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Old 22nd November 2003, 10:28 AM   #1
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Default crossover advice please

If a 3way-crossover is rated at 400wrms, is that 400w to each channel or 400w between all 3?
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Old 24th November 2003, 08:03 AM   #2
Jay is offline Jay  Indonesia
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I guess the rating relates to the maximum allowable input power from amplifier. (IMO, it is a rough number that I will never bothered with. It is RMS, very big power for home audio application).

The crossover circuit, input frequencies and the driver's characteristics will determine how the power (current) from amplifier will be distributed among components. Normally the woofer (LF) path will handle the biggest share.

So if you do a detailed analysis of the power distribution among crossover components, you will find a critical component who will fail before any other do, could be a resistor in the tweeter path, could be an inductor in the woofer path.

If you plug in a MAX 400W woofer and a high power amplifier, with a standard 16AWG inductor, even with 8mH, I think the woofer (coil) will fail before the crossover inductor. May be not for 18AWG@10mH!? (the smaller the diameter and the longer the cable, the higher the resistance and the higher power dissipation).

For standard tweeter (HF) crossover, the capacitor is never more critical than resistor. This is because MKP usually rated for up to 250V or up to 300w, while for resistor, I have never seen bigger than 10W.

Just an opinion.
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Old 24th November 2003, 09:03 PM   #3
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er.......... i don't know what he said ..........

My understanding is that a 400W crossover will handle 400W total. In that:- it distributes 400W across the speakers. You still need each need to be 400W because at some point all of that signal will be either bass OR treble.


I might be wrong
but its a post that's worth a definitive answer.
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Old 24th November 2003, 09:15 PM   #4
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Give them a little more info regarding your application, and they will be able to help you better. But check the actual values of the components of the crossover and check it out with a xo caculator; drivers rarely have a real impedence value corrolative with their Znom.
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Old 25th November 2003, 08:44 AM   #5
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the crossover im using is a EMINENCE PXB3-3k5.

And i'm using the following speakers on it(all eminence):
Delta15LF (400w)
Alpha10 (150w)
APT:80 (tweeter)

Would that crossover be ok(it is rated at 400w)?
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Old 30th November 2003, 04:43 PM   #6
Jay is offline Jay  Indonesia
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Quote:
Originally posted by welly_59
Would that crossover be ok(it is rated at 400w)?
I don't think you need to worry the crossover, especially if it complies to the specs. The crossover was designed for high power system and thus have a specially designed protection, especially for the tweeter and midrange (by means of a specially designed "fuse" and a power attenuation at clipping). Remember this is just an advertisement. Looking at the tweeter, I think you may want a spare for the fuse.

What you need to worry are the drivers (tweeter and mid), and the amplifier you use to drive them. You will need to limit the (amp) power to drive the drivers, and you will need powerfull enough drivers.

Common practice in the old days was to assume a rough power sharing between woofer, mid and tweeter. It is something like 55:30:15. So for a critical 400W you will need a 220W woofer, 120W mid and 60W tweeter.

Newer "opinion" is something like what Pbassred mentioned. You will need 400W woofer, 400W mid and 400W tweeter.

IMO, in practice you will never/rarely need 400W tweeter for most cases of operation. And in your case I believe the fuse will blow before 300W of pure 3K5Hz.

You should know the power rating of your amplifier. Will you use a 400W amplifier? Will you drive the amplifier to it's fullest output (clipping)? IMO, almost all amplifiers will break drivers being driven to clipping. 400W pure RMS is a very big number, and IMO will break either your driver or crossover. But I also believe you will hear distortion or so before 300W output, something to prevent you to drive the amp to the fullest output.

I hope you will be just fine with the crossover. Think about this: all of the Eminence tweeters (on the site) are rated for 45W, and 400W is the maximum rating for the 2/3-way crossovers. The fuse is to increase the safety factor of the 45W tweeter (There are situations where anyone may break his tweeter, once in a lifetime).

Again, just an opinion. May be you need to tell us your amp.
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Old 30th November 2003, 07:33 PM   #7
sreten is offline sreten  United Kingdom
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The simple answer is that a 400w crossover indicates the maximum
power of the amplifier it is to be used with in my experience.

So given the original question 400w between all three.


/sreten.
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