4 or 8 Ohms?

Mr. Mojo
Mr. Mojo Posts: 53
edited November 2007 in Basic Hookup/Wiring Questions
The specs for the RM10 say nominal impedance 8 ohms, minimum impedance 4 ohms. The receiver I'm looking at (Onkyo 605) has 90 watts per channel at 8 ohms.
I have to buy the right gauge of speaker wire and was wondering if I should base it on 8 ohms (or 4)?
Thanks for any help!
Post edited by Mr. Mojo on
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  • beardog03
    beardog03 Posts: 5,550
    edited September 2007
    12 guage wire should be fine

    and I believe they are 8 ohm

    correct me if I`m wrong , guy`s...


    oh, and welcome to the forum !!
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  • zx_toth
    zx_toth Posts: 417
    edited September 2007
    The Rm series is 8 ohms. I have the RM20s as rear surrounds and RM30s soon to be rear surround backs when I get my LSi25s up and running.

    Zsolt
    My Home Theater Rig
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  • Mr. Mojo
    Mr. Mojo Posts: 53
    edited October 2007
    Excellent.
    Thanks for the quick response!
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  • frazier.ray
    frazier.ray Posts: 1
    edited October 2007
    New to this.
    I just got the Yamaha RX-v3800 with Lsi 9s, Lsi fxs and the LsiC. I know the Lsis are 4 ohm, but I can only set the Yamaha at 8 or 6 ohms. Which one is best? Can this damage my speakers in any way? Thanks for the help.
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  • John K.
    John K. Posts: 822
    edited October 2007
    Ray, welcome. The provision for setting the receiver to a lower impedance is a type of safety measure required by various regulations, such as those of the UL(Underwriters Laboratory), to help prevent overheating of the amplifier. It in no way optimizes the receiver for driving the lower impedance speakers. The effect is to lower the maximum voltage that the power supply section of the receiver can deliver, and because of Ohm's Law, when the maximum voltage is reduced so is the maximum current and power available. Although this reduces the chance of overheating, it likewise reduces the performance capabilities of the unit. Leave the setting at 8 ohms and your 3800 should have no problem in driving the Lsis to very high sound levels. If there was a problem the protective circuits of the 3800 would simply shut it down, but there would be no damage to either the receiver or the speakers.
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  • F1nut
    F1nut Posts: 50,722
    edited October 2007
    frazier.ray wrote: »
    New to this.
    I just got the Yamaha RX-v3800 with Lsi 9s, Lsi fxs and the LsiC. I know the Lsis are 4 ohm, but I can only set the Yamaha at 8 or 6 ohms. Which one is best? Can this damage my speakers in any way? Thanks for the help.

    Your AVR isn't rated to drive 4 ohm loads, period. Time to shop for new power.
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  • Frank Z
    Frank Z Posts: 5,860
    edited October 2007
    Gotta go with F1 on this one. a receiver that is not rated for the lower impedance of a speaker like the LSI series (4 ohm nominal) will most certainly shut down early and often.
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  • cmorey
    cmorey Posts: 1
    edited October 2007
    I have the LSI15's and want a new AV receiver. I found the Denon 4308 to do everything I want. (HD Radio, Network[play for sure capability] HDMI 1.3a, 7.1 channel, etc. The only problem is that it is not rated for 4 ohms.. Only 8. Their website says it won't be a problem, but I don't necessarily believe it.

    Does anyone have a suggestion for a AV receiver in the 2K price range. I'm trying to stay way from separates due to the cost and I don't really have to space for the separates....


    Any help or suggestions would be appreciated.

    Craig
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  • bigaudiofanatic
    bigaudiofanatic Posts: 4,415
    edited October 2007
    I have to agree with F1 and Frank. I am getting a set of LSi15's and needed to get a 4 ohm amp so i went with Outlaw 970 Preamp, and Outlaw 7125 Amp.
    HT setup
    Panasonic 50" TH-50PZ80U
    Denon DBP-1610
    Monster HTS 1650
    Carver A400X :cool:
    MIT Exp 3 Speaker Wire
    Kef 104/2
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  • hockeyboy
    hockeyboy Posts: 1,428
    edited October 2007
    Either one of these should work:

