Fake audiophile opamps: OPA627 (AD744?)

They think that the embedded chip (which they call a dielet), which responds to a crytographic challenge from a handheld device on an assembly line, can avoid testing, which is much more time consuming and complicated. To test, you need to connect the device's pins to something and power it on. These devices are for military systems: you'll need to test lifespan and performance under a variety of environmental conditions. I don't know if the dielet idea will work out, but it's specifically to verify authenticity without having to test.

A public test suite wouldn't reveal features introduced by a hostile foreign government, such as a security backdoor that only activated in response to a secret key too long to brute force. Presumably for DARPA this is a worry.

Agree a public test suite would be good for other fake component risks though.

Both. Counterfeiting, or substituting recycled parts, can be for economic reasons, or can be a hostile government that managed to substitute its hardware into the supply chain, for sabotage or to create backdoors.

I am and this looks awesome. Thank you!

I was being facetious; but my point was that for audiophiles, you shouldn't need to be disassembling components in order to tell the difference between systems.

Sure, if you can notice a difference, then go ahead and track down where it is coming from. But if you start from the wrong end (i.e. the 'AD744 has higher noise and higher offset voltage') then you should stop and question your actions, IMO.

The difference in noise is readily measurable. I've done op amp based design for commercial products, including an audio product for my side business. (n.b., it's not targeted at the "audiophile" market). I've measured the noise of dozens of op amp types for a specialized application. Impressively, the measured noise performance typically doesn't stray very far from datasheet values. You can measure it with a few dollars worth of parts, and the audio input of your PC.

Now, it's not a slam dunk that every application should use the quietest chip. Noise trades against some other factors such as current consumption. And of course from an engineering standpoint, cost matters too.

exactly. We use them e.g. for amplifying signals where low noise matters. Never compared against the AD device but did compare them once against your standard 741 and the difference is obvious, eben simply by looking at the signal on an oscilloscope.

Exactly, I believe they were designed for instrumentation amplifier duty, hence the wide bandwidth and low noise.

stinos and Serow225, I accidentally downvoted your comments. Sorry, I need to abstain from HN when I haven't had enough sleep.

If someone would upvote these comments to compensate for my carelessness, I would be much obliged.

Exactly this. There are many cheap (I mean cheap, not merely inexpensive) versions of "industrial" electronics on eBay. Most of them will probably work just fine in an office environment at room temperature. But put them in a factory where the temperature near the doors in winter can be below freezing and up near the roof in the middle of summer it's well over 100F, then your cheap eBay-purchased sequencing timer starts having hiccups, dumping hot asphalt on the floor.

Fake resistors? How is one supposed to fake a resistor? There are no manufacturer markings on them, just (easily testable) resistance/precision indicators...

In China, pulling a fast one is de rigueur.

So it might be just a typical business "f u, because we can."

>The margins for counterfeiting this part can't have been very good.

Unless they were stolen, and repackaged in order to hide their origin. Like a chop shop, only no chopping

While most of the discussion here is technical from engineering and business perspectives, your question digs more at the root of the problem: this is a cultural and institutional problem.

I live in China: people pinch pennies (or mao) here without taking into account the overall cost. This is why you have a large market for imported goods; even amongst the most nationalistic Chinese consumer, there is an assumption that imported goods are better because domestic products are made by cutting corners.

There's a strong suspicion of things that are priced cheaply but, bizarrely, people still buy cheap goods but are resigned to the product failing rather quickly. This just doesn't apply to electronics, but also to clothes, vehicles, etc.

There's a very strong tension between value-pricing and product quality. That is, there is a demand low prices but assume that the product quality is poor. On the other side of the spectrum there is a demand for high-quality "luxury" goods too. Thus pricing your product too low, even though it may be a quality product, basically indicates that it is a low-quality product.

Part of the myopia here is that people will cut corners without figuring out the benefit/risk ratio. That is, is it worth losing a contract to improve your bottom-line by a negligible percentage? Culturally (and I'm speaking in a broad generalization here) there's a desire to "win" at a contract... to make the contract be better for yourself than what's on paper. So even if the contract spells out your profit margin, it's a matter of pride to be able to improve on it (aka, "sticking it to the man"). With China's large population and widening gap between rich and everyone else, there's a perception that you have to get rich or die trying; no one else is going to help you... certainly not the government.

China's future could be a lot brighter than it is; the problems aren't technical.

He didn't test it. He suspect the chips were fake because of the price.

That said, the very small difference is very important on laboratory applications. It's completely irrelevant for audio.