A/V Receiver Impedance Selector Switch

What setting is your receivers impedance switch on?

  • high setting (factory default)

    Votes: 51 71.8%
  • Low setting

    Votes: 6 8.5%
  • My receiver doesn't offer this feature

    Votes: 14 19.7%

  • Total voters
    71
S

sedonalar

Audioholic Intern
Line Level

I am using my Onkyo TXNR-906 as a pre/pro and it only had 4/6 ohm as a selection, 8 ohm wasn't an option. I agree that it does not matter since I am using a seperate amp. I tried to tell if there was a difference between 4/6 ohm selection and there was no sound change. I am using a brand new Emotiva XPA-5. I have noticed a small volume impact with the Emotiva, but I thought it would have been louder and much more dynamic. I do here more detail but I expected much more. Any thoughts?

Is it possible that another brand of receiver would have different or better line levels, causing the Emotiva amp to really shine?
 
Pyrrho

Pyrrho

Audioholic Ninja
Interesting article. A part that struck me was:

Is it worth potentially damaging your speakers to protect your receiver? I guess that’s a philosophical question depending on which is more valuable to you.​

http://www.audioholics.com/education/amplifier-technology/impedance-selector-switch-1/amplifier-and-power-supply-basics

As for the poll, I use Aurum Cantus Leisure 2SE (original U.S. version) speakers which are rated at 8 ohms and, I believe, have no really nasty low impedance dips that should ever cause my Yamaha RX-V2700 any issues, and are of ordinary efficiency. I had a Yamaha RX-V730 (about half the power of the RX-V2700) before that drove them as loud as I ever wanted without noticeable distortion (I use subwoofers and set all channels to "small"). So I doubt I would ever encounter an actual audible difference, though there is no reason to limit the power output in my case. I don't try to realistically recreate the loudest Who concert ever, as I value my hearing and wish to continue to hear, so the demands are never as great as they could be for someone who is no lover of sound.

For my living room stereo, I use a Crown K2 power amp to drive Apogee Stage speakers, which are rated at 3 ohms, which from reading reviews, seems a proper rating for them, without dipping much below that if at all. (I don't have the necessary equipment to measure the impedance curves of anything, so I am stuck with taking reviewers' word for such matters.) I suspect that I could get away with running them with my Pioneer SX-1250's power amplifier, though it is rated to use nothing less than 4 ohms. Gene, if you have an opinion on that topic, I would like to know it, especially if you are familiar with both the speakers and the receiver.

As for the philosophical question you asked, if people spent their money properly, they would have more invested in their speakers than in their receivers, so they should set the receiver to high (or use a separate power amplifier). But given what many people do, they spend proportionally more on the receiver than they ought to, and so they might want to consider protecting it more than their cheap speakers.

Now, if I had Apogee Stage speakers for all channels of my surround system, I would use the receiver as a preamp/processor and use separate power amps, as I don't think inefficient 3 ohm speakers for all channels would be a good idea with any multichannel receiver I have encountered.
 
avliner

avliner

Audioholic Chief
Very nice writing Gene!

Now I'm even more convinced that I really don't need the so-called impedance selctor switch at all ;)
 
K

kaiser_soze

Audioholic Intern
Still as confused as ever

So, if you select the lower of the two settings for speaker impedance, the voltage rails will be lowered, and the signal level at which clipping distortion occurs will shift to a lower signal level.

The question that immediately begs to be answered is this:

When the volume is set adequately low to avoid clipping when using the lower impedance setting, will distortion be the same regardless of which setting is selected?

Moreover, there are other questions that I really, really wish that someone as knowledgeable as Gene would answer:

From the standpoint of how transistors behave, how is it, exactly, that in the low-impedance setting, idle current in the output devices is lowered?

The Onkyo receiver that I recently purchased runs much, much cooler when I select the low-impedance setting than when I select the high-impedance setting. The difference is night and day even when the volume control is turned down fully and left down, which suggests to me that it has nothing per se to do with clipping.

It also has nothing to do with the actual speaker impedance, manifestly, because the output load does not affect idle current. Nevertheless, reducing the idle current is a highly effective means to lower the heat dissipated within the output devices, notwithstanding that idle current is not coupled to output load.

It thus seems apparent to me that either (a.) bias is intrinsically, unalterably coupled to the supply rail, or (b.) the supply rail affects idle current without altering bias, or (c.) the switch is altering the bias directly, i.e., adjusting the operating class.

