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I've recently noticed that most AV receivers are rated for 8 ohms (some are rated at 6 and 8 ohms). My Front L&R Avance Epsilon 980's are 4 ohm/ 89db. Will this work? I'm running 8 ohm speaker on the center and B&W 301's (I think they are 8 ohms) on the surround channels.
Follow Ups:
I have an HK 520 reciever,and the ability to drive 4 ohm speakers was a priority since the AR 510's I was using at the time were 4 ohm.If you ck HK's web site ,in the FAQ the is a reference to 4 ohm loads,and it says that there will be no problem.
Greg,
Where did you see that? I just checked the harmankardon.com site faq's and could not find a reference to 4 ohm load speakers.UP
it was in the FAQ for the ARV 520,Greg
H/K amps will drive a friggin' PENCIL!!!! 4 ohm speakers are NO problem
Your HK AVR525 will function and perform just fine using 4-ohm speakers for your front LR. It would be beneficial to check the specs on your speakers, though. Any speaker that dips to a 2-ohm load or lower will degrade your receiver's performance over time. 4-ohm speakers are nothing out of the ordinary.
Any amp will drive a 4 ohm load even an S.E.T. It's just that they will not do it efficently. Therefore their performance and sound quality will suffer. You will limit the performance of your speakers, especialy at higher volumes. A.V. Receivers just work better with high sensitivity high impedance speakers, as do S.E.T.'s. The other thing that is important is how flat their impedence is. Flatter is better except when talking about women!Remember an A.V. Receiver does a hole lot of work. The more work it does the worse it's sound quality. At least thats been my experience. When freinds ask for my advice on a A.V. Receiver I always tell them simpler is better, same with the speakers i.e. when it comes to impedance loads. The only way to know is to try the combo and let your ears tell you what you want to know.
Quote:"Any amp will drive a 4 ohm load even an S.E.T. It's just that they will not do it efficently. Therefore their performance and sound quality will suffer."
That's not completely true. There are low-end mass-market receivers out there that will overheat and/or go into overload protection mode when pushing 4 ohm loads. Either the receiver's power supply can handle it or it cannot. An amp that is 4-ohm stable will run all day. Sound quality is a whole other issue.
No that is completely true. What you are talking about is pushing the receiver, I wasn't. Also driving multiple 4 ohm speakers would be a problem. The louder you play the harder the load. A man has to know his systems limitations. I don't see even a cheap A.V. Reciever not being able to drive a pair of 4 ohm speakers at low volume levels.
"Also driving multiple 4 ohm speakers would be a problem. I don't see even a cheap A.V. Reciever not being able to drive a pair of 4 ohm speakers at low volume levels."I was talking about typical real-world use of a HT receiver: All 5 channels driven, at real-world volume levels. This is probably what the original question was in regard to. I don't consider this pushing a receiver. That's what it's supposed to do.
At least that's what I've heard from some manufacturers. Apparently, the UL testing criteria for driving 4 ohm loads are pretty tough for a receiver to pass. Rather than jeopardizing their UL rating (no prob with 6/8 ohm cert), manufacturers choose to drop the 4 ohm testing even though real-world operation at 4 ohm is not a problem.Austin
Well, the test procedures are mandated by the Federal Trade Commission (not UL) which has regulations regarding audio amplifier power output claims in advertising.Power bandwidth must be specified and distortion levels must be specificed. You will notice that many inexpensive recievers specify a power bandwidth of 40-20,000 Hz, not 20-20,000 Hz. That's because the receiver will not deliver rated power at 20 or 30 Hz. Similarly, since the same number of watts at 4 ohms as at 8 ohms requires more amps (current), many receivers do not specify a 4 ohm output because their wimpy power supplies will not deliver enough current to generate a respectable rated power over a decent bandwidth and with respectable distortion figures.
I would think that, for all but the most expensive receivers, the use of 4 ohm speakers would not be a good idea if you're interested in the best sound quality.
Wrongo, wrongo.I'm not talking about FTC power rating rules - I'm talking about UL product testing. The receiver manufacturers consider the 4 ohm test procedure unfair as it does not reflect real-world operating conditions. They feel it overly stresses the amplifier sections of their receivers and that they are therefore likely to flunk the UL test. Since flunking the test flunks the whole receiver, manufacturers choose to undergo only UL tests that they are sure they can pass. Therefore, 6/8 ohm ratings.
Talk to some folks in the industry - they'll sort things out for you.
