EEVblog + The Signal Path Discussion

[Hugoneus]

TOPIC CHANGE:

Shariar - In your day to day work, how much of your time is spent on practical experiments? One of my high school friends is also a PhD EE that works for a prominent computer manufacturer. From the way he has described his job - he has lab technicians that do most of the setup and execution of various experiments that he designed. He has to make a specific effort to stay on top of the tools and techniques to make sure he is taking advantage of all available resources. Is that true in your world as well? The way you setup, conduct, and interpret your video experiments shows that you have pushed the button yourself enough to be nearly second nature. My gut feeling is that you have the personality that would go nuts if you never pushed the buttons and did the experiments yourself.

The Bell Labs lore is that folks in your position kind of design their job to best fit they way they work best - curious if that is based in reality.

Well, I am a researcher so I perform most of my own experiments. Especially because as an ASIC designer you really have to test your own ASICs, specially at mm-wave frequencies as the testing procedure is a skill in itself. I do get some help as I have trained one of my staff to help me out when I am really busy.

Plus who doesn't love to push buttons! 

[Hugoneus]

Shariar,

Hello! Watched most of your videos. As a cat owner staff myself I know how they are. Mine currently likes to take over my computer chair and sit by while I do bench work. I have seen your gray cat in several videos. Does yours like to take naps on warm test equipment?

Thanks for reading my question and for your informative videos. 

Pooch is very curios and likes to sit on top of the tallest instrument and observe what is going on. He also steals any Q-tip that is on the table, so I have to hide them. Same with shrink tubes, elastic bands and little shiny things.

[nctnico]

In car audio those crazy people who put 100's of Watts into their cars have to use huge multi-Farad capacitors to quiet down the power supply and avoid drops/distortion.

The only person who benefits from those capacitors is the one who marks them up 1000% and sells them. The internal resistance of a car battery is probably lower than the ESR of those capacitors. If you need to take a huge amount of power from a car battery you need the appropriate wiring though.


Edit: in a high power car amplifier there has to be a boost circuit which has to be controlled to a certain level. This will level out any power supply irregularities because in a car you can expect the voltage to vary between 10V and 17V (not taking load dump spikes into account).

[EEVblog]

Nope. This thing about Albert Einstein is an urban legend.
https://en.wikipedia.org/wiki/Religious_and_philosophical_views_of_Albert_Einstein

Check your reference. Einstein did in fact believe in God, just not the anthropomorphic god promoted by many religions.

Why does this rubbish persist?

In his own handwriting:
http://www.livescience.com/23758-einstein-god-letter-auction.html
http://www.lettersofnote.com/2009/10/word-god-is-product-of-human-weakness.html

The word God is for me nothing more than the expression and product of human weakness, the Bible a collection of honorable, but still purely primitive, legends which are nevertheless pretty childish. No interpretation, no matter how subtle, can change this for me. For me the Jewish religion like all other religions is an incarnation of the most childish superstition.

and

"It was, of course, a lie what you read about my religious convictions, a lie which is being systematically repeated. I do not believe in a personal God and I have never denied this but have expressed it clearly. If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it."

End of argument.

[EEVblog]

As long as religion (or anything else) is a personal belief that makes you happy and does not (negatively) influence your interaction with other people, is there any reason to debunk it?

Sure, but it isn't like that.
ALL mass religions create power structures that have an effect on governments and therefore on the non-participants. They must therefore be debunked. Vigorously.

Indeed.
And ridiculed instead of having their belief "respected", because, you know, it's religion, and religion is special 

It reminded of the classic Sam Harris line (because, on topic, Shahriar mentioned Sam Harris in our talk)

[EEVblog]

Carl Sagan's most misunderstood sentence was "extreme claims require extreme evidence," by which he meant that to persuade someone that their strongest-held beliefs are false, you need to make an overwhelming case to that person.

