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PostPosted: Mon Jun 19, 2017 10:03 pm 
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Benjamin
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And, no, it isn't assuming you are The Devil, when you are not. (Yes, talking about you, Mr. "I don't know why he hates me." I don't hate you, and you are not important enough to even be one of The Devil's henchman. Gee, you really have a bur under your saddle, about that one. Give it a rest, will you?)

And, no, it isn't not being talked about. (Well, unless you are Phred. I think it kills him. No, he isn't dead. He just smells bad!)

It is being talked about, when you are not around to stick up for yourself.

AKA "Here we go again, about friggin' SPDIF and stupid damn connectors".

So, where to start?

OK, since I am not an idiot (are you reading this, Mr. IC Designer Man), the rule of thumb is "If it is under 300 MHz, who gives a crap about the connector?"

Makes sense, since you would be surprised how bad you can butcher a signal, and still get it to work. (Back when I had a real job, I did an extensive study on what you can do, to a DS1 signal, and still get it to pass the ATT mask. You name the cable...............I had data on how long it could be, etc.) So, contrary to what the Masters of the Universe think, I know a lot more about this crap than they think. Which means probably more than they do!

But, there comes a time when you have to believe the results, and invent a new theory.

Which is what happens to crappy SPDIF. (Hey, I didn't design it: I just had to find a way to make it work. Yes, it works, in stock form, but it can be made to sound better. OK, marginally so. But, it can be done. And it can be done very cheaply.)

So, without going through the whole damn history lesson, again, it only took 1/2 hour, the first time we built any SPDIF crap, to know it had problems.

Every cable sounded different. They also sounded different, with different lengths. And don't ask when there was a Z mismatch.

So.............long story short, here is what we found:

Yes, everything needs to be 75R. (You can make it any Z, as long as they are the same.)

We found a value, of return loss, where you could stick in any cable, at any length, and the problems pretty much went away.

What if you didn't have a good Z match?

We found a length where the cables still sounded different, but much less so.

Now, here is the key:

All of this is dependent on rise time.

Slow rise time......................yeah, not much you can do about it.

Now, if you are willing to deal with some EMI (yes, I know.............some design guru thinks that is a dumb risk), then you can improve the performance.

If you are willing to run the risk of some EMI (not something you would want to do, if you are making millions of something), but since this is DIY, well, engineering is a series of compromises, and you have to decide what compromises you are willing to live with. Not my job to tell you it has to be 1 nSec, or "you are nuts, if you go with less than 5 nSec". That is your call. Just so that you know..................the faster you make, the more attention to detail that you have to pay. Makes no sense to run LVC logic, and design the PCB like it is a tube amp, with transformers all over the place. (And point-to-point wiring, on the tube socket.)

So, if all that you have is some fairly slow stuff, you will not see much of an improvement, by doing anything. If that is your world, then fine. Just don't try to tell me that I have no idea what I am doing, because I do something different than you.

And can measure the difference.

Yes, you can measure the difference. Granted, it isn't much, but it is there.

Why?

How the hell do I know? I just an idiot, remember? I didn't design the interface. (The funny thing is...................they guy who did only intended it to be a test port! Maybe that is why it has problems. But, once the marketing weenies found out about it.....................................)

Yes, I know.............the newer RX chips lock onto a different part of the waveform, and in a slightly different manner. While they may be marginally better, than the old crappy ones, they still have pretty much the same problems.

Ah, "but I can measure the jitter, and it is x Sec."

OK, so what?

A number. BFD.

Come up with the spectrum, next time.

And how 'bout how much correlation is in it?

Yeah..................I know..................not necessary. (Funny how these same guys are also the ones who don't think close-in phase noise is the problem. I think not having the right gear, to measure the right stuff, is the problem.) (Yes, I am sure that you use the same stuff everyone else does. My statement stands. It can not do what really needs to be done. Probably because it would cost too damn much for anyone to buy one. Not that they are cheap, to begin with.)

So, if you live in the land of make-believe, and want to pretend close-in phase noise is not important, well, that explains everything. (Ironic part of this is no matter what you do, to that damn SPDIF signal, you do not screw up the close-in phase noise.)

So, if that is you, just shut up, go away, and stop bothering the rest of us. You really are boring.


OK, now that we have all of that out of the way.....................

What about the stupid connectors?

Unless you get the rest of the damn circuit right, it won't matter a rat's rear end what you do with the damn connector.

I have said this, so damn many times, yet some of you seem to have forgotten it. Then we have the Masters of the Universe, who go into auto-babble trance-spout on how I have no idea what I am talking about. Just because some putz mentions me, out of context, and leaves out the most important part.


You guys.................

And yet, you wonder why I hate y'all so dang much.

So, let's try this again:

You need to get the circuit Z right, before you worry about the damn connector! If you do not do that, then what is the point of any of this? There isn't. Period.

First, you get the TX Z right. Then, you get the RX Z right. And you get a cable, that is the same Z.

