How important is doubling down power to 2 ohm or 1ohm on Hi Fi Speakers on high dynamic range music?

[audio2design]

I was asking whether double down is the attribute because that is what is published in spec but there may be a new attribute that is not yet found or published that explains the better dynamic range.

It is not the metric.

It is almost completely meaningless. What matters is how much power your amplifier will put out at the lowest impedance of your speakers at an acceptable level of distortion, and even that may not be the most important unless that peak is in lower frequencies as the highest power peaks in music are rarely at high frequencies.

If your speakers don't go down to 1 ohm, what do you care about the power at 1 ohm. In fact, an amplifier that does not double down in power down to 2 ohms or 1 ohm may be able to support louder peaks with your speakers.

Let's say your speakers never dip below 4 ohms. You have two amplifiers, 1 - 200 watts at 8, 400 at 4, 800 at 2, 1600 at 1. Lets say you have another amplifier 300 at 8, 600 at 4, 750 at 2, 650 at 1. Which will play louder on your speakers? The 2nd one. Why? Because it can hit 600 watts at 4 ohms, versus the other that can only hit 400.

Apparent, real, reactive power can almost be taken out of the equation w.r.t. amplifier power ratings. You need voltage to excite current, and the amp that does 600 watts at 4 ohms has more available voltage (likely) than the amp that can only reach 400 watts.

Why an amp does not double down, can be varied. A pure class-A may not because it just down not have enough current. A class-AB may not due to stability and/or hold up capacitance / power supply limitations. A class-D may hard limit current to prevent inductors saturating or to protect output devices. None of these indicate that prior to the amplifier entering clipping that it will not work properly.

To much of this is just marketing BS meant to confuse the less technical and even the pseudo technical get pulled in because it almost sounds right.

 

[audio2design]

The opposite is also true; an amplifier not rated to "double down" all the way to 2 ohms may provide more power but simply not have the heat sink and power supply to sustain long-term high-current output for low loads. So it might not be rated to "double down" but in real life may sound far more powerful.

Like many things, there is not a simple single specification that tells everything about the amp.

Many of these amps can't sustain their doubling down at all due to simple limitation of what they can pull out of the wall, not to mention they would burn up, even the massive ones.

 

[pjug]

Ahofer posted this video

and very useful the materials that explain apparent power, real power, and reactive power.
https://www.pema.ie/TECHTALK LIBRARY/APT/True vs. Apparent Power.pdf
http://www.cromptonusa.com/Watt_Var_VA.pdf
https://www.audioholics.com/loudspeaker-design/understanding-impedance-electrical-phase/page-2

I am looking for technical attribute (may be it not yet defined or published in measurement) that explains the higher sound quality dynamic.
I was asking whether double down is the attribute because that is what is published in spec but there may be a new attribute that is not yet found or published that explains the better dynamic range.

On that video, keep in mind that they are measuring peak power. A 300W amplifier will give 600W peaks. Some 200W amplifiers might be able to do 300W dynamic power, and so also able to do 600W peaks. But still I don't understand that video since the Pan Sonic track is not dynamic.

Here is another CH-precision video that shows even higher power peaks. But the crest factor on that track is is >25dB so no wonder! I don't worry if that track would clip on my system because the crest factor is so out of the ordinary.

 

[Alice of Old Vincennes]

You may not like this, but the odds are, your B&W 801's cannot do the 1812 overture by Telarc justice. Most speakers cannot, not matter how much power you give them. This is one time that efficiency (and serious subs) really does come into play. It is called an 8 ohm speaker, but is much closer to 5 or 6 ohms, and the efficiency is 91db/2.83V, not 1W. Really it is closer to 88db/w. In the lower base it is closer to 6-8 ohms, so the Krell is peaking at 200-300W, and down to 3 ohms in high bass, so the Krell is peaking at 500W. Its sounds like a lot, but your speakers while not inefficient, are not efficient. The first time I heard a system do the 1812 overture justice was a custom set of massive horn loaded speakers with equally massive subs. Total power was several thousand watts and efficiency likely in the high 90's . It was the first time I heard the cannon come across as anything truly life life. After that, I realized how hard most people were pushing their systems playing this and how terribly distorting they were. That "compressed" version I would not be so certain are wrong. Woofer flopping is not how this piece actually sounds. I have heard this sound better with relatively cheap electronics and really sensitive speakers compared to uber expensive systems that just did not have the "oomph" everyone seems to turn it too loud for their system.

