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Protecting compression drivers


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Ok, so now I've sorted my Idex Horns thanks to Mr Si. The problem, I think, is that my students plug things in while phantom power is on and this makes an exciting loud noise and wrecks the driver.


I've seen things called filters which look like a coil and a capacitor on a pcb. What are they and would they solve the problem? Would they have an adverse affect on the sound? Where and how are they fitted? Is there a better solution? Any comments welcome. Thank you in advance.

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these things are filters, but not perhaps the sort of filter you are thinking of. They are an LC network - basically, a frequency device. depending on how you use it, it can stop hf, or lf or a bi of both. a bit basic, but a capacitor in series passes hf, an inductor in series passes lf. neither will stop the loud crack that wrecks speakers as it has a large dc component. You just need to impress on them that faders must be down before hittinfg the switch. My old college even gave one student an invoice when he wrecked something he had been told about. causes a lot of grief with parents, but makes them think the next time.


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I'm glad to have been of help matey


I personally didn't think that plugging something in when phantom power was on along with the unmuted channel would damage a speaker component, horn or cone.


But maybe it does!


I'd personally be more worried about damaging the pre amps in the mic inputs - I've done this on a channel of a spirit F1 mixer before and the result is worse than digital distortion! and costly to repair if you go to the wrong company! (like I did)


Anyway, I've blown 2 of the APT50 tweeters and that was because my speakers are 4 Ohm impedance but only 300W RMS power handling. I drive the speakers using an amp which delivers more than twice that - 650 per side into 4 Ohms and I have just sent too much constant power to them and they've gone. In fact, the tweeters can only handle 45W RMS and 85 Peak, so that's even less!


I think this is more likely to be a problem (in my experience) - lack of knowledge and understanding - and over driving the speakers.


Also, if the amp clips at all, the speaker will give up in the end, and I think tweeters are more prone to damage because they can't handle a great deal and you're giving the speaker a square wave - which it doesn't understand how to recreate.


Can't be good!


Put a limiter in between your main outputs and your amps and set it at a point which you know will protect your speakers - (trial and improvement there)!


for the speakers you have - I saw them online, I think a behringer ultracurve will be a nice investment - not too expensive either, plus it has 2x31 band (1/3 octave) graphic EQ and you can us the real time analyser to get a basic setting for each new room you setup in - which can be handy. It also has delay. Along with, of course, the limiter setting.


Mr. Si


Fathered Sounds


anyway I hope something of this makes sense!

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Plugging things in when the phantom power is on can certainly damage loudspeakers.


This from the Shure website:






"Is there a proper convention for applying and removing phantom power to a microphone, so as not to damage the mic? Can the phantom supply be on when plugging or unplugging a mic? Should the phantom power be turned on after the mic is plugged in? Does it matter?


Solution Database Answer:


First, we assume the microphone is low impedance and balanced like all professional mics. That being the case, you will not damage the microphone regardless of how you do it. You do not need to worry about turning off the phantom power before plugging in a mic. But, you could damage your loudspeakers if your mixer is turned up when you plug in a microphone. This often results in a loud "pop". Turn the mixer's Master control down before connecting or disconnecting any microphone. This will prevent damage to your loudspeakers. "



My loudspeakers have lots of headroom and the power amp is kept well below its capacity. My technicians keep the mixer below clipping so I don't think that's the problem. Thanks for the advice.

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