I always see 2 spools of wire inductors in every cross over what do they do,I also noticed they are almost always next to a resistor.
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I always see 2 spools of wire inductors in every cross over what do they do,I also noticed they are almost always next to a resistor.
Low pass filter.
Sometimes they have a resistor in circuit to stabilise the speaker drive unit impedence.
In the case of an inductor feeding a bass/mid it rolls off the treble. An inductor has a property known as inductive reactance & effectively what this means is that the resistance of the coil of wire increases the higher the frequency goes - so it rolls off the treble because it's in series with the bass/mid!
In the case of a tweeter it will be in parallel with the tweeter & as it's resistance increases with frequency it will tend to shunt less power to ground the higher the frequency goes ;) In co-operation with a capacitor this will increase the power to the tweeter as the frequency increases.
Resistors are generally on the tweeter side as these tend to be a bit more efficient than bass/mids :)
Passes them on.
Ok,so inductance creates the roll off,I always thought caps did that.
Caps are hi-pass.
Capacitors do the opposite :) Well no, they do create a rolloff but in the opposite sense :eyebrows:
Capacitive reactance as it's known creates a reducing impedance (resistance) with increasing frequency.
So imagine your bass/mid again, it has a choke (inductor) feeding it in series & a capacitor shunting the driver. As frequency increases the choke will increase in its AC resistance & the capacitor will decrease in it's AC resistance - it creates a steeper rolloff :)
In the case of a tweeter being fed in series from a capacitor & having an inductor shunting it you get this... As the frequency decreases the capacitor displays more AC resistance thus rolling off the power to the driver & the inductor also has less AC resistance also creating a steeper rolloff..
It seems a miracle speaker crossovers work at all.
What alot going on for so few parts.
Jeff it gets worse as no drive unit has a fixed impedance, they all vary all over the place as well which can bugger up the crossover frequency & driver phase. As you can imagine this make things more complicated :eyebrows:
& just to make things even worse the driver sensitivity varies over frequency as well :eek:
So yeah, it's a minefield out there :eyebrows:
This is why I like electronic crossovers as they are accurate. A whole lot of problems get left behind ;)