Vintage Polk 8 ohm speakers

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Which ones are they? My 7 and 10 are all 6 ohm

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  • codycatalist
    codycatalist Posts: 2,662
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    Monitor 4, Monitor 5JR+ and Monitor 12 all come to mind when thinking of 8 ohm vintage Polk Monitors.
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  • F1nut
    F1nut Posts: 49,787
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    Which ones are they? My 7 and 10 are all 6 ohm

    How did you arrive at that conclusion?
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  • mhardy6647
    mhardy6647 Posts: 33,027
    edited August 2018
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    Early 7 was nominally 8 ohm; early 10 was nominally 6 ohm, per the Polk brochure (ca. 1976 or 77).

    11224559586_ec0e7fda63_z.jpgorigpolkmonitorspecs by Mark Hardy, on Flickr

    I really do need to re-scan this brochure some day...

    11224531455_cfc885853d_b.jpgpolk_brochure_back_pg by Mark Hardy, on Flickr
  • 55LS70
    55LS70 Posts: 184
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    My LS70's are 8 ohm. I believe the LS50's and LS90's are 8 ohm as well.
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  • Cylontymany
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    Both my 7 and 10 have the peerless tweeters in them. But in my research so far they are both still 6 ohm
  • DaveHo
    DaveHo Posts: 3,480
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    Who cares? Any good amp will drive them regardless of the impedance.
  • mhardy6647
    mhardy6647 Posts: 33,027
    edited August 2018
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    Indeed. Not sure why the OPs' worried. Nominal impedance is just a number and, as such, doesn't really say much about how easy or difficult of a load any given loudspeaker is.

    What can matter is the frequency dependent impedance curve of the loudspeaker. If it dips to, say, 2 or 3 ohms in the neighborhood of, say, 75 to 200 Hz (where there is a lot of "musical energy", i.e., signal being delivered to it when listening to actual music), it might be an issue.

    The other thing that can be an issue is what the frequency dependent phase shift plot looks like for any given loudspeaker.

    There have been some amplifier killer loudspeakers made and sold over the years. I've never thought of the Polk 7 (nor even the 10) as among that rather unsavory group.


    Here's an example of a classically difficult loudspeaker load - the Infinity IRS Beta.
    Two sets of impedance curves on this plot (separate woofer and widerange units) -- no phase data, unfortunately.

    988BETAFIG1.jpg

    source: https://www.stereophile.com/content/infinity-irs-beta-loudspeaker-measurements

  • Cylontymany
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    Is it true that the series 2 is 8 ohm for the Monitor 7 plus I am not worried about whether its 6 or 8 ohms my 7 are 7Bs which are 6 ohm I believe. I just want to nail down if there is such so I can get a pair.
  • mhardy6647
    mhardy6647 Posts: 33,027
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    Is it true that the series 2 is 8 ohm for the Monitor 7 plus I am not worried about whether its 6 or 8 ohms my 7 are 7Bs which are 6 ohm I believe. I just want to nail down if there is such so I can get a pair.
    FWIW, I totally don't get what your concern is, and I don't know, so I can't help, sorry.