Powering 4 Ohm Speakers

unclestoolieunclestoolie Posts: 8
I am shopping for a receiver to power my new 5.1 setup, all Polk in-walls. The fronts are LC265i (4 Ohm impedance, 200 Watts), the center is LCiC (4 Ohm impedance, 150 Watts) and the rears are LC65i (4 Ohm impedance, 125 Watts). I am having a hard time getting good answers from the local stores about output and speaker impedance. Most specs on all new receivers are given assuming an 8 Ohm impedance. Will all of these also drive my 4 Ohm loads, or do I need to be "specialty shopping" for my setup? I am really trying to avoid needing an amplifier.
Post edited by unclestoolie on

Comments

  • Dennis GardnerDennis Gardner Posts: 4,801
    edited December 2008
    Congrats on your new Polk LCi speakers..........You really have a choice between higher end receivers such as NAD, Rotel, etc. that have proven to handle 4 ohm loads or get a cheaper receiver with preamp outputs to go to a nice 5 channel amp. You really won't need much more than 100 WPC to sound great, but low end receivers claiming to push 100WPC into 8 ohms usually go into thermal shutdown when pushed hard into 4 ohm loads.

    What receivers are you looking at specifically?
    HT Optoma HD25 LV on 80" DIY Screen, Anthem MRX 300 Receiver, Pioneer Elite BDP 51FD Polk CS350LS, Polk SDA1C, Polk FX300, Polk RT55, Dual EBS Adire Shiva 320watt tuned to 17hz, ICs-DIY Twisted Prs, Speaker-Raymond Cable

    2 Channel Thorens TD 318 Grado ZF1, SACD/CD Marantz 8260, Soundstream/Krell DAC1, Audio Mirror PP1, Odyssey Stratos, ADS L-1290, ICs-DIY Twisted , Speaker-Raymond Cable
  • unclestoolieunclestoolie Posts: 8
    edited December 2008
    Currently, the Onkyo SR806 seems to be the receiver I keep coming back to.
  • dorokusaidorokusai Posts: 25,454
    edited December 2008
    No. Unless it publishes 4ohm power ratings for all channels, you need to keep looking. It isn't hard to find one but it is usually more expensive. It isn't neccesary to use external amplification with those choices. I'd look into Rotel, Adcom or B&K
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
  • unclestoolieunclestoolie Posts: 8
    edited December 2008
    Lasareath wrote: »
    The Onkyo will clip and shut-down.

    My Onkyo ran everything ok until I hooked up 4 ohm speakers and turned it up.

    That's when I bought (2) Carver TFM-35X's

    Which Onkyo????
  • seeclearseeclear Posts: 1,240
    edited December 2008
    Wouldn't the Rotel in the FM work well for this application? No affiliation.

    http://www.polkaudio.com/forums/showthread.php?t=74542
    "Don't forget to change your politician. They are like diapers they need to be changed regularly, and for the same reason."
  • Murray1Murray1 Posts: 193
    edited December 2008
    I am also trying to figure out the best way to go. Wondering if NAD,Rotel,etc offer HD audio(True Dolby,etc). Do not believe I necessarily need radio if I can save $ going with just a tuner and amp. I have been considering 706 Oink so far. Any suggestions for us guys.


    Congrats on your new Polk LCi speakers..........You really have a choice between higher end receivers such as NAD, Rotel, etc. that have proven to handle 4 ohm loads or get a cheaper receiver with preamp outputs to go to a nice 5 channel amp. You really won't need much more than 100 WPC to sound great, but low end receivers claiming to push 100WPC into 8 ohms usually go into thermal shutdown when pushed hard into 4 ohm loads.

    What receivers are you looking at specifically?
  • cfrizzcfrizz Posts: 13,420
    edited December 2008
    ALL OF THEM!

    Onkyo's are not designed to run 4ohm speakers.

    If you are set on an Onkyo, make sure you also plan to get at least a 200wpc @8ohm 5 channel amp to pair with it.

