Critical thinking... Or lack there of

[gsr]

As a lifelong cabinet maker and garage band bassist who got into building amps and effects after I brainwashed my son into loving Pink Floyd as much as I do, I want to say there are those of us that appreciate the patience of the senior members of this forum. While it should be incumbent upon the newbie to lurk for info with due diligence prior to posting a stupid question, often it is only after the answer is presented that the poster sees how ignorant they were. You guys provide a great service on the best forum on the web. Thanks

[Wilder Amplification]

Enzo...load lines are simple. &@#!ing Google them! jk

In all seriousness, the ones that get me are the ones who claim to possess "golden ears" and anything they can hear has the power to dispel any sort of elementary theory or proven engineering data. Case in point...wire type solid vs stranded wire. "Skin effect" has been the mode of defense on this numerous times when even the guys in the RF community will tell you that skin effect does not apply to anything in the audio pass band.

I'll recall my ultimate favorite question among Randall Aiken's FAQ section on his site. I'm sure most of us here will enjoy this -

Q: Why is it, when discussing circuits in internet forums, that people with no technical background always seem to claim that they can hear so much better than someone with an electronics background?
A: That's the "golden ears" strategy, a time-honored internet arguing technique used with limited success by those who are usually "technically challenged", i.e. "internet armchair engineers", who cannot produce supporting data to back up their side of the argument. These people tend to rely heavily on tenuous, unprovable concepts, such as "magic" and "luck"to describe circuits, rather than anything concrete, like mathematics, scope plots, or plain old reason and common-sense.

The laws of "golden ears" are a bit complex. Here they are, at least as far as I have been able to ascertain:

(1) "You are not allowed to make any mention of golden ears until you are losing an argument and have no way to save face."

(2) "He who first proclaims to have golden ears is the only one in the argument who can truly have golden ears." The opponent, therefore, must, by the rules, have tin ears, since there can only be one golden-eared person per argument. Now, everyone else on the board may have golden ears, but only if they choose not to perform the test in question that may disprove the theory. These people may be brought up as often as possible, until that point where they actually perform said test and obtain results not in accordance with the original golden-eared proponent's position.

(3) "Golden ears can only exist on a person who has no formal education in the subject matter." The minute a person receives an engineering degree, his ears automatically turn to tin, and he cannot be trusted with even the simplest test of tone or frequency response, no matter how long he or she has been in the field of interest.

(4) "Once you have proclaimed golden-ear status, you can no longer answer any questions, nor put forth anything of a technical nature, because you may slip up and show that you really have no clue as to what you are talking about." At this point, your golden ears have become tarnished, and everyone will see the emperor has no clothes, so this situation should be avoided at all costs. Should this happen, you have no choice but to either slink away and hope nobody notices and soon forgets about you, or loudly proclaim victory in the vain hope that someone will believe you.

I'm sure there are more rules, I'll post them as I learn them.

[mooreamps]

Case in point...wire type solid vs stranded wire. "Skin effect" has been the mode of defense on this numerous times when even the guys in the RF community will tell you that skin effect does not apply to anything in the audio pass band.

Well, I personally use stranded wire mostly since I've had issues with solid wire breaking on me. Ahm, skin effect is a property they discuss how waveguide operates at frequencies starting above 400 Mhz.

-g

[R.G.]

Ahm, skin effect is a property they discuss how waveguide operates at frequencies starting above 400 Mhz.

Skin effect was first described in 1883 by Horace Lamb for spherical conductors and generalized for conductors of any shape by Oliver Heaviside in 1885. It's the distance into a conductor where the current falls by 1/e.

Skin depth happens at all frequencies.

At DC, the "skin" amounts to the entire conductor, no matter how deep. At 20kHz, the skin (current falls by 1/e, e=2.718281828...) is 0.0212 inches, so wire smaller than 0.0424" in diameter has the skins meeting in the middle, and could be said to have no skin. That is an oversimplification, but a useful one. The skin actually tails off after 1/e, but this adds to the skin conduction coming in from the other side, so it's not quite as bad as it would be on a single surface, which is what the classical computation does.

0.0424 is a bit bigger than 18Ga solid wire. Stranded wire has "skins" that effectively go all the way through, but proximity effect between the conductors causes much the same thing. Skin depth at 1MHz is about 0.003". It's really a skin at higher frequencies.

So: skin effect happens at all frequencies, depending on the frequency. But for rational sized wires at audio frequencies and below, it's calculable but almost certainly negligible. The nice thing about knowing the math and details is that you can figure out when something can be neglected and why.

Of course, all that stuff comes out of textbooks, so it needs personal measuring to find out if it *really* acts that way or not, right?

Well, I personally use stranded wire mostly since I've had issues with solid wire breaking on me.

The military and space agencies used to specify thermal wire stripping to avoid nicking wires, which is the most common cause of breaking wires in soldered installations. But you knew that already, cause you work for a space/rockets place, right?

Get yourself a PTS-10 and your solid wire breaking is largely over. It is just amazingly faster on stranded wire, which it also does not nick.

So how's that measuring the reflected impedance for multiple secondary loads going? I really want to see how the story turns out. I have a reminder set up in my chron file so I won't accidentally forget about it.

[Koreth]

Though I like to think that I approach these circuits that catch my fancy with critical thinking, there's still the nagging feeling that I'm one of the ones being complained about.

[R.G.]

Though I like to think that I approach these circuits that catch my fancy critical thinking, there's still the nagging feeling that I'm one of the ones being complained about.

Here's a test: Have you ever taken an amp in to a tech for repairs after it erupted in smoke and silence at a gig, and said " ... you know, it really sounded great just before it blew out. Can you make it sound like that all the time?"

