FTC Amplifier Rule

[D Murphy]

The Federal Trade Commission will be publishing a Notice of Proposed Rulemaking in the Federal Register in a day or two. The Notice will seek comment on proposed amendments to the Rule that may affect how power ratings for multichannel receivers must be measured. Currently, such AVR's need only publish power and distortion specs for 2-channel operation. The new Rulemaking will revisit this issue. The press release concerning the upcoming Federal Register Notice is pretty foggy except for the recommendation that THD must be lower than .1% at the rated power. That will prove controversial to say the least. Currently there is no cap on distortion--you just have to disclose what it is. Here's the press release, which asks for comments on:

• "whether the Commission should amend the Rule to simplify power output measures by standardizing the test parameters used by amplifier sellers as follows: a load impedance of 8 ohms, a power band of 20 Hz to 20 kHz, and a THD limit of less than 0.1%; and
• the parameters of consumers’ normal use of multichannel home theater amplifiers."

I have no idea what they mean by "the parameters of ...normal use..." But we'll know shortly. I'll post a link to the Federal Register Notice when it's published.

 

[gene]

The Federal Trade Commission will be publishing a Notice of Proposed Rulemaking in the Federal Register in a day or two. The Notice will seek comment on proposed amendments to the Rule that may affect how power ratings for multichannel receivers should be measured. Gene and I submitted comments to the FTC over a year ago when they were first considering amending the Rule. The press release concerning the upcoming Federal Register Notice is puzzling and may contain a typo. Here it is:
"After evaluating the comments received, the FTC is now seeking additional comments on:

• whether the Commission should amend the Rule to simplify power output measures by standardizing the test parameters used by amplifier sellers as follows: a load impedance of 8 ohms, a power band of 20 Hz to 20 kHz, and a THD limit of less than 0.1%; and
• the parameters of consumers’ normal use of multichannel home theater amplifiers."

I think the Commission may have meant "1%" instead of ".1%" I'm not aware of any public comments suggesting a maximum THD level of .1%, and that would be really dumb. And I have no idea what they mean by "the parameters of ...normal use..." But we'll know shortly. I'll post a link to the Federal Register Notice when it's published.

Actually 0.1% may not be such a bad idea. Gives companies less wiggle room to overstate power. Usually when you exceed 0.1%, the harmonics look pretty nasty when plotting an FFT. Not sure what they will define as "normal use".

 

[D Murphy]

Actually 0.1% may not be such a bad idea. Gives companies less wiggle room to overstate power. Usually when you exceed 0.1%, the harmonics look pretty nasty when plotting an FFT. Not sure what they will define as "normal use".

We may have to agree to disagree on this one. That would mean a substantial number of manufacturers couldn't even publish a complying power specification. I don't think consumers would be very well served that intrusive a regulation. I'm still hoping it's a typo.

 

[TLS Guy]

Actually 0.1% may not be such a bad idea. Gives companies less wiggle room to overstate power. Usually when you exceed 0.1%, the harmonics look pretty nasty when plotting an FFT. Not sure what they will define as "normal use".

Absolutely correct, as after 0.1% distortion rises in an almost vertical line as power is increased. Not only is it not useable power, but calculated to destroy the amp and connected speakers.

 

[TLS Guy]

We may have to agree to disagree on this one. That would mean a substantial number of manufacturers couldn't even publish a complying power specification. I don't think consumers would be very well served that intrusive a regulation. I'm still hoping it's a typo.

If they can't publish a complying power specification, then they are adding to the piles of junk, we are already awash in. I sincerely hope it is NOT a typo.

 

[Verdinut]

IMO, most of us audiophiles would not purchase an amplifier with a THD getting close to 1% for the full 20-20K frequency range.

We have to bear in mind that the electronics produced by the popular brands which we already own and have bought in the recent past 50 years or so, have been meeting the low THD figures of less than 0.1%. By accepting a THD limit close to 1% would not be any improvement over what we are experiencing at present, without enactment of a new FTC ruling.

 

[D Murphy]

Absolutely correct, as after 0.1% distortion rises in an almost vertical line as power is increased. Not only is it not useable power, but calculated to destroy the amp and connected speakers.

Are we using the same metrics? I think there's a failure to communicate here. You're saying tube amplifiers just can't quote power specs even if they disclose the maximum THD? The current Rule doesn't set any upper limit on distortion--you simply have to disclose what the maximum is. Disclosure is always a better approach than government bans unless there is very compelling evidence to the contrary.

