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Query for Reconing Techs

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AJ113 View Drop Down
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    Posted: 23 February 2025 at 9:32am
In your experience, when drivers are fried, which is the most common cause: amps clipping or thermal overload/excessive excursion?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 23 February 2025 at 1:15pm
GROSS OVERPOWING.....The REAL Power Handling of a Woofer is Pink Noise for an extended Time (RMS).....This Number is many Times too low for the Sales Depart so They Rate it at Peak for 1/10000 of a Second...You will get more Sound by adding more Woofers than by playing a Woofer many Times RMS....1/10000 of a Second is a very short Song....Send Your Blown Woofers to VECTORSONICS for Recone Work... 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AJ113 Quote  Post ReplyReply Direct Link To This Post Posted: 23 February 2025 at 4:07pm
OK thank you. My subs are rated 600w (8R) and the power amps are (allegedly) 700w per channel. They work quite well together but the amps peak too much and I am concerned about possible sine wave damage. (I don't think they are outputting 700w, even at peak) I'm wondering if I will get better results, and if it will be better for the equipment to run in bridge mode coupling two subs in parallel per amp. The alleged output bridged is 2900w into 4R, obviously too high at 1450w per cab, but I'm thinking if I keep the input level sensible, this mode of operation might be better for both amps and drivers. Assuming no more than 1200w per cab as a result of optimistic marketing and keeping the input level low, as far as I know that is about right for amp-power-to-driver ratio.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 23 February 2025 at 10:30pm
If you're frying drivers with a 700w amp then you're going to do it even faster with twice as much power behind them. 

Bridging into 4ohms is harder on an amp.
Lowering level controls does nothing to limit output power.

What processing do you have to protect the speakers? If the answer to that is nothing that is your problem.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AJ113 Quote  Post ReplyReply Direct Link To This Post Posted: 23 February 2025 at 10:38pm
I'm not frying drivers; I'm looking to optimise my operation.

"Lowering level controls does nothing to limit output power."
If the input is reduced, isn't the output also reduced?

"What processing do you have to protect the speakers? If the answer to that is nothing that is your problem."

It's crossed over at the appropriate frequency; I also high pass the masters (belt and braces), plus the amps have limiters.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 24 February 2025 at 2:29am
Originally posted by AJ113 AJ113 wrote:

If the input is reduced, isn't the output also reduced?
For the moment yes, but the tendancey of operators at live events is to turn it up somewhere else.. if not immediately then slowly over a period of time as we become accustomed to the sound level.

Originally posted by AJ113 AJ113 wrote:

It's crossed over at the appropriate frequency; I also high pass the masters (belt and braces), plus the amps have limiters.
Those basics work reasonably well when the speakers and amps are equally matched, but extracting every last ounce of potential from speakers requires much more comprehensive limiting. When the amp has enough power to easily exceed the drivers thermal capacity(rms) well below its own clipping/limiting it's possible to blow a driver without warning, so another level of limiting is necessary. 
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Post Options Post Options   Thanks (1) Thanks(1)   Quote jacethebase Quote  Post ReplyReply Direct Link To This Post Posted: 24 February 2025 at 10:52am
Funktion One have a very simple Limiter Calculator on their website that may help you 

www.wedding-production.co.uk

www.stage2sound.com
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Line Array Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2025 at 1:13pm
Originally posted by AJ113 AJ113 wrote:

In your experience, when drivers are fried, which is the most common cause: amps clipping or thermal overload/excessive excursion?

not a reconing tech, but the way clipping kills speakers is it sends distortion into the tweeters killing them.

if you aren't using passive tops clipping isn't that big a deal.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RoadRunnersDust Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2025 at 5:11am
Originally posted by VECTORDJ VECTORDJ wrote:

The REAL Power Handling of a Woofer is Pink Noise for an extended Time (RMS).....

You are describing "Program" there. RMS would be a continuous signal such as a sine wave.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AJ113 Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2025 at 7:15am
Isn't pink noise a continuous signal?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RoadRunnersDust Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2025 at 8:14am
No, and once you start getting into it it becomes harder to explain because the old style power ratings were based on essentially arbitrary figures and not very accurately named to boot!

Essentially the old term "RMS" means "low crest factor signal" where the peak to RMS amplitude ratio is incredibly small. It's also been intended to mean things like "continuous power" or "average power". It never had a unified standard for how it was measured or what it meant but if you take it to mean "you can feed the speaker a sine wave of this power and it will be safe" then you're usually not far wrong with it.

Meanwhile pink noise has a crest factor of 4 meaning that the peak amplitude of the signal is +12dB greater than the RMS (Root Mean Square) amplitude of the signal. This gives you a signal that behaves more like music in terms of it's amplitude whilst the "pink" part of it means that the energy is equally distributed per octave (meaning 20-40Hz has the same amount of energy in pink noise as the 200-400Hz band does). This also better represents a music signal compared to a sine wave which has *all* of it's energy at one frequency.

There's a reason all the reputable manufacturers have moved over to the AES standard for loudspeaker power rating LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AJ113 Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2025 at 8:27am
Well I have to say I'm none the wiser in terms real-world application. On their website, Crown Amps specifically advise amps that are rated up to 2.5 times(!) the speaker rating. Surely they must know a thing or two about amps and speakers?

I've gone ahead and bought a couple of QSC 1850HD which will deliver a reliable 1850 watts per side in bridge mode. I am assuming this will give me a bit of headroom on my 1200-watt pairs and allow me to operate at optimum level, especially since QSC's rating is based on a short burst at 1kHz, so probably not a true 1800 watts. If I fry the drivers, well, I've learned the hard way. 

Edit: typos

Edited by AJ113 - 16 April 2025 at 8:32am
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