Why not just buy a real cannon and time it?

 

[RayDunzl]

Many of these amps can't sustain their doubling down at all due to simple limitation of what they can pull out of the wall, not to mention they would burn up, even the massive ones.

My amps will trip the breaker in the garage if given free reign.

Spec'd at 1600W draw (max, each, which would be sustained for 30 or more seconds if only a peak triggered that level) x 2 plus all the other stuff in and on the rack plus my PC stuff across the room on an 1800W (120V 15A) circuit. Plus anything else on that branch.

As for heat, when used in a spirited manner, for example on an Audio Buddy Visit and Beer Saturday,140F on the heat sinks has been seen, without apparent strain.

No, they aren't green, but they've caused me to make money off their inefficiency, so I've got that going for me, which is nice.

 

[Spkrdctr]

Dynamic range is a function of noise floor (SNR) and power output. Different manufacturers may specify amplifiers differently, even within their own product line. A conservatively specified amplifier may actually provide more power than one rated for higher power especially if it is specified for low-impedance loads and "doubling down". Thermal (heat) requirements, power supply capacity, output device safe operating area, and a myriad of other factors come into play. The opposite is also true; an amplifier not rated to "double down" all the way to 2 ohms may provide more power but simply not have the heat sink and power supply to sustain long-term high-current output for low loads. So it might not be rated to "double down" but in real life may sound far more powerful.

Like many things, there is not a simple single specification that tells everything about the amp.

This should be put in every amp/receiver thread on the forum. The perfect answer. For a quick and dirty example, Denon just came out with an amp rated at 80Watts per channel at 8 ohms and 160 at 4 ohms. Testing on Audioholics showed it EASILY met both requirements. So if someone bought it for its advertised power, they will easily see that power. Many amps and receivers will not do that. "Burst" power testing is pure crap and should not be allowed.
Just a quick example.

Great Post though on power.

 

[MrPeabody]

It is not the metric.

It is almost completely meaningless. What matters is how much power your amplifier will put out at the lowest impedance of your speakers at an acceptable level of distortion, and even that may not be the most important unless that peak is in lower frequencies as the highest power peaks in music are rarely at high frequencies.

If your speakers don't go down to 1 ohm, what do you care about the power at 1 ohm. In fact, an amplifier that does not double down in power down to 2 ohms or 1 ohm may be able to support louder peaks with your speakers.

Let's say your speakers never dip below 4 ohms. You have two amplifiers, 1 - 200 watts at 8, 400 at 4, 800 at 2, 1600 at 1. Lets say you have another amplifier 300 at 8, 600 at 4, 750 at 2, 650 at 1. Which will play louder on your speakers? The 2nd one. Why? Because it can hit 600 watts at 4 ohms, versus the other that can only hit 400.

Apparent, real, reactive power can almost be taken out of the equation w.r.t. amplifier power ratings. You need voltage to excite current, and the amp that does 600 watts at 4 ohms has more available voltage (likely) than the amp that can only reach 400 watts.

Why an amp does not double down, can be varied. A pure class-A may not because it just down not have enough current. A class-AB may not due to stability and/or hold up capacitance / power supply limitations. A class-D may hard limit current to prevent inductors saturating or to protect output devices. None of these indicate that prior to the amplifier entering clipping that it will not work properly.

To much of this is just marketing BS meant to confuse the less technical and even the pseudo technical get pulled in because it almost sounds right.

