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Low Pass Filter Wasting Power?

Folks,

If I use a low pass filter in the speaker wire am I "wasting" power? It has been suggested to me that these devices, which keep the higher pitches off the woofer, are modifying an already amplified signal and thus wasting power. I wonder. If the speaker isn't producing those upper pitches, and if the filter doesn't heat up, where did the "wasted" energy go?

Regards,
Troy Scott
tscott1217d0eb
3 responses Add your response
tscott1217d0eb OP
12 posts
 
Thanks Ghostrider45 and Joeylawn36111,

That's what I thought, though I'm not always sure how to express it in electrical terms.

Regards,
Troy Scott
joeylawn36111
574 posts
 
The speaker crossover has basically a low pass filter for the woofer anyway, and as far as wasted power, probably not. Audio signals are AC, and AC into coils and capacitor loads (that's basically the kind of load a speaker is) don't produce the resistive 'heat loss' like a purely resistive load.
ghostrider45
449 posts
 
Above its cutoff frequency the low pass filter looks like a high impedance to the amp. Thus the amp won't be driving significant current into the load at these frequencies and won't expend power.

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