 

[Verdinut]

What is of utmost importance is the frequency range over which THD is calculated. It should be between 20 Hz and 10 KHz as a minimum. Nobody will be able to hear a harmonic distortion of the frequency of 20KHz, it's obvious. Many popular brand manufacturers only quote the THD figure at 1 KHz nowadays which is far from describing the real performance of an amplifier. Also, it's about time to impose abolishing publication of the ridiculous figures for a 10% THD.

 

[BoredSysAdmin]

Are we using the same metrics? I think there's a failure to communicate here. You're saying tube amplifiers just can't quote power specs even if they disclose the maximum THD? The current Rule doesn't set any upper limit on distortion--you simply have to disclose what the maximum is. Disclosure is always a better approach than government bans unless there is very compelling evidence to the contrary.

Pardon my ignorance, but does a tube amp that measures THD less than 0.1% in the 20-20 band even exists? Regardless of cost.

 

[TLS Guy]

Pardon my ignorance, but does a tube amp that measures THD less than 0.1% in the 20-20 band even exists? Regardless of cost.

Yes, Harold J, Leak broke that barrier in 1945.

Point One[edit]
In September 1945 the company released the first of the "Point One" series of amplifiers, so named because the total harmonic distortion was 0.1% at rated output. This represented a major leap forward in accepted standards for high-performance amplifiers (with 2% distortion generally considered acceptable at the time). This first "Point One" amplifier was known as the Type 15, and produced 15 watts output, at 0.1% distortion, using push-pull KT66 valves connected as triodes, with 26 dB feedback applied over four stages. The amplifier has a similar topology to the Williamson amplifier published in Wireless World in 1947.


LEAK TL/12 Point One Amplifier
In 1948, the original four-stage circuit was replaced with a three-stage design that was designated the TL/12. This amplifier had the same high performance at reduced cost, and it was responsible for establishing and securing the future of the company as a dominant player in the "hi-fi" boom of the 1950s and 1960s.

Subsequent amplifiers from the company all used the same circuit topology as the TL/12, but took advantage of newer more efficient power valves and the so-called "ultra-linear" connection of the output stage to obtain higher power output with triode-like characteristics. These amplifiers included the TL/10, TL/25, TL/12-Plus, TL/25-Plus, TL/50-Plus, and the Stereo 20, Stereo 50 and Stereo 60

I owned a Leak TL 10 for many years. I gave it to my nephew some years ago, and he still has it in use.

They were beautifully made.

That was a far higher build quality, than we often have to put up with now.

 

[D Murphy]

What is of utmost importance is the frequency range over which THD is calculated. It should be between 20 Hz and 10 KHz as a minimum. Nobody will be able to hear a harmonic distortion of the frequency of 20KHz, it's obvious. Many popular brand manufacturers only quote the THD figure at 1 KHz nowadays which is far from describing the real performance of an amplifier. Also, it's about time to impose abolishing publication of the ridiculous figures for a 10% THD.

Unfortunately, the current rule is ambiguous when it comes to the frequency bandwidth. The Rule requires that the relevant bandwidth be "stated." There's no question that any actual bandwidth can be used--not just 20 Hz to 20 kHz--but is 1 kHz a "bandwidth." Technically it is (one Hz), so we were never able to enforce this part of the Rule. It looks like the propose revision would require 20 to 20 kHz, but we'll see.

 

[D Murphy]

If they can't publish a complying power specification, then they are adding to the piles of junk, we are already awash in. I sincerely hope it is NOT a typo.

Your "pile of junk" may be an affordable entry level receiver for a college student.

 

[Verdinut]

Unfortunately, the current rule is ambiguous when it comes to the frequency bandwidth. The Rule requires that the relevant bandwidth be "stated." There's no question that any actual bandwidth can be used--not just 20 Hz to 20 kHz--but is 1 kHz a "bandwidth." Technically it is (one Hz), so we were never able to enforce this part of the Rule. It looks like the propose revision would require 20 to 20 kHz, but we'll see.

We were never able to enforce this actual bandwidth of 20-20 kHz? I thought the FTC did enforce that for years, but for some reason which I think was of an economical nature, they stopped at some point enforcing minimum standards for high fidelity reproduction.

 

[TLS Guy]

Your "pile of junk" may be an affordable entry level receiver for a college student.

There is still no point in a useless spec. There is no point at all in quoting distortion at a single frequency. I agree if distortion rises a little below 80 Hz or so, then no harm done, but above that distortion needs to be low. However low distortion over the whole audio bandwidth is something that should be achieved, and probably is. The real issue is that the current rating allows manufacturers getting away with posting unrealistically high power specs.