Good post. The best laid plans ... the intent of the single power metric is not mysterious. Unfortunately, it does muddle things, because it represents two attributes that are distinct. One of them is the ability for the amplifier not shut down or smoke up the house when the current it is forced to deliver by low-impedance speakers is greater than the amount of current it can withstand. The other thing is the amplifier's voltage clipping threshold. Audiophiles who are easily confused should start by using the speaker impedance stated with the power specification to calculate the voltage for that combination of power and impedance, and also the current for that combination of power and impedance.

 

[Head_Unit]

lack of double down?...power rating at 8 ohm...2ohm

Doubling down is generally a fantasy as @Sir Sanders Zingmore noted. At least it represents an attempt from the manufacturer, but almost always the higher impedance power level is simply under-rated to give the appearance of doubling. (I used to work for a $3BN sound company and their chief amp engineering director said that the 50-60% increase at half the impedance was basically a condition of typical circuits and design decision and cost cost cost). Plus amplifiers are tested just with resistors due to time and money-the Power Cube being a cool but rare exception. So I'll tend to agree with @Rip City Dave and @ahofer. Plus as @Spkrdctr notes it's hard to know what is going on without a storage oscilloscope. Or maybe a peak-hold voltmeter to get you close.

 

[Head_Unit]

the old Apogee Scintilla.

Oh wow, the only speakers I ever heard cables make a difference with! I believe because they were around 1 ohm, and one of the cables were MIT with a passive network on the end.
http://www.lippaudio.org/old/MySystems/Scintilla/impedance.html

Yes high end speakers do NOT have to have ugly impedances. After all, Richard Small worked on flattening impedance with conjugate networks and said KEF were making your amp twice as powerful! (Some years later he told me he felt rather sheepish about that...although actually nowadays that seems a prescient idea and perhaps not an exaggeration at all). Another example would be some De Vore models, I think the O/96 is like 12 ohms.

 

[MasterApex]

Which measurement or spec attribute explain why certain amp A will provide more "life-life" dynamic sound over Amp B on the same speaker (complex load that goes down to 3 ohm at certain frequency)?

 

[tvrgeek]

I experimented with Levinson 333 300W@8ohm , doubling down to 1200W @2ohm , Krell KSA 200s 200W @8ohm that double down to 1600W @ 1ohm vs a few highly rated class D 200W - 400W @8 ohm amplifiers.

On my B&W N801 speaker, the sound quality is comparable below 75dB....do show different "brightness" and "bass punch" which can be subjective in term of preference.

But when playing high dynamic classical music like 1812 overture at peak (not sustained) volume above 94dB, the Class D amplifier sounds compressed relative to Levinson or Krell.

Why is that?

The lower the impedance, the higher the distortion. Physics of BJTs. Not quite as bad with FETs. I wish we had 16 Ohm speakers.
Now an amp that will do close to twice the power from 8 to 4 Ohms means it has sufficient power supply to supply the current without collapsing. You expect that in a ML or Krell, not in a modern Rotel. Power supplies are expensive.

Looking at class D amplifiers are different and I don't think such rules apply. Switching supplies are equally different and I need to learn more about them. I understand dynamic loads on linear, but not switchers. Much to learn as I have yet to buy a Class D as I have yet to hear one I could stand. Granted, I am a couple generations slow. Going to start cheap as I am still cheap. Maybe the new Topping. Should compare to my old Creek. Tempted by the March to compare to my old Mosfet. Of course, tempted by the Benchmark, AB but a SMPS.

Bentley always rated their car HP as "adequate" I suspect Mac had a similar concept.

 

[witwald]

Which measurement or spec attribute explain why certain amp A will provide more "life-life" dynamic sound over Amp B on the same speaker (complex load that goes down to 3 ohm at certain frequency)?