    That way your fine speakers operate to their full potential & you won't blow up the Onkyo or your speakers!
    Which Onkyo????
    Marantz AV-7705 PrePro, Classé 5 ch. 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony Bravia KDL-40R510C TV, Polk S60 Main Speakers, Boston VR-920 Center Channel, SVS NSD-12 SB12 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers
  • cfrizzcfrizz Posts: 13,420
    edited December 2008
    While those receivers will run the LSI's, they more than likely will not have all the bells and whistles that you might want it to have. You will have to do your research into them to see if they do. Otherwise, you will need another receiver that does have what you want with preouts for a separate amp.

    Murray1 wrote: »
    I am also trying to figure out the best way to go. Wondering if NAD,Rotel,etc offer HD audio(True Dolby,etc). Do not believe I necessarily need radio if I can save $ going with just a tuner and amp. I have been considering 706 Oink so far. Any suggestions for us guys.
    Marantz AV-7705 PrePro, Classé 5 ch. 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony Bravia KDL-40R510C TV, Polk S60 Main Speakers, Boston VR-920 Center Channel, SVS NSD-12 SB12 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers
  • unclestoolieunclestoolie Posts: 8
    edited December 2008
    Murray1 wrote: »
    I am also trying to figure out the best way to go. Wondering if NAD,Rotel,etc offer HD audio(True Dolby,etc). Do not believe I necessarily need radio if I can save $ going with just a tuner and amp. I have been considering 706 Oink so far. Any suggestions for us guys.

    Murray,

    I am led to believe by your reply that you are in the same predicament I am in. What speakers are you trying to drive, and where has your research led you so far concerning receivers? So far, the 806 oink has a little more power per channel, and the downloadable owners manual says it will drive my load, FYI.
  • cfrizzcfrizz Posts: 13,420
    edited December 2008
    The only thing the Onkyo will do is limit the amount of power that the LSI's will get. Meanwhile it will get hotter & hotter from the strain of pushing them until finally it goes into protect mode & shuts down. Hopefully it won't take your speakers with it.

    You might just be better off listening to the people who have actually OWNED the speakers, thereby knowing what they are talking about rather than going by some manual.

    The manual can't help you if you blow a tweeter from being overdriven by lack of power.

    Murray,

    I am led to believe by your reply that you are in the same predicament I am in. What speakers are you trying to drive, and where has your research led you so far concerning receivers? So far, the 806 oink has a little more power per channel, and the downloadable owners manual says it will drive my load, FYI.
    Marantz AV-7705 PrePro, Classé 5 ch. 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony Bravia KDL-40R510C TV, Polk S60 Main Speakers, Boston VR-920 Center Channel, SVS NSD-12 SB12 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers
  • doug langdoug lang Posts: 261
    edited December 2008
    I would agree. I owned a 987 Onkyo and with the lsi line of speakers my receiver got very hot. I was using fans just to cool it down. As cfrizz has said sometimes it is better to listen to experience than a manual. A five channel amp would be the safe way to go if you are set on the Onkyo.
    Oppo bdp 93 Blue Ray
    Integra DTR-80-2
    Polk LSi9s (mains)
    Polk LSiC (center)
    Polk LSiFXs (surrounds)
    Sub SVS 20-39+
    Samsung 60" Led 3-d
    Blue Jean Cables
  • ben62670ben62670 Posts: 16,077
    edited December 2008
    cfrizz wrote: »
    The only thing the Onkyo will do is limit the amount of power that the LSI's will get. Meanwhile it will get hotter & hotter from the strain of pushing them until finally it goes into protect mode & shuts down. Hopefully it won't take your speakers with it.

    You might just be better off listening to the people who have actually OWNED the speakers, thereby knowing what they are talking about rather than going by some manual.

    The manual can't help you if you blow a tweeter from being overdriven by lack of power.

