6ohm AMP with new 4/8ohm signature elite speakers?

traxman

HI,

I have 2 questions about my home theater receiver and the new 5.0 polk audio signature elite set that is on the way…

My “last” setup was Yamaha RX-V467 (2010.) and 5.0 jamo S426 set, they were both 6ohm in specs.
https://europe.yamaha.com/en/products/audio_visual/av_receivers_amps/rx-v467/specs.html
One detail, my Yamaha AMP is the Europe version, which is locked on 6ohms, and the USA version has and option to change between 6 and 8 ohm.
I’m not an electrician or audio geek 😊 and I can’t find the right answer on the Internet so I will need some help and clarification about two things.
I sold my old jamo speakers and kept the Yamaha AMP. I ordered polk audio ES55,35&10 which are coming soon.
Now you know what I got, and here comes the “problem” 😊

Polk specified that the speakers are 4ohm and 8ohm compatible, how is this possible? From my knowledge speakers and amps are always declared with one figure, not as a range. Or the amp has an option to change the impedance like 4,6,8,16…
So I don’t know what will happened (in theory) when I have amp with 4, 6 & 8 ohms and I connect these speakers?
I know that if the amp is 8ohms, and speakers 4ohms, the amp can die or shutdown if it has the right protection (like mine). I know that in the opposite way, nothing very bad will happen, except the final dB will be lower that it would be if the both components are on the same impedance. And I read somewhere that in this case there may be some distortion in the sound??? This is my first question (hypothetical)

And the second one is related to my AMP and new speakers. My AMP is 6ohms and speakers 4&8ohms. How will this work and how can speakers be declared 4 and 8ohms? What is synchronizing the impedance between amp and speakers?
What will happened when connect amp with 4 or 6 or 8 ohms?
And finally do I need to change my AMP for the AMP with 8 or 4 ohms? Is there any drawback in this combos?

treitz3

Hello, traxman and welcome to Club Polk. If the Polk speakers are compatible with both 4 and 8, then they should be about 6 ohm nominal. Now, as to how can speakers be declared 4 and 8 ohms?

I dunno, as I have not been in the market for new speakers in a while and have not heard of this practice before. Marketing (with any company) always loves to mess with the numbers and spin things to attract new buyers.

Tom

txcoastal1

The word compatible...i.e. they likely have a nominal in between. Like all speakers pending on material played the impedance will drop during playback. Most decent actual amps are 8ohm, then they will spec 4ohm and even lower (capable) to 2ohm etc.

When you see 4ohm capable on a AVR this spec is usually misleading as the test is usually ran at 1khz. AVR amp specs are usually misleading in general because there is only so much you can produce especially in an HT multi channel configuration which is why we will likely recommend adding an amp for at least the front L/R and even the center channel.

mhardy6647

As @txcoastal1 says above, any time you see one number associated with an audio performance specification, at the best, you're getting a very rough guideline. Loudspeaker impedance is (literally) complex, in that it is determined by three different components, two of which depend on frequency. A "nominal" 8 ohm speaker does not have a fixed, frequency independent impedance. it goes up and down with frequency. If the impedance drops low in the upper bass or lower midrange frequencies, it will demand a lot from an amplifier, compared to one that doesn't.
It's actually even worse than that, because it's not just impedance but "phase" that enters into the equation of how difficult of a "load" a given speaker is for an amplifier. Phase is the literally "complex" part, in a mathematical sense (i.e., as in complex numbers... there is an imaginary component to the phase-dependent parts of impedance, mathematically speaking... but we ain't goin' down that rabbit hole!).

Here, for example, is the impedance curve measured for a Polk L200 loudspeaker (from "Audioholics".) The blue curve is impedance, the purplish one is phase angle.
https://www.audioholics.com/bookshelf-speaker-reviews/polk-l200-l400/conclusion



By modern standards, this is a pretty benign load for a power amplifier. Note that the measured impedance is fairly low (6 ohm) at 50 Hz and between 100 - 200 Hz. This is pretty much a "textbook" 6 ohm loudspeaker. An amplifier will spend much of its effort supplying the needs of this speaker in those frequency ranges.

The best bet is to use power amplification rated for high 'continuous' output power across a broad range of frequencies into a low (4 ohm) impedance load, and made by an established manufacturer with a good reputation. An example would be McIntosh (not that there aren't many others!).

EDIT: Oh, the other, fairly important and meaningful specification for a loudspeaker in terms of how it might mate with a given amp is its sensitivity. In @txcoastal1's example, above, the sensitivity of 90 dB (of sound pressure level output at 1 meter away from the speaker, with an signal input of 2.83 volts) is actually pretty high (again, by modern standards). Higher is better, in the sense that a more sensitive loudspeaker will require less electrical power delivered to it to produce a given level of output sound volume (acoustic power output).