If both amplifiers are driven within their linear operating range, and both have similar frequency responses an low intrinsic levels of distortion (say, 0.05% or less), then I guess that the more powerful amplifier will be the one that ends up sounding more "life-like". The extra power enables high-level transients to be cleanly reproduced without clipping, so that's a better and more authentic response when the required sound levels call for it.

 

[tvrgeek]

If both amplifiers are driven within their linear operating range, and both have similar frequency responses an low intrinsic levels of distortion (say, 0.05% or less), then I guess that the more powerful amplifier will be the one that ends up sounding more "life-like". The extra power enables high-level transients to be cleanly reproduced without clipping, so that's a better and more authentic response when the required sound levels call for it.

Sorry, that is salesman speak. You first said, "driven within their linear range" which means neither is clipping. There are many other factors. I am not positive at what level of distortion, and these other factors, amps will all sound the same. .05 is probably not quite there and a number like that does not characterize sufficiently distortion. You need to see distortion against frequency against level and this is unfortunately where the complexity of the load impedance effects the amplifiers distortion. At least on AB. We can plot it, but can we understand it and what it means to our perception? I do not know how it effects class D.

Speakers do not have to be ugly loads, but they mostly do. Yes, Dick showed how you can make them easier. I pay attention to that in my own designs, but it can cause a lot of catch -22 issues. No free lunch.

Which measurement can provide the best indication? The hell if I know, or anyone else for that matter. If there was one nice simple spec, we would know it. We can give a Bode plot, but these days, flat from subsonic past hearing is easy. We can give SNR, but again, easy today. DF, which is actually about irrelevant, 1K 5W THD, IM, whatever. They can weed out the real crap, but not tell us much more. They can't even tell us which factors are more important for amps that are not superb as which defects bother each of us varies. I do suggest, that you can usually correlate, for a A or AB amp, a linear correlation of current to load will sound less constrained. Want to make it hard? Try to make a realistic load that has the same properties at 4 and 8 Ohms? A power cube can't and though it may tell a designer something, it does not give marketing anything they can put on a glossy back page ad or "fact" sheet ( the long narrow strip in a roll) given to reviewers so they have something to quote and make up a story about.

I can tell you, an amp that has .01% distortion at all frequencies, sounds different from one that starts @ .03, is .01 @ 1K, but .001 @ 20K sound different and which sounds preferable depends on the design of the tweeter and the execution of it. And it depends on the mix of low order and high order, if even or odd are predominant and the peculiarities of the speaker.

What we have is a SNIAD. We can pretty much identify what will sound like garbage. We can pretty much identify a group that is worth looking at. We have not yet, I do not believe, reached a understanding where they all sound the same. Will a new Topping P5 thingy sound the same as a Benchmark at moderate levels before clipping? 20W? How about that new NAD amp where one of the subjective reviewers threw up his hands and said, "it has no sound". Nothing else to say. I think it was the C298, but not sure. Does a March have a sound? Wish I could try one. Some try to describe the sound of a Vidar, but they seem to be reaching. SNIAD quite a bit lower, but "good enough" Or godd enough fr some not others? Does it matter more if your speaker is 84 dB 1M, 1W, 1K or 87?

 

[Spkrdctr]

And it depends on the mix of low order and high order, if even or odd are predominant and the peculiarities of the speaker.

Wonderful, talented very good engineers can't control the consumers speakers. The big elephant in the room of audio is the speakers. Take the flattest most precise, pure sound from the engineering lab and then horror of horrors, you have to pick a set of speakers. Which speakers will the customer use? Mini bookshelves, bookshelves, floor standing or large floor standing? Then you have at least 40 speaker manufacturers to pick from and probably more than that. So, now the speaker options are up to about 600 combinations. That wonderful, powerful pristine signal goes to speakers that all have different deficiencies across the board. So a giant inaccurate, uncontrolled difficult to deal with wet blanket known as speakers gets to turn that signal into everything from garbage to pretty good. This is why worrying about electronics and fuses, resistors, caps, and other exotica is a waste of time once you buy that awesome Benchmark or other great brands amp. The speakers are the crazy uncle in the room. Oh, and another crazy other uncle is in the basement called the room effects. Deal with those two crazies and you then have audio nirvana. So, the speakers and room are everything. Amir is giving us the speaker info, the room is up to the individual owner to deal with.

