The FTC Proposes Eliminating Its "Amplifier Rule"

When I joined Hi-Fi News in the mid-1970s, one of that magazine's stable mates reviewed cars. An automotive writer appeared in the pub one lunchtime—"I rolled another one," he said, as he joined us at the bar. It turned out that one of his tasks was to take a car he was testing to the skid pad to see how many lateral G's the car could handle. Of course, the chances of a consumer turning that car over were minimal, but the reviewer was investigating the edges of the performance envelope.

As I became familiar with audio measurements, it struck me that the equivalent of the skid pan test was the thermal preconditioning we perform when we get an amplifier on the test bench. Even if an end-user doesn't drive his amplifier into thermal meltdown, the edges of the envelope need to be explored.

This preconditioning is based on the FTC's original recommendation in what came to be called the "Amplifier Rule (Title 16 Part 432)," which, at the end of 2020, the FTC proposed eliminating. The FTC regularly examines and revises its rules, and according to FTC commissioner Christine S. Wilson: "Freeing businesses from unnecessarily prescriptive requirements benefits consumers." (Wilson's comment can be downloaded here.)

"Unnecessarily prescriptive requirements?" Some history is in order. (My thanks to Jim Austin for the on-line research.)

In the hi-fi boom that began in the 1960s, the Institute of High Fidelity became alarmed by amplifier manufacturers exaggerating their products' output power. Such mystical numbers as "Peak Power" and "Music Power" were used willy-nilly to produce sales-oriented ratings that had nothing to do with reality. The IHF's proposed standard was examined in a paper presented at a 1967 Audio Engineering Society convention by Daniel von Recklinghausen, then with manufacturer H.H .Scott, and reprinted in the Journal of the Audio Engineering Society in July 1968.

The IHF proposal resulted in much discussion in audio engineering circles and in 1974, following open hearings, the FTC published its first Amplifier Rule. The purpose was to impose uniform, conservative standards on how domestic amplifier powers were rated and advertised.

The Amplifier Rule was revised in 2000. It imposed the following conditions on manufacturers:

• Power output is to be expressed as "average continuous power in watts."
• Load impedance shall be 8 ohms or cited if otherwise.
• All associated channels must be driven at rated power. (This was later dropped for multichannel home-theater amplifiers, where only two channels needed to be driven.)
• Power bandwidth or power frequency response must be cited.
• Maximum THD from 0.25W to rated power must be cited.
• The amplifier must be preconditioned at 1/8 rated power for 60 minutes.

The latter is a modification of the original IHF requirement, which involved operating both channels of the amplifier at 1/3 power into 8 ohms for 60 minutes. With an amplifier that biases its output devices into class-AB, this results in the maximum dissipation in those devices, hence imposing the maximum thermal stress on the amplifier. The Consumer Electronics Association (CEA) was concerned about the impact of the original rule on multichannel home-theater amplifiers and in its own standard (CEA-490-A), changed the preconditioning operating time from one hour to 30 minutes.

Why was the CEA concerned? For an amplifier to pass the original 1/3 power preconditioning, its heatsinks need adequate thermal capacity. After an amplifier's chassis and power transformer, the heatsink is the most expensive part, so underspecifying the heatsink is a way of reducing both the manufacturer's bill of materials and the retail price. It is also fair to argue that in actual use, with music recordings that have a normal crest factor (the ratio between the peak and average levels) and loudspeakers with a sensitivity around 88dB/2.83V/m (the average of all the loudspeakers reviewed in Stereophile) an amplifier will never get close to being operated at 1/3 power for an hour. The consumer will therefore be paying for a capability that he will never need.

Even so, I have always felt the preconditioning information will be useful to the magazine's readers, which is why we have been doing it since we started accompanying Stereophile's reviews with measurements in 1989 (footnote 1). For example, though there aren't many true high-end class-AB amplifiers that fail this test, our publishing the temperature of the heatsinks and chassis does reveal amplifiers that should not be enclosed in a cabinet or stacked.

