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Are there any possible problems powering two 8-Ohm speakers in parallel with an audio amplifier designed to drive 4-Ohm per channel? (Both the speakers and amplifier are generic, and the speakers are identical). The amplifier's power rating is greater than the sum of the speakers, and would not be pushed beyond the combined power rating of the speakers. I can't think of any reason for there to be any drop in audio quality, or for there to be any other issues, but I just wanted to do a sanity check by asking.

Thanks

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    \$\begingroup\$ Provided the speakers are identical (same make, type etc) it should be fine. \$\endgroup\$ – JIm Dearden Jun 1 '13 at 10:54
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Parallelling identical 8 Ohm speakers to get a 4 Ohm load (and the opposite: putting 4 Ohms speakers in series to get an 8 Ohm load) is normal practice.

"The amplifier's power rating is greater than the sum of the speakers" - That can get problematic: at full power the speakers might be damaged. You want the speakers (combined) rated power to be at least the maximum power produced by the amplifier.

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  • \$\begingroup\$ Thanks, good to know about it being normal practice. I could argue against the power aspect though, I have often been told that to get the most out of speakers, it is better to have a more powerful amplifier because it's better to slightly overdrive the speakers than to have the amplifier clip. But I suppose if the more powerful amplifier clips, that is doubly bad! If I'm correct, however, the more upmarket professional amplifiers have protection against both scenarios. How they protect against over-driving the speakers is beyond me though, very clever stuff. \$\endgroup\$ – CL22 Jun 1 '13 at 11:50
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    \$\begingroup\$ I don't think they can know the power rating of an attached speaker, hence they can not protect it. \$\endgroup\$ – Wouter van Ooijen Jun 1 '13 at 12:25
  • \$\begingroup\$ Although it couldn't detect when the power is exceeded, I think it feasible that when the cone reaches its apex, the 'unusual' back EMF (if that's the right term) could be detected as the current drawn from the amplifier would show distortion? \$\endgroup\$ – CL22 Jun 1 '13 at 14:39
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This is OK, and the higher amplifier power is unlikely to be a problem as long as you aren't driving either speaker into obvious distress , i.e. audible distortion. (If you are : don't!). The harsh spectrum from clipping an underpowered amplifier is a bigger problem.

The main downside comes if they have different sensitivities : one may be louder than the other. Just use them where you need more volume : the larger room, noisier environment, whatever.

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  • \$\begingroup\$ +1 Good point, even speakers of the same model, from the same batch could have different qualities, and I suppose they could play on each other to some degree, as well as each producing different sound. \$\endgroup\$ – CL22 Jun 1 '13 at 14:47

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