4 ohm speaker to 8 ohm crossover

[dyingsaturn3]

I'm looking on switching a sub that was ruined by the previous owner. The crossover was designed for a 8 ohm speaker, but I have a sub lying around that is 4 ohm. will the crossover effect the output of the sub? the main reason i ask this is cause i want to connect it to a receiver with a 8 ohm recommendation, but i don't want to blow the receiver in doing so. thank you in advance

 

[doolittle]

Crossovers are tuned for a specific frequency related to impedance, most basic (1st order) crossovers low freq are usually 1/2 so for 100hz @ 8-ohm it will change to ~50hz @ 4-ohm.

As long as it can handle the power of using the 4-ohm driver (will be double the 8-ohm load) should be fine. If the sub is dual-coil you can always wire in series to make an 8-ohm load, which I did for my DIY sub for home audio use to drop the power demand (used and old PC power supply lol)

 

[CaptainCretin]

To add to the above, a cross-over is also usually tuned to match the characteristics of the speakers it will be used with; although generic crossovers do exist.

If the new sub has a diffferent roll-off frequency (the point at which output suddenly drops of), you may get a significantly different sound out of it compared to the old one.

 

[americanaudiophile]

If the subwoofer is active then the sub amp will have to be stable into 4 ohms and you will need to change the woofer level.
If the crossover is passive then when you insert the 4 ohm woofer it will play 3db louder than the 8 ohm woofer. The crossover frequency might change but the impedance that the amp sees will be lower than before. That could damage the amp or make it go into protection.