And in his recent book on amplifier design, Bob Cordell recommends that heatsinks should be designed so that their temperature shall not exceed 60°C when operated at 1/3 power into 8 ohms. "The FTC metric may seem conservative," he writes on p.186, "but things get worse rapidly when the amplifier is called on to deliver its power into the many loudspeakers that exhibit much lower impedances than 8 ohms."

I asked Cordell for his thoughts on the proposed ending of the FTC Amplifier Rule:

"My first reaction is that it is silly for them to be revisiting this much-needed rule. I think it is important to recognize that there are numerous facets to this rule, so repealing the whole rule because of one facet is not necessary. For example, the preconditioning rule is probably the one that bothers all the manufacturers the most, and yet has the least to do with sound quality, and has only modest relevance to quoting power honestly in average ('RMS' [footnote 2]) watts.

"That part of the rule could probably be loosened up without too much angst. But continuous average power over a short interval remains important. For example, there is little real-world reason to spec it in such a way that the heatsinks have that huge amount of time to reach nearly final temperature. I would be happy with 1/8 continuous average power over as little as 5 minutes.

"The gross abuses that took place before this rule (like 'music power') actually had little to do with heatsink capacity."—Bob Cordell

Comments (footnote 3)? Has the Amplifier Rule outlived its relevance, particularly when so many amplifiers now use class-D output stages?

Footnote 1: We have recently been performing both the original preconditioning and the CEA's 2008 revision. If the amplifier being tested passes the 30 minutes at 1/8 power into 8 ohms test without the heatsinks becoming very hot, I then operate it at 1/3 power into 8 ohms for 60 minutes. I monitor both heatsink temperature and the THD+noise percentage during this time to make sure that the amplifier is still operating correctly.—John Atkinson

Footnote 2: "RMS" is in quotes because there is no such thing as "RMS power." This was the subject of discussion in the early 1970s—see, for example, "RMS Power: Fact or Fancy" by John Eargle and Bart Locanthi, J. Audio Eng. Soc., Vol.20, p.45 (Jan/Feb 1972). While the RMS (Root Mean Square) values of voltage and current waveforms can be calculated, when these are used to calculate power, the result is an average value.—John Atkinson

Footnote 3: The deadline for sending comments to the FTC on the proposed ending the Amplifier Rule is February 16, 2021. Guidelines for sending comments can be found here.—John Atkinson

CG's picture

Aside from a segment of the population that is anti-government on general principle and that there's all sorts of political considerations associated with this kind of rule changing, you have to ask why companies would want relaxation of this one. Companies, or at least one company, are behind this, after all.

Obviously, the initial testing may be somewhat of a nuisance, but in general that's done once or twice and that's the end of the time and cost associated with it. So, it must be something else.

I'm going to presume that it's the cost of the metal used for heat sinking and the follow up additional cost for shipping a finished product with more mass found in the heat sinks.

But, here's the thing.

An awful lot of consumer electronics products have marginal thermal designs. I'm specifically not speaking of audio amplifiers. All the products that use processors and SOCs generally dissipate a fair amount of heat in a small area, or at least try to. This leads to poor performance and often melted plastic. Or worse. (I won't tell you how I know this from a professional standpoint...)

So, it could be a safety issue in the end.

I'll also note that although they tend to generate less heat, all the switching type amplifiers and switching power supplies I've looked at have specific requirements for heat sinking. Go look at

Jim Austin's picture

>>Companies, or at least one company, are behind this, after all.

And yet, it's worth noting that when, in the past, this rule has come up for review--and it comes up periodically--*some* audio companies have been among the commenters on the rule change advocating against dropping the rule.

Jim Austin, Editor

CG's picture

That isn't surprising at all. Most of the companies making products reviewed in Stereophile make a great effort to build solid products.

Aside from affirming their own integrity, it's in their own best business interests to do so. When JA Classique finds that an amplifier melts down during pre-test, that can't be a good thing for whoever is selling that product.

