Hello. I have one little question about amplifier and speaker's impedance.
I was going to buy some car speakers for home theatre use (I can get them cheap, and most speakers designed for home use are too expensive here... :angry: ) that have a nominal impedance of 4 Ohms, but most decently priced recievers have a nominal impedance of 8 Ohms . The question is, can I connect a 40 Watt 4 Ohm speaker to a ~ 100 Watt 8 Ohm amplifier without destroying it?
If I'm doing my math right (and I doubt it... ), the amplifier should provide enough current to the speakers, but I'm not sure (otherwise I wouldn't have posted this).

Thanks for any help and comments.

The Ohm measurement is how much resistance the circuit of the speakers will give the power source. In this case you would effectively double the amount of power going to your speakers, BUT! Some amps are not designed to run at 4Ohm loads and they will overheat and eventually die. You could wire them in series and use two on a channel to give you an 8 Ohm load.
Personally I would pay the money for new speakers. Car speakers are tuned and built for different applications. They expect to be able to have to overcome road noise and variable enclosures so they dont behave in the same way that house speakers do. The end result is usually a loss in the subtleties of the sound, which you dont want to do in home theater.

If you need inexpensive speakers, the the ATHENA line. I have seen some rave reviews of these little fellows and their cost is negligible.

You should also keep an eye on your local paper. There are a lot of folks out there who "trade up" speakers every 6-9 months.

SamuraiJack

Car speakers are built with many compromises due to the very harsh environment that they're expected to be placed in. They're lower resistance because of the limited voltage typically available in a car application, so that's a compromise as well. As home speakers, I would generally not recommend them.

Given that this manufacturing process is more expensive than for home speakers, it then stands to reason that quality for quality, indoor/home use speakers will be cheaper than car speakers. The main difference is that for home speakers, you (usually) have to buy the cabinet as well. You can buy "raw" speakers, which will cost less than a car speaker OF EQUIVALENT QUALITY. You can then build a cabinet for these, and end up with a better end result.

The one place that car speakers are easier is in the crosover. Individual indoor speakers won't have one, but a simple coaxial car speaker will have something that at least works.

Thanks a lot for your answers .
So car speakers sound worse than home speakers?? How 'worse'? Will it sound like a crappy speaker (really BAD, with boomy bass, or too bright), or just a little worse than something great?
Keep in mind that now I have a 2.1 I-Trigue 3200 'system' for listening to music and films (yeah... limited budget ), so I doubt I'd find them worse than what I have now, but if they'll only improve a little, then I'll buy something else.
Now, a small question. Can you tell me if an 8 Ohms amplifier can power 4 Ohms speakers if the power the amplifier can output is way more than the rated speaker's power (ie. 200w amplifier (8Ohms) powering 40w speakers (4Ohms))?
I was thinking on wiring 2 speakers in series so they have 8 Ohms, but I'd rather buy half the speakers .

Thanks for your help.

By the way, the speakers I was thinking on buying were the Panasonic TS-A6961R (http://www.pioneerelectronics.com/pna/v3/p...8235276,00.html), which I can get rather cheap and the specs aren't too bad (yes, I know that the manufaturers always 'expand' the specs of everything, but at least they seem pretty good ).

If I were to build another set of speakers I would consider these. I’ve built a pair of clones of the Orion and am more than happy with them. The problem with the Orion is that they are not a cheap speaker even for DIY but Pluto use much cheaper drivers and relatively easy to construct. Just a thought.

DJ

Thanks DAZZZLA, but I think the price (even if it's cheaper than the orion) is just too expensive... (unfortunately; because I'd love to have a pair of those).

If you're also buying a receiver, if you aren't already you might take a closer look at Yamaha, they sometimes have a switch or something that will let you choose 4Ω or 8Ω. Also, the receiver I have (a Pioneer) has a switch that will let you choose between 6Ω and 8Ω. I don't know if it's smart or not, but I'm currently running 3 8Ω and 2 4Ω speekers on it in 6Ω mode.

Maybe I should get some 4Ω bass shakers and hook them up with the 4Ω speakers and make every channel 8Ω.

By the way, Ω = Alt + 234

Thanks. I was wondering, what makes one reciever be able to drive 4Ω (it worked!! ) speakers, and other recievers just 8Ω? Is it just the current it can provide, or other factors too?

Good idea about the shakers .

Lower ohms raises the load demand of the amp. No use in trying to get techical about it.

In short, it should work fine at low volumn levels. You can EASILY blow the hides off those speakers if they are only rated at 40 watts @ 4ohms.

You can find REALLY cheap speakers on the auction site that would probably be better. Have you looked there? ....And I mean CHEAP!

Yeah, no intention to use them at full volume, but I was worried that they wouldn't work.
So a 100watt (8Ω) amplifier can power 40watt 4Ω speakers? If I use Ohm's law, there should be enough current to drive those speakers, even at 4Ω ( I suppose that is what I need to use to calculate that...).
Auction site: eBay?
I was looking into building them myself, but if they're cheaper, I might think it twice.