The other issue is that manufacturers of receivers need to be forced to quote an all channels driven spec. This is especially important now that more and more 9 and 11 channel mixes are becoming available. Even now the latest up mixers do an incredible job of recreating the ambience of venues. If you are playing back music recorded in ambient spaces, like RAH for instance, there will be significant power on all channels. The BPO have stated AV streaming is Dolby Atmos now. I bet if you drive all the channels on these Atmos receivers, the results would be dismal in most cases if not all.

 

[D Murphy]

There is still no point in a useless spec. There is no point at all in quoting distortion at a single frequency. I agree if distortion rises a little below 80 Hz or so, then no harm done, but above that distortion needs to be low. However low distortion over the whole audio bandwidth is something that should be achieved, and probably is. The real issue is that the current rating allows manufacturers getting away with posting unrealistically high power specs.

The other issue is that manufacturers of receivers need to be forced to quote an all channels driven spec. This is especially important now that more and more 9 and 11 channel mixes are becoming available. Even now the latest up mixers do an incredible job of recreating the ambience of venues. If you are playing back music recorded in ambient spaces, like RAH for instance, there will be significant power on all channels. The BPO have stated AV streaming is Dolby Atmos now. I bet if you drive all the channels on these Atmos receivers, the results would be dismal in most cases if not all.

You're welcome to comment. But you have to realize that the FTC has no in-house expertise in audio. Technical regulations like this just aren't within the agency's comfort zone. They're probably going to follow the course of least resistance, and that won't include an all-channels driven requirement. To do that, they would need a very rich set of public comments that showed a compelling justification and a broad consensus supporting it.

 

[D Murphy]

We were never able to enforce this actual bandwidth of 20-20 kHz? I thought the FTC did enforce that for years, but for some reason which I think was of an economical nature, they stopped at some point enforcing minimum standards for high fidelity reproduction.

I couldn't enforce 20 - 20 kHz because it's not required by the rule. It had nothing to do with economics.
As I explained above, the Rule only requires sellers to state what frequency bandwidth pertains to the claimed power output. A range of 73 Hz to 12,749 Hz would meet that standard.

 

[gene]

I'm fine with sticking with 1% THD+N. If you can't see amp clipping on an OScope, than it's legit real power IMO. I think we need some enforcement of # of channels driven though or a way to test max capability of the power supply.

 

[PENG]

The Federal Trade Commission will be publishing a Notice of Proposed Rulemaking in the Federal Register in a day or two. The Notice will seek comment on proposed amendments to the Rule that may affect how power ratings for multichannel receivers must be measured. Currently, such AVR's need only publish power and distortion specs for 2-channel operation. The new Rulemaking will revisit this issue. The press release concerning the upcoming Federal Register Notice is pretty foggy except for the recommendation that THD must be lower than .1% at the rated power. That will prove controversial to say the least. Currently there is no cap on distortion--you just have to disclose what it is. Here's the press release, which asks for comments on:

• "whether the Commission should amend the Rule to simplify power output measures by standardizing the test parameters used by amplifier sellers as follows: a load impedance of 8 ohms, a power band of 20 Hz to 20 kHz, and a THD limit of less than 0.1%; and
• the parameters of consumers’ normal use of multichannel home theater amplifiers."

I have no idea what they mean by "the parameters of ...normal use..." But we'll know shortly. I'll post a link to the Federal Register Notice when it's published.

Would it be okay if they make it 1%, but also require manufacturers to specific the output at 0.1%?

 

[PENG]

I'm fine with sticking with 1% THD+N. If you can't see amp clipping on an OScope, than it's legit real power IMO. I think we need some enforcement of # of channels driven though or a way to test max capability of the power supply.

They should also specify the test duration, such as for 30 seconds minimum. We both know the current popular way of specifying 100 W, 8 ohms, both channel driven "continuous".., the "continuous" is a misnomer, often means just using a continuous sine wave, but could be for only seconds, or minutes.

 

[D Murphy]

I'm fine with sticking with 1% THD+N. If you can't see amp clipping on an OScope, than it's legit real power IMO. I think we need some enforcement of # of channels driven though or a way to test max capability of the power supply.

I'm sorry I wasn't faster on the uptake concerning the .1% figure. I didn't know where that came from, but now I understand the concern about amplifier clipping above .1%, assuming the amplifier is capable of sub-.1% distortion before clipping. The problem is that not all amplifiers can provide such low distortion, and they wouldn't be able to make power claims. For the record, the 1% figure originally was just a suggestion by CEA. There is no 1% requirement in the current Rule. You just have to disclose distortion, whatever it is at the rated power.