Which, while it is not hard, no one can seem to be able to do it!!!!!!!!!!!!!!!!!!!!!

Let's concentrate on the most obvious problem. (No, I am not going to give detailed lecture, on every stupid dumb thing that you can do. I've seen them all, and it is not my job to teach you guys.)

How do audio guys design a RX input?

They stick a resistor (maybe a leaded one), right at the connector. Then, you run 6" of wire, to the next point in the chain. Which is probably an axial-leaded film cap (with really long leads!), and then some more PCB trace, to the chip.

And you wonder why it sounds the same, when you take out the cheap RCA, and stick in a mil spec 75R one.

IDIOT ALERT!

So, unless you have a really nice "system", with the return loss down to some number that most of you can only dream of, if really doesn't matter what kind of connector that you use.

If you go to all the bother, of making a really good "system", then why would you stick a junk part in, at the last minute?

"So, how good is good?"

No comment. I will say that I can routinely build stuff that has a return loss of 40 dB, through the most important signal range. The "magic number" is not that low. Nor is it unattainable. (And this is with a transformer stuck in there. Shows I must be an idiot, right?)

Granted, while I can measure how nasty a stinking RCA is, I have to say I have not measured its actual effects, in a circuit.

Look, if I am going to all the bother to measure something, I am not going to do it, with one of those dumb things in there. Yes, the TDR has the resolution to do that. But, it is a lot more work to measure the recovered jitter, and its spectrum, so why make the job harder?

And to be honest, most of you probably couldn't hear the difference. Especially with what you are working with, to begin with.

In any case, it doesn't hurt to buy a cheap PCB-mount, RA 75R BNC connector, from Mouser.

Which is what I do..................especially since it basically has the same footprint, and price, as a cheap PCB-mount RA RCA connector. (OK, maybe it costs a buck more. Who really cares?)

See how easy that is? And how much needless hand-wringing, not to mention needlessly dragging me in the foray, you just saved?

I hate you guys....................

Sincerely,
Gen. Cartman Lee


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PostPosted: Mon Jun 19, 2017 10:21 pm 
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Benjamin
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One last thing...................

Back when I belonged to the stinking AES, I was shocked to open the latest Journal, and read the details of the new AES/EBU interface.

So, I find out how to contact the guy who was in charge of that group. (He was a loudspeaker guy. Sharp, but not an RF guy.)

Anyway, he is driving through midtown Manhattan, talking on a cell phone (back in the days when they weren't exactly something easy to hold in your hand), and I started in on him....................

I can only imagine him driving, with his mouth open, wondering why I could predict all the problems they were going to find, just be looking at the spec.

I can say he listened intently. He did take my contact info, but I never heard back from him.

About 1 year later..................

The new version came out. All of my suggestions were the new version, with the exception of nailing down a fixed TX level.

In retrospect, I should have told him to make sure there was no damn DC, on the TX signal. Those tiny transformers (even the ones they tell everyone that you need to use) have very tiny cores, and saturate easily.

Not to mention the TX might burn up, if it drives a DC short.

Yes, I have run into all of those problems. Blame me: I should have seen that problem, as well. But, since I did all of this off of the top of my head...................yeah, I should have known, someone (like Philips!) would have DC on the output.

And smoke the RX side. (Didn't see that one coming, either.) (No, wasn't one of my designs. I forget what it was that burned up.)


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PostPosted: Tue Jun 20, 2017 10:42 pm 
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Benjamin
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Hey! Look what someone posted, at some goofy forum that most people have the sense to avoid...................

Image

Yeah, let's talk about why I was banned. (Hint: it had nothing to do with "he doesn't know what the hell he is talking about.")

Some putz wanted the schematic to one of Signore Guido's designs. So, he wanted someone to post it, so he could copy it, and deprive Guido of a few shekels. (Mind you, this was after he and Bruno had left Philips, and were trying to make it on their own.) He was particularly upset that someone had it, but would not give it to him for free. Instead, he wanted to sell it to him!

What a crook.....................he wants to sell something that is not his.

But the complainer is also a crook, because he wants something, for free, that is not his.

So, I had to 'splain to him that this is crap, and should not be allowed to be posted. Plus, I pointed out that since we know one of the guys is a crook, how do you know when he stops ripping off Guido, and instead rips you off? IOW, what if he sells you a bogus schematic? (It would serve him right.)

Of course, this putz takes exception to this. I, in turn, report his posts to the Mod Squad.

Who, in turn, delete my post, and put me under moderation!!!!!!!!!!!! (His managed to stay.)

Now, to be fair..............

They did tell him, in very polite terms (stinking Pommies) that what he was asking was not nice, and that he should refrain from that, in the future. Plus, they continued, that maybe he should ask Guido, and he might be kind enough to give his work away, for free. (Easy for them to say. Take money out of a guy's mouth, when he is trying to start a bidnis. Because it won't cost them anything, so what is the problem?)