Jim Austin's picture
Love that. I also agree with your point. Also, for those who truly self-police, rules like this pose no extra burden. Jim Austin, Editor Stereophile
CG's picture

One of the uber VPs of engineering I worked for along the way had a 10 point list of engineering maxims. Kind of like the character Mark Harmon plays on the TV show NCIS, in fact.

But, there really was a Rule 0 that came before anything and everything else. "Cause no fires!"

A local (to me) audio amplifier company had a reputation for burning amplifiers. It may not have hurt their audiophile cred, but I think it ultimately hurt their reputation amongst people who don't change amplifiers as often as they change their socks.

Glotz's picture

LOL. I love JA Classique... err, his measurements!

Jim Austin's picture

... JA Moderne?

Jim Austin, Editor

Glotz's picture

I love it!

jimtavegia's picture

Misguided and unnecessary is all I can say. Waiting for the anti-skating police to show up any day now. If they knew how much jitter was going on in my house there would be a congressional summit I would think.

smargo's picture

totally agree

tonye's picture

OK, I'm not a Ludditte.. I do have an assortment of various Class D amps from several manufacturers... even an NCore. Plus some monster AB solid state receivers from the 70s!

But, honestly, those of us with tubes and Class A stuff in the main room just won't care much. Come to think about it, I don't recall seeing any heat sinks in my Audio Research amp... and my FET Class A amps, well, let's say they dissipate 300 watts each at idle. I think they always heat the room that way! Talk about heat sinks on those babys!

Will this actually affect the High End world anyhow? High End speakers tend to be beasts in terms of impedance and power demands. Put 100 watts into a Maggie.. Pfft... just warming up the sound! And no High End aficionado will put a 200 watt beast on a LS3/5. We tend to be a bit, ahem! more careful about system matching.

IMHO, no High End consumer will buy a "300 watt" SS Class AB amplifier that weights 15 lbs and costs 200 bucks. Part of being in the High End is to understand these things, so I don't think it will affect our little World of Audio. I expect the manufacturers and designers will be honest about things -as they tend to be most of the time...

I figure it will likely result in Exploding Watts Numbers in the low end consumer world with concomitant Flaming Results in the dens of America!

And yeah, those Home Theater ratings have been a joke for a long time. Specially in those mass consumer receivers that are rated for a Kilowatt yet have heat sinks smaller than my old Sansui G7500 or the Marantz 2125 in the closet shelf.

a.wayne's picture

@JA ,

Many in the business at the time felt the original 1hr @1/3 power output was an attack against phase linear which was the hot amp at the time and was way under built by Carver .. I do suspect Mcintosh will love the new rule, god only know why they hate to size heatsinks correctly for good SOA ..


John Atkinson's picture
a.wayne wrote:
Many in the business at the time felt the original 1hr @1/3 power output was an attack against phase linear which was the hot amp at the time and was way under built by Carver...

I hadn't heard that. But my opinion of Phase Linear amplifiers was colored by a repeated experience with a band I toured the UK with in the 1970s. We had 3 Phase Linear amplifiers: one for the left PA stack; one for the right PA stack; and a third that was being repaired after the previous gig.

John Atkinson
Technical Editor, Stereophile

Jack L's picture


Agreed. I was involved in sales & service of Phase Linear 400 & 700 for some years when I was young young, since day one when they took audio world by storm with their class B mega-watt O/P operation using HV tv power transistors.

Very encouraging response from many my consumer customers who dumped their old mickey-mouse like power amps no regrets. Repair was minimum when compared to Quad II power amps which loaded up frequently our service benches.

Jack L

tonykaz's picture

Perhaps we do or should/could we describe it as a Loudspeaker Rated Impedance mystery .

Tube amps struggle with nominal 8 ohm loudspeakers that might perform nicely with SS Amps.

It's probably just an Audiophile issue that our Professor J.Atkinson willingly & judicially solves for us Stereophile Readership ( which constitutes close to 100% of the astute & literate Audiophile Caste )

The rest of the larger world will have Class D devices making their noises ( like most of the sounds we had to endure watching this latest Super Bowl ).

