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4 ohm speakers on a 8 ohm amp

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  • 4 ohm speakers on a 8 ohm amp

    I know the question has been asked but my manual to one of my receivers is not making sense to me. I want to use this receiver in my garage to test speakers I make, whether they are 4 ohm or 8 ohm, if it's possible. Below is the print out from the manual. To me it reads I can use 4 ohm speakers if it's just a pair and not four speakers connected to the amp.

  • #2
    Taken literally, one pair of 4 ohm speakers is OK. Assuming two pair of 4 ohmers would do it in.

    4 and 8 ohm speaker ratings are so misleading. The impedance varies with frequency. You will often read a designer stating his design is an easy or difficult amp load depending on the impedance dips.

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    • #3
      Probably a poor translation as the second sentence contradicts the first. I would assume you can use one pair of nominal 4 ohm speakers. If it gets hot and shuts down, you'll know why.

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      • #4
        Originally posted by djg View Post
        Taken literally, one pair of 4 ohm speakers is OK. Assuming two pair of 4 ohmers would do it in.

        4 and 8 ohm speaker ratings are so misleading. The impedance varies with frequency. You will often read a designer stating his design is an easy or difficult amp load depending on the impedance dips.
        Yes, I understand that completely now that I have dove head first into the world of speaker building, and I pretty much answered that question myself. But...Sometimes I just think I know what I am doing when I really don't. The older I get, the more that is easier to say.

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        • #5
          I don't know if I would assume that amp could handle all 4 ohm rated speakers. The odds that a receiver will have adequate protection circuitry get slimmer the older the receiver gets. How hard would it be to just get a cheap car audio amp for a few bucks and a suitable power supply? Personally I use an older QSC PA amp for listening and testing. I've seen them go for a hundred, but sometimes less. I know it will handle 2-ohm loads and the response will be flat to well below and above my testing frequencies.

          Then again, if you're just doing testing at like 2.83v or whatever, might be fine. Although some like to do 28v at 10m instead for better accuracy.

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          • #6
            Do you have a make and model number for the amp?

            Many amps have connections for two pairs of speakers driven by the same power output stage and that power output stage is good down to 4 ohms. So, if you you have two pairs of 8 ohm speakers connected, the amps outputs (i.e., L and R) each see two speakers in parallel for a 4 ohm load. If you were to connect two pairs of 4 ohm speakers, the amp would see 2 ohm loads on each channel and can't handle that low an impedance.

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            • #7
              Originally posted by Millstonemike View Post
              Do you have a make and model number for the amp?

              Many amps have connections for two pairs of speakers driven by the same power output stage and that power output stage is good down to 4 ohms. So, if you you have two pairs of 8 ohm speakers connected, the amps outputs (i.e., L and R) each see two speakers in parallel for a 4 ohm load. If you were to connect two pairs of 4 ohm speakers, the amp would see 2 ohm loads on each channel and can't handle that low an impedance.
              Onkyo TX-88

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              • #8
                Originally posted by breadfan View Post

                Onkyo TX-88
                You can view or download the owner's manual from my google drive. Top left of page 9 alludes to my earlier description as the controls allow for one set, the other set or bpth sets of speakers to be driven simultaneously.

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                • #9
                  Don't worry about it. It can handle one pair of 4 ohm speakers without a problem. Also it does have protection circuitry built-in per the manual.

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                  • #10
                    Thanks guys, I appreciate it.

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