    Very well put:)
    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
  • Murray1Murray1 Posts: 193
    edited December 2008
    Uncle Toolie,

    I will be purchasing LSi9 for the front with LSiC for center. LSi 7 will be my rears. Hoped to get some specifics regarding if NAD and the like offer True HD audio but no response yet. Anyone have any info please post as I have posted this question several times but no response. Also wanted specifics regarding tuner and amp combo versus receiver and amp combo if no need for radio. If amp is required no matter what receiver or tuner we go with, I would be going with a Yami 663 or Oink 706. If I hear that a tuner and amp combo is the way to go, I will need recommendations on manufacturers to go with. Definitely not looking for big $ stuff-more in line with above yami/oink price points. Thanks again guys.
  • pearsall001pearsall001 Posts: 4,335
    edited December 2008
    Here's the NAD site: http://nadelectronics.com/index. The info you're looking for is there. And yes their AVR's have everything you're looking for. Not cheap!!
    "2 Channel & 11.2 HT "
    Panny 65" 3D Plasma
    Yamaha AVENTAGE RX-A3010 AVR
    Crown XLS 1002 DriveCore 2 Series - center channel
    NAD Dac
    Oppo BDP-93
    SONOS Music System
    KEF Q300 / mains
    KEF Q600 / center
    KEF Q800 / surrounds
    KEF Q100 / rear surr.
    Def Tech ProMonitor 1000 / front & rear presence
    Velodyne SPL-1200R subs / dual pair
    DSPeaker Anti-Mode 8033 sub EQ
    Extensive room treatments
  • HHStuartHHStuart Posts: 263
    edited December 2008
    I have LSi15's and a LSiC with a Sony 3400ES receiver. On advice from this forum I added an amplifier. I narrowed it down to the Emotiva 5 channel and the Outlaw 7125. The latter is 50 pounds and the former is 70 pounds. I just felt that 70 pounds was over the limit. It's like buying an old Cadillac. Big iron will let you drive comfortably from coast to coast but it's not my thing. The Outlaw hardly gets warm running 5 channels (190 w per channel into 4 ohms).
    Front - Polk LSiM 705, Center - Polk LSiM 704c, Rear - Polk LSi 7
    Subwoofer - Epik Legend
    Receiver (as Preamp) - Sony STR-DA3400 ES
    Amplifier - Outlaw 7125
    Television - 58" Samsung Plasma PN58B860
    Blu Ray - OPPO BDP 83
  • pkhoopespkhoopes Posts: 7
    edited January 2009
    Hi all,

    I am new to this forum, and have read this thread with interest. I am upgrading my home theater, which is a 5.1 setup. I ordered a pair of LSi9's, which should be arriving tomorrow. I am also expecting delivery of my new Yamaha rxv-3900 a/v receiver, which will be powering the system. The LSi9's will be the fronts, center is CS400i, rears RC85i, Hsu sub.

    I selected the Yamaha receiver after much research. I know the LSi9 needs power, but I do not want a separate amp, at least not yet. The specs for the Yamaha state 'Max power per channel (1 khz, 0.7% THD, 4 OHMS), at 200w. I spoke with a sales rep at Yamaha, and a Polk rep at this site (who sold me the speakers), and both agreed that this combination would work fine. The manual for the receiver says to set the switch at 6 ohms instead of 8, and that 4 ohm speakers are ok.

    I would love to get additional input from you experts as to whether you agree that this combo will work. Thanks.

    Paul
  • John K.John K. Posts: 825
    edited January 2009
    Paul, welcome. Yes, the 3900 will drive the Lsi9s to sound levels that are probably higher than you want(or would be safe for your hearing). One point though, is to not set the impedance to the lower setting rather than 8ohms, regardless of the statement in the manual. This is a type of safety precaution to help prevent overheating and keep the UL(Underwriters Laboratory)happy. It does this by reducing the voltage that the power supply section of the receiver can output, and following Ohm's Law, when the voltage is reduced so is the current and power. The lower setting cuts the maximum power capability roughly in half. So, although this reduces the chance of overheating, it also reduces the maximum performance. Keep the setting at 8ohms.
  • cfrizzcfrizz Posts: 13,420
    edited January 2009
    And you got it if you read this thread. Welcome to Club Polk, but proceed at your own risk since you now KNOW what you are risking.
    pkhoopes wrote: »
    Hi all,

    I am new to this forum, and have read this thread with interest. I am upgrading my home theater, which is a 5.1 setup. I ordered a pair of LSi9's, which should be arriving tomorrow. I am also expecting delivery of my new Yamaha rxv-3900 a/v receiver, which will be powering the system. The LSi9's will be the fronts, center is CS400i, rears RC85i, Hsu sub.