    http://hifitrader.com

    Onkyo TX-NR905
    ADCOM GFR700HD
    My Main Gear
    Mitsu HC5000 (Proj.)
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  • vonnie123
    vonnie123 Posts: 326
    edited November 2007
    That is a beautiful Yamaha AVR. Although I'm sure it would run your LSis adequately, it would be safer to go with a high current power amp. Your AVR is equipped with pre-outs to enable this. Lots of good equipment is out there, as well as nice used equipment. Some good suggestions can be had on this forum by the experts, in addition to stuff you can find in the archives. Good luck and enjoy.
    [
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  • Ricardo
    Ricardo Posts: 10,636
    edited November 2007
    John K. wrote: »
    Leave the setting at 8 ohms and your 3800 should have no problem in driving the Lsis to very high sound levels. If there was a problem the protective circuits of the 3800 would simply shut it down, but there would be no damage to either the receiver or the speakers.

    Very risky advise IMO. Probably the AVR's circuits will shut it down before the AVR is damaged.....but it could be too late for the speakers; very high sound levels? Not sure if the LSi line has any protection for the tweeters...I would not do this with my own equipment.
    _________________________________________________
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  • MSALLA
    MSALLA Posts: 1,602
    edited November 2007
    Running 5 4ohm speakers on an AVR is not the best idea. The way most AVR's amps are rated is with only 2 channels driven. They may have the watts but not enough amps to handle a 4ohm load. Even if the AVR will drive the speaker, you won't get the full performance that you can from the lsi. Do a search on this site for pages and pages on this subject.
    Michael


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    Lsic center
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  • skipf
    skipf Posts: 694
    edited November 2007
    Here Ya go.

    http://cls.audiogon.com/cgi-bin/cls.pl?miscrcvr&1198009297
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  • engtaz
    engtaz Posts: 7,664
    edited November 2007
    No pre amp outs so adding an amp is out. Need a amp that says it supports 4 ohms. 8 ohm amps can damaged 4 ohms speakers when they clip.

    engtaz
    engtaz

    I love how music can brighten up a bad day.
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  • danger boy
    danger boy Posts: 15,722
    edited November 2007
    i'm just surprised how often I read this on here.. people using Yamaha receivers trying to power 4ohm speakers, then their AVR not having pre amp outs. just making an observation is all.
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  • Bill Ayotte
    Bill Ayotte Posts: 1,860
    edited November 2007
    skipf wrote: »
    Here Ya go.

    http://cls.audiogon.com/cgi-bin/cls.pl?miscrcvr&1198009297

    400W/CH@4ohms FTW!:D

    It would take a lot of $$ to move up from this...
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  • beardog03
    beardog03 Posts: 5,550
    edited November 2007
    skipf wrote: »
    Here Ya go.

    http://cls.audiogon.com/cgi-bin/cls.pl?miscrcvr&1198009297

    That`s 15 min. away !

    I wish I had the cash !!

    Very nice unit...might get a good deal with the local pick-up...
    Maybe not, who knows !!
    Cary SLP-98L F1 DC Pre Amp (Jag Blue)
    Parasound HCA-3500
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    SVS PC-Ultra Sub
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    MIT Shotgun S1 I/C`s
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  • McLoki
    McLoki Posts: 5,231
    edited November 2007
    skipf wrote: »
    Here Ya go.

    http://cls.audiogon.com/cgi-bin/cls.pl?miscrcvr&1198009297

    Well, that would certainly do it. (and sound great in the process) you could also look at B&K or Arcam recievers...
    Mains.............Polk LSi15 (Cherry)
    Center............Polk LSiC (Crossover upgraded)
    Surrounds.......Polk LSi7 (Gloss Black - wood sides removed and crossovers upgraded)
    Subwoofers.....SVS 25-31 CS+ and PC+ (both 20hz tune)
    Pre\Pro...........NAD T163 (Modded with LM4562 opamps)
    Amplifier.........Cinepro 3k6 (6-channel, 500wpc@4ohms)
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  • vonnie123
    vonnie123 Posts: 326
    edited November 2007
    No worries, this Yamaha AVR is equipped with preouts. Link listed below.




    http://www.yamaha.com/yec/products/productdetail.html?CNTID=558316&CTID=5000300
    [
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