F1nut

By now his head is spinning...lol

traxman

Thanks all you guys, but like the F1nut said I now know even less 😊

I read all things you wrote and even understood most of them, but still I can’t figure out what is ohm in audio business and how it relates to todays specs of the equipment. How to choice the right equipment. Like you said, many things are written misleading and maybe inaccurate just to show companies in better light. Like low quality equipment like to point out PMPO power or similar crap 😊 Like I said, I was always focused on RMS power and ohm specs, that was my main concern when choosing/combining the right amp and speakers, in car and at home.

I’m really not that much interested in technical/theoreticalparts but I just want to know what ohms stands for in specs and to know do I have OK equipment or I have to change it for something else. I would appreciate if someone could tell me if my yamaha amp is ok for this speakers or do I need a “better” model. Not in quality/feature/price range but in aspect of compatibility and will everything work ok or there might be some distortions and other problems in the sound because of the wrong impedance setup/amp+spk combo?

treitz3

You will not have a problem. Set the Yamaha to 6, hook up the speakers and enjoy the music.

Tom

mhardy6647

So: @treitz3 gave you the best answer.
What "ohms" are is a measure of the impedance a loudspeaker presents to an amplifier. Impedance is analogous to "resistance" in a simple direct current (battery) circuit, like a light bulb, so they use the same unit (the ohm) to measure both. Impedance is essentially a measure of how cooperative the speaker is to accept the power presented to it by the amplifier. The details do get complicated, but basically a good amplifier is capable of delivering all its got into any halfway reasonable speaker, irrespective of its impedance characteristics. That is a mammoth oversimplification, but the old "FTC" power specs were a decent, and at least consistent, way of assessing that.


This is the output power spec for a very old (1977) Yamaha receiver per the FTC spec. The fact that it cannot deliver twice the power into a 4 ohm load compared to an 8 ohm load suggests that it is limited in its ability to produce high current. A good modern amp, is much more likely to "double down" its full output power into a 4 ohm speaker relative to an 8 ohm speaker. This doesn't mean that the old Yamaha receiver was " bad" -- but in those days, 4 ohm speakers weren't as common as today, so the kind of performance it demonstrated in the FTC test was typical of affordable consumer hifi equipment.

How well any amp and speaker work together can really only be determined one way: empirically (i.e., try and see). At extremes (i.e., an amp that has trouble with a low or difficult impedance speaker, a difficult speaker, complex and dynamic music, and high volume levels), the amp may shut down or, simply, fail. But those are extremes.

TL/DR? Go with @treitz3's suggestion.

F1nut

"ES55 Towers deliver spacious, clear, enveloping and realistic sound reproduction from nearly any amplifier or receiver—whether 4- or 8-ohm"

"Impedance - Compatible with 4 and 8 ohm outputs"

What Polk is saying is confusing, but basically they are saying you can drive the speakers with any power source.

They are not saying the speakers are 4 and 8 ohm nominal.

Bottom line, you're good to go.

traxman

Thanks F1nut.
Yes, I presume that everything will work ok, but I’m still confused with that 4 & 8 ohm speaker compatibility. I don’t buy that 😊 How is this possible? I don’t have enough knowledge so I live in belief that these speakers are 8ohms, not 4 ohms and “compatibility” is just some marketing polk’s crap that they wrote. If you have 4 and 8 ohm AMPs and let say they don’t have “that” protection, both amps will work without a problem with these speakers. Except that 4ohm amp will have less dB at the end than it should have.
Am I right or wrong again? 😊

F1nut

Wrong again. They talking about the power source, not the speakers.

mhardy6647

traxman wrote: »

Thanks F1nut.
Yes, I presume that everything will work ok, but I’m still confused with that 4 & 8 ohm speaker compatibility. I don’t buy that 😊 How is this possible? I don’t have enough knowledge so I live in belief that these speakers are 8ohms, not 4 ohms and “compatibility” is just some marketing polk’s crap that they wrote. If you have 4 and 8 ohm AMPs and let say they don’t have “that” protection, both amps will work without a problem with these speakers. Except that 4ohm amp will have less dB at the end than it should have.
Am I right or wrong again? 😊

It doesn't work like that.
A watt is a watt. It actually doesn't matter if one's talking about a sound or electricity or water or car or a horse, for that matter. Horsepower and watts both measure power. 1 HP = 746 watts
There are some interesting interrelationships between voltage, current, and resistance (or impedance), and -- in the specific case of speakers -- SPL ("sound pressure level").

A truly 4 ohm speaker will deliver 3 dB more SPL than an 8 ohm speaker for the same input power (oops!) voltage, all else being equal (which 'all else' rarely is) -- but there's no magic. The 4 ohm speaker ingests its power in a different way (more current for a given voltage) than the 8 ohm speaker. One watt into 8 ohms is two watts into 4 ohms, which happens to be a 3 dB increase. How can that be? The voltage is the same, but the current doubles, and power = voltage x current. Again, no magic, just physics and arithmetic.

If you want to understand this stuff more/better -- start with Ohm's law, which is simple yet incredibly profound. All electronics depend on it!



For now, as Steve Winwood might've put it: just go roll with it.

https://youtu.be/MoGHGaN_HQs