Well, OK, we've all done that. But did you do it *more than once*?

Seriously, it's not what you know. It's how you approach it. If you think you already know it all and don't need any steenkin' more information, then you may be the subject. If you know something, know you don't already know it all, and are willing not only to admit you don't know it all but are willing to learn, you're NOT one of the ones being complained about. If you can discuss issues with a reasonable back up for your statements and are willing to be open to learning more, you're part of the solution, not part of the problem.

It's not information. It's *critical thinking*, like the man said. No jokes here, no smilies. Dead straight.

[nashvillebill]

...I want to say there are those of us that appreciate the patience of the senior members of this forum...You guys provide a great service on the best forum on the web. Thanks

A hearty "Thanks!!" from me as well.

On a similar vein, as an engineer I've worked in factories for 30 years. I see lots of broken stuff, machine downtime issues. Usually the problem is obvious, but many times it is not. That's when you can tell who the good maintenance guys are and who isn't. We have lots of "parts changers". They diagnose problems by merely changing parts. If that doesn't fix, change another part--or, I've seen it happen, change the first part over yet again! "Gee must've gotten a bad part out of Stores!" The concept of a methodical, logical troubleshooting, based on a decent technical knowledge...too difficult for them to grasp.

[mooreamps]

The military and space agencies used to specify thermal wire stripping to avoid nicking wires, which is the most common cause of breaking wires in soldered installations. But you knew that already, cause you work for a space/rockets place, right?

No, it's more of I put quite a few more parts inside these chassis's I build, and things can get a little tight inside.

-g

[R.G.]

Quote Originally Posted by R.G.
The military and space agencies used to specify thermal wire stripping to avoid nicking wires, which is the most common cause of breaking wires in soldered installations. But you knew that already, cause you work for a space/rockets place, right?

No, it's more of I put quite a few more parts inside these chassis's I build, and things can get a little tight inside.

I'm confused.
- no, you didn't know they used to specified thermal wire stripping to avoid nicking?
- no, you didn't know nicking was a common cause of breaking soldered wires?
- no, you put more parts inside your chassis than are in military/space equipment?
- no, you don't work for a space/rockets place?
- no, you just put in so many parts that the wires are prone to breakage?
or
- some of the above?
- most of the above?
- other reason not listed?

I'm confused about that. Help me out.

But I really think you'd like the PTS-10 if you tried it. And was the skin effect info useful to you?

And how's that impedance measurment going? I'd like to know.

[mooreamps]

I'm confused.

Really ??

- no, you didn't know they used to specified thermal wire stripping to avoid nicking?

No. I did not know that.

- no, you didn't know nicking was a common cause of breaking soldered wires?

No. I did not know that.

- no, you put more parts inside your chassis than are in military/space equipment?

No. more parts than what one would find in a standard fender build.

- no, you don't work for a space/rockets place?

Yes, I still work for the space/rockets place. The spacecraft that I work on is on the launch pad at the Cape. T minus 9 hours ; and counting.

- no, you just put in so many parts that the wires are prone to breakage?

they tend to break because I have my fingers inside the chassis all the time when I am working on it.

But I really think you'd like the PTS-10 if you tried it.

I'll take a look at it.

And was the skin effect info useful to you?

Not applicable to audio frequency amplifiers.

And how's that impedance measurement going? I'd like to know.

It's in work.


-g

[R.G.]

Quote Originally Posted by R.G.
I'm confused.

Really ??

Yes. But better now that you've cleared some things up. Thanks!

Quote Originally Posted by R.G.
- no, you didn't know they used to specified thermal wire stripping to avoid nicking?

No. I did not know that.

Glad I could help.

Quote Originally Posted by R.G.
- no, you didn't know nicking was a common cause of breaking soldered wires?

No. I did not know that.

Glad I could help.

Quote Originally Posted by R.G.
- no, you put more parts inside your chassis than are in military/space equipment?

No. more parts than what one would find in a standard fender build.

So there are the same or fewer parts than in a standard Fender amplifier?

Quote Originally Posted by R.G.
- no, you don't work for a space/rockets place?

Yes, I still work for the space/rockets place.

Cool. I have your name on file as my friendly local rocket scientist in case there's any issues with rockets.

The spacecraft that I work on is on the launch pad at the Cape. T minus 9 hours ; and counting.

Are there any non-thermal stripped wires in it?

Quote Originally Posted by R.G.
- no, you just put in so many parts that the wires are prone to breakage?

they tend to break because I have my fingers inside the chassis all the time when I am working on it.

Perhaps if you used tools they'd break less. Or thermal strippers. Just a thought.

Quote Originally Posted by R.G.
But I really think you'd like the PTS-10 if you tried it.

I'll take a look at it.

They're really nice once you get used to them.

Quote Originally Posted by R.G.
And was the skin effect info useful to you?

Not applicable to audio frequency amplifiers.

Yeah - that was the point.

Quote Originally Posted by R.G.
And how's that impedance measurement going? I'd like to know.

It's in work.

Cool. I'll ask again when the chron job reminds me. I'd really like to see what comes out of that.

[Chuck H]

You opened this one R.G. But I did expect Gary to enter the post soon enough and I actually anticipated it... Sigh

[mooreamps]

T minus 6 hours ; 30 minutes....

[R.G.]

You opened this one R.G. But I did expect Gary to enter the post soon enough and I actually anticipated it... Sigh

There was no real question in my mind that it would happen. I won a side bet on that one.

I'm going to ... um, purgatory, aren't I?

Sorry. I'll try to stop.

[mooreamps]

Launch !!

YouTube - 20100814(070637).m2ts