RF Attenuators = Jitter Reducers

[jkeny]

........One of the posters (who seemed quite focused on gigahertz) pooh-poohed the Chinese unit I was using because of a slower rise time than the expensive jkeny-modified Hiface, but the system locks, data is accurately transferred to the DAC, and frankly, the square waves look a whole lot less cluttered.

No, what George said was that the Chinese unit had a slower rise time & that's why the SPDIF wave looks cleaner - faster rise time will be less forgiving of impedance discontinuities & give rise to reflections, hence the cleaner looking waveform

 

[SY]

You might want to re-read the stuff you just quoted, John.

 

[jkeny]

How about you correct me!

 

[SY]

Start by changing "no" to "yes."

 

[wakibaki]

@stormsonic

So your position is that RF attenuators produce an improvement in ANY SPDIF interface as long as the DAC doesn't fail to lose lock? That users should load their connections with as much attenuation as doesn't cause them to fall over. Or perhaps you have another suggestion as to how the exact amount of attenuation to be applied should be determined by naiive users? Oh, that'll be a listening impression, won't it?

And you're going to be the one to post a screenshot of the analog output showing an improvement in the jitter. Great. Which I presume you've been withholding up until now because you find it entertaining to watch us squabble amongst ourselves.

I notice you didn't repeat your suggestion about the 100pF capacitor. No, because if it was in series the input would appear as open circuit, and there's no good reason for having one in there in shunt.

OK, you have the floor. Put up or shut up.

w

 

[jkeny]

Yes, I'm fairly familiar with the Fourier decomposition of square waves, Gibbs and all that, but what bandwidth do you need to transmit spdif? One of the posters (who seemed quite focused on gigahertz) pooh-poohed the Chinese unit I was using because of a slower rise time than the expensive jkeny-modified Hiface, but the system locks, data is accurately transferred to the DAC, and frankly, the square waves look a whole lot less cluttered.

What he told you was why you had a reasonably reflection free SPDIF waveform from the Chinese unit - something you obviously still fail to grasp from the above quote.

The difference is that Your cheap Chinese transmitter is having a rise time at about 6nsec. That is ~58MHz equivalent bandwith.
The hiface driver is having 1.5 nsec rise time in reality. (measured by me on 6GHz, 3,5GHz, 2GHz analog bandwith scopes)
Pardon, the most recently tested unit had less than 1nsec rise time. The older one is 1.5nsec.

At this speed (1.5nsec > ~250MHZ, 1nsec >350MHz ) your test setup has to be much more refined so as not to cause reflections. This is the difference what You see.

 

[SY]

something you obviously still fail to grasp from the above quote.

Only if you don't actually read what I wrote.

 

[wakibaki]

And we're back to quoting Joseph K.

The same Joseph K who didn't mind putting up a load of screenshots that he thought would convince people with no technical expertise but when asked to provide evidence of a test acceptable to you, jkeny, found it was suddenly too much trouble.

w

 

[wakibaki]

@stormsonic

Oh, and if you think quoting that trick circuit with the amplifier makes a blind bit of difference to your case, think again. It's not typical.

w

 

[stormsonic]

@waki

will quote Joseph K again

You are welcome, Mr. Wakibaki.
Was a pleasure to serve You well!

 

[wakibaki]

Thanks, where's the screenshot?

w

 

[wakibaki]

I did not put up here the Hiface driver, because:
-I do not intend to discuss about it's output waveform

So what the hell does that mean if not that he's talking about the generality of other (DAC) waveforms? And if he does intend it to be representative only of the HiFace as he later asserts, and what we're looking at is a language problem, then HE doesn't agree that the attenuators are appropriate in the generality.

w

 

[Pano]

Wow! This really is going around in circles.

 

[wakibaki]

Circles, yeah. Love 'em. Here's the trick:

Keep your eye on the ball.

w

 

[wakibaki]

Still no sign of any evidence from stormsonic. I think he's gone off for a consultation with Jocko Homo. Or maybe he IS Jocko Homo...

w

 

[jkeny]

Wow! This really is going around in circles.

Yes, Pano, it was at this point that you closed down my other thread after I posted the following: http://www.diyaudio.com/forums/ever...easurements-show-not-show-14.html#post2267208

Appreciate your clarity! I'm saying I will submit the unit to testing - eye patterns, etc - tests which have some chance