8 ohms centre with 4 ohms fronts

Hi all,
I have a pair of LSi7 which I am very fond of and have been using just the two of them without any sub nor any centre for 10 years.

I have already upgraded from the old Onkyo tx-sr600 on to a new Onkyo TX-NR686. I did not move away from that price point for I am not looking to have a full 5.1/7.2 setup: I simply don't have the room to house surround speakers, so power wise the Onkyo should do.

But I am having a problem: I can't find a 4 ohms centre speaker and current Polk Audio's are all 8 Ohms. Since I am newbie on this subject matter, can I drive an 8 ohm centre while keeping my LSi front pair? I really want to keep the LSi :smiley:


  • EmlynEmlyn Posts: 2,528
    The 4 ohm or 8 ohm rating is a nominal, or average, rating not an absolute. A speaker's impedance varies quite a bit depending on frequency. There are no issues with mixing speakers with different impedance ratings as long as the amplifier can handle the total load. The receiver can adjust output sound levels so they are similar if you use the setup microphone or a sound pressure level meter to do it manually.

    However, you would likely find there to be a mismatch in perceived sound quality if using speakers from different lines because the drivers would be different. For example, the tweeter in a speaker from the RTi line would sound "brighter" than the tweeter from a speaker in the LSi or Signature lines. Sounds panning from left to center to right would sound mismatched.

    The LSiM 704C would be the best available choice it you're looking for something new. If you're ok with used, then an LSiC is the best choice or buy another pair of used LSi7s and just use one for a center channel. I would probably do the latter if it was my system.

    1. Polk LSiM707, 704C, 703; Dual SVS SB2000 subwoofers; Marantz SR7011 receiver; Parasound A23 amp; Oppo 205; Sony 65" 4K TV; FIOS; PS Audio Power Plant Premier; MIT S2 cables
    2. JM Labs Electra 920.1; Sonic Frontiers Line 3 Preamp; Classe Model 25 amp; Sony HAP-Z1ES; Oppo 105D; Music Hall MMF7 and Acoustech phono pre; PS Audio Power Director; MIT S1 Cables
    3. Polk LSiM703; Parasound JC2BP and A21; Sony 48" 4K TV; Wyred4Sound DAC 2; Oppo 203; Squeezebox Touch; MIT S3 cables
  • Thanks for the input.

    I am not a fun of mixing speaker lines, and in my country Polk Audio has neven been a popular product. I'll be on the look out for a LSiC, as it would be a shorter speaker (and height is a premium under the TV) then an LSi7 put orizontally.
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