 

[kongwee]

Reading about the equipment folks would want to hear a recording of a cannon, I have to wonder if you might just want to buy a cannon.

In military mandatory country, yes the feel of big guns.

 

[Alice of Old Vincennes]

Wonderful, talented very good engineers can't control the consumers speakers. The big elephant in the room of audio is the speakers. Take the flattest most precise, pure sound from the engineering lab and then horror of horrors, you have to pick a set of speakers. Which speakers will the customer use? Mini bookshelves, bookshelves, floor standing or large floor standing? Then you have at least 40 speaker manufacturers to pick from and probably more than that. So, now the speaker options are up to about 600 combinations. That wonderful, powerful pristine signal goes to speakers that all have different deficiencies across the board. So a giant inaccurate, uncontrolled difficult to deal with wet blanket known as speakers gets to turn that signal into everything from garbage to pretty good. This is why worrying about electronics and fuses, resistors, caps, and other exotica is a waste of time once you buy that awesome Benchmark or other great brands amp. The speakers are the crazy uncle in the room. Oh, and another crazy other uncle is in the basement called the room effects. Deal with those two crazies and you then have audio nirvana. So, the speakers and room are everything. Amir is giving us the speaker info, the room is up to the individual owner to deal with.

Wonderful talented engineers can't control the speakers they use to engineer whatever they are trying to do. What is a "consumer" speaker anyway?

 

[Spkrdctr]

In military mandatory country, yes the feel of big guns.

I love the sound of the US 155mm artillery. It just doesn't get old. But, ear protection is mandatory and I know most artillery youngsters do not use it. They pay dearly later in life. But I like the sound. Like a 50 cal ripping off 500 rounds. Mortars, rockets oh heck, I like the sound of all of it! Music of a different sort.

 

[Spkrdctr]

Wonderful talented engineers can't control the speakers they use to engineer whatever they are trying to do. What is a "consumer" speaker anyway?

Oh, so you want to go there? Reading my post with an engineering eye? I was just meaning speakers as all speakers are consumer speakers. I could have said that better but I didn't. You may spank me later. Well, if your a female you can spank me now......

 

[DonH56]

Wonderful talented engineers can't control the speakers they use to engineer whatever they are trying to do. What is a "consumer" speaker anyway?

No, wonderful talented engineers cannot control the consumers' choice of speakers that they use for reproduction. Or their room, tone controls, etc. Realistically, in the real world engineers have input at various points in the build process, but generally the engineers work with the monitors the studio provides since they are already in place.

I tend to group speakers into a few categories: consumer includes virtually everything a typical consumer considers a home or portable speaker. Monitors include things like Genelec and other speakers targeting near-field use for mixing and mastering. PA speakers include those used on stage and in other sound reinforcement applications. Not a complete list and many sub-categories, natch.

 

[dlaloum]

I plan to replace the old Krell KSA200s with something newer (so was testing Class D Amp).

Therefore, I am asking the question whether the double down attribute is important (in playing dynamic music) for my next amplifier purchase/upgrade. Sounds like the consensus is "it is".

Depends on the speakers - if the speakers have impedance down below 4 ohm, then 2 ohm doubling down from 4 ohm is important - but if they don't.... you need them to linearly "double down" to as low as your speakers go... anything more is wasted. (but nice to have for potential future speakers?)

Having said that - my current main's are run by Crown XLS2500 class D (drivecore amps) - 440W@8ohm, 775@4ohm, 1200@2ohm - no they do not double down.... but they have ample headroom at 2 ohm, for my speakers, which do go down to 2 ohm.