Of course, for an amplifier that is already operating very close to class B when in the high-impedance setting, the question is moot. But for many amplifiers, possibly the majority, it is likely possible to effect a significant reduction in heat by adjusting bias. And it seems to me that if I wanted to reduce the amount of heat within the output devices, to protect them from a modest reduction in output load, that I would take this approach when possible, notwithstanding that idle current is independent of load.

In any case, the behavior of my Onkyo amplifier suggests to me that in the high-impedance setting, it is operating very close to class A, and that the principal effect of the low-impedance setting is to cause it to operate much closer to class B. As such, it seems reasonable to me that the increased distortion at higher volume setting, when the low-impedance setting is selected, does not necessarily imply clipping per se, since the amplifier becomes increasingly less linear as the input signal amplitude increases.

If my reasoning is flawed, than I hope that Gene will enlighten me. But if my reasoning is sound, then it seems to me that there is a simple test to discover, for a given amplifier, whether the speaker impedance switch directly changes the operating class of the amplifier. If this switch has a pronounced effect on the amount of heat given off by the amplifier even when the volume is turned fully down and left down long enough for the temperature to stabilize, then it seems to me that the primary effect of the switch is to alter the amplifier's operating point directly.

Regardless, the bottom line is this: if your amplifier runs cooler in the low-impedance setting and you never hear any difference at all, then why would you not use the low-impedance setting, even if you have 8-Ohm speakers? Do you not trust your own ability to discern what you can and cannot hear? What possible reason would there be to use the setting that causes your amplifier to run hotter, if you are unable to discern any difference?

Gene, I would very much appreciate it if you would try to answer some of these questions. Thanks in advance.
 
gmichael

gmichael

Audioholic Spartan
Mine is set on high. When I bought my RX-V2500 I had read on AR that all the lower setting does is limit the amout of power available to you.
 
K

kaiser_soze

Audioholic Intern
Let me try to claify what I really meant ...

Lowering the DC supply rails will in fact have the effect of limiting the maximum current in the output devices, by way of limiting the voltage at the speaker terminals. This makes perfect sense as a strategy for dealing with lower load impedance, as Gene says.

However, the points that I would like to make plain, and that I believe that Gene obfuscated, are as follows:

1. This may well cause distortion to increase, but ordinarily not unless you are playing so loudly that the amp is caused to run much hotter than it ordinarily runs.

2. The effect of the switch is not necessarily to lower the supply rails. In the case of my Onkyo receiver, it is manifest that the primary effect is to reduce the idle current, i.e., the operating mode of the amplifier is shifted further toward class B, where idle current is reduced and the amp runs cooler. This again may well cause an increase in distortion, but it is not necessarily the case that you will be able to hear the difference, whereas it is necessarily the case that you will use less electricity.

3. Even in the case where the lower impedance setting causes your amp to clip at a point in loudness where otherwise it would not clip, this is not likely to cause any damage to your speakers. This is a myth that started back in the early days of the battle waged by tube aficionados, who claimed that because clipping in transistor amplifiers produced stronger high-order harmonics as compared to tubes, that clipping in transistor amplifiers would be more likely to damage speakers.


On our beloved Internet, you can find several half-baked attempts to prove that clipping distortion will fry your tweeter. I have read several of them, and they all use erroneous, convoluted reasoning. The question that they end up answering is not the correct question. They do this because they are hell bent on finding an answer different from the one they get when they stick to the correct question.

The correct question, stated succinctly, is this: When sound is played at the same perceived volume level through an amplifier that is clipping and an amplifier that is not clipping, is the RMS power sent to the tweeter greater for the amplifier that is clipping than for the amplifier that is not clipping?

I have yet to see one of these so-called proofs stick to this correct question. In all of the analyses that I have seen, that purport to prove that clipping damages tweeters, it is virtually impossible to infer exactly what question they eventually did manage to answer.

Clipping does not increase the total RMS power that the amplifier delivers to the speaker. As such, it is manifest that the only way that it is possible for clipping to increase the power delivered to the tweeter is if the spectral power distribution shifts significantly from lower to higher frequency. For the most part, clipping removes some of the original high-frequency content and replaces it with harmonics of the lower-frequency content. Possibly, there is some shift in spectral content from low to high frequency. However, in the hypothetical case where the spectral power content is ordinarily distributed evenly between the woofer and the tweeter in a two way system, the entire spectral content below the crossover frequency would have to shift above the crossover frequency in order for the RMS power delivered to the tweeter to increase by 3 dB. Granted this is not entirely realistic because the spectral power division between the woofer and the tweeter is not ordinarily 50/50. But the point is that an enormous shift of spectral power would have to occur before the tweeter RMS power would increase by 3 dB, and way, way before that happens, you would hear the difference, not because you would hear the 3 dB increase in high-frequency content, but because when this occurs, the shift in overall tonal quality would be absolutely impossible to miss. It would be practically the same as disconnecting your woofer and turning up the volume by a tad.

