seanadams wrote: 
> Just to clarify I was talking about AES/EBU _in general_. There's
> nothing wrong with how I did Transporter's AES/EBU output. The interface
> is defective by definition, and therefore not possible to execute
> reasonably by anyone.

Hope no one is upset I found this old thread and dredged it back up!

Too bad Sean is not around here these days. You will note what he
said..................."The interface is defective by definition, and
therefore not possible to execute reasonably by anyone."

Yeah, it is! Which is too bad. By using a balanced cable, it could have
been better than plain ol' SPDIF. Especially when some jerks down in
Texas try to isolate things with a transformer, which makes the shield
"hot", and..................well, it isn't the best approach, but it
works. But, they (AES et al) messed up. (In fact, the original version
was MUCH WORSE. I had a long phone conversation with the guy who headed
up the AES working group on that, and without ever seeing an
implementation of it, I 'splained to him what was obviously wrong with
it. I can only imagine the look of horror, on his face, as I told him
what was wrong and why. Funny thing is.............................less
than a year later, they came out with a new version of it! With all of
my suggestions. Too bad I didn't nail him down on the output voltage,
and some of the other dumb things that were in it. Just goes to show how
hard it is to make things idiot proof when the idiots are so dang
ingenious. And the worst piece of gear I ever saw, with AES/EBU outputs
came from Philips! And cost several grand. Go figure. Guess they never
thought putting DC on the output would be a problem. Worked for them, as
it was designed to go with something that needed DC on the
output........................oy vey.)

OK, where was I?

Ok, TOSLINK..............

A few years back, I measured the "jitter" of the old Toshiba TOSLINK
parts, and compared them to the flavor-of-the-month Chinese brand. Since
someone paid me to do this, I can not share the details. But, I can give
you a rough idea.

All of them have a very high noise floor. That is the part that gives
the "jitter number". (See other posts on why that number is useless.)
The Toshiba is a bit better. The FOTM Chinese one performed better if
you used the "high-speed" one. You could see the effects caused by using
a crappier phototransistor in the regular speed one. It was bad. And
right where you should expect a noisy transistor to have noise.

In all cases, all of the "jitter" contribution was caused by the noise
floor. IOW, they DID NOT affect the "close-in" jitter, which is what is
really important. (No, I am not going to into that. I have done so
numerous times over the last decade or two, and I am not going over it
again. If it annoys you, keep it to yourself. I am not interested in
hearing why you think I am wrong.)

The fact that none of these methods (SPDIF, AES/EBU or TOSLINK) do not
totally wreck the sound, even though they are  highly flawed and have a
ton of problems, is because it does not do anything to the signal in the
most critical region. IOW, down around 1 Hz, and lower.

And back to the question of return loss..............

Yes, it does make a difference. I find it odd few ask about it. I'll
just add if you get the return loss of the source, the cable and the
receiver all correct (iow, below a certain level we put a lot of work
into figuring out what that number is), then guess what?

They all sound the same. Which would put a lot of cable companies out of
bidnis. Where would this industry be without something to sell the
punters that will make their system sound "different"/"better"?

Peace. Out.



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