Speaker signal frequency range

[UKenGB]

How important is it to filter out frequencies that a speaker cannot reproduce?

If say, a mid-range speaker has a range from 1k -> 5k, what will be the effect of feeding it a full range (i.e. unfiltered) signal rather than filtering out the sub 1k and >5k frequencies? Would it noticeably adversely affect the audio quality or would the speaker act as its own filter and simply not reproduce those frequencies outside its normal response range?

[Brian-bmw]

Yes, you will get a noticeably adverse effect, and you could even damage the speakers. The problem is that a speaker will distort badly when it is fed a signal to which it can not respond. Bass probably has the worst effect. If you fed 80 Hz into a speaker that is only rated down to 1 KHz, then you will get massive distortion in the bass that will also distort its midrange output. Trebble might not be as bad, but the higher frequencies fed into that same speaker would produce some distortion, and it could also produce excessive heat in the voice coils which could lead to damage.

[ncx]

You would not want to feed low bass (including subsonic bass) into a speaker designed for 1k-5k hz. Feeding it anything above 5k would not be as much of a problem, but you definitely do not want to send low bass as that will cause the driver to distort as it attempts to play frequencies below the bottom of it's range. This can ruin the driver very quickly. I strongly suggest that you either use a crossover before the amp (or at the amp) or at the very least, put a high-pass filter on the midrange to keep low frequencies out of the midrange which will allow it to operate at it's designed wattage safely. You can buy cheap in-line filters for a few dollars.

edit: thx Brian, you beat me to it

[UKenGB]

What about a speaker rated from 50 - 6000 Hz. Wouldn't that be able to handle a full range signal?

[ncx]

A woofer/mid-woofer with that range should be fine with a full range signal and power within it's specs. But if you are going to run a subwoofer, you might still consider taking the subsonic bass out of the signal, such as 80hz and down or at whatever frequency your subs are going to be crossed-over at.
Good luck and have fun!

[UKenGB]

I think I have finally worked out a solution that will allow me to filter appropriately for all speakers.

Thanks for the help.