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  1. #1

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    Default using 4 ohms LSI F/X surrounds with 8 ohms receiver

    Hi - I am a novice and have a question. I recently bought LSI F/X surrounds for my home theatre set up. I made the mistake of not checking the impedence of these speakers before purchasing. Now I realize that these are rated at 4 Ohms where as my receiver (Denon AVR 3803) is rated at 8 ohms. Before I hook them up I wanted to get some opinions from other users out there if it really matters. Specially, considering that these are surrounds, does it make a huge difference? I got them at a good price so would not want to return them, but if the difference between the receiver and surround speakers resistance REALLY matters so much that it will either blow up my receiver or the speakers, then I don't want to keep them. Thoughts/comments? Thanks.

    (Not sure if it matters, but if it does, my front speakers are RTi A9s and the sub woofer is micro dsw 4000.)

  2. #2

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    Welcome to Club Polk.
    From the reviews I've read, I don't believe that the Denon 3803 has a particularly strong amp, however
    I believe that it does have preamp outputs which is great. It allows you to add an external amp.
    Get yourself a good 200W, 4 ohm capable, 5 channel, SS amplifier and you will have no problems.
    The RTiA9's will sound better. Are you using the CSiA6 for the center channel?
    Last edited by xcapri79; 12-20-2009 at 05:40 PM.

    Main HT/2 ch:
    Pioneer SC-07, BDP-05FD, Emotiva XPA-5 x 2, XPA-1 x 2,
    Polk Audio LSi25, RTi12 x 2, LSi15 x 4, LSiC x 2, PSW1000 x 4,

    MB HT/ 2 ch:
    LG 47LM5800, Pioneer SC-1523, BDP-23FD, Sony BDP-S790, Emotiva XPA-2, XPA-5,
    Polk Audio LSi25,15, CSi5, LSiFX, PSW505 x 4

    Listening Room 2 ch:
    McIntosh MC162, MC202, C15, C41, C42, MA6500, MA6900, MCD201
    Emotiva RSP-2, RPA-1, ERC-2
    Adcom GCD 750, GFP 750, GFA 5802
    Polk Audio LSi7,9, 15

  3. #3

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    Welcome to the Club!

    You may be ok since those are your surround speakers.
    Linn AV5140 fronts
    Linn AV5120 Center
    Linn AV5140 Rears
    M&K MX-70 Sub for Music
    Odyssey Mono-Blocs
    SVS Ultra-13 Gloss Black:D

  4. #4

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    Quote Originally Posted by danz1906 View Post
    Welcome to the Club!

    You may be ok since those are your surround speakers.
    He needs an amp with the 3803. If anything for the RTiA9's.

    Main HT/2 ch:
    Pioneer SC-07, BDP-05FD, Emotiva XPA-5 x 2, XPA-1 x 2,
    Polk Audio LSi25, RTi12 x 2, LSi15 x 4, LSiC x 2, PSW1000 x 4,

    MB HT/ 2 ch:
    LG 47LM5800, Pioneer SC-1523, BDP-23FD, Sony BDP-S790, Emotiva XPA-2, XPA-5,
    Polk Audio LSi25,15, CSi5, LSiFX, PSW505 x 4

    Listening Room 2 ch:
    McIntosh MC162, MC202, C15, C41, C42, MA6500, MA6900, MCD201
    Emotiva RSP-2, RPA-1, ERC-2
    Adcom GCD 750, GFP 750, GFA 5802
    Polk Audio LSi7,9, 15

  5. #5

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    Thanks for your responses. I have not bought a centre speaker as yet. Thinking of a CSi A4 or A6. Also, point noted regarding the pre-amp but can't afford it as of now. Like I said, I am a novice, so till the time I actually hear the RTis with a power amp, I wouldn't know any better. To my untrained ear they sound good even with just the Denon 3803.

    Going back to my original question regarding the difference between the impedance of LSi (4 ohms) and the receiver(8 ohms), since these are just surrounds I am thinking I may be ok. Polk audio tech support also says that it should not matter that much. Wanted to validate my thought process with the experienced folks on the fourm. Thanks.

  6. #6

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    Don't get an LSI speaker for the rears if you are using RTi's up front. They won't match properly.
    Welcome to Club Polk
    Ben
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  7. #7

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    Quote Originally Posted by newpolkuser View Post
    Thanks for your responses. I have not bought a centre speaker as yet. Thinking of a CSi A4 or A6. Also, point noted regarding the pre-amp but can't afford it as of now. Like I said, I am a novice, so till the time I actually hear the RTis with a power amp, I wouldn't know any better. To my untrained ear they sound good even with just the Denon 3803.

    Going back to my original question regarding the difference between the impedance of LSi (4 ohms) and the receiver(8 ohms), since these are just surrounds I am thinking I may be ok. Polk audio tech support also says that it should not matter that much. Wanted to validate my thought process with the experienced folks on the fourm. Thanks.
    If you have RTiA9's then the matching enter is the CSiA6.
    An external amp will make your system sound better and you don't need to have a trained ear to hear the improvement.
    If budget was a concern, you should not have purchased the LSiFX's and stuck with choosing either the FXiA4 or A6 surrounds.

    Once you get into the RTiA9's or the LSiFX speakers you have moved up the food-chain. This is where you should consider using an external amp to get the sound out of your speakers that they're capable of.
    A capable external amp will cost less than the RTiA9's and is well worth the investment.