Perhaps we, as a citizen population, should require the FTC to contract the services of Stereophile's world famous testing lab. conveniently located in NY,NY! and pay enough to supply him with a Bently Drop Head Electric Car & a Yachtmaster Rolex in Ocean Blue & Gold!

Amplifier ratings seem like marketing sizzle if Nelson Pass's "first watt" concept is as important as it seems to be with the majority of the DIY group.

I was required to wear the JVC lapel pin for the two years in the 1980s that I represented the Japanese Victor Corporation, Amplifier Watt Rating was a big thing to those people, but it was a sort of "fake" rating system that NO-body embraced.

If we lose John Atkinson, we might need FTC standards but I still doubt it. ( we'd still have Mike Moffat, J.Stoddard & Paul McGowan for gods sake )

Tony in Venice Florida with 82F Air and 84F pool temps.

Jack L's picture


I must envy you living in such warm spring weathers.

Surely you don't want to come up over the North Boundary of New York state, where we are still shivering under the Extreme Cold Alert of -14 C this morning. My car was -10C inside while driving to my work earlier before noon. No kidding !

Jack L

tonykaz's picture

Dear Sir,

I know fully well what everyday life is like in the Frozen North. I lived and worked there for 7 Decades. I would encourage you to abandon the 4 Seasons of Clothes and migrate to Florida.

That is, providing you could cope in a Capitalistic World ruled by those with the most $$$,$$$,$$$.

I am working to establish the USA as a Social Democracy ( which I'm failing/failed at ).

Migrating to Central America is a common solution to Climatic Issues as is Camper living in. our South West ( like Stereophile's Tyll is doing )

"MY" Venice Florida features the finest weather I've ever experienced as it only wanders from 60F to 90F , my HVAC costs amount to approx. $1,000 per year total. ( which includes all of our Electrical Usage at a billing rate of .12cents per Kwh ) Water is essentially free and taxes are remarkably Low. Our home is Hurricane proof to Level 3 ( 130 Mph winds ). Pool water temp is 88F which amounts to a weightless Nirvana. Sunsets over the Gulf every night, drum circles twice per week, Seafood everywhere, fresh Fish available to anyone with a Rod & bait. All of the local Bird population seem to be nesting for their first hatchlings and a bicycle will take a person anywhere they need to go. Florida is said to be "God's waiting room", I think our Venice is an "Incubator for Old people". It's Paradise for an old industry geezer like me!

Tony in Venice Florida

Jack L's picture


Wow! So I guess you should be born up here in the Great White North.
I moved up here for over 3 decades now with my family for hopefully better education & future for my 2 sons.

Today I believe my expectation for moving up here in this cold country (still bitter cold last nite down to -16C with heavy snow blowing)!!) is fulfilled.

My younger son, his wife & 2 kiddie boys are doing pretty well in the Silicon Valley, making good money enoough to own 2 houses after only some 13 years moving down there. I can't complain about this "capitalistic World" at all !

I love the weather down there in the Bay Area : year-long mild weathers & gorgeous clear blue skies which I miss big-time up here. I go down there every year to visit them. Except for last year up to now due to the pandemic. So we virtually see each other via free WhatsApp every Sunday note.

Jack L

tonykaz's picture

I owned an Injection Moulding Company in the Bay Area and worked at Product Development in the Bicycle Industry based in the Bay Area. I love BART ( Bay Area Transit Authority ) and all things California. I was about to retire around Monterey Bay until I discovered the phenomenal Quality of Life on easy offer here in Venice Florida.

California is the Global Center of technical Civilisation and the most exciting place for any career, it is the most fertile intellectual environment that I'm aware of. Although it has 42,000,000 people and seems impossibly crowded, England is the same size and has far more population ( with two lane roads ). California is probably Civilization's greatest social achievement, to date ! Florida is "out to pasture", albeit a beautifully tropical pasture !

