6 ohm speakers to 8 ohm receiver - AVS Forum
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post #1 of 11 Old 04-05-2007, 12:52 PM - Thread Starter
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Looking to pick up a set of Yamaha speakers that are 6 ohm and an Onkyo TX-SR504 receiver that is 8 ohm. Would this cause a problem at all? The Yamaha set is just a small sattelite set with a sub. Either the NS-P1600 or the NS-SP5700.

Any input would be greatly appreciated! Thanks in advance!
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post #2 of 11 Old 04-05-2007, 01:42 PM
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Receiver power ratings are (supposed to be) quoted in reference to impedance and frequency range, but receivers themselves do not have an ohm rating per se. However most are designed to work best with speakers nominally rated at 8 ohms and recommend against using with 4 ohm speakers. But most will be okay with 6 ohm speakers if not driven too hard, and especially if lower frequencies are sent to a subwoofer. Speaker efficiency (sensitivity) rating is also important, so if rated at 90 dB or higher that makes for an easier load for the receiver. This article will explain better than me:

http://www.goodsound.com/howto/2001_08_01.htm

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post #3 of 11 Old 04-05-2007, 07:35 PM - Thread Starter
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Quote:
Originally Posted by dsmith901 View Post

Receiver power ratings are (supposed to be) quoted in reference to impedance and frequency range, but receivers themselves do not have an ohm rating per se. However most are designed to work best with speakers nominally rated at 8 ohms and recommend against using with 4 ohm speakers. But most will be okay with 6 ohm speakers if not driven too hard, and especially if lower frequencies are sent to a subwoofer. Speaker efficiency (sensitivity) rating is also important, so if rated at 90 dB or higher that makes for an easier load for the receiver. This article will explain better than me:

http://www.goodsound.com/howto/2001_08_01.htm

Thanks for the info. The satellites are 82dB and the center channel is 85dB. Think that will be ok? Also, the subwoofer is rated at 5 ohms while all the other speakers are rated at 6 ohms. I believe I'll be ok with this setup though. I don't plan to push it too hard. It will be used for TV/DVD watching 98% of the time.
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post #4 of 11 Old 04-06-2007, 12:54 AM
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Most power amplifiers react in the same way when you attach a lower resistance load to them- power output (and heat) goes up and so does the THD usually going up orders of magnitude. So even if the Amp can handle the load heat wise you will be ruining your experience with the horrible amounts of distortion.

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post #5 of 11 Old 04-06-2007, 04:23 AM
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Most power amplifiers react in the same way when you attach a lower resistance load to them- power output (and heat) goes up and so does the THD usually going up orders of magnitude. So even if the Amp can handle the load heat wise you will be ruining your experience with the horrible amounts of distortion.

Well-built receivers can easily handle 4 ohm loads reliably and furthermore, the unpreventable gain in distortion won't affect the sound quality by an unacceptable level by any means. I dare anyone to claim that they can hear the difference between 0.02 and 0.04% THD, blindfolded and without a meter to tell them that "this is bad!"
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post #6 of 11 Old 04-06-2007, 08:33 AM
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Quote:
Originally Posted by chunkisagoonie View Post

Well-built receivers can easily handle 4 ohm loads reliably and furthermore, the unpreventable gain in distortion won't affect the sound quality by an unacceptable level by any means. I dare anyone to claim that they can hear the difference between 0.02 and 0.04% THD, blindfolded and without a meter to tell them that "this is bad!"

You will definitely hear it when the amps start clipping, which they will do pretty quickly with 82 dB 4 ohm speakers if you play it too loud (granted surrounds do not see as much demand as the fronts, but they can be stressed when the loud explosions start in a soundtrack). If the OP wants best sound quality at higher volume levels and/or his room is overly large but he does not want to use a separate power amp, then I recommend he go with a receiver known for superior amps, such as H/K, NAD, or Sherwood Newcastle, all of which should be okay for 4 ohm speakers.

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post #7 of 11 Old 04-06-2007, 06:03 PM
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Well, I never really said that this can't happen, but what I meant about a "well-designed receiver" are ones that have amps with overbuilt transformers, good output caps, good heat dissipation, etc. Rotel and Arcam receivers can also easily drive 4 ohm loads, along with the other brands you mentioned.
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post #8 of 11 Old 04-07-2007, 09:29 AM
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Also note that when you lower the impedance the THD doesn't go from .02% to .04% more often than not the THD will do something like this: 8 Ohm = 0.02% THD 6 Ohm = 0.09% THD 4Ohm = 0.20% THD Now would you EVER buy a receiver / speaker setup with 0.20% THD? hearing it all the time or not, thats not something I would EVER do (and I own a POS sony receiver).

If that kind of THD is acceptable you might want to look at the Bose AM series


EDIT* Wow I tried to locate THD numbers for Amps running different loads (other than the ones marketed with that ability) and no one posts them, I can only assume it's worse than I said because if there is something that makes a product look bad (even if it's not normal operation) companies will not list it.

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post #9 of 11 Old 04-07-2007, 08:07 PM
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So I guess by this logic, you would be absolutely horrified at the THD a tube amp produces.

The McIntosh MC275, one of the most highly regarded tube amps in HISTORY has a THD rating of 0.5%.
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post #10 of 11 Old 04-07-2007, 08:24 PM
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Quote:
Originally Posted by chunkisagoonie View Post

So I guess by this logic, you would be absolutely horrified at the THD a tube amp produces.

The McIntosh MC275, one of the most highly regarded tube amps in HISTORY has a THD rating of 0.5%.

I must agree with this. Even today, there are some solid-state rigs (Sunfire for example) in the several-thousand dollar range rated at 0.5% THD. I guess those manufacturers must be going hungry huh?
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post #11 of 11 Old 04-07-2007, 09:24 PM
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These speakers are designed for a typical receiver of 70 - 100 watts into 8 ohms. If you think about it, most boombox speakers are rated at 6 ohms and are powered by low output amplifiers, so impedence is only one criteria.
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