Big (?) news from the US FTC -- updated regulations for power output claims

mhardy6647

https://www.ftc.gov/system/files/ftc_gov/pdf/p974222amplifierrulesnprm.pdf
Remarkably reasonable -- less abusive than FTC '74, but still a serious attempt to add some rigor back to power claims for home entertainment amplification devices.

PART 432—POWER OUTPUT CLAIMS FOR AMPLIFIERS UTILIZED IN
HOME ENTERTAINMENT PRODUCTS
Authority: 38 Stat. 717, as amended; (15 U.S.C. 41-58).
Source: 39 FR 15387, May 3, 1974, unless otherwise noted.
...
§ 432.1 Scope.
[39 FR 15387, May 3, 1974, as amended at 63 FR 37235, July 9, 1998]
This content is from the eCFR and is authoritative but unofficial.
(a) Except as provided in paragraph (b) of this section, this part shall apply whenever any power output (in watts or otherwise), power band or power frequency response, or distortion capability or characteristic is represented, either expressly or by implication, in connection with the advertising, sale, or offering for sale, in commerce as “commerce” is defined in the Federal Trade Commission Act, of sound power amplification equipment manufactured or sold for home entertainment purposes, such as for example, radios, record and tape players, radio-phonograph and/or tape combinations, component audio amplifiers, self-powered speakers for computers, multimedia systems and sound systems, and the like.

(b) Representations shall be exempt from this part if all representations of performance characteristics referred to in paragraph (a) of this section clearly and conspicuously disclose a manufacturer's rated power output and that rated output does not exceed two (2) watts (per channel or total).
[emphasis added]

Dude.
The FTC has even abolished reference to the fabled "RMS watt"!
Bless their hearts!
(in fairness, maybe they did this back in the 1998 revision -- I don't know... but maybe we'll finally stop reading about RMS watts

from Section 432.2 "Required Disclosures":
The manufacturer's rated minimum sine wave continuous average power output, in watts, per channel (if the equipment is designed to amplify two or more channels simultaneously) at an impedance of 8 ohms, or, if the amplifier is not designed for an 8-ohm impedance, at the impedance for which the amplifier is primarily designed, measured with all associated channels fully driven to rated per channel power. Provided, however, when measuring maximum per channel output of self-powered combination speaker systems that employ two or more amplifiers dedicated to different portions of the audio frequency spectrum, such as those incorporated into combination subwoofer-satellite speaker systems, only those channels dedicated to the same audio frequency spectrum should be considered associated channels that need be fully driven simultaneously to rated per channel power.
[again, emphasis added]

Full, disclosure: I read about this at ASR. Yeah, I know, I know...
https://www.audiosciencereview.com/forum/index.php?threads/the-ftc-may-consider-dropping-the-amplifier-rule.20303/page-2#post-2024836

pitdogg2

Does mean no more 1khz ratings claims and back to full ratings for all channels?

daddyjt

What a sterling example of government inserting themselves into areas that they really have no business with. I mean seriously - how many tax dollars would you guess were wasted on this? Probably over 1,000 man-hours @ ~$50/hr….

Sorry, rant over (and no disrespect to OP!)

mhardy6647

Well... it might limit the proliferation of "200 watt" Class D amps which are, realistically speaking, 20 watt amplifiers.
It might also encourage manufacturers of cheap Class D (and other amp class) hardware to provide adequate heat sinking and ventilation -- which would be a nice thing to see.
Finally, it'll be interesting to see what AVR (more to the point, multichannel amplification) specs look like, going forward.
Is it government overreach? Probably, but on the other hand -- well -- the manufacturers aren't going to regulate themselves, nor will the market select for honest power claims (based on decades of history -- which is what spawned FTC '74 in the first place).
I am just amazed and surprised that they actually kept some reasonable standards in place. I was expecting this to be the end of any rational assessment of power claims for any components.
On the other other hand -- you'll still be able to buy all of the 500 watt per channel amps you want on Aliexpress... and with your choice of name tags, too -- Krell, McIntosh, marantz...

Oh, and of course, the regs won't apply to "pro" audio components nor to vehicle audio products, so the Wild West will still be the standard in those markets.

msg

Any mention in there of LED headlights? (fingers crossed)

OleBoot

mhardy6647 wrote: »

Well... it might limit the proliferation of "200 watt" Class D amps which are, realistically speaking, 20 watt amplifiers.
It might also encourage manufacturers of cheap Class D (and other amp class) hardware to provide adequate heat sinking and ventilation -- which would be a nice thing to see.
Finally, it'll be interesting to see what AVR (more to the point, multichannel amplification) specs look like, going forward.
Is it government overreach? Probably, but on the other hand -- well -- the manufacturers aren't going to regulate themselves, nor will the market select for honest power claims (based on decades of history -- which is what spawned FTC '74 in the first place).
I am just amazed and surprised that they actually kept some reasonable standards in place. I was expecting this to be the end of any rational assessment of power claims for any components.
On the other other hand -- you'll still be able to buy all of the 500 watt per channel amps you want on Aliexpress... and with your choice of name tags, too -- Krell, McIntosh, marantz...

