Ohms Question

[Morpheus77]

If my receiver is rated for 8 Ohms, will I have any problems driving a pair of speakers rated at 6 Ohms? Thanks

Tommy

[Dusty Chalk]

It depends.

The best thing you could do is see if you can find an impedance graph of your speaker (it's a function of frequency). If it's 6 ohm minimum, then you're probably alright. But sometimes when they say 6 ohm nominal, they mean "average".

And then you need to let us know what receiver it is you have. Some of them which are not rated for 4 ohm performance can handle 4 ohm performance, as long as you have adequate ventilation (it will run much hotter). But some of the BPC (Black Plastic...you get the idea) won't be able to handle it.

[kexodusc]

Just to tack on to Dusty's good advice, the impedance ratings on amps/receivers and speakers is provided to account for the current handling capacity of the system. We can't really just look at the imedance rating in isolation - the sensitivity of the speakers, power of the amp, desired loudness of the listener all affect whetehr or not you can get away with using "4 ohm nominal" speakers.
Most 8 ohm systems shouldn't have a problem handling reasonably efficient, 4 ohm speakers. In terms of current demands, the lower 4 ohm impedance presents the same load that a +3 dB volume increase with 8 ohm speakers would present the amplifier (assuming the impedance curves are shaped the same). Assuming there aren't any wild 1-2 ohm swings (and that's a very safe assumption even on 4 ohm speakers), you should be fine. As you add more than 2 speakers of lower impedance to a receiver for home theater, you're really just cutting down the maximum playing level of the system.

A lot of 4 ohm speakers have relatively high efficiency (88-91 dB or better) and can play fine on most receivers. You're still only using a few watts at a time to play very loud, and even dynamic peaks aren't going to overtax a power supply unless you're looking for 105 + dB levels in your room or something. The 6 ohm rating comes from slightly lower "average" impedance, most 6 ohm speakers I've tested still rarely drop below 3.5 ohms at their minimums, which you'll find in many 8 ohm speakers as well. These days, you're seeing fewer companies claim "6 ohm" impdance and instead just saying "compatible with 8 ohms".

Go ahead and try it - but a bit of advice - if things start to sound bad, turn the volume back down.

[Morpheus77]

If I'm not mistaking, they are 6 Ohms Nominal. You see I'm bidding on them now on Ebay, and it's just like me to jump into something without doing my research. I did to do spec check, and they are rated simply at 6 Ohms. My receiver is an Onkyo TX-D575X. I have never worried about Ohms in the past, and I guess I just dodged the bullet, because I never had any problems that I'm aware of.

[kexodusc]

What speaker model is it?

[Morpheus77]

I'm probably going to get hammered if I tell you.......but here goes. Cerwin Vega RE-25's. I wanted a smaller pair because we now live in an Apartment, and those 15's are a little much, so I bid on some tens, that have the same color cabinets.

[audio_dude]

theres nothing wrong with cerwin-vega's!! well, as long as you lovee to partay!!

or...if you just like the sound, nothing wrong with that!! just trust your ears...