Austin
What folks would that be?Unfortunately, accessing the UL standard would cost me $400. But, I am curious, since UL is concerned with safety, not performance issues, as to why the UL test is "unfair" to receivers driving 4 ohm speakers.
Is it because the receivers burst into flames when delivering 1/3 rated power into 4 ohms (1/3 power usually places maximum thermal stress on a transistor amp)?
Or is it that parts of the receiver get dangerously hot under those conditions?
It seems odd that UL would permit equipment to be certified safe for use with less than all of the speakers that are out there -- and, let's face it, 4 ohm speakers are hardly unusual.
Bruce,I'll try to dig up some more info for you. As to your safety/performance question - the manufacturers desire UL listings for any number of competitive and liability reasons. There are a number of test suites for which a manufacturer can undergo certification testing.
Let's say (just as an example) that the test procedure for a 4 ohm listing consists of 110% rated power all channels into a purely resistive 4 ohm load for 45 minutes. If the receiver's overtemp protection circuit engages at any time, you flunk. If the temperature of the receiver increases by more than 25 degrees C at any time, you flunk. And IF you flunk the 4 ohm test, your entire test submission fails even though you passed the 6 and 8 ohm procedures with flying colors. See how it works?
Austin
Now you're sounding like the FTC test. Lots of inadequately heat-sinked amps will flunk the 1/3 power "preconditioning" aspect of the FTC test because the amps' thermal protection will kick in. (I still think its flaky that UL will certify an amp that does not work to their specification on the great bulk of the speakers out there -- i.e. 8 and 4 ohm nominal speakers. That's almost as good as the sun visor stickers that every SUV manufacturer now includes that say, in essence: This vehicle handles funny; watch out!)I really would like to know the details about the UL test; it must be fairly recent. I'm just too cheap to pay for the whole thing off their website. Thanks.
The FTC test originated in the 1970s because the IHF (Institute of High Fidelity) test was such meaningless b.s.
Some AV Receivers are rated for 4 ohm...Off the top of my head:
Harman Khardon
NAD
Rotel
B&K
You don't specify which you have or what you are looking at..One of my favorites (Denon) is not...
One idea would be if the receiver you have has Pre-Outs for external amps you could use an outboard stereo amp rated for 4 ohm and use the receiver's amps section for your 8 ohm speakers...
If this is a new setup then just get something like the Rotel and be done...Good Luck
Charlie
None of thoes companies you listed rate their A.V. Receivers power into a 4 ohm load.
because HK does not provide those ratings on their summary spec sheets; however, a closer review of the owners' manuals will show that they are capable of driving 4-ohm loads. If I recall correctly, they only caution about speakers that might dip below 2-ohms.
I have the HK AVR525 rated at only 8 ohms.
H/K only rates their receivers for 8 ohms but it is common knowledge that they will drive 4 ohm speakers without too much fuss. As long as the speakers aren't 2 ohm "amp killers", you should be just fine.
Actually, if you go to the Harman Kardon International site, on the English page, you can see the Euro equivalent receivers listed with 4 ohm speaker specifications. For example, their 55 watt per channel receiver (continuous into 8 ohms) will put 110 watts(peak)into 4 ohms. I've also seen independant reviews of H/K AVR receivers where they bench test the power with similar results.http://international.harmankardon.com/international/default.asp?language=ENGLISH
Back the truck up dude. Your asking about 4 ohm speakers, but if i'm reading the posts right, your running MULTIPLE speakers(5?) off the recievers outputs? That my friend could lead to trouble in paradise. You should investigate adding an impedence matching device. Unless you want your amp to shut off frequently. 4 ohm speakers are not a problem for H/K but more than 4 are a problem for any reciever not designed for 5 channels, ok? Is this a 5.1 equipped amp?
.
Uncle Pete, since I already know you have the HK AVR525 from our past conversations, here is your succinct answer: Using 4-ohm speakers in your HT system is not a no-no. Espcially since you are using them as your front LR.
So it's OK to run the Front L&R speakers at 4 ohms, the center at 8 ohms and the rears at 8 ohms safely? I checked the link you pointed at and am somewhat puzzled why they rate at 4 in the UK, but not in USA. BTW, the Avance speakers I have are made in Denmark; but then again, the B%W LCR600 S3 center and B&W 301 surrounds are made in the UK.
It really doesn't matter where the speakers are made. The only thing you will notice when running different impedence speakers in surround mode is the 8 ohm speakers are not going to sound as loud at the same volume level as the 4 ohm models. This can easily be compensated for by raising the level of your center and surround channels.
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