrong with my woofers?
« Reply #23 on: October 19, 2011, 07:36:37 PM »

In hindsight it's probably a safe bet that the 600 watts or so that the PLX was throwing at that woofer before it's own limiting engaged was probably too much for the driver to take, and if you keep the same components you need some more help in the signal chain. Used DRPAs are pretty cheap... $250-300. Something to think about anyway.

The limiters in those amps are really just clipping limiters. They're not power/output limiters in the sense of what's incorporated into some other amps discussed here.
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Joel North

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Re: What's wrong with my woofers?
« Reply #24 on: October 20, 2011, 03:31:27 PM »

I'll keep you posted on the situation and what happens next!
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Tyron Jon

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Re: What's wrong with my woofers?
« Reply #25 on: November 01, 2011, 02:20:48 AM »

Hi all, first time poster, my name is Tyron, own a live sound business in Cape Town, South Africa - and I Googled this topic because of a similar experience. One of my guys blew an 18" woofer on a gig (JBL2268H - found in the SRX, VRX 18" subs) running it off our Crown Macro-Tech i 9000.

Anyway, it was the first woofer I've ever had to recone (in 5 years) and I was always under the impression that the majority of speaker failures occur when a short, albeit loud spike is put through the P.A resulting in mechanical burst of failure. However, our JBL (which gets used mainly at band type events) was in the hands of a dubstep DJ (after the bands had finished, and this JBL was 1 of four) even though our RMS limiting was set to the continous level of the SRX 718's specs and we had the Peak Voltage Limiters on, sadly - this dude took a fall - not due to the loudness of the music, but due to the constant, constant battering and +3dB at 80hz bumps the lil dubstepper-DJ was doing... (sigh...)

What the result was was thermalling, and as described above, thermalling is just a constant battering of the woofer, with no dynamics (Dynamics? Mastering? that's so 15 years ago!) so it's at its max nearly 95% of the time - it gets hot, and burns ( I have the burnt 18" JBL cone that I got back from my recone guy - and it's guite a gruesome sight)

Anyway, I learn't a bit from that - so RMS limiters are the things to have, and watch them like hawks! Esp when it's a DJ, I've started setting ours slightly below the boxes ratings now - just to keep em dubsteppers in check.

« Last Edit: November 01, 2011, 02:27:44 AM by Tyron Jon »
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Joel North

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Re: What's wrong with my woofers?
« Reply #26 on: November 01, 2011, 10:51:55 AM »

Thanks for sharing your experience, Tyron! Glad to know I'm not the only one. I had another woofer blow which was part of a proprietary amp/speaker system and that was designed not to blow. But it did! Your story is more evidence that speakers under this kind of abuse in club/DJ settings will eventually fail no matter what.


An update to my situation... The 2 blown woofers are off to be re-coned, we'll save at least $400 vs buying new ones. I will post when I find out details from the repair guy. In the meantime, I found an old Klark Teknik DN8000 not being used. Going to use that now instead of the Peavey crossover. It's great. Has limiters, and also let's me put delay on some of the fill speakers around the club (which were noticeably out of sync with the main system)
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Spenser Hamilton

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Re: What's wrong with my woofers?
« Reply #27 on: November 01, 2011, 07:00:34 PM »

Ah, speakers blowing up isn't normal. It is simply their way of telling you that you are exceeding what they were designed to do :-)

I sure wouldn't tell the DJ he was being "punished". I would instead tell him that is the indicator of the maximum capacity of the rig. If he thinks he needs it louder he should talk to management about upgrading the rig. It is a business decision for them. Heck, how loud is it after the speakers blow?

I expect that either the Aphix or some other device to put the brakes on is going to be cheaper than even one set of recones let alone multiples. Again, put it to management. Do they want to keep buying repairs or fix it? Also, how does having the system fail improve their bottom line. If I want to dance and the system blows up every so often, perhaps I will find another venue to spend my cash.

I have only had one woofer destroyed in 20 years... and that was when a crew member powered off FOH before the amps (twice - even after being warned not to...).

Just a thought...

+1, or if management just wants to ignore the problem, you could always walk. I did just that recently, a local DJ has managed to blow up two Macrotech 3600's in the last 6 months, in addition to the dozens of JBL HF and LF drivers. Management doesn't want to spend the money to upgrade the rig, and doesn't want to hire a new DJ. See ya later, I have enough work as it is without going into a job every weekend wondering what story I'm going to have to concoct to appease the band.
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Joel North

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Re: What's wrong with my woofers?
« Reply #28 on: November 20, 2011, 12:50:18 AM »

Well, things are back to normal for now. 

The two temporary replacement speakers worked fine while the blown woofers were being re-coned by Fab Audio, so I had no reason to assume there was any issue with the amp.

Installed the repaired woofers this past Friday. Used them over the weekend and everything sounds great. I was a bit nervous since it's the first time I've ever had recones done, but they work perfectly. We saved a lot of money going with the recone option. Hopefully this won't happen again anytime soon.

Thanks for all the advice!
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Poopedi Kwena

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Re: What's wrong with my woofers?
« Reply #29 on: November 22, 2011, 02:06:28 PM »

I will tell you 1 thing I learned the hard way. Nobody loves you rig more than you do. It may b ur dj friend, or your family or anybody.

The moment you leave they crank up the system to destruction. A limiter is the solution. It may not be the best on the market but as long as it will apply breaks it will save you hustles. Instead of spending ur $$ replacing cabs, u will see urslf expanding the sound

P.S. Hi there Tyron, I'm also in ZA, nice 2 hav a homie out in there
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ProSoundWeb Community

Re: What's wrong with my woofers?
« Reply #29 on: November 22, 2011, 02:06:28 PM »


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