Could something like the automotive emission fraud happen in a similar way with audio measurements?

[anphex]

Amir is in the process of setting a a industry wide benchmark. The amount of high quality reviews, users and visitors on this board is probably too high to be ignored by manufacturers. That made me think. Since almost everyone knows the usual steps and measurements Amir is making it's like a checklist you could tick. Could manufacturers implement a kind of circuitry that, for example, makes an amp go into special mode @ 5 Watt so noise and distortion are as low as possible at 1khz? I can't name another example right now but you get my point.

 

[AnalogSteph]

Not a good analogy IMHO. Amir isn't any kind of regulating body, and the more varied tests you run the more likely any irregularities will be found (e.g. you could stuff a device's signal path full of crappy ceramic capacitors and low-power opamps and still get decent distortion at 1 kHz, but in SMPTE or CCIF IMD testings things would fall apart quickly).

The electronic equivalent would be something like cheating on RF emissions testing to get into a market. Which at least in the EU isn't much of a thing as the importer can slap a compliance (CE) sign on anything, they should just be prepared for a costly legal battle if a device is actually found not to be. Or sending something into UL / TÜV etc. electrical safety certification that doesn't actually correspond to the finished product (again, not something I imagine to be particularly funny if found out).

 

[escksu]

Distortion is never an issue today for solid state amps. Even low cost amps have very low distortion at low power. Distortion becomes audible only when the amp is hitting its limits.

 

[anmpr1]

The issue with VW diesels, if that is what you are referring to, was an attempt to run around the EPA (and CARB) schedule, which dictates whether automobiles can legally be sold in the US (and California, which has its own view of things). [FWIW, the reason VW got in trouble wasn't because VW couldn't produce a 'clean diesel' engine. They just couldn't do it at their price point. The main issue was that the company didn't want the end user to use as much DEF additive, which gets expensive. DEF is required for diesel engines to have any chance at meeting EPA/CARB regs. So it was really a cost cutting measure that caught up with the company, costing them more than they ever could have guessed at the time.]

There are no comparable regulations covering hi-fi gear. The FTC ruling is limited to advertising, and does not establish a measurement threshold for the sale of amplifiers. The ruling can be ignored by manufactures if they choose not to advertise power ratings. [FWIW I have read that California wants to set a rule limiting energy consumption of high-end PCs (actually, video cards), but I haven't heard if they are also thinking of banning Class A hi-fi amps. ]

Finally, as @escksu states, distortion in amplifiers is pretty meaningless. Distortion measurements you read at ASR may give you an indication of who is doing good engineering at a price point, but other than that the values won't tell you much else. There are other more important factors to consider than a distortion measurement (build quality, warranty, ease of service, dealer support, manufacturer reputation, aesthetics, form factor, overall power, possibly current ability, and so forth).

From a marketing standpoint, a lot of hi-fi manufacturers don't even care about measuring this stuff. It goes against their business model, so there is no incentive for them to provide specs, much less cheat or otherwise lie about them. Many manufacturers sell 'magic', and many if not most 'reviewers' exist in symbiosis with these manufacturers. The few that are interested in decent engineering will publish measurements for all to see, and those that don't care about it will talk about something else. Each group of customers have their own priorities, and the two usually don't mix.

As far as amps 'going into a special mode' at low power level?. That is actually an old trick. Back in the day Japanese manufacturers were famous for 'sliding' Class A amps (maybe they still make them). Then next year's models would feature something else, new and different, to market. After being in the hobby for so many years it's easy to laugh at it all.

 

[drfous]

I've asked a similar question.

I wonder more about speakers. Can you make a speaker that's great at frequency sweeps, but sucks at the complexities of music?

 

[escksu]

I've asked a similar question.

I wonder more about speakers. Can you make a speaker that's great at frequency sweeps, but sucks at the complexities of music?

I would say, yes! However, most of the people who buy speakers don't even look at frequency sweeps. so, there isn't much of a point to design a speaker just to excel in frequency sweeps. I would say it more of one of the design goals. Some speakers are also purposely designed to give a certain character to the sound.

 

[MakeMineVinyl]

I don't believe there's any motivation to create a 'special mode' per se. The rating of amplifiers has always been subject to marketing spin, and to some extent that is still the case today; but I think its more in the AV receiver power ratings area. Since these products are so price competitive, there is always pressure to serve up power ratings which involve a good deal of fine print which is difficult to impossible for the average consumer to make sense of.

But as far as some hardware 'trick circuit', it would probably cost more to implement something like that than its worth! Since today's gear is so software intensive, sure, there's unlimited mischief some programmer could get into, but that's true of any software driven device. From all the things I hear about Smart TVs and the supposed data gathering (and other snooping) for advertising purposes, I'd be more worried about that.

