Powering 4 Ohm Speakers

unclestoolie

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.

Dennis Gardner

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?

unclestoolie

Currently, the Onkyo SR806 seems to be the receiver I keep coming back to.

dorokusai

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

unclestoolie

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????

seeclear

Wouldn't the Rotel in the FM work well for this application? No affiliation.

http://www.polkaudio.com/forums/showthread.php?t=74542

Murray1

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.

Dennis Gardner wrote: »

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?

cfrizz

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!

unclestoolie wrote: »

Which Onkyo????

cfrizz

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.

unclestoolie

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.

cfrizz

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.

unclestoolie wrote: »

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.

doug lang

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.

ben62670

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:)

Murray1

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.

pearsall001

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!!

HHStuart

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).

pkhoopes

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.

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.

cfrizz

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

Kex

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.).

cfrizz

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.

pkhoopes

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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