DIYHiFi.org

It's not a hobby - it's a gift.

Of course, Jocko is speaking only for and of himself here.

There was a time in my life (back in the 80's) that I listened to bands like Einstürzende Neubauten.
That didn't warped me - it might take some strong RF exposure for that.

_________________
Carlos Filipe

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction." Albert Einstein

Don't make me smack you!

Or, how 'bout this one..........I think it went something like..........."The more I think about it, the more I am offended." Can't quote it exactly, because it seems that those posts have mysteriously vanished in the middle of the night.

Typical!!!!!!!!

Jocko

_________________
"Because, I hate you guys. I hate you guys so very, very much.

Yours,
General Cartman Lee"

It's not a gift - It's a divine right

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There is a crack in everything, that's how the light gets in!

And they can't take that away from me here!!!!!!!!!!!!

So, I do. I hope they enjoy reading what they won't allow me to say there. (I know that they read this crap. They would never admit it, but they do.)

Jocko

_________________
"Because, I hate you guys. I hate you guys so very, very much.

Yours,
General Cartman Lee"

This is an ode to Head-Fi, which is slowly swirling the drain to me.

A person can hardly recommend a headphone amp / source without getting into a DBT debate. Couple that with the generally clueless masses on RF design and lack of knowledge of distortion (or any electronics for that matter; or that perhaps they're measuring the wrong thing...) and it's just a disaster.

"RCA digital out cables matter? Digital terminations make a difference? THD+N at 1KHz is the only distortion that matters! Bah! My *consumer audio thingamabob* is just as good!"

I don't know what's gotten into some people over there, but it's really turned me off. DBT? Alright, I can handle that; but all this spouting of simple measurements (THD) without looking at the more complicated factors (poor opamps as a I/V converter, slew-rate limiting from jitter, IMD, PID, frequency response, crosstalk, etc...) is just horrible. If designing audio were as simple as tailoring to THD or anything other thing alone, audio would've ended in design decades ago (along with most other electronics design, actually).

Fancy that! Things are more complicated than people expected...where have I heard this before? (I'm a physics afficianado; scientific, but very willing to explore).

This is the only forum to which I look for design techniques and tips in RF audio design. It's taught me a lot and it's taught me to look into things more meticulously (rather than the "bits are bits" attitude I get from there).

All the other forums are crap really, plain and simple.

Thanks for the non-crappy forum.

~Thomas

Glad that you found something useful here. Don't be afraid to ask what you don't know. We try to be helpful in between being cheeky.

Jocko

_________________
"Because, I hate you guys. I hate you guys so very, very much.

Yours,
General Cartman Lee"

Great post, Thomas.
Yes, I see those attitudes spreading from forum to forum, including The Pub.

I have extensive experience with double blind tests, sometimes performed with a wide audience (!), usually a mix of audiophiles and non audiophiles, and I must say this again, as I said years ago at the other place but most were not prepared for the shock:

DBT is NOT a reliable test, and proves nothing.
It is actually one of the worse "methods" of evaluating audio gear.

Most people feel stressed to decide and when in doubt just pick one.
For the casual listener it is not possible to concentrate on the music (and he/she doesn't really know what to search for, other than bass/mid/treble) when there is some schmuck constantly switching.
Then you get the numbers: one guy has always got it right in the middle of 10 persons.
Could be that he/she is an experienced listener while the others listen to boomboxes at home but the result is: statistically, it is not possible to detect a difference.
Ridiculous.

_________________
Carlos Filipe

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction." Albert Einstein

I have a friend who knows a lot about DBTs as used in medicine. He's an NIH guy, doling out money to researchers who use DBT as part of their test regime. He knows some about audio - just enough.

Anyway, he points out the flaw in DBT as applied to audio testing.

In medical research, they use DBTs across a group of test subjects and then they measure the results, just like in audio. For example, with a blood pressure medication, they might give group A drug 1, group B drug 1 with half the dose, and group C a placebo.

Now, in the audio type of test, the next step would be to ask the subject under test what s/he thought.

In the medical realm, they'd take the subjects' blood pressure.

See the difference? In one case, an objective test is used to determine how the DUT is working. In the other, a subjective test (which is funny given how the DBT guys hate subjectivity) is used to determine how well the DUT is working. This means that a lot of the result is all up to the interpretation and "listening ability" (and it *does* vary a lot between people - subject of another post...) of the people who are being used as the test instrumentation.

Sure, in the medical world part of what they do is ask the subjects how they feel and if they've observed any other effects. But that is in addition to the objective measurements made by test equipment like blood pressure monitors. With audio DBT, it's entirely based on the subjective interpretation of the test subject.

As far as other forums go, too many people on many of them are far too defensive of whatever position they hold. Urination competitions over whose position is right often becomes the main event.

Besides, many of these places lack a certain sense of humor. That brings back the eternal question, "Does Humor Belong in Music?"

Thanks for the medical confirmation.

_________________
Carlos Filipe

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction." Albert Einstein

Good post mr. gmarsh, underlining very important problems in linear power supplies. But a small note:



Later in your "experiment" you'll want to increase this resistor, but a note to whom may not be seasoned with SPICE programs: to measure currents in a net avoiding components that influence the results (30A over 1mOhm is 30mV) just use a fixed voltage source with 0V. It enables measuring the current through it, avoiding influence to the circuit.

Because the actual circuit is 0 ohms, not 1mOhm, right? Good tip anyway.

Oddly enough, I encourage adding 'influences' like this to SPICE simulations.

There's a few different ways you can build something like a passive LC filter for RF - some are more sensitive to source and load impedance to others. There's no guarantee that a customer will put a perfect 50/75 ohm load on your equipment, and if they don't, there's no guarantee they won't call you bitching and saying it's your fault that your equipment doesn't meet spec. So if you're designing such a thing in SPICE, first thing you should do when you're happy with a design is start changing stuff, like source/load impedance, and see if it still works.

This also applies to audio amplifiers. I cringe every time I see a single R with an "8" across it on the output of a SPICE-simulated audio amp...

So, a guy (me) walks into an audio store to check out a new product built by a some time contributor to this forum. You hear this one already?

A sales guy jumps out of his office and says,

"Can I help you?" I must've set off his get-ready-to-call-the-cops alarm.

"Yes! I'd like to hear the <company name and model deleted to not embarrass anybody> if you have one."

"The what? I don't have it."

"The <company name and model deleted>. It's their new <deleted>" (I didn't actually say <deleted> you understand...)

"<deleted company name> <mumble, mumble> I don't have it." (He did actually say <mumble, mumble>...)

I thanked him with a smile and left the store, no doubt to his delight.

Later it occurred to me that my encounter in this store, where presumably the point of their existence and this guy's presence there as owner is to trade me some piece of equipment they paid X for in exchange for nX dollars from me - where n is much greater than 1 - was almost identical to how most audio forum encounters play out. Some guy shows up on a forum and asks what he thinks is an innocent question. (I know that isn't always the case - humor me here.) What he gets is a tangential answer or a series of attacks about how wrong he was to even be asking. (Again, I know that a significant bunch of posters show up on a forum, throw down a statement, and dare everybody to knock the chip off their shoulder - humor me here.)

Maybe the problem isn't really with the forums. Maybe it's with people who have some sort of interest in audio. Or, maybe it's even just with people in general.

A company is made out of people so people make a company. For the best or for the worse.
Forums are no different.

_________________
Carlos Filipe

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction." Albert Einstein