 

[escksu]

I don't believe there's any motivation to create a 'special mode' per se. The rating of amplifiers has always been subject to marketing spin, and to some extent that is still the case today; but I think its more in the AV receiver power ratings area. Since these products are so price competitive, there is always pressure to serve up power ratings which involve a good deal of fine print which is difficult to impossible for the average consumer to make sense of.

But as far as some hardware 'trick circuit', it would probably cost more to implement something like that than its worth! Since today's gear is so software intensive, sure, there's unlimited mischief some programmer could get into, but that's true of any software driven device. From all the things I hear about Smart TVs and the supposed data gathering (and other snooping) for advertising purposes, I'd be more worried about that.

Regarding AV, I would say its the things they don't mention, esp. budget ones. Eg. when they mention 100W per channel into 8ohms. No doubt each channel is totally capable of 100W, but when all channels are drive simultaneously, the transformer cannot supply that much power. This is something they don't mention. Then, they have their reasons. There is no need for a transformer to supply 100W to all channels at the same time when most of the sound comes from the front (sides and rears are mostly for effects). If they include a massive transformer, the cost will go up.

 

[Inner Space]

Regarding AV, I would say its the things they don't mention, esp. budget ones. Eg. when they mention 100W per channel into 8ohms. No doubt each channel is totally capable of 100W, but when all channels are drive simultaneously, the transformer cannot supply that much power. This is something they don't mention.

Yes. No one really questions the power issue. It never became a thing. And it should have, because it's easily quantifiable and easy to understand in print. To answer the OP's question, it shows how the manufacturers absolutely don't need to scam a test, because somehow they stopped the test from being conceived in the first place.

 

[jhaider]

https://www.audiosciencereview.com/...r-devices-for-measurements.22063/#post-732650

 

[MakeMineVinyl]

Regarding AV, I would say its the things they don't mention, esp. budget ones. Eg. when they mention 100W per channel into 8ohms. No doubt each channel is totally capable of 100W, but when all channels are drive simultaneously, the transformer cannot supply that much power. This is something they don't mention. Then, they have their reasons. There is no need for a transformer to supply 100W to all channels at the same time when most of the sound comes from the front (sides and rears are mostly for effects). If they include a massive transformer, the cost will go up.

The transformer capacity is important, but just as important is the problem of adequate cooling for all those channels - at least in the case of a non-class D amplifier, heat management is a huge issue. Large and heavy heatsinks cost a lot - in material, in space and in added shipping costs. Looking inside an average AV receiver at the relatively meager heatsinks and comparing them to those in a high quality dedicated multi-channel power amplifier can be eye opening. Fans help, but can't perform miracles.

 

[JJB70]

As anmpr1 points out, the VW cheating and use of defeat devices broke statutory requirements, further, those requirements were in place to mitigate pollution and negative impacts on public health.
In the case of audio testing there is already a significant element of checking manufacturer claims but in most cases finding differences is an embarrassment for the manufacturer and a warning for consumers and not a legal issue and in many cases is unlikely to be noticed by users anyway.
That said, measurement standards and protocols are important in any application.

 

[chelgrian]

[FWIW, the reason VW got in trouble wasn't because VW couldn't produce a 'clean diesel' engine. They just couldn't do it at their price point. The main issue was that the company didn't want the end user to use as much DEF additive, which gets expensive. DEF is required for diesel engines to have any chance at meeting EPA/CARB regs. So it was really a cost cutting measure that caught up with the company, costing them more than they ever could have guessed at the time.]

It actually is possible to meet the limits using alternative technology such as exhaust gas recirculation but that is even more expensive than DEF and to my knowledge the only manufacturer which does it is BNW on a few models.

 

[solderdude]

Amir is in the process of setting a a industry wide benchmark. The amount of high quality reviews, users and visitors on this board is probably too high to be ignored by manufacturers. That made me think. Since almost everyone knows the usual steps and measurements Amir is making it's like a checklist you could tick. Could manufacturers implement a kind of circuitry that, for example, makes an amp go into special mode @ 5 Watt so noise and distortion are as low as possible at 1khz? I can't name another example right now but you get my point.

They can even do it without realizing it. Below SINAD at 1kHz.

Perfect isn't it.

Same amp but measured using multitone.

I don't think this is on purpose to trick Amir into a positive review though.
It did come to light much later though.

One needs to realize though that 0dB for 1kHz in a SINAD test is not the same level as the 1kHz '0dB' in the multitone test is about 24dB lower.