This is what the audible effect would have to be in order for the power delivered to the tweeter to increase by a few dB. But even if you were so deaf that you could not hear this happening, this much of a shift in spectral power distribution does not occur. When an amplifier clips, the spectral power distribution takes on a character inherently similar to white noise. All you really need to ask yourself is whether you believe that if you were to play white noise loudly through your amplifier that is guaranteed to never clip, if this would burn out your tweeter. If you think the answer is yes, then you had better pay very close attention to the sort of music you play, because there is plenty of prerecorded commercial music where there are significant periods where the spectral power distribution is shifted more toward high frequency than is the case with white noise.
 
elwaylite

elwaylite

Audioholic
Not a problem for me, I bought a preamp and an outlaw 7500, I just let her loose!
 
highfigh

highfigh

Audioholic Slumlord
I think we should demand power cube graphs from manufacturers.

Jim
That wouldn't be a bad idea. If car audio companies could do that in the '90s, home audio manufacturers can do it now. Rockford Fosgate was one of the brands that did best and they didn't really seem to care if the load was inductive or capacitive. I'll have to dig out my book to see the comparisons.

The great thing about that is the ease of understanding.
 
highfigh

highfigh

Audioholic Slumlord
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? :confused:

Hopefully it will post by the end of this week.
Which Denon clipped at 40W? Was it a current model, or the old one you showed in the video?
 
gene

gene

Audioholics Master Chief
Administrator
The avr-x5200w. The data is in the video.
 
J

John Daddabbo

Audioholic Intern
Question if I may... So what of the Yamaha RX-Z11 and any other Amplifier which retains its full output into 4 ohms using the 4 ohm setting. If one possesses a truly 4 ohm on average speaker, should one then use the 4 ohm setting? I for one have an Amplifier with this option (Harman Kardon Citation 22) and speakers which dip below 1 ohm (Infinity 9 Kappa), and I swear that the sound is better using the 4 ohm setting.

Thank you for your input / insight on this.
 
Stanton

Stanton

Audioholics Contributing Writer
Good time to bust out the "impedance switch" article! We are heading into a major AVR upgrade cycle, and these switches are never going away: just say no (to flipping the switch from it's default).
 
gene

gene

Audioholics Master Chief
Administrator
Question if I may... So what of the Yamaha RX-Z11 and any other Amplifier which retains its full output into 4 ohms using the 4 ohm setting. If one possesses a truly 4 ohm on average speaker, should one then use the 4 ohm setting? I for one have an Amplifier with this option (Harman Kardon Citation 22) and speakers which dip below 1 ohm (Infinity 9 Kappa), and I swear that the sound is better using the 4 ohm setting.

Thank you for your input / insight on this.
I'm not sure how I can make this topic any clearer than I have already done both editorially or with our YouTube Video. I suggest watching the video again and reading the article.
 
highfigh

highfigh

Audioholic Slumlord
Brilliant! UL says they need to survive 4 Ohms, so they drop the rail voltage.

And they wonder why people switch to other brands and separates.
 
L

lupuscom

Audiophyte
Hello,

this subject interests me very much I have 4ohm speakers with Denon receiver that supports speakers from 6 to 16 ohm. can I add in speakers circuit serially 4ohm resistor and then my receiver will thisk that speakers are 8 ohms? what do you say about this solution?

Regards,

Ron
 
M

markw

Audioholic Overlord
Adding resistors in SERIES with your speakers will raise the effective impedance/resistance of the speakers and will east the load on the amp, it may well have a detrimental affect on the sound.

Remember, although impedance, a variable based on frequency, is expresed as "ohms", this is not the same as DC resistance, which is a constant that a resistor provides, which is also stated as "ohms".
 
L

lupuscom

Audiophyte
HI markw,

thank you for your answer, I understand what you wrote. but just for sake of brainstorming do you know of case that somebody tried this "solution" ?
or do you have any other solution for this issue? except buying the receiver that supports 4ohm speakers

Regards,
 
M

markw

Audioholic Overlord
Not really. Nobody I've known has tried it but, from a theoretical standpoint, it will work.

just make sure that the resistors you choose can handle the wattage.

As for alternatives, go with what you have but don't blast it.
 
newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top