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FTC Power Amplifier Rule

Dennis Murphy

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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.
 

mhardy6647

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I'm guessing that "the parameters of consumers' normal use" means that there's no expectation for all 11 or 13 or whatever channels to be capable of delivering their full continuous rated power all at the same time(?).

And I am darned glad to see that the FTC know how to use an apostrophe correctly for plural possessive. :)

As to the 0.1% I mean, it's OK (hifi reproduction was long considered to be better than 1% THD) -- although I personally am fine with 'publish the specs one's product can reliably meet', such as this vintage Lafayette 4-channel receiver. Not great, but it seems honest, which ought to count for something.

1657289953175.png

source:
 

DVDdoug

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The manufacturers don't seem to be following the current rules so I still won't trust the published specs. :( They follow the specified format but when independently tested, it seems like they rarely make the rated power.

And, I'm assuming that's just an example for the format. It probably doesn't have to be 0.1%, 20-20kHz, and 8 Ohms as long as those details are included.
 
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Dennis Murphy

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The manufacturers don't seem to be following the current rules so I still won't trust the published specs. :( They follow the specified format but when independently tested, it seems like they rarely make the rated power.

And, I'm assuming that's just an example for the format. It probably doesn't have to be 0.1%, 20-20kHz, and 8 Ohms as long as those details are included.
Actually, it's worse than that. It's often difficult to find a power spec with the required format even for 2-channel operation.
 

Katji

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They're is always hope? ;)
:) I noticed only one in about 100 of them had one of those mistakes, Quite unusual with memes.
I spent about 10 times longer than I thought I would. From "the Arch" to Stephen Hawking, Anne Frank, Kierkegard...
One referred to faith as well, that gave pause for thought.
 

MakeMineVinyl

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This thread already exists HERE.
 
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Dennis Murphy

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The Federal Register Notice concerning the proposed amendments to the FTC Rule has finally been published:
Federal Register :: Request Access

The main issue with the stereo testing requirements will be the .01 limit on THD. As excepted, the FTC is still punting on specific proposals for testing multichannel amps. The Notice reports some of the suggestions made in the last comment period, and then states that the authors presented no evidence that the proposed testing requirements represent common consumer usage (e.g., specifying that the surround channels should be run simultaneously at some reduced percentage of rated power for the mains, or that all channels should be run at full rated power simultaneously. So the ball hasn't been advanced on the most critical issue. Public comments are due by September 26.
 

DonH56

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How are we supposed to define and prove "common consumer usage"? AFAIK, Dolby makes no exceptions for surrounds and rears with respect to frequency and SPL limitations... And are they completely punting on any multichannel ratings (can't access from work, sorry)?
 
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