Oh, and of course, the regs won't apply to "pro" audio components nor to vehicle audio products, so the Wild West will still be the standard in those markets.

Would you please explain this? I have not done much investigation of Class D amps so far due to the questionable reputation they have acquired.

mhardy6647

OleBoot wrote: »

mhardy6647 wrote: »

Well... it might limit the proliferation of "200 watt" Class D amps which are, realistically speaking, 20 watt amplifiers.
It might also encourage manufacturers of cheap Class D (and other amp class) hardware to provide adequate heat sinking and ventilation -- which would be a nice thing to see.
Finally, it'll be interesting to see what AVR (more to the point, multichannel amplification) specs look like, going forward.
Is it government overreach? Probably, but on the other hand -- well -- the manufacturers aren't going to regulate themselves, nor will the market select for honest power claims (based on decades of history -- which is what spawned FTC '74 in the first place).
I am just amazed and surprised that they actually kept some reasonable standards in place. I was expecting this to be the end of any rational assessment of power claims for any components.
On the other other hand -- you'll still be able to buy all of the 500 watt per channel amps you want on Aliexpress... and with your choice of name tags, too -- Krell, McIntosh, marantz...

Oh, and of course, the regs won't apply to "pro" audio components nor to vehicle audio products, so the Wild West will still be the standard in those markets.

Would you please explain this? I have not done much investigation of Class D amps so far due to the questionable reputation they have acquired.

It's very simple, and only misleading to those who assume power specifications are all created equal(ly): almost all (not all... but most) products incorporating Class D power amplifiers built around OEM Class D boards made by a handful of manufacturers which are incorporated as-is into the brand-name products. Most of those board manufacturers rate most of their boards' power output based on short-term (burst) testing of a 1 kHz signal at 10% THD into a 4 ohm load. The THD, impedance, and frequency 'standards' chosen add (and this is a SWAG, but not an outrageous guesstimate) ca. 6 to 9 dB (i.e., a factor of 4 to 8) to the output rating relative to "FTC '74". FTC '74 specified steady state output over a specified range of frequencies and a specified, "hifi" level of harmonic distortion (e.g., 20-20 kHz at <<1% THD) into a specified (typically 8 ohm) load, measured only after a preconditioning period.
200/8 = 25 watts 200/6 = 33 watts.
So, yeah, OK, I was a bit hyperbolic.

mhardy6647

In other words. The same amplifier might be claimed, with complete legitimacy, to be:
25 watts into 8 ohms, 20 Hz to 20 kHz at < 0.1% THD
and
200 watts into 4 ohms, 1 kHz at 10% THD

OleBoot

OK, so nothing really concerning Class D per se. Sort of back to "music power".

mhardy6647

OleBoot wrote: »

OK, so nothing really concerning Class D per se. Sort of back to "music power".

Exactly.
That said, I don't know how any given Class D amp board'll fare when (if) tested to FTC specs.
That said McIntosh uses 'em in (at least) one of their "installer-grade" A/V amplifiers: Hypex NC-500 modules (i.e., nice ones) in the MI254 4-channel amp.



source: https://www.audiosciencereview.com/forum/index.php?threads/mcintosh-mi254-power-amplifier-teardown.21807/

mhardy6647

I am, FWIW, very favorably impressed by the one and only Hypex product here -- although (in full disclosure) it contains no class D (pulse-width modulation) amplification devices.
Hypex's kit brand is called "DIY/Class D".

mhardy6647

So -- @OleBoot, if you're still interested in this topic.
I happened to be looking at a fairly long, fairly new thread ahem Elsewhere on one of these cheap does-everything integrated amps from... a large & fairly populous Asian country.
https://www.amazon.com/LOXJIE-Amplifier-Headphone-Transmission-Bluetooth/dp/B0CNXLH1CY


The amp is based on class D chips from a German company called Infineon, specifically their Merus MS5352MA (2-channel) chip.
https://www.infineon.com/dgdl/Infineon-MA5332MS-DataSheet-v02_00-EN.pdf?fileId=5546d4627a0b0c7b017a3f402ad026a2

So, the nice folks at Loxjie (bonus question: how the heck would an Anglo pronounce that?) have all kinds of specs for their $215 amplifier.

