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Posted: 1/8/2005 10:12:42 AM EDT
Why are house speakers 8 ohms and car speakers 4 ohms?
Link Posted: 1/8/2005 10:21:44 AM EDT
It's been awhile, from the way I understand it, the impedence is only a nominal rating, ie a rough guideline, because I think in reality it changes with frequency.
Link Posted: 1/8/2005 10:25:23 AM EDT
Part of the reason is that you might want to run home speakers in your living room and your bedroom at the same time. That would cut 8 ohm speakers to 4 ohm. Not many receivers are capable of driving 2 ohm speakers.

Dennis Jenkins



Originally Posted By sgtar15:
Why are house speakers 8 ohms and car speakers 4 ohms?

Link Posted: 1/8/2005 10:58:44 AM EDT


Main reason is because it's easier for a small, 12 Volt powered Amp to drive a lower load.... ie. the 4 ohm speaker, as opposed to an 8 ohm....


It's really just economics and efficiency..... The home amp / stereo can be bigger without much concern, as opposed to the car amp, that needs to be compact, and shed a lot of heat, while in operation, without smoking....


Takes less power to push a 4 ohm driver, than it does an 8 ohm one, so you USE less power, and that reduces the amount of heat produced, and component sizes can therefore be designed smaller.


in a nutshell

JB
Link Posted: 1/8/2005 11:01:49 AM EDT
So then why are not ALL speakers 4 ohms?

SGat1r5
Link Posted: 1/8/2005 11:16:05 AM EDT
[Last Edit: 1/8/2005 11:17:36 AM EDT by V-Match]
actually, it's harder for the amp to drive a lower impedance load. for a given power, as the voltage goes down the current goes up. higher output currents are much more demanding re/ output stage parts, lots easier to blow up your amplifier if something goes wrong.

however, in the car audio world you don't have much choice. you've got 12v to work with (unless you're dealing with switching power supplies, price goes way up here) so if you want more power you've gotta shove more current. with home stereos you've got a lot more voltage available so you can get away from the low impedance compromise, easier to design a robust amplifier with higher impedance speakers.
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