Please cite proof for that.
AFAIK that was not what he meant, nor has he ever suggested such in relation to that quote.
It comes from Cosmos when talking about UFO's:

[EEVblog]

I've only just found time to watch these videos, and I'd like to say how much I enjoyed them. One topic that you almost touched on I would have loved to hear you discuss - why are there so few women in electronics, and to a lesser extent, in technology generally?

Part social upbringing etc, part evolution and brain physiology and development etc that we most surely don't understand enough (borderline anything?) about.
The same can be said about countless different fields, for both a lack of men and women.

[EEVblog]

P.S. Why are these three videos not numbered 992, 993 and 994?

Because there is pressure to do something for #1000 but we don't really have much of a clue 

[EEVblog]

2) They didn't like the fact that I hate cats

Well, you are wrong about cats. 

No, I can say with 100% confidence and certainty that I hate cats.

Nobody is perfect!  But you've got to do something about hating cats though! It just ain't healthy... 

Knowing that expressing such a position pisses off a good percentage of the population keeps one very happy and healthy I can assure you

[GeorgeOfTheJungle]

Knowing that expressing such a position pisses off a good percentage of the population keeps one very happy and healthy I can assure you

That's something almost... religious.

[xrunner]

2) They didn't like the fact that I hate cats

Well, you are wrong about cats. 

No, I can say with 100% confidence and certainty that I hate cats.

Nobody is perfect!  But you've got to do something about hating cats though! It just ain't healthy... 

Knowing that expressing such a position pisses off a good percentage of the population keeps one very happy and healthy I can assure you

I'm so ready to post a pic of a cute adorable kitten I can hardly stand it ...

But I will resist that urge. 

[Fungus]

josecamoessilva seems to think that a drop in the power supply leads to a drop in the output amplitude of an audio amplifier. That just doesn't happen unless the power supply voltage drops below the design limits of the amplifier.

No, I think he's saying that as you increase the current to the speakers the voltage drop in the cables increases (Ohm's law). This somehow 'clips' the sound.

Any half-decent speaker cable will have resistance measured in milliohms so I can't imagine it will have an audible effect, but, hey... I haven't read many books and I think digital sound doesn't have stairsteps so what do I know? 


Math: A 200W amplifier produces 40V peaks. That gives about 5 amps into 8 Ohms.

A 3 meter cable with 3mm² of copper (quite skinny by speaker cable standards) has 12 milliohms of resistance there and back again. It loses 0.06 Volts in the cable. That's only 0.15% loss at a 200W peak into a skinny cable.

Conclusion: This diagram is massively exaggerated, methinks.



(Yes, I know it's not that simple because speakers are inductive and have to physically move the cone, etc., but those numbers will approach truth as the speaker cone reaches the end of its travel. )

Saying the speaker cone won't quite get there because of voltage loss in the cables doesn't pass the sniff test. Many other problems will be orders of magnitude bigger, eg.:
* Mechanical resistance to movement in the speaker cone (they're hard to push in/out).
* The inertia of the speaker cone making it go past the desired position when it gets there.
* Inductance in the wires/coils.

Note: Some manufacturers are now adding DSPs and mathematical speaker models to their amplifiers to correct for things like speaker cone inertia. Welcome to a brave new digital world, analog fanboys. 

[nctnico]

josecamoessilva seems to think that a drop in the power supply leads to a drop in the output amplitude of an audio amplifier. That just doesn't happen unless the power supply voltage drops below the design limits of the amplifier.

No, I think he's saying that as you increase the current to the speakers the voltage drop in the cables increases (Ohm's law). This somehow 'clips' the sound.

His picture says 'PSU' and 'Amplifier' not speaker cable. At low frequencies and high currents a thin speaker cable could cause a lot of losses but is has to be really bad before you notice it.

Math: A 200W amplifier produces 40V peaks. That gives about 5 amps into 8 Ohms.

No it doesn't. A speaker is an inductor so the impedance increases when the frequency gets higher. 8 Ohms is an impedance at a specific frequency.

