A/V Receiver Impedance Selector Switch

[gene]

I have just finished up a comprehensive article dealing with Impedance Selector switches found on many A/V receivers. I'd like to get your feedback on how you set these and why. I think everyone will find my article quite informative and shocking (no pun intended).

The High Setting is usually the factory default and pertains to speakers rated above 6 ohms.

The Low Setting pertains to speakers under 6 ohm impedance.

Read the Article

 

[fightinkraut]

High impedance, I like to squeeze all the power I can out of the thing! Speakers are 6 ohm, my tx-sr805 does very well with them. Looking forward to the article...perhaps some advice against using the low impedance switch unless absolutely necessary?

 

[gene]

The impedance selector switch article is under peer review by UL labs and a few manufacturers that have this so called "feature". It will post next week.

 

[Alex2507]

I go with the high setting because I think somebody smart like PENG said it was the way to go so long as you don't crank it too loud. What do I know? This week I'm a dog.

 

[jostenmeat]

Mine is set to low, because I find the heat is greatly curtailed (I don't care if people don't believe me, and I already offered to measure heat if they really cared), and to reduce consumption . . . because it's acting as pre/pro.

However, I may have come across a post saying that even as a pre/pro, high impedance may be desired to get proper preout voltage. Unmeasured, my ears cannot tell any difference. I do have a Samson S-convert at my disposal (which I used for less than 1 minute on my subwoofer because I thought the house was going to collapse).

There is a person I greatly trust who also owns the Onkyo 805, who uses its amps, and yet still has it set to low impedance. I can try to find his post(s) from AVS if anyone really cares to see.

 

[its phillip]

high for my yamaha, and i don't think my onkyo offers that feature since it's dirt cheap and doesn't support 4-ohm loads i think

 

[gene]

Mine is set to low, because I find the heat is greatly curtailed (I don't care if people don't believe me, and I already offered to measure heat if they really cared), and to reduce consumption . . . because it's acting as pre/pro.

However, I may have come across a post saying that even as a pre/pro, high impedance may be desired to get proper preout voltage. Unmeasured, my ears cannot tell any difference. I do have a Samson S-convert at my disposal (which I used for less than 1 minute on my subwoofer because I thought the house was going to collapse).

There is a person I greatly trust who also owns the Onkyo 805, who uses its amps, and yet still has it set to low impedance. I can try to find his post(s) from AVS if anyone really cares to see.

If you are using it as a pre/pro its a moot point since it won't affect the line level outputs.

 

[Jeepers]

Doesn't it depend on the quality of the amplifier and what it can deliver ? I use high because that is the default.

From Gene's review on the Z11.

Choosing the Speaker Impedance
I tested the RX-Z11 in the “8 ohm or more” and “6 ohm” settings and for the first time in my experience of reviewing Yamaha receivers, the setting made NO difference in output power. It’s almost as if the option is there to reassure customers that their receiver is safe with speaker impedances lower than 8 ohms. I was quite surprised as I usually advise folks to keep it in the “8 ohm or more” setting regardless of speaker impedance. Feel free to do what you like here as it doesn’t make a difference whatsoever.

 

[avliner]

IIRC, the impedance selector switch doesn't make any difference and it's kinda useless. It seems to comply to some UL norm though.
I read something like that way back when, but don't remember where at.

 

[Audioholics]

IIRC, the impedance selector switch doesn't make any difference and it's kinda useless. It seems to comply to some UL norm though.

It's not useless as you'll see with the article. It serves a specific purpose and affects the way the amplifier puts out power.

 

[avliner]

Good to know then.
BTW Clint, how many AVR brands has this switch as a standard feature?
Never saw in Denons though.

 

[3db]

Mine is set to low, because I find the heat is greatly curtailed (I don't care if people don't believe me, and I already offered to measure heat if they really cared), and to reduce consumption . . . because it's acting as pre/pro.

However, I may have come across a post saying that even as a pre/pro, high impedance may be desired to get proper preout voltage. Unmeasured, my ears cannot tell any difference. I do have a Samson S-convert at my disposal (which I used for less than 1 minute on my subwoofer because I thought the house was going to collapse).

There is a person I greatly trust who also owns the Onkyo 805, who uses its amps, and yet still has it set to low impedance. I can try to find his post(s) from AVS if anyone really cares to see.

I thought the impedance switch only affects the output stage of amplifiers. I would think it very wrong if the pre-outs were messed with as I was under the impression that pre-outs are usually defined to have a certain output voltage ie. industry standards analogous to inputs such as found on a display for component/composite video/audio inputs. That just sounds a little weird to me.

 

[ski2xblack]

I've got some old NAD and Yamaha amps/receivers which have this feature. Like 3db, I was under the impression that the low impedance setting would limit the current available from the supply rails to keep the amps from overheating when asked to push a low impedance load (thus protecting the amp from thermal shutdown/failure, but limiting output somewhat when in the 'low impedance' setting). I'm not sure if the Yammie and the NADs are similar in implementation of this feature or not. I would suspect that an amplifier actually built to drive low impedance loads would not require this feature, but that would be a burly amp, and probably more expensive to produce than just using a cheap current limiting band-aid like the impedance selector on an amp with lesser capabilities. I've also played around with autoformers to raise/lower the impedance seen by the amp; this allowed my inefficient 4 ohm monitors to play nice with my limited power Yamaha receiver, and allowed me to use higher impedance speakers with some tube amps I have, which for some reason use the two-ohm taps on the output tranny's. (Oh, no, I mentioned tubes, there goes the reputation!)

 

[BoredSysAdmin]

It's not useless as you'll see with the article. It serves a specific purpose and affects the way the amplifier puts out power.

Doesn't it depend on the quality of the amplifier and what it can deliver ? I use high because that is the default.

From Gene's review on the Z11.

Choosing the Speaker Impedance
I tested the RX-Z11 in the “8 ohm or more” and “6 ohm” settings and for the first time in my experience of reviewing Yamaha receivers, the setting made NO difference in output power. It’s almost as if the option is there to reassure customers that their receiver is safe with speaker impedances lower than 8 ohms. I was quite surprised as I usually advise folks to keep it in the “8 ohm or more” setting regardless of speaker impedance. Feel free to do what you like here as it doesn’t make a difference whatsoever.

Why do I get the feeling we have another myth/bs/marketing debunking coming up?

 

[avliner]

Why do I get the feeling we have another myth/bs/marketing debunking coming up?

Guess you're pretty darn right though... let's wait'n see than

 

[gene]

I started this article as a simple guideline under 1500 words. It is now 6k words and hopefully done. Honestly why did I do this?

Hopefully it will post by the end of this week.

 

[Alex2507]

I started this article as a simple guideline under 1500 words. It is now 6k words and hopefully done. Honestly why did I do this?

Hopefully it will post by the end of this week.

I was only gonna read like 150 words and then PM PENG for Cliff Notes.
Don't sweat it.

 

[Jeepers]

Gene - thanks for this interesting article, although I had to re-read some things a few times to understand what you wrote. I am out far too long of that stuff.

 

[tattoo_Dan]

it's an interesting read,thanks

my thing is this, on my Onkyo TX-SR876,the speaker impedance setting is either 4 or 6 ohms,

my Paradigms are all 8 ohm rated ,or Paradigm says "Compatible with 8 ohms",so the best I can do is set the AVR to 6.

 

[jliedeka]

I think we should demand power cube graphs from manufacturers.

Jim