The Frozen North is shovelling snow today while I'm swimming, I wish I could fly up there to help but for Covid, hmm, maybe next year.

Tony in Venice Florida struggling with fierce head winds while bicycling

Jack L's picture


HOW "tube amps struggle" ??

Jack L

tonykaz's picture

Hello Mr.Jack L,

I was referring to Loudspeaker transducers rated Impedence of 8 ohms but having dips to down below 4 ohms as referred to by the DeVore Loudspeaker designer in one of his YouTube reveals.

I was a Conrad-Johnson Premier & Full Line Dealer and I imported the Esoteric Audio Research tube electronics out of England. My experience from working with these products was discouraging, success eluded me.

Conrad-Johnson made a wonderful little MV-45a that was magical driving Magnapans thru MH750 Brissom Cables, that amp was only useful for me when selling trade-in MGs ( I was Never a Maggi dealer ).

I also owned a vintage Stereo 35 (ST35 Dynakit ) amp that was a beautiful performer in driving most of the little loudspeakers we kept on hand.

These two tube amps, alone, are amps that I wish I'd kept and am keeping an eye out for now-a-days ( for my own use ) .

I'm told that Large Loudspeakers, like Klipsch, can be properly driven by small Tube Amps, DeVore Loudspeakers can also be driven by Tube gear but, for the most part, Loudspeakers with smallish size but full range aspirations demand high current Amplifier Designs typical of SS Amps able to double output as ohms diminish. This is also my Retail Experience from owning & operating my Esoteric Audio Salon of Farmington Hills, Mi. Digital's facility in ultra low frequency content ( as is common with Masterings from guys like Bob Katz ) will create havoc in the form of tube amplifier's low frequency weakness capabilities. ( I suspect that tube amps are intended for vinyl rigs that don't hope for lower that 60hz or so. )

Tony in Venice Florida

ps. Somehow, I'm getting the feeling that new gear today is not performing better ( or delivering more satisfying performance ) than gear from the mid-1980s. But... I'm thankful for Schiit & PS Audio's useful gear at affordable prices.

Jack L's picture


I agree to your comment above with exception of some tube amps with are made better than the old timers.

Also addressing yr comment on tube amps not producing deep enough bass below 60Hz, I tend to disagree to it as I auditioned in depth, some 8 years back, the bass powerful Canadian made Tenor OTL 76W all tube monoblocks driving the gigantic Hyperlion flagship bi-wired loudspeakers !!! Frankly, I am still so impressed by the powerful performance of the Little David Tenor tube power amps driving the Goliath type Hyperion loudspeakers. Deep deep & wide soundstage & deep deep clean bass !!!

I knew too well HiFi business would not be an easy business to be really successful as I was handling hi-end audios when I was young young many decades back. So after a few years working in a top top audio boutique, I decided to further my study in electrical engineering. I think I made the right choice in taking audio as my leisure hobby instead of my business though I love classical music like an addiction !

Surely there are ways of making easier monies than audios: funds & stock markets which I invested some good money there, managed daily by my better half. Thanks her for acting like my right hand in this money business.

Listening is believing

Jack L

tonykaz's picture

Of course, you are correct! Arnie Nudel had some treasured Tube Amps .

I spent considerable funds buying and auditioning tube amps for my retail business. I could never discover any tube amp that would pass jury scrutiny against our Electrocompaniet Mono Ampliwires.

I wasn't in the Audio business long enough to come to any useful Tube understandings other than Art Ferris's Audible Illusion's astonishing Pre-amp performance. Now, I feel that a Pre-amp tube from Russia will give music systems a Virtuoso singing Voice and hence become one of the three hearts of a wonderful Musical performing home system. i.e. 1). Source : a Koetsu , 2). a beautifully Tubed pre-amp, 3). any nice loudspeaker/headphone.