[Fungus]

His picture says 'PSU' and 'Amplifier' not speaker cable.

The picture is this:


And he says:

Code: [Select]

Louder sound raises i, which leads to a drop in voltage Vin which leads to amplitude compression
(not clipping like output stage saturation). Very noticeable in iPods if you know how to tell the difference
OK, he's probably referring to power supply. In that case I guess the concept he's missing is "bypass capacitors".

(and even so, the same math applies: It simply won't be an issue unless you're using really crap cable)

Math: A 200W amplifier produces 40V peaks. That gives about 5 amps into 8 Ohms.

No it doesn't. A speaker is an inductor so the impedance increases when the frequency gets higher. 8 Ohms is an impedance at a specific frequency.

Yeah, I mentioned that.

I'm just trying to get a very finger in the air idea of the numbers. See if it passes the sniff test.

[mtdoc]

Nope. This thing about Albert Einstein is an urban legend.
https://en.wikipedia.org/wiki/Religious_and_philosophical_views_of_Albert_Einstein

Check your reference. Einstein did in fact believe in God, just not the anthropomorphic god promoted by many religions.

Why does this rubbish persist?

In his own handwriting:
http://www.livescience.com/23758-einstein-god-letter-auction.html
http://www.lettersofnote.com/2009/10/word-god-is-product-of-human-weakness.html

The word God is for me nothing more than the expression and product of human weakness, the Bible a collection of honorable, but still purely primitive, legends which are nevertheless pretty childish. No interpretation, no matter how subtle, can change this for me. For me the Jewish religion like all other religions is an incarnation of the most childish superstition.

and

"It was, of course, a lie what you read about my religious convictions, a lie which is being systematically repeated. I do not believe in a personal God and I have never denied this but have expressed it clearly. If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it."

End of argument.

Dave, you're making the classic mistake of arguing that the personal god put forward by many (but not all) of the worlds religions defines the concept of god in it's entirety.

As your quotes accurately demonstrate, Einstein did not believe it that type of personal god and felt it was a childish concept (I agree, FWIW) .  BUT - he did in fact believe in "God" in the non-personal sense - and as defined by Pantheism and elucidated by Spinoza.  This is not a minor point - though I realize it may appear that way to those who identify the Judeo-Christian-Islamic view of god to be all encompassing.

In his own words:

I cannot conceive of a personal God who would directly influence the actions of individuals..'' My religiosity consists of a humble admiration of the infinitely superior spirit that reveals itself in the little that we can comprehend of the knowable world. That deeply emotional conviction of the presence of a superior reasoning power which is revealed in the incomprehensible universe, forms my idea of God.

and

I believe in Spinoza's God, Who reveals Himself in the lawful harmony of the world, not in a God who concerns himself with the fate and doings of mankind.

So any blanket argument that Einstein had no believe in god in any form, is demonstrably false, regardless of any proclamations about "end of argument"

It  also seems clear that Einstein would be dismayed to see his lack of belief in a personal God being misused by strident atheists. Again, in is own words:

"[T]he fanatical atheists...are like slaves who are still feeling the weight of their chains which they have thrown off after hard struggle. They are creatures who—in their grudge against the traditional 'opium of the people'—cannot hear the music of the spheres. "

And while he did not believe in a personal god, he specifically declined to try to persuade those who do. Again in his own words:

"such a belief seems to me preferable to the lack of any transcendental outlook."

BTW- as the links above indicate - those quotes come from:  Jammer, Max (2002). Einstein and Religion: physics and theology. Princeton: Princeton University Press. Highly recommended.

[josecamoessilva]

josecamoessilva seems to think that a drop in the power supply leads to a drop in the output amplitude of an audio amplifier. That just doesn't happen unless the power supply voltage drops below the design limits of the amplifier.

No, I think he's saying that as you increase the current to the speakers the voltage drop in the cables increases (Ohm's law). This somehow 'clips' the sound.

