Will playing 4ohm speakers be damaged by playing them on a 8 ohm receiver? - AVS Forum
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post #1 of 26 Old 03-12-2008, 07:10 AM - Thread Starter
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Specifically I'm talking about the Polk Audio LSi15's and Pioneer Elite VSX-92TXH.


On my Polk LSiC there is a single tweeter and two main mid drivers (5.25").

The driver on the left sounds great, but the driver on the right hardly has any sound coming out of it. Any idea's? Do I have a bad center?
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post #2 of 26 Old 03-12-2008, 09:21 AM
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Your receiver might struggle with speakers that are 4ohms. As a rule, 4ohm speakers are somewhat hard to drive by a receiver unless it is very beefy. It could be that the specific driver is blown out. What happens with this kind of issue is that you are probably overdriving the receiver and it is causing the amp to clip which is bad for your speaker. The damage comes from overdriving the speaker in trying to get to listening levels that you like. This may have damaged the speaker.

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post #3 of 26 Old 03-12-2008, 10:04 AM
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Swap the speaker leads with unit off and then turn unit back on keeping the levels normal and see if the problem is the speaker or the pio
as MikeDuke pointed out louds levels at 4ohms without an amp or rec that can handle 4ohm=damage.
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post #4 of 26 Old 03-12-2008, 10:35 AM
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There's no such thing as a 4 ohm speaker, or an 8 ohm receiver, or a 3/4-ton pickup truck. The terms are nebulous, and they omit many other variables.

A speaker rated at 4 ohms may have resistance at various frequencies varying from 4 ohms to 20 ohms, or higher. Some 4 ohm speakers don't dip below 5 ohms at any frequency, but others dip to 3.2 ohms or lower, and they can cause amplifier problems and current limiting. Then there's the question of where the low resistance occurs. If it's for an LCR switched to "small" and the impedance is 3 ohms at 30 Hz, no big deal. Also, what is the speaker's sensitivity? If it's high, the receiver may not be pushed hard enough to draw enough current through the outputs to shut it down.

You can generally drive a 4 ohm speaker with a receiver not rated to drive below an 8 ohm load (I hate those, BTW), as long as you don't turn the volume up too toasty, and as long as you add NO treble or bass boost. It's living on the edge, though.

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post #5 of 26 Old 03-12-2008, 10:44 AM
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I'm sure it's not an issue of the receiver being able to drive the load. That Pio should have generous amounts of power and the capability to drive 4 ohms. I'm guessing you have a bad driver, but I doubt it was the receiver, unless you are playing it unusually loud. you are more apt to wreck a speaker by underpowering it than overpowering it.

Gently push on the funky driver if it feels scratchy at all then you have a damaged driver. Are the speakers new? If it's always been that way then check the warranty, they are usually covered for a longer time than electronics are.

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post #6 of 26 Old 03-12-2008, 10:55 AM
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1.) Paul is quite correct. Some 4 ohm speakers will be relatively easy for a typical receiver to drive, some won't. You would need an impedance curve to truly answer the question.

2.) tvtommy is also correct, it doesn't sound like your problem has anything to do with the speaker impedance. It could be as simple as just having a bad connection on one woofer.
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post #7 of 26 Old 03-12-2008, 11:36 AM
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ditto what Paul said. Generally, HK and Denons have been pretty compatible with most 4 ohm rated speakers.

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post #8 of 26 Old 03-12-2008, 02:06 PM
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Quote:
Originally Posted by Hyper_Lite View Post

The driver on the left sounds great, but the driver on the right hardly has any sound coming out of it. Any idea's? Do I have a bad center?

Check your main speakers, they too, should be working a similar way. The two drivers are crossed over at different frequencies, and if center is set to small the mid-bass unit only goes from about 200Hz to the crossover frequency, which is usually 1 to 1 1/2 octaves only.
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post #9 of 26 Old 03-12-2008, 02:32 PM
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Quote:
Originally Posted by Hyper_Lite View Post

Specifically I'm talking about the Polk Audio LSi15's and Pioneer Elite VSX-92TXH.


On my Polk LSiC there is a single tweeter and two main mid drivers (5.25").

The driver on the left sounds great, but the driver on the right hardly has any sound coming out of it. Any idea's? Do I have a bad center?

Sounds like you permanently damaged both the Polks & the Pioneer while voiding both warranties in the process.

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post #10 of 26 Old 03-12-2008, 02:48 PM
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Quote:
Originally Posted by biffva View Post

Sounds like you permanently damaged both the Polks & the Pioneer while voiding both warranties in the process.

Uh..........doesn't sound like that to me.

Just an fyi......... most receivers and amps will shut down before any damage is done if they are driven to a load that they can't handle.
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post #11 of 26 Old 03-12-2008, 03:21 PM
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Quote:
Originally Posted by lwien View Post

Uh..........doesn't sound like that to me.

Just an fyi......... most receivers and amps will shut down before any damage is done if they are driven to a load that they can't handle.

That's not correct, actually. The receiver will shut down if it overheats, too much current is being drawn through the output stage, or if the impedance is too low, but it has no idea how badly it's trashing the speakers.

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post #12 of 26 Old 03-12-2008, 03:28 PM
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Question. Will a receiver that is trying to drive a 4 ohm load that is very sensitive to being driven to 4 ohm loads (ie, a receiver that is only designed to drive 8 ohm loads), will it overheat, will too much current be driven through the output stages, and by definition of the above scenario, the impedance is too low.........will that receiver shut down? It has only been my experience, Paul, that when the above happens, typically, a receiver or amp will shut down before any speaker damage is done.
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post #13 of 26 Old 03-12-2008, 03:59 PM
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lwien,

If you go back through the OP's previous posts, you'll find that he's trying to fill a large room while armed with little knowledge and no auditions. It's quite possible he wanted to try out his new gear and "cranked it"! Not sure about your experience but I've seen my share of blown drivers.

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post #14 of 26 Old 03-12-2008, 04:17 PM
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Yeah, I've seen quite a few blown drivers also from amps being driven to clipping, but most, if not all times, every time I've seen an amp trying to drive a 4 ohm load that is basically designed not to do that, the amp has shut down before any speaker damage occured. And even when an amp is being overdriven and clips, the audible distortion is usually enough to give the user enough time to run over and shut down the volume before any damage is done.

But you said he damaged not only his speakers but his receiver as well. I don't understand why you think that to be true. His speakers, maybe, but his receiver?-
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post #15 of 26 Old 03-12-2008, 04:25 PM
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Perhaps he didn't damage the receiver. (Though I think there's a solid possibility that he blew a driver.) But if he took the receiver somewhere to be benched, then he might--notice I said might--receive some face-to-face advice that would move him further along. Posting polls here while not performing any auditions isn't the best way to buy equipment.

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post #16 of 26 Old 03-12-2008, 04:34 PM
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Alright then, on my Onkyo 705 receiver, there is a menu setting for speaker type... choose either 4ohm or >6ohm. So based on the limited info. in my manual, it seemed appropriate for me to choose >6ohm for my Polks. Besides, I kinda had the idea that most speakers were rated 8ohm type speakers.......So, just for chits and giggles, if I were to change it to the 4ohm setting, would my speakers play OK? Would I do damage to either the speakers or receiver by doing this?

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post #17 of 26 Old 03-12-2008, 04:38 PM
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"Posting polls here while not performing any auditions isn't the best way to buy equipment."
----biffva

Best way to BUY equipment? Posting polls while not auditioning? Where did he say that he was in the market for new speakers?
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post #18 of 26 Old 03-12-2008, 04:40 PM
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Quote:
Originally Posted by lwien View Post

"Posting polls here while not performing any auditions isn't the best way to buy equipment."
----biffva

Best way to BUY equipment? Posting polls while not auditioning? Where did he say that he was in the market for new speakers?

You familiar with the "Find More Posts by . . . " function?

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post #19 of 26 Old 03-12-2008, 04:42 PM
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Yeah, but I just take one thread at a time.
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post #20 of 26 Old 03-12-2008, 04:56 PM
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Quote:
Originally Posted by lwien View Post

Yeah, but I just take one thread at a time.

That explains quite a bit about you.

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post #21 of 26 Old 03-12-2008, 05:01 PM
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The LSiC has a cascade array crossover (I think that's what it's called), it's not unusal for one driver to be getting most of the work. It's the way it's designed.

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post #22 of 26 Old 03-12-2008, 05:02 PM
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Driving a 4 Ohm speaker on a receiver that is designed for 8Ohm will put more stress on it. It more than likely will not cause damage unless you crank up the volume past half way
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post #23 of 26 Old 03-12-2008, 05:27 PM
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Like Paul alluded to, there really isn't any way to determine how tough a load a loudspeaker presents an amplifier without seeing the impedance curve. Some 4 ohm rated loudspeakers may work just fine, others will trigger the amplifier's protection circuitry quite quickly.

AV receivers offer a lot for relatively little. The trade off is that they generally have feeble amplifier sections and are going to limit your loudspeaker choices somewhat.

I know that someone with a brand X flagship avr is going to chime in with how wrong I am about avr power sections. My reply to you: for what you paid for that thing you could have gotten some good used separates on audiogon.

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post #24 of 26 Old 03-12-2008, 05:48 PM
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Quote:
Originally Posted by biffva View Post

That explains quite a bit about you.

Uh..........okay..........
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post #25 of 26 Old 03-13-2008, 09:19 AM - Thread Starter
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Quote:
Originally Posted by Ron Temple View Post

The LSiC has a cascade array crossover (I think that's what it's called), it's not unusal for one driver to be getting most of the work. It's the way it's designed.

Any reason they do this?
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post #26 of 26 Old 03-13-2008, 09:30 AM
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Quote:
Originally Posted by Hyper_Lite View Post

Any reason they do this?

See my earlier comment.
Each driver in the array has a narrower frequency band, so the midrange doesn't also have to play the mid-bass. Also interference between the two identical drivers is reduced. Your end result is better imaging and clarity at a cost of pure BANG... but some people don't really appreciate that... Very sad.

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