Do crossovers split the power coming to the speakers?

[pintich]

Hey. Do crossovers split the power coming to the speakers? by that i mean like this. Lets say we have a amp doing 4x 120wRMS, 2x 240wRMS (bridge), and the speakers can handel 120wRMS.

So you connect 1 mid 1 tweeter to one crossover then the crossover to 1 channel on the amp. Will that split up the power so the mid is getting 60wRMS and the tweeter 60wRMS to? and if its like that then it should be safe to bridge them?

[8ight]

No, a crossover is a component designed to separate frequencies. Passive crossovers come after the amplifier and send the high-end of the full range signal to your tweeters, the mids to the mids, etc. This may have the effect of limiting the power reaching any given component connected to the crossover since of course it will lose energy as heat.

[pintich]

No, a crossover is a component designed to separate frequencies. Passive crossovers come after the amplifier and send the high-end of the full range signal to your tweeters, the mids to the mids, etc. This may have the effect of limiting the power reaching any given component connected to the crossover since of course it will lose energy as heat.

So in the theory both the tweeter + the mid on each crossover gets 120wRMS at the same time or?

[8ight]

No, a crossover is a component designed to separate frequencies. Passive crossovers come after the amplifier and send the high-end of the full range signal to your tweeters, the mids to the mids, etc. This may have the effect of limiting the power reaching any given component connected to the crossover since of course it will lose energy as heat.

So in the theory both the tweeter + the mid on each crossover gets 120wRMS at the same time or?

No, a tweeter would blow on 120w RMS unless it was particularly manly since they are way more sensitive and have a very small (by comparison) xmax/xmech. Since each driver is only receiving a filtered range of frequencies they are not each seeing full power, the mids will see the most obviously. Couple that with the loss of energy as heat in the crossover components and each driver is getting less than you would think. This is why running active and giving each driver its own channel is ideal but certainly not for everyone, that way each speaker gets as much power as you can throw it since you can adjust individually.

[pintich]

No, a crossover is a component designed to separate frequencies. Passive crossovers come after the amplifier and send the high-end of the full range signal to your tweeters, the mids to the mids, etc. This may have the effect of limiting the power reaching any given component connected to the crossover since of course it will lose energy as heat.

So in the theory both the tweeter + the mid on each crossover gets 120wRMS at the same time or?

No, a tweeter would blow on 120w RMS unless it was particularly manly since they are way more sensitive and have a very small (by comparison) xmax/xmech. Since each driver is only receiving a filtered range of frequencies they are not each seeing full power, the mids will see the most obviously. Couple that with the loss of energy as heat in the crossover components and each driver is getting less than you would think. This is why running active and giving each driver its own channel is ideal but certainly not for everyone, that way each speaker gets as much power as you can throw it since you can adjust individually.

Thanks for the info, it all makes sense now

[bcbrassard]

I have read that Passive crossovers can use 15-30% of power coming into them to split the freqs to the mids & highs. Not sure how true it is but its was enough to make me want to go active on my set up. I thought using 2 t400-4 i was close to under powering 2 sets of T265 comps in my set up. I had a passive set up to start with and after changing out HU to the DEH80-PRS to go active i can hear a big difference in the same speakers using the same amps. I was amazed and dont think i would go back to passive again, but thats me.

[pintich]

I have read that Passive crossovers can use 15-30% of power coming into them to split the freqs to the mids & highs. Not sure how true it is but its was enough to make me want to go active on my set up. I thought using 2 t400-4 i was close to under powering 2 sets of T265 comps in my set up. I had a passive set up to start with and after changing out HU to the DEH80-PRS to go active i can hear a big difference in the same speakers using the same amps. I was amazed and dont think i would go back to passive again, but thats me.

I have actually been thinking about testing that one day I am probably going to test set the HPF to 60hz today, because i saw that my mid/midbasses could actually respone down to 45hz, (and i havent thought to much about that before, it sruck me right now that they can do that lol) and i whould like them to bump litle more

[john253a]

something i cut from another site, too long to explane it myself

The crossover isn't magic, it's purely physics. Mostly Ohm's Law.

Internally, a two-way M/T crossover will have separate crossovers for the midrange and tweeter. The inputs to the individual sections are tied together in parallel.

Let's look at a simple first order (6dB) HP tweeter crossover:

It's just a capacitor in series with the tweeter...

The value of the capacitor is chosen so that it presents an impedance (Xc) equal to the tweeter's at the desired crossover (-3dB) frequency. Here's the formula: C=1/(2*pi*f*Xc)

Let's say the tweeter is indeed 4 ohms, and you want to crossover at 4000 Hz.

C=1/(2*3.14*4000Hz*4ohms) = 0.00000995 Farads or 9.95uF

Now, lets look at what's happening with a 4000 Hz sine wave running through that system... You have a 4 ohm speaker in series with a 4 ohm capacitor. So that's an 8 ohm load at 4kHz as far as the amp is concerned. The tweeter is only "getting" half (4/8) of the crossover's input voltage, and output would be 3 dB less than it would be without the capacitor.

Turn the equation around to find the capacitor's impedance (actually called reactance) at 8000 Hz:
Xc=1/(2*3.14*f*C)
Xc = 1/(2*3.14*8000Hz*9.95e-6uF) = 2 ohms

So, at 8kHz the capacitor is 2 ohms. The cap and tweeter in series present a 6 ohm load to the amp, and the tweeter "gets" (4/6) 2/3 of the crossover's input voltage, more than half. The capacitor's reactance continues to fall until it is effectively out of circuit.

OK, let's go down below the crossover f3 to 2000Hz and see what's happening.
Again, Xc=1/(2*3.14*2000Hz*9.95e-6) = 8 ohms

So the capacitor is 8 ohms at 2kHz. The cap and tweeter in series present a 12 ohm load to the amp, and the tweeter "gets" (4/12) only one third of the crossover's input voltage. The capacitor's reactance increases as frequency goes down until the tweeter is effectively out of circuit.


Exactly the opposite happens in the low pass circuit, and the two circuits in parallel are a reasonable equivalent to the load of the individual speakers in the region where they are effectively working.

Higher order crossovers simply add more components to increase the rate that the output voltage changes with frequency.

[bcbrassard]

I have read that Passive crossovers can use 15-30% of power coming into them to split the freqs to the mids & highs. Not sure how true it is but its was enough to make me want to go active on my set up. I thought using 2 t400-4 i was close to under powering 2 sets of T265 comps in my set up. I had a passive set up to start with and after changing out HU to the DEH80-PRS to go active i can hear a big difference in the same speakers using the same amps. I was amazed and dont think i would go back to passive again, but thats me.

I have actually been thinking about testing that one day I am probably going to test set the HPF to 60hz today, because i saw that my mid/midbasses could actually respone down to 45hz, (and i havent thought to much about that before, it sruck me right now that they can do that lol) and i whould like them to bump litle more

I Played with that alittle and it does hit harder but starts to distort on my sytem at full tilt so i kept it at 80hz. Plus i am planning on building kicker panels with a 6.5 midbass driver lowered to 60hz for a 4-way active system. My T265 would handle the lower freq but i was lazy to retune it to keep it there since i have plan for kicks. But ya try it and let us know.

[pintich]

I turn down the HPF to 63hz and i can only say that it was fitting me more the 80hz hehe and they could handel it really good, I tested to set it to 50hz to, it worked great to but i will probably have it on 63hz