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speaker impedance???????

eirejam

Established Member
Hi,

I don't know if I have my system if fully compatible.
I have a Onkyo SR605 which has a setting for 4ohm or 6 ohm speakers.

My front floorstanders are Monitor Audio BR6's which are 4ohm speakers
My centre speaker and rears are all Monitor Audio 8ohm speakers.

I have the amp set to 6ohm in the menu.
Are these speakers suitable for this amp or does it make a difference what I have the impedance set to?
I don't ever plan on pushing the speakers close to thier limitations.
The sound is excellent the way they are setup at the moment.
 

BlueWizard

Distinguished Member
Most amplifiers are rated for a range of speaker impedances. That standard range for many many decades now has been 4 ohms to 16 ohms. As long as the combination of speakers on any given amp channel is in that range you are safe.

I speculate that what ever adjustment the 4 ohm/6 ohm switch makes is minor. So, either setting should work fine. Personally, I would probably go for the 6 Ohm setting, but you can try both and see if you hear a difference.

I really don't see this a a critical problem.

Steve/BlueWizard
 

Zigster

Standard Member
Similar question from me!

I'm rejigging my set up as part of a "baby proof the sitting room" project and my 4 ohm hi-fi speakers will be used as AV speakers for a while. My AV amp says use 6-16 ohm speakers. Obvious question: will using 4 ohm speakers cause a problem? I don't tend to turn the speakers up very high (as the baby's nursery is above the sitting room).

Thanks in advance. :)
 

Etienne A

Established Member
The impedance rating is just an indication of what's the speakers resistance most of the time ... so your 4ohm speakers will vary ... probably from 2 to 16ohm depending on the frequency being reproduced at a particular instance.

Whether or not you'll have issues depends on what speakers, and what amp we're talking about (and also what volume you'll be running them at). Generally speaking if you're saying you're gonna run it at moderate volumes - it should be ok.

Having said that - there are BAD speaker/amp combinations - a most infamous incident is a particular setup actually recommended by What HiFi (it was a low-end Denon amp, with Epos ELS speakers - an accident waiting to happen).
 

Zigster

Standard Member
Cool - I've wired in the speakers and it seems to work just fine at sensible volumes (not tested any higher ;) ).

Thanks
 

eirejam

Established Member
No, your BR6s are rated at 6ohm.

The monitor audio websites states they are 6ohm.
However the manual that came with them indicates they are 4ohm and everyother website I checked states 4ohm aswell.

a resistance test across the + and - terminals gives me 3.5 ohms.
 

sibeer

Prominent Member
My understanding was that you should set to the Ohm level of the highest speaker (i.e. 8 Ohm).
 

Etienne A

Established Member
a resistance test across the + and - terminals gives me 3.5 ohms.

that doesn't mean much - impedance varies with frequency, so whislt your speakers might read 3.5 out of a circuit, they will vary much lower & higher once they're in action

My understanding was that you should set to the Ohm level of the highest speaker (i.e. 8 Ohm).

setting amps to the highest impedance rating means you're getting all the juice from the power supply w/o nasties in series (as protection for the amp) .. this should give you the best sound quality - but it could potentially be risky at high volumes as current demands on the power supply increase
 

BlueWizard

Distinguished Member
mat1110 :
"So if i have a 6Ohm amp then what speakers should you really use because mine are 4-8 Ohm."

You don't have a 6 Ohm amp, you have an amp with a power rating at a specific impedance, but even that doesn't mean much.

Like I said earlier, as long as your combined load impedance per channel is in the range of 4 ohms to 16 ohms, then your OK.

As to amps, as suggest by the original poster, that have a 4_ohm/6_ohm switch, I think it is more likely a 4_ohm/normal switch. Some internal change is made to protect the amp under 4 ohm loads. So, I suspect if your amp is set to 6 ohms then every thing is fine.

The only true Standard Amp rating is power rated at 8 ohms across the 20 to 20,000 hz range measure against an RMS power standard and yielding fraction percents of Harmonic Distortion or THD.

Amps rated at 6 ohms or 4 ohms, are for information only. For Hi-Fi amps in the USA there is a government Trade Commission standard for uniform amplifier power ratings as described above. When you compare amps, that is the only standard you want to use. Or...of course... the equivalent standard in the country where you live.

Steve/BlueWizard
 

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