85 watts x 2 into 8 ohms.
They also show some data on "THD+N" vs. output power, presumably measured on a standard testing platform like the one ASR uses, so presumably determined using a 1 kHz sine wave in a short-term test.

At 85 watts, it looks like the THD+N is about 6%
By the looks of this graph, at 75 watts, the THD+N into 8 ohms at 1 kHz is about 1%
(the contribution of noise at these levels of output power is almost certainly negligible, essentially all of the distortion is THD for these numbers)
What would "we" consider a hifi level of distortion (i.e., negligible clipping, in this type of testing)? Maybe 0.1%
Now we're talking about ca. 62 watts.
at 1 kHz into an 8 ohm resistive load, probably with one of the two channels driven.

Both channels driven, 20 to 20 kHz, after preconditioning, continuous sine wave power output at a "hifi" level of THD will be considerably less than any of those values. I'd guess at least 3 dB less (i.e., 31 wpc), and maybe even more less than that.

In other words, I'd call this a 30 watt per channel amplifier (probably) in an FTC world. Loxjie wants us to think of it as a 165 wpc amplifier (into a 4 ohm load).
We'll see what happens to products like this one in terms of power claims on the US market.


EDIT: Oh, that "0.003%" THD+N spec from Loxjie? At 1 kHz, it meets that number at about 9 watts.

OleBoot

Does that graph use data obtained by ASR?

mhardy6647

Nope, they haven't 'tested' one of these amps yet. The 8 ohm plot I posted is from Loxjie's website (the "expired certificate" URL link I posted). Probably obtained using a very similar audio analyzer.

OleBoot

Sorry, didn't read your original post correctly. I am, however, mildly surprised that this was published by the manufacturer (rather than by some other audio source) - they give themselves enough rope to hang themselves many times over as you have pointed out. But how many prospective buyers of this piece would even know how to interpret this information? There are still many out there who believe that Class D is somehow inherently "digital", so it must be good, right?

Even the old purveyors of "music power" that I mentioned were smart enough to use new (albeit meaningless) terminology.

It all works out, though - see lots of aughts in front of the THD number, big numbers for watts and you're good to go. Go home, pump up the volume and stream your latest Taylor Swift offering with the now stratospheric distortion levels either because you are ignoring them or (more likely) not able to identify them unless they include high level pops, bangs or whatever.

billbillw

I'm just now reading through this. Mark, I think you are generalizing Class D.
Some of the better known Class D, like from ICE-Power are very capable of putting out way more than 20 watts at full range with sufficiently low distortion.
From ASR:



Notice that is full range on the last one. That's pretty close to the rated 125wpc rating.
The amp tested above uses a single 125 board wired to produce stereo output. My Wyred4Sound amp has a pair the bigger 250 ICEPower boards and they are configured so each board is bridged. So its like a pair of monoblock boards in each ST500 chassis and it does put out a realistic 500+ watts per channel into 4ohms.
It should be noted that most Class D amps are more efficient into 4ohms so they often more than double their power in a 4ohm load. In my case, the ST500 does 250wpc into 8ohms and 550wpc into 4ohms.

mhardy6647

Of course, and I am not (at all) anti-Class D (PWM) amplification for hifi.
There are some very fine Class D modules. They're not inexpensive.
I don't know how any of them will hold up to the new FTC standard, yet. We'll see.

invalid

billbillw wrote: »

It should be noted that most Class D amps are more efficient into 4ohms so they often more than double their power in a 4ohm load. In my case, the ST500 does 250wpc into 8ohms and 550wpc into 4ohms.

I know that no class A or A/B amp can double down when impedance is halved. Can your class D amp double again into 2ohms?

billbillw

invalid wrote: »

billbillw wrote: »

It should be noted that most Class D amps are more efficient into 4ohms so they often more than double their power in a 4ohm load. In my case, the ST500 does 250wpc into 8ohms and 550wpc into 4ohms.

I know that no class A or A/B amp can double down when impedance is halved. Can your class D amp double again into 2ohms?

There are quite a few A/B amps that can double power into 4ohms, but usually not more than double.
I haven't seen any Class D rated for 2ohms. Most home audio isn't except some of the extreme high dollar stuff. That's a car audio thing and usually for running multiple subs in parallel.

invalid

There are no a/b amps that double down, the manufacturers who claim this don't rate the actual full power at 8ohms.

billbillw

invalid wrote: »

There are no a/b amps that double down, the manufacturers who claim this don't rate the actual full power at 8ohms.