Conclusion: This diagram is massively exaggerated, methinks.

Sigh. Maybe "he" was talking about the power limitations of the apple wireless earbuds, and nonlinear response, not clipping, as per "his" actual post,

http://sitacuisses.blogspot.com/2016/09/the-problem-with-wireless-earbuds-for.html

as opposed to distorted representations of that post in the replies that aren't "his"; and making the sole point in this thread that

People who say that the only thing that matters in digital are the headphones, as a criticism of audiophiles, don't understand how a digital file becomes the analog signal driving the speaker.

(Which is a paraphrase of one of "his" replies above. Sourcing, it matters.)

The problems with the earbuds are larger versions of the problems with a cheap sound chip on a computer or discount phone. As per the previous analogy, most people who call all audiophiles audiophools are like non-car people saying that a Fiat 500 and a Bugatti Veyron are the same because they're both usable in a drive to the store.

Most audiophiles are reasonable, and painting them all as audiophools (there are some) or audiosnobs (there's a few) isn't an accurate representation of the crowd.

Note: Some manufacturers are now adding DSPs and mathematical speaker models to their amplifiers to correct for things like speaker cone inertia. Welcome to a brave new digital world, analog fanboys. 

Actually, people had been doing that for a long time with feedback control. It was a novelty in the late 70s, but still made it as a problem in tests when I was in college.

One of my classmates published a paper in the 80s about using the variations of the counter-inductive force in a speaker to determine (and compensate for) the frequency response of the speaker enclosure, without having to build a model a-priori. That's how old this idea is. (Unfortunately his name is Paulo Monteiro, which is second only to Jose Silva as the most common name in Portuguese.)

[josecamoessilva]

Carl Sagan's most misunderstood sentence was "extreme claims require extreme evidence," by which he meant that to persuade someone that their strongest-held beliefs are false, you need to make an overwhelming case to that person.

Please cite proof for that.
AFAIK that was not what he meant, nor has he ever suggested such in relation to that quote.
It comes from Cosmos when talking about UFO's:

Well, maybe my memory of Sagan was giving him too much credit then. But since this isn't literary criticism, where interpreting "The Source" is what matters, I'm happy to take credit for the idea in this paragraph:

To persuade someone that their strongest-held beliefs are false, you need to make an overwhelming case to that person. Mental midgets take that sentence to mean that "anyone whom I disagree with must prove to me that they're right," which is the opposite of how persuasion works.

And to point out that when the mode is discourse from atheists to religious is mockery, that only persuades the religious of one thing: that atheists are the adversary. That's all fine and dandy to monetize the atheists' echo chamber, but not out in the real world, where atheists are a small minority.  (I'm an agnostic, BTW, which is what most "atheists" are.)

[Fungus]

Sigh. Maybe "he" was talking about the power limitations of the apple wireless earbuds, and nonlinear response, not clipping, as per "his" actual post,

You posted that pink image as well:

https://www.eevblog.com/forum/blog/eevblog-the-signal-path-discussion/msg1208808/#msg1208808

Clearly both things were open to discussion.

[Fungus]

And to point out that when the mode is discourse from atheists to religious is mockery, that only persuades the religious of one thing: that atheists are the adversary. That's all fine and dandy to monetize the atheists' echo chamber, but not out in the real world, where atheists are a small minority.

Nope. Mockery, if done well, is a powerful tool. See the "Elvis" video a few messages back for a good example.

The religious also use mockery, eg. "Evolution's only a theory", so why should they be spared?

If we all sit back and respect each other's beliefs then nothing will ever change.

[josecamoessilva]

Sigh. Maybe "he" was talking about the power limitations of the apple wireless earbuds, and nonlinear response, not clipping, as per "his" actual post,

You posted that pink image as well:

https://www.eevblog.com/forum/blog/eevblog-the-signal-path-discussion/msg1208808/#msg1208808

Clearly both things were open to discussion.