So, I jump on the mod, who deleted my post, let the putz's posts remain (I guess as something to scare off other skivers), and demand an explanation why the hell that merits being put under moderation.

"Because it is our job to do that, not yours."
"They why the hell aren't you doing a better job of it?"

Shortly after that...................yeah, you can guess what happened.

(Might I point out, at this stage, that the one person who was affected by all of this, Signore Guido, was able to read it all, before they snuffed it out. He thanked me. Nice to know who your real friends are, and who are the schmucks.)

Of course, if any of those folks are still around, they will deny that is what happened, and why they booted me. Easy to do, when you write the history book. But, that is why.

It has nothing to do with my rantings on jitter.

So..............to those who think otherwise.................

Yerz aal a bunch o' reet coonts, yerz are, ya pooftahs.

"Jocko, does this mean that you are really a Geordie, and not an eye-tie?"

Nae, man. It jes cood mean ays an eye-tie wut lived wi' the Geordies, at one time, man.

Or not.

Or maybe it was my bidnis partner who was the Geordie.

Or not.

Yerz caan all fack reet ooff. An' Sunderland, too. Ay. Toon Army!

"But, Jocko, the Geordies, and all of the Tyneside, are a bunch of Labour Party drunks. Maybe you should have lived in Maidenhead, instead."

Aye, lad. Maybe.

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PostPosted: Wed Jun 21, 2017 2:17 am 
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Goat

Joined: Mon Nov 28, 2005 1:10 pm
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Jocko Homo wrote:
Yeah, let's talk about why I was banned. (Hint: it had nothing to do with "he doesn't know what the hell he is talking about.")
There´s no need to say this. I think all the people in this forum and most people in that other forum have always known that you are very knowledgeable and sound Jocko Sir.


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PostPosted: Fri Aug 11, 2017 12:50 am 
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Sheep

Joined: Wed Apr 13, 2005 11:21 pm
Posts: 24
Hi Jocko,

I am not sure why you pay so much attention to what people write, especially at the pub… Everyone half-serious about doing DIY things right comes to this place anyway. Your posts (I think they should be called Jocko’s white papers) have an immense influence to those willing to read and listen, in particular in the area of S/PDIF transmission line theory, low phase noise crystals and influence of vibrations and temperature/air disturbance principles. All this supported with the hard fact and measurements.

Your impact in a DIY community, and more broadly – to High-End sound reproduction, has reached the point where you have left the clear mark and made the difference.

I am gratefully for your input and suggestions.

Nick


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PostPosted: Sat Aug 12, 2017 2:50 am 
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Benjamin
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Extreme_Boky wrote:
Hi Jocko,

I am not sure why you pay so much attention to what people write, especially at the pub…


Why? Because more than DIYers read this stuff.

While I am mainly retired, I do get inquiries, of a commercial nature, from folks (unknown to me), wanting "us" to do work for them. From reading the various forums. Even when I am not doing anything, other than doing nothing! (Yes, it surprises even me.)

When I say "us", I am referring to "bidnis associates" (none of whom you guys know, so I am obviously not talking about Phred), so when they slag me, they are also taking a swipe (indirectly) at my cohorts.

None of us appreciate that. And since some of the worst kvetchers are also "consultants", well, I kinda sorta think some word gets around that we are unstable and unreliable.

Quote:
Everyone half-serious about doing DIY things right comes to this place anyway. Your posts (I think they should be called Jocko’s white papers) have an immense influence to those willing to read and listen, in particular in the area of S/PDIF transmission line theory, low phase noise crystals and influence of vibrations and temperature/air disturbance principles. All this supported with the hard fact and measurements.


I appreciate your comments, but the constant push-back, by the Masters of the Universe, can not be allowed to stand. Just because they are "experts" in one aspect of technology, or have more (or fancier) educations doesn't mean they are 100% correct, all of the time, in all manners. They just think so.

We all are tired of it. Snide remarks like "well, we don't know who this guy is and if we can believe his measurements" are not slander, but definitely not welcome. Not to mention incorrect. (OK, they really don't need to know who I am. That is a moot point.)

To them, it is just anecdotal nonsense. They could do all the same work, but guess what....................it takes a lot of time! So, they are not willing to invest the time (or money), and we are. But, we are the idiot losers, who are not to be taken seriously.

Quote:
Your impact in a DIY community, and more broadly – to High-End sound reproduction, has reached the point where you have left the clear mark and made the difference.

I am gratefully for your input and suggestions.

Nick


Thanks, but I am afraid that you are in the minority.

Just as an aside, some of the same applies to "T". We don't agree on a lot of things, but it is probably safe to say we respect each other. We both get results, doing vastly different things, and while we occasionally quibble over minor details, we can do so in a semi-professional manner.

Compare that to the other "experts". Some of who are not even "experts", but just spurts!

All for now...................I think.............


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