30+ years in audio, I've never heard anyone say that. Maybe you've read or been told something I haven't. Now, I know they often quote the power into 8ohms at absurdly low distortion rates and it is usually a higher, but still low distortion into 4ohms, but that is often because they want nice even numbers for power, like 150w instead of 158w or something along that lines. Most of these have a sorta cliff they run into where distortion is low then ramps up very fast at the limit.

invalid

Look at the stereophile measurements of the krell ksa 250 as an example, 325 watts into 8ohms, 635 watts into 4ohms and 1000 watts into 2 ohms

billbillw

invalid wrote: »

Look at the stereophile measurements of the krell ksa 250 as an example, 325 watts into 8ohms, 635 watts into 4ohms and 1000 watts into 2 ohms

I'm not sure what you're argument is here. 1st, the KSA250 is a class-A, right? Not A/B. 2nd, that amp is rated 250 into 8ohms, 500 into 4. The testing shows it meets both. Effectively a doubling. 635w before clipping into 4ohms? That's way above 500w.
It is all marketing. Whether is is exactly double, close to double, it doesn't matter. The issue is when they design a poor amp that doesn't have the power supply capable of handling 4ohms without clipping (or worse) at near the same watt output as into 8ohms. That's what everyone wants to avoid.

VR3

Mark levinson has multiple amps that double 8 4 2 and even 1 ohm...

Biggest restriction on amps in this regard is the power coming from the wall

invalid

All the class A/b amplifiers that claim this doubling are underrated on the 8ohm spec. The mark Levinson no.536 measured at 510 watts at 8ohm and 800 watts at 4ohm. These amps come close but it's not possible. Both the krell and the mark Levinson are class A/b amplifiers.

billbillw

invalid wrote: »

All the class A/b amplifiers that claim this doubling are underrated on the 8ohm spec. The mark Levinson no.536 measured at 510 watts at 8ohm and 800 watts at 4ohm. These amps come close but it's not possible. Both the krell and the mark Levinson are class A/b amplifiers.

You realize those stereophile tests are extreme and taken to clipping. Good manufacturers don't rate at clipping, they rate at a low distortion level.
In reality, those amps very well designed and are able to double their rated 8 ohm power into 4 ohms. You are just confusing the situation.

invalid

No arguing that they are not very well designed, I happen to own a krell ksa 300s, but it cannot double it's power output when impedance is halved, to do that it would need to be a perfect voltage source, which no amplifier can achieve. The stereophile measurements are taken before clipping at 1% distortion.

pitdogg2

I can actually vouch for my amp as I watched it being tested on the bench by the gentleman I purchased it from. My amp, Aragon 8008bb. It is stated by Mondial to be 200 watts @ 8 ohm and 400 watts @ 4 ohm. In reality on the bench it tested at 300 watts @ 8 ohm and 400 @ 4 ohm, a little over 700 @ 2 ohm.
It is basically two Aragon 4004mk2, one for each channel. Much much larger caps and 2 huge toroidal transformers for each channel. So as advertised by Mondial the 8008bb had double the toroidal, output, rectification and capacitance of a single 4004mk2 BUT still rated the same as the 4004mk2 at 200/400 eight and four ohm respectively.

I believe Richie @SCompRacer told me one time his Krell doubled down to a half ohm, which is impressive if it truly can.

invalid

[quote 1st, the KSA250 is a class-A, right? Not A/B.
[/quote]

It's class A to just over 28 watts, some of the earliest versions had a little more bias current, to be 250 watts of class a would require way more heat sinking or a fan.

VR3

Levinson doesn't post class specs as the bias adjusts as power demands increase, according to the manual

The 33 Monoblock is rated at 300/600/1200/2400 watts at 8/4/2/1 ohms.

They also require a 50 Amp circuit per amp.

invalid

VR3 wrote: »

Levinson doesn't post class specs as the bias adjusts as power demands increase, according to the manual

The 33 Monoblock is rated at 300/600/1200/2400 watts at 8/4/2/1 ohms.

They also require a 50 Amp circuit per amp.

VR3 wrote: »

Levinson doesn't post class specs as the bias adjusts as power demands increase, according to the manual

The 33 Monoblock is rated at 300/600/1200/2400 watts at 8/4/2/1 ohms.

They also require a 50 Amp circuit per amp.

I bet if it was measured by a 3rd party it would exceed its 8ohm measurements by quite a margin. My point here is that the 8 ohm measurement will always be rated lower in the spec sheet, not saying these types of amps aren't built to the max, just that this doubling is marketing.