I attended a Linn Store Audio Show in Ann Arbor Michigan where a Customer brought in a Schiit Valhalla Headphone amp to demo one of the Store's headphones. The little Headphone Amp delivered outstanding performance ( to my ears ). I asked for the little Shiit to be auditioned as a Pre-amp ( which it is ) and again it delivered an amazing floor Showing performance. It had well rolled Russian Glass. I was at that Show to audition pricy DACs only to discover the little tube to be the important thing. hmm.

Music is a Mood-Altering-Drug where today a person can achieve an amazing high for not much $,$$$ !!!

Tony in Venice Florida

Jack L's picture

Hi Tony.

While you mentioned in yr post below about Tenor 75W tube monoblocks, 4 tubes in the driver stage & 4 power tubes in the OTL output power stage were "Russian Glass".

Is was the then famous Russian 6C33C-B twin-triode power tubes, once used in certain Russian military fighter planes, that made the Tenor monoblocks so fondly raved in most audio journal reviews.

All tubes used in the Canadian made Tenor power amps bore 3-year or 10,000-hour lifespan warranty !!! Tell me which other brandname tube amps makers ever offer such long warranty on tubes used in their products ??

Jack L

tonykaz's picture

Your Tenor people might be the only ones making 3 year promises or they might not. ( I've heard of tubes lasting extensively but I've owned Mac Tube Gear with very short half-lives & and other vintage Consumer Tube Gear )

I admire what I've learned from you about Tenor.

The ability to have a good relationship with the folks making one's Amplification is priceless, especially if that gear features outstanding performance.

Stereophile's Mr.HR just released a published review of two Decware low-power Amps made in Illinois USA. This is another Small Manufacture building Sound Quality and customer relationships.

Tenor & Decware is what my Audiophile Hobby is all about : Loyal Employees making Quality Products at a Fair Price.

Bottlehead & Schiit might be two other outfits with looooonnnnggg supporting promises.

I haven't called Tenor and I'm a bit timid about Beautiful Gear Pricing. ( I'll hunt for a used piece )

Tony in Venice Florida

Jack L's picture

...... Decware low-power Amps " quoted Tonykaz

Where in Stereophile can I read HR's review ???


tonykaz's picture

It's in this months Print Issue that I got in the mail a week ago.

On the Internet Site:

I think that it's a KeyNote Review that will probably follow As We See It, the Wilson Loudspeaker Introduction/Promotional pseudo Review and what ever the Planet guy has to say now that his electricity went dirty. I'd suggest a PS Audio Powerplant for anyone with dirty voltages & to convert to 240 VAC like the rest of the modern world. ( is the analog planet a 110 volt place ? )

Anyway, the Decware Reviews might be the best writing for this month's Issue.

Tony in Venice Florida

John Atkinson's picture
Jack L wrote:
Where in Stereophile can I read HR's review ???

It's in the March 2021 issue's Gramophone Dreams column. This will be posted to the website next week.

John Atkinson
Technical Editor, Stereophile

Jack L's picture

Hi John.


Jack L's picture

...........other vintage Consumer Tube Gear )" quoted Tongkaz

Your bad luck or the line voltages at yr local power grids SURGE too often to blow your vintage tubes ??? Please check up the AC line voltage at your place there !!!!

FYI, my design/built phonostage/linestage has been working fine since day one quite a few years back, installed with 50-year young Telefunken ECC83s. I play it pretty frequently, a few hours a day at least in the weekends & on my days-off from work. The AC line voltage up here in 125V60Hz. I got no AC line voltage stabilizer at all.

Jack L

tonykaz's picture

Back in the day, Mac mono amp, 45 watt, that was before we had Transistor Amps.

Stereoland would have a Mac Clinic every 6 months or so, my Amp would get re-tubed every time.

ARC Amps were thought to need "fresh" tubes fairly often.

I'm a bit of a tube roller and don't quite feel like I have a tube life problem, rather, I have a tube cost problem in that I can't seem to stop buying the more expensive ones.

Tony in Venice Florida

Jack L's picture

Hi Tony.

