Receiver/Amp for 6&8ohm speaker mix - AVS Forum
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Old 02-14-2013, 01:00 PM - Thread Starter
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First of all, a big Hello to everyone since I am new to posting at AVS. Also, a big THANKS for all the information that I have gathered since jumping into the home theater scene recently.

I have a very small budget set aside for this home theater since the wifey is not giving it much of a "nod" since it doesn't come in her particular color or fabric...LOL. I would like to have a 7.1 sound setup and there is enough room to build a 200" screen with just enough viewing distance.

I have enough funds to get a mid-range projector under $1000 (just bought the BenQ W1070), a receiver around $500, Blu-ray player under $200, and an amplifier if needed under $200. I have no choice but to recycle some old college speakers for the time being and that is where my problem lies.

I have some old "party" Wharfedale tower speakers: one pair of Valdus 400 and two pairs of the MFM-7's. I do know that the Valdus are 8 ohm / 150 watts and the MFM-7's are 6 ohm / 150 watts. I was going to use the MFM-7's as the front pair and the side pair. I figured the Valdus pair would be a good rear pair. I also have a Wharfedale Diamond center and a self powered 15" sub-woofer.

So how does one go about running two different ohm settings without buying a separate amplifier? Is that possible on any receiver? Or should I just run the entire setup at 6 ohm? Also, what type of receiver is going to feed a true 150 watts at 6 ohms without breaking the bank?

Any suggestions would be awesome; I just don't have enough knowledge for this stuff yet!
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Old 02-14-2013, 01:19 PM
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with any recent solid state amp there is no setting necessary to make the amp work with different speaker impedances. It's a different deal with tubes. The recent receivers that have a switch for 4 ohm operation aren't using it to improve performance. In fact it degrades performance (limits available power) in order to meet government requirements regarding heat, etc. developed when running hard. I would not run a bunch of 4 ohm speakers on a receiver that is not specified to be able to handle 4 ohms, because solid state amps have gerater problems (heat, mostly) when driving lower impedance speakers. (Tube amps are just the opposite, BTW). But that's not what you're talking about.

In short, especially if you don't intend to listen painfully loud, your potential issues are more about ability to provide enough power to each channel without running into undesirable (ie audible) distortion. And that's a real can o worms, becuase while almost no receiver can put full power ointo five or 7 cnhannels simultaneously, they also are never called upon to do so except on a test bench. If, for example, the surrounds are audibly "one notch" quieter than the fronts (3 dB) they are using one half the power the fronts require. Everythings's constantly slideing on a constantly sliding scale. I havent' gone looking for receiver reviews with power tests in a while, but they exist. If you're worried, look at them and get a feel for what seems to do teh best within your price range.

I will say that as a VERY broad generality, it seems to me that Denon, Onkyo, Pioneer and Yamaha are roughly comparable at roughtly comparable price points in terms of all channel driven power and (to a lesser and less-well-known extent) ability with truly low (4 ohms or lower) speaker impedances.
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Old 02-14-2013, 03:21 PM
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Check the pioneer sc1222.
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Old 02-14-2013, 03:37 PM
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Quote:
Originally Posted by Craz3d View Post


I have some old "party" Wharfedale tower speakers: one pair of Valdus 400 and two pairs of the MFM-7's. I do know that the Valdus are 8 ohm / 150 watts and the MFM-7's are 6 ohm / 150 watts. I was going to use the MFM-7's as the front pair and the side pair. I figured the Valdus pair would be a good rear pair. I also have a Wharfedale Diamond center and a self powered 15" sub-woofer.

So how does one go about running two different ohm settings without buying a separate amplifier? Is that possible on any receiver?

Yes. Any good receiver should have no problems with mixed 6 and 8 ohm speakers.
Quote:
Also, what type of receiver is going to feed a true 150 watts at 6 ohms without breaking the bank?

Just because the speakers are rated at 150 watts doesn't mean that the receiver has to be rated at 150 watts.

Speaker power ratings are kinda fluid and flexible. Almost all AVRs run within +/- 3 dB of 100wpc, and that is close enough for most applications like yours. Most people don't run their systems with the pedal to the metal.
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Old 02-15-2013, 10:51 AM - Thread Starter
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Thanks for the great info guys! I hope to eventually save up enough to replace these speakers in a year or two, but surely they will work for fine for now.

That Pioneer looks like a great option; hopefully, Newegg will have a deal on it soon.
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