That "pink picture" is true for every amplifier, the only difference is the Rint, which is very high for the earbuds. But I just realized you don't know even this little bit of high-school electronics, so I won't be elaborating on this anymore.

[Fungus]

That "pink picture" is true for every amplifier, the only difference is the Rint, which is very high for the earbuds. But I just realized you don't know even this little bit of high-school electronics.

You're right, I wasn't ever taught that!

Please enlighten me: How high is the Rint of Apple earbuds, exactly? (in Ohms).

[nctnico]

josecamoessilva seems to think that a drop in the power supply leads to a drop in the output amplitude of an audio amplifier. That just doesn't happen unless the power supply voltage drops below the design limits of the amplifier.

No, I think he's saying that as you increase the current to the speakers the voltage drop in the cables increases (Ohm's law). This somehow 'clips' the sound.

Conclusion: This diagram is massively exaggerated, methinks.

Sigh. Maybe "he" was talking about the power limitations of the apple wireless earbuds, and nonlinear response, not clipping, as per "his" actual post,

http://sitacuisses.blogspot.com/2016/09/the-problem-with-wireless-earbuds-for.html

Well this page is littered with nonsense and false assumptions so it is -to say the least- very far from accurate.

People who say that the only thing that matters in digital are the headphones, as a criticism of audiophiles, don't understand how a digital file becomes the analog signal driving the speaker.

And by this you are saying people who design audio electronics know jack sh*t about their jobs  Well thanks for that!

[EEVblog]

Dave, you're making the classic mistake of arguing that the personal god put forward by many (but not all) of the worlds religions defines the concept of god in it's entirety.
As your quotes accurately demonstrate, Einstein did not believe it that type of personal god and felt it was a childish concept (I agree, FWIW) .  BUT - he did in fact believe in "God" in the non-personal sense - and as defined by Pantheism and elucidated by Spinoza.  This is not a minor point - though I realize it may appear that way to those who identify the Judeo-Christian-Islamic view of god to be all encompassing.

No one cares about semantics like that, it adds zero value to any practical mode of discourse on issues with religion in the world.
You know that a personal god is all that matters to practically all of the religious population that's worth dealing with.
I will not debate this further.

[mtdoc]

Dave, you're making the classic mistake of arguing that the personal god put forward by many (but not all) of the worlds religions defines the concept of god in it's entirety.
As your quotes accurately demonstrate, Einstein did not believe it that type of personal god and felt it was a childish concept (I agree, FWIW) .  BUT - he did in fact believe in "God" in the non-personal sense - and as defined by Pantheism and elucidated by Spinoza.  This is not a minor point - though I realize it may appear that way to those who identify the Judeo-Christian-Islamic view of god to be all encompassing.

No one cares about semantics like that, it adds zero value to any practical discussion on religion.
You know that a personal god is all that matters to practically all of the religious population that's worth dealing with.
I will not debate this further.

It has nothing to do with semantics and it has everything to do with a discussion of religion.  Belief in god != religion.    And there are philosophies/religions with tens of millions of followers whose concept of god is almost identical to Spinoza's and Einstein's.  Those are just the facts, not semantics.  And many millions of people do care about that distinction.

Most people raised in a Judeo-Christian culture equate God with what those religions teach. Like them you seem to have a blindspot here. Don't kill the messenger. Embrace new knowledge.

FWIW - I find the Judeo-Christian-Islamic concept of God just as childish as Einstein.  I just take issue with misrepresentation of Einstein's views since I've read quite a bit about them and find them fascinating.

[mtdoc]

There may be a creature somewhere in the universe with abilities and technology which would appear godlike to us (as we would appear to a peasant in the 5th century). But that is nothing like a god who supposedly cares about what your thoughts, what you eat, who you sleep with and whether you "believe" in him. To draw false equivalency in this manner is dishonest at best.

And I have done no such thing. Please read Einstein's words and what I posted. I was only clarifying his views by posting his words.  He would agree with what you wrote and so do I.