Per an audio shop owner locally, now retired, whose main business was custom building amps for audiophile customers.

He told me he only installed certain makes of tubes for lasting lifespan with minimum problems : Mullard of England.

In fact, I also installed ECC82 of Mullard UK for my design/built linestage for a few years now, good sound !! But they are not cheap at all !!

Jack L

tonykaz's picture

Tubes are a fun part of DIY.

Discovering nice tubes at Hamfests is one of the parts of this hobby.

For me, various tubes are like various virtuoso performing voices, they are like miniature musician people.

I know other Tube folks who seem to feel the same excitement about tube's singing voices.

Phono Cartridges also have unique voices so having an Arm with detachable headshell enables larger phono cartridge collections. Koetsu seem to outperform....

Tony in Venice Florida

Jack L's picture

..... miniature musician people." quoted Tonykaz

Yes, tube sound is for those music lovers who love live music performance, I being one for sure.

Tubes of different makes all sound different like voices of performing artists. Say Spanish tenor Domingo vs Italian Pavarotti !

I would vote tubes made by Western Electric sound most musical, e.g. 300B direct-heated triode. Yet vintage model asks for a lot of money assuming still available in the marketplace.

I love its sound & I would describe its musicality as:
"A Cinderella spinning ballet on her dancing shoes !" So elegant so lively !!

Listening is believing

Jack L

tonykaz's picture

Lovely Woodwork

I'd probably impulse buy if I ever encountered some of this gear.

Tony in Venice Florida

Lewis Edge's picture

Although it seems that we have no shortage of government regulations, stereo and home theater equipment is difficult enough to compare even when standardized measurements are used.

During the mid 1960's I was the Chief Engineer of Atlanta's only commercial classical music station, WGKA AM-FM, which had common ownership with a music and component stereo equipment store, Baker Audio. Both occupied the same building. Many new solid state components were being introduced to the market then along with some impressive claims for their performance. Knowing that I had high-end audio test gear and the skills to use it, the store owners asked me to put those new equipment performance claims to the test before agreeing to stock and sell it.

One of my requirements, to which the manufacturers or distributors had to agree prior to testing, was that if their claims were inflated and my tests caused equipment failure we could return the component without any liability for its damage. Not surprisingly some of the power amplifiers failed during my 10% rated power stress test or during tests for upper frequency response.

dc_bruce's picture

The issue came up before Phase Linear. I think the legit manufacturers, who rated their products honestly, were tired of cheap Japanese stuff that underpriced them significantly and also claimed oodles of power output.
In those days, 50 watts per channel was a lot, either from transistors or tubes. The problem was that the wildly popular "acoustic suspension" speakers from people like Acoustic Research ("AR") were power-hungry, and consumers were desperate for enough power to get realistic SPLs from these guys, not to mention the original Bose 901, whose equalizer put something like a 10 dB boost at 40 Hz. Oddly, AR came out with a 60 watt/channel transistor amplifier; but it had a tendency to go into thermal runaway and self-destruct.

A lot of people love to dump on "Stereo Review's" Julian Hirsch, but he did measure these amps carefully and reported the news -- good or bsd.

Charles E Flynn's picture

I remember paying a visit to the AR Music Room in Cambridge, shortly after the AR amplifier was introduced. In the middle of a demonstration of an all-AR stereo system, the amp failed. The AR rep asked if anyone in the audience was familiar with the amp, and had a screwdriver. I got to do some audience participation. Out of sight of the audience was a stack of four or five amplifers, in their boxes.

My AR receiver (model R) was still defective after three attempts to repair it. It was replaced by a special model W ("W", the joke went, stood for "works"), with military grade matched transistors, which required the signature of two AR executives on the warranty card for release to a customer. It worked flawlessly for many years, after which I sold it to a dealer, for the same $300 I had paid for it. The $300 went towards a mint used Apt Holman amp and pre-amp, at Q Audio, in Cambridge.

scottsol's picture

If the news was bad Stereo Review would usually not publish the review.

tonye's picture

Yeah, but Stereo Review did "review" Bose stuff.

