6 ohm Speakers with 8 ohm receiver power question.



Quote:
Originally Posted by schan1269 /forum/post/20805690


Run the 1067 and make sure it doesn't get overly hot at the volume you will be normally achieving. If it never gets too hot, it won't shut down.

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Thanks for the reply. After running it loud for half an hour , I put my hand on the grill at the top and noticed it was only warm, but not hot, so I think its ok.


However, my next question is,


1. Will there be reduced power output If i switch the receiver to

6 ohms ? Would the sound come out cleaner perhaps ? Or would it not make a difference. ?


2. Would it be worth my while to change to 8 ohm speakers ?


Thanks in advance.

MgFred has it backwards...


The amp will create more power if you LEAVE IT ALONE.


The point of a 6(or 4 ohm) setting is to tell the receiver to LOWER its gain.


Essentially, an amplifier is built to only dissipate "so much heat". Heat is a by-product of power production. When you connect 6 ohm speakers you are asking the amp for MORE power. You "could" ask for more power than the amp can effectively cool off, rendering it to go into shutdown.


All a 6 ohm setting is for is to lower the gain, so it will produce the same amount of "safe" power. However, if you leave it alone...and make sure it never gets "too hot", you really are getting the extra power(at the brief instances you really will be asking for it) when you need it.



Quote:
Originally Posted by abumuqaatil /forum/post/20826841


Thanks for the reply. After running it loud for half an hour , I put my hand on the grill at the top and noticed it was only warm, but not hot, so I think its ok.


However, my next question is,


1. Will there be reduced power output If i switch the receiver to

6 ohms ? Would the sound come out cleaner perhaps ? Or would it not make a difference. ?


2. Would it be worth my while to change to 8 ohm speakers ?


Thanks in advance.

Click to expand...

The speaker impedance is not static. Most 8 ohm nominal rated speakers will read 5-6 ohms.


Having said that, the amp output/load will vary to power the speaker's load. In the case of well built receiver/amp, the lower impedance of speaker would require increase in watt output/load from the amp.


In any case, the tolerance of amp really depends on available power from it's transformer. In most cases/rule of thumb, high current capable amps can manage low impedance speakers much better to power dynamic loads during audio playback.


Heat is one sign of amp stressing, but most obvious sign is increase in distortion which will eventually lead to clipping. Now, hard clipping will most likely damage your speakers. Most SS amps have safety features built in and will shut down before it kills itself.



Anyway, my in-law drives 4 ohm rated speakers, in 7.2 surround mode with his HK 7550HD. All 7 speakers are 4 - 6 ohms(Citation 7.2 x5 and Citation 7.3 x2), and he drives it loud without an issue. The receiver fans do kick in, however. I believe HK7550HD is only rated for 8 ohm speakers on paper. I told him to get a separate amp to drive the front 3, but he seems to be happy so far with the performance from his AVR. YMMV.

Technically, the 6 ohm switch will reduce the voltage supplied to the amplifier section. So it could conceivably limit power. Some people suggest not to use it for that reason (I am inclined to agree with them, why arbitrarily limit power?)


At reasonable playback levels, I would think the Yamaha receiver will have no problems.


One thing I thought about. Music is not like movies. It has less dynamic range. So when played loudly, the receiver will be more stressed. If you are trying to push the system really hard, lower impedance speakers could cause the receiver to overheat as mentioned above - but if it's only two channels, you are probably ok.


Your receiver has a number of protection circuits to protect itself - ideally, it shuts down if it's unhappy.


Not trying to make you nervous - as I say, you are unlikely to have issues. Just pointing out a few things about impedance.


Some people run 4 ohm speakers with no issues, which is a more difficult load than 6 ohm speakers.

@ MgFred...


That is all fine and dandy, however.


There are (one of) two things that happen when you change the setting from 8ohm to 6ohm(or when the receiver/amp/AVR allows for 4ohm).


1. The power supply is restricted(by reducing what it can suck off the wall, or it starts metering what it can send out).

2. The gain is lowered


The measurements of your Elite were probably measured while it was still in 8ohm mode...in short bursts. Not "for hours on end".


That is part of the FTC bull crap. FTC "power ratings" are crap filled toilet paper. The FTC does NOT have a time limit for RMS ratings. So, was the amp on for 5 minutes? 20 minutes? An hour? All day?



Quote:
Originally Posted by MichaelJHuman /forum/post/20829130


I think they reduced pre conditioning to 1/4 power (which is probably reasonable for movies.) But I had not heard they removed the hour.

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Latest statue CEA490, requires preconditioning @ 1/8th rated power for 1 hour....

However the 1 hour can be cumulative as the AVR amplifier may cycle ON/OFF for thermal shutdown..


Just my $0.02...



Quote:
Originally Posted by MichaelJHuman /forum/post/20829171


Wow, only 1/8 power, and it can cycle off? Why even bother with rules anymore, heh

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The 1/8 power is like having only 1 channel driven (7/8) in 7.1 AVR..

No surprise since the CEA standards committee is comprised of representatives from Sony, Bose, Panasonic, Samsung..


Just my $0.02...



Quote:
Originally Posted by bitemymac /forum/post/20829538


This is one of the reasons why I do not want to get an AVR. I hope there are more pre/pro options... preferably from HK and Denon at tangiable consumer pricing.


I have been sticking with pre + older amps from 90's for the honest power output. They were also built much better, as they seem to last all these years.

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That can work for the category of amplifiers..

But if one wants the latest technologies for audio, video and connectivity he will need to purchase an AVR...


Just my $0.02...

Quote:
This. AVRs already have a number of overheat mechanisms. The only purpose of the 6/4 ohm switch is to please regulatory agencies. You are not going to be able to actually overheat it, and even if you were, I'd rather put the receiver at jeopardy than the speakers. If you google this topic there was a long blog post by a former product developer on this topic confirming pretty much exactly what schan said.