Ohms Question [Archive] - Audio & Video Forums


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10-16-2006, 08:26 PM
If my receiver is rated for 8 Ohms, will I have any problems driving a pair of speakers rated at 6 Ohms? Thanks


Dusty Chalk
10-16-2006, 11:21 PM
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.

10-17-2006, 03:56 AM
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.

10-17-2006, 05:02 AM
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.

10-17-2006, 05:04 AM
What speaker model is it?

10-17-2006, 09:58 AM
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.

10-18-2006, 01:13 PM
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...