    Main HT/2 ch:
    Pioneer SC-07, BDP-05FD, Emotiva XPA-5 x 2, XPA-1 x 2,
    Polk Audio LSi25, RTi12 x 2, LSi15 x 4, LSiC x 2, PSW1000 x 4,

    MB HT/ 2 ch:
    LG 47LM5800, Pioneer SC-1523, BDP-23FD, Sony BDP-S790, Emotiva XPA-2, XPA-5,
    Polk Audio LSi25,15, CSi5, LSiFX, PSW505 x 4

    Listening Room 2 ch:
    McIntosh MC162, MC202, C15, C41, C42, MA6500, MA6900, MCD201
    Emotiva RSP-2, RPA-1, ERC-2
    Adcom GCD 750, GFP 750, GFA 5802
    Polk Audio LSi7,9, 15

  8. #8

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    Welcome to CP :)

    Even though i think the Denon could run a 4Ohm speaker i don't think it would be wise to mix impedence's :o

    Quote Originally Posted by ben62670 View Post
    Don't get an LSI speaker for the rears if you are using RTi's up front. They won't match properly.
    Welcome to Club Polk
    Ben
    +1 I would return the LSI's and use the money toward's the correct "timbre" matched speaker's

    Quote Originally Posted by xcapri79 View Post
    If you have RTiA9's then the matching center is the CSiA6.
    An external amp will make your system sound better and you don't need to have a trained ear to hear the improvement.
    If budget was a concern, you should not have purchased the LSiFX's and stuck with choosing either the FXiA4 or A6 surrounds.

    Once you get into the RTiA9's or the LSiFX speakers you have moved up the food-chain. This is where you should consider using an external amp to get the sound out of your speakers that they're capable of.
    A capable external amp will cost less than the RTiA9's and is well worth the investment.
    Definately get the CSi A6/FXi A6 to match with the a9's ;) The a9's LOVE the juice and only get beeter as the power goes up! :D Going from AVR power to separate power is like night/day :D There are good product's available to get you into separate's without breaking the bank ;)
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  9. #9

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    Thank you for all your responses.

  10. #10

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    I ran 2 LSi15s, 2 LSi7s, and an LSiC off a Denon 3805 for a year without any issues. I suspect you are okay for surround speakers since most energy is either in the center, fronts, or sub.

  11. #11

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    Quote Originally Posted by sTiLlLeArNiNg View Post
    Welcome to CP :)

    Even though i think the Denon could run a 4Ohm speaker i don't think it would be wise to mix impedence's :o



    +1 I would return the LSI's and use the money toward's the correct "timbre" matched speaker's



    Definately get the CSi A6/FXi A6 to match with the a9's ;) The a9's LOVE the juice and only get beeter as the power goes up! :D Going from AVR power to separate power is like night/day :D There are good product's available to get you into separate's without breaking the bank ;)
    i concur w/sTiLlLeArNiNg on the "timbre" topic. The layperson's explanation is lengthy and detailed that can be summed up in one word: phase.

    Also concur w/xcapri79 "If you have RTiA9's then the matching enter is the CSiA6." I (Tony) would NOT mix lines of Polk speakers. Again: phase. I've seen other mix different brands for LCR... ARGH!!

    If you get a separate amp for the LR or LCR you can likely get away w/ using your Denon's* amp to drive surrounds regardless of impedence.

    * I'm assuming the Denon of today is the Denon of old ('80s & '90s)

    cheers & have fun! tony

  12. #12

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    Splice 4ohm resistors into your speaker wires. I've never tried but it would match the resistance then to the receiver.
    ~Dan
    --------

    Projector: Epson 705HD on 106" DaLite
    TV: Samsung 50" Plasma PN50B550
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    Fronts: Polk 1000i
    Center: Polk Csi40
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  13. #13
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    Quote Originally Posted by dvran View Post
    Splice 4ohm resistors into your speaker wires. I've never tried but it would match the resistance then to the receiver.
    Nooooooo!!!
    -Eric
    -Polk Audio

  14. #14

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    How about we make it simple for the dude, No, bring them back. See..simple.

  15. #15

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    You are going to blow those Lsi F/X speakers if you underpower them with a 8 ohm receiver at higher volume. Either buy an amp for the Lsi's or take them back. I have a 7.1 HT system of Lsi speakers and use F/X speakers for the surround and rear mains. They are great speakers. I went the external amp way to power my system even though my Yamaha can do 6 ohm speakers. I would hate to see you blow your speakers and be out the money you paid for them. Just some advice from someone who has been there. They will sound much better with an external amp.
    Polk HT system 1: LSIC, LSI25 mains, LSI F/X rears, Lsi F/X rear centers, Lsi 7's presence speakers,
    Yamaha RX-V2500 System, Sunfire grand 5 channel, Carver A753 3 channel amp.

    Polk HT system 2: ,Polk CS1000 center, Polk cs400rear center, Polk RT800 mains stacked with RT55's, Polk F/X 1000 rears running on a Yamaha RX-V2200

    Polk Speaker collection: SDA SRS 1.2tl x 2, SRT system, SDA SRS 2 P/B, SDA 2A, SDA 1C Studio, SDA CRS+, Monitor 12 series 2, 7B & 4, SRS 3.1tl, RTA 15tl

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