As I recall, Julian Hirsch loved that stuff.

Dr.Kamiya's picture

Welcome back, my old friend PMPO! It's been a long time.

MacProCT's picture

I bought a Phase Linear amp and preamp in the 80's.... they looked awesome... but the amp malfunctioned either right out of the box or in the first 24 hours (can't remember which, but effectively it was immediately useless). I returned them for a full refund (and bought an NAD 3155 that faithfully served me for many years).

I dearly hope the FTC doesn't weaken the amplifier guidelines. It only opens the door for the potential for amps that just aren't up to the performance they claim. The change would hurt us consumers and the FTC is supposed by about protecting us.

-Chris Hart, Connecticut

David Harper's picture

No one here seems to be aware of the fact that their speakers are producing far more distortion than any amplifier. At least ten times more. Especially in the case of typical dynamic drivers in wooden boxes. And that to claim to hear amp distortion thru speakers like these is absurd given the fact that any distortion created by an amp would be eclipsed completely by the speaker distortion.

John Atkinson's picture
David Harper wrote:
No one here seems to be aware of the fact that their speakers are producing far more distortion than any amplifier. At least ten times more. . .

Except that the second- and third-harmonic distortion produced by loudspeakers doesn't mask the fifth-, seventh-, and ninth-harmonic distortion that some amplifiers offer.

John Atkinson
Technical Editor, Stereophile

BigDave823's picture

.... or at least unenforced. Some years back I worked at a chain electronics retailer whose name most of you would recognize. I remember '650 Watt' HTIB systems that listed power consumption as 275 watts. Even taking two-channels-driven into account, it still seems like there was some 'creative accounting' going on.

R Johnston's picture

Ok before everyone starts yelling hear me out.
Unless the amplifier is used in a few commercial sound applications the FTC 1/3 power soak is a far more extreme condition then high fidelity music reproduction will ever present. As safety and EMC approval testing all require operation at 1/8 power the 1/3 power test rule seems out of place.
Ok so everyone agrees a really over designed audio amplifier must always be a good thing after all who doesn't like the look and feel of a big heavy amplifier?
Myself a high end audio designer for over 40 years (think Camber acoustic, Definitive Technology, Golden Ear) I spent most of my working life on how to turn X amount of money into X++ amount of audio performance. The path to price point leading audio performance is to spend design time and money ONLY on that which results in improved sonic performance.
All other stuff is just bling and can be left behind if sonic performance is what you are really striving for.
So if I add unnecessary heat-sinking to the amplifier (one of the most expensive parts) then there is simply less money to be spent on the parts that are truly critical to sonic performance. The performance difference that re-deploying the cost saving of the over sized heats sinks into other sonic critical parts of the system is often not small and can change a chosen price point product from a so so performer into a category leading performer. I consistently chose to spent the product's budget on what had the largest sonic return and that was not over sized heat sinks. Just my perspective from the design lab.
Bob J.

deckeda's picture

and so here I am

It advertises either 60w or 40w of power, depending on whether you want output power or FTC output power. All other variables are stated as the same. Even the "ohm rating" is shown as 4-16. Can I see some hands raised for who thinks ANY amp will deliver the same power into 4 ohms as with 16 ohms? Is this new math?

We're a long way from the SA-1000 and others in the "receiver wars," but at least back then they competed on common ground.

When I got into this hobby in the '70s, RMS power was a comparable claim of strength in many ways. Later, we learned that continuous power is a good starting point but if you had something capable of meaningful short-term power, that was even better.

Ask me how many NAD 3225PE 25WPC amps we demoed against some crappy '80s 100WPC receiver. That Power Envelope did seem to mean something. The earlier 3020 was a first salvo in that fight.

40 vs 60 watts. Gosh, it's only a 1/3 difference. Imagine if cars were advertised as either 200 or 260HP, your choice. You, the consumer, gets to decide how much power it has. Enjoy!