    I selected the Yamaha receiver after much research. I know the LSi9 needs power, but I do not want a separate amp, at least not yet. The specs for the Yamaha state 'Max power per channel (1 khz, 0.7% THD, 4 OHMS), at 200w. I spoke with a sales rep at Yamaha, and a Polk rep at this site (who sold me the speakers), and both agreed that this combination would work fine. The manual for the receiver says to set the switch at 6 ohms instead of 8, and that 4 ohm speakers are ok.

    I would love to get additional input from you experts as to whether you agree that this combo will work. Thanks.

    Paul
    Marantz AV-7705 PrePro, Classé 5 ch. 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony Bravia KDL-40R510C TV, Polk S60 Main Speakers, Boston VR-920 Center Channel, SVS NSD-12 SB12 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers
  • KexKex Posts: 3,514
    edited January 2009
    For any of you considering NAD, Spearit Sound is an excellent source. They also have refurbished models which will bring the price tag down significantly, and they ship, so you don't have to live in Massachusetts to shop there.

    http://www.spearitsound.com/nad/nadspec.htm

    I already own a NAD T754, since I am expecting to experiment with 4 ohm LC80i ceiling speakers as soon as I can get everything ready for the required installations, and I am absolutely delighted with the performance, especially sound dynamics overall and much better, much tighter bass.

    All the T7xx models are surround sound receivers, if that is what you are looking for. Pricing starts at just under $400 for a refurbished T744. They are rated not only for 4 ohm performance, without the trick of using a power limiting switch, but they are even rated for 2 ohm performance ... important, since 4 ohm speakers will sometimes dip much lower. When looking at power ratings, NAD will always have lower numbers than the likes of Oink, Yamaha, Denon etc., because they measure output more conservatively, but my T754, rated 70w/ch, seems to drive my current (large) speakers with more authority than an Emotiva external amplifier that was rated 125w/ch, and the Emotiva did not improve bass response or detail anywhere remotely close to the extent that the NAD has done IMO.

    As for the new HD audio formats, I believe that these have not been implemented by NAD, or many other higher end models, as yet, but may be on many of the new T7_5 models early this year, If you feel that you need this feature (they may get renamed from T785 to T785HD, etc.).
    Alea jacta est!
  • cfrizzcfrizz Posts: 13,420
    edited January 2009
    You obviously missed this post Xcapri, as well as the others who know better.

    But if you want to put such nice & expensive speakers at risk, it's your money, knock yourself out.
    cfrizz wrote: »
    The only thing the Onkyo will do is limit the amount of power that the LSI's will get. Meanwhile it will get hotter & hotter from the strain of pushing them until finally it goes into protect mode & shuts down. Hopefully it won't take your speakers with it.

    You might just be better off listening to the people who have actually OWNED the speakers, thereby knowing what they are talking about rather than going by some manual.

    The manual can't help you if you blow a tweeter from being overdriven by lack of power.
    Marantz AV-7705 PrePro, Classé 5 ch. 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony Bravia KDL-40R510C TV, Polk S60 Main Speakers, Boston VR-920 Center Channel, SVS NSD-12 SB12 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers
  • pkhoopespkhoopes Posts: 7
    edited January 2009
    John K. wrote: »
    Paul, welcome. Yes, the 3900 will drive the Lsi9s to sound levels that are probably higher than you want(or would be safe for your hearing). One point though, is to not set the impedance to the lower setting rather than 8ohms, regardless of the statement in the manual. This is a type of safety precaution to help prevent overheating and keep the UL(Underwriters Laboratory)happy. It does this by reducing the voltage that the power supply section of the receiver can output, and following Ohm's Law, when the voltage is reduced so is the current and power. The lower setting cuts the maximum power capability roughly in half. So, although this reduces the chance of overheating, it also reduces the maximum performance. Keep the setting at 8ohms.

    Hi John K.,

    Thanks for the informative post. I will add that after I posted my message, I decided to try my first foray into external amplification. I had read good things about the Emotiva products, and the XPA-3 is on a good sale right now. So I bought one! I will use that to power the fronts and center CSi400.
    That should keep those 4 ohm speakers happy! Thanks again for your reply.

    Paul
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