Recievers handle a 4 ohm load? - AVS Forum
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post #1 of 10 Old 08-16-2008, 01:32 PM - Thread Starter
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I am wondering is a Pioneer 918 can handle a 4 ohm load on the L/R channels and 8 ohm everywhere else.
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post #2 of 10 Old 08-16-2008, 01:43 PM
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I would seriously doubt it...
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post #3 of 10 Old 08-16-2008, 01:56 PM
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Doesn't the manual indicate the answer to that?
Maybe the Pioneer toll free tech line could answer your question...

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post #4 of 10 Old 08-16-2008, 02:10 PM
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Most receivers will but not at full power. Understand that most of the time, in a typical home theater with a powered subwoofer, the main speakers will be drawing less than a single watt during most of the movie. During loud peaks, you may get to 15 or 20 watts. What that means is that the amplifiers in most receivers are serious overkill for their intended purpose. With a 4 ohm load you could double the current draw from the power supply but that still isn't serious in most instances. If you get somewhere near full power output (extremely rare in a typical home installation) then you could exceed the power supply's ability to deliver current and cause the amplifiers to clip. You don't want that for sure. Same with 8 ohms speakers, by the way. It is just that the 8 ohm speakers will hit the wall at a higher power level than the 4 ohm speakers.

If the manufacturer provided a 4 ohm rating for the receiver then the "power" figure would be a lot lower and consumers seem to like big power numbers. So the manufacturers simply don't provide a lower impedance rating preferring to call an amp 100 watts per channel instead of 50 or 60 watts per channel. The amps with lower impedance ratings normally have stronger power supplies so they can simply push more watts out the door as the impedance falls.

There isn't anything magical about 4 ohm speakers other than the fact that they draw more current to produce the same volume as a higher impedance speaker. As long as you don't exhaust the power supply's current delivery, then all is well. There you go. Try it if you like. Buy a bigger amp if you don't want to try it.
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post #5 of 10 Old 08-16-2008, 02:29 PM
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You don't say what your L/R speakers are, and the fact is many speakers are rated 4 ohms that (according to Consumer Reports) are in fact closer to 6 ohms. All speaker impedance ratings are nominal because impedance varies by frequency, so they approximate an average. My full range front speakers are rated 4 ohm but are above average in sensitivity (91 dB), and when I first got them I drove them with a 55 watt Harman Kardon AVR20II with the recommendation of the speaker manufacturer (Digital Phase). I never had a problem, even without using a sub, but of course Harman Kardon receivers are known for having better current capability than most other mass market receivers. If your speakers are at least 90 dB sensitive then you may not have a problem even with the Pioneer receiver. You could check with the speaker manufacturer for their advice if you want more assurance. Otherwise I would suggest switching to a H/K receiver or a separate power amp. Emotiva and Outlaw make decent low-cost amps. The difference in impedance between your front and center/rear speakers should not otherwise be a cause for concern.

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post #6 of 10 Old 08-17-2008, 06:03 AM
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Quote:
Originally Posted by FMW View Post


If the manufacturer provided a 4 ohm rating for the receiver then the "power" figure would be a lot lower and consumers seem to like big power numbers. So the manufacturers simply don't provide a lower impedance rating preferring to call an amp 100 watts per channel instead of 50 or 60 watts per channel.

Only if your head office is in Japan, South Korea, or you are an American based mass marketer (the exception being H/K).

Quality amps produce equal or greater wattage at 4 ohms.

It isn't rocket science to be able to build an amp with adequate power supplies, heat sinks and components to handle all types of loads. European, Canadian and some American designed products such as H/K, Outlaw and Emotiva still do.

The others have discovered that higher profits are made by spending money on marketing rather than on engineering and quality components.
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post #7 of 10 Old 08-17-2008, 06:12 AM
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You can also look for receivers that are THX ULTRA ll spec'd they have to handle 3.2 ohms.
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post #8 of 10 Old 08-17-2008, 06:20 AM
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Note that Harmon Kardon rates their receivers lower in power for the same price. Harmon Kardon's specs don't show a 4 ohm rating. They have always claimed a "high current design" which implies good performance into a lower impedence.

It does cost money to build a power supply specifically designed to handle 4 ohm loads. But many people have reported being able to run 4 ohm speakers without problems. Some people have had problems with their receivers going into protection mode, though.

It's rare for any receiver to quote a 4 ohm spec. That makes it hard to know how receiver will handle a 4 ohm load.

Some receivers have a 6ohm switch, but that almost certainly limits the voltage supply. Using that setting is not reccomended for that reason.

"But this one goes up to 11"
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post #9 of 10 Old 08-17-2008, 06:46 AM
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Quote:
Originally Posted by Filthy McNasty View Post

Only if your head office is in Japan, South Korea, or you are an American based mass marketer (the exception being H/K).

Quality amps produce equal or greater wattage at 4 ohms.

It isn't rocket science to be able to build an amp with adequate power supplies, heat sinks and components to handle all types of loads. European, Canadian and some American designed products such as H/K, Outlaw and Emotiva still do.

The others have discovered that higher profits are made by spending money on marketing rather than on engineering and quality components.

Making profits is the primary goal and requirement of any business.

OK, so you don't like amplifiers with Japanese brand names. But what I said was the truth nevertheless. I've driven electrostatic speakers with my Pioneer 92 at earsplitting levels without so much as a meaningful increase in surface temperature. I offer that as merely one example. There isn't anything particularly special about my receiver and it isn't rated below 6 ohms. The electrostatics spend most of their time below 4 ohms.

I'm willing to bet you can drive a 4 ohm nominal load in a typical family room with any 100wpc receiver without ever having a problem. Home theaters that have powered subwoofers are all overpowered for the amplifiers' required performance. All of them. The powered sub removes the majority of the power requirement from the central amplifiers. I'm not guessing. I keep a recording wattmeter connected across my right front speaker.

The reality is that it is safer to rate the equipment only for high impedance loads. That will keep it out of trouble better in abusive situations and reduce lawsuits. Are you aware of a receiver failing to drive a 4ohm load in a typical home theater environment with no abuse? Ever heard of it happening? Is there a reported failure that occurred under normal circumstances somewhere? If so, I'll change my opinion and my comments.
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post #10 of 10 Old 08-17-2008, 06:51 AM
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Quote:
Originally Posted by chood View Post

I am wondering is a Pioneer 918 can handle a 4 ohm load on the L/R channels and 8 ohm everywhere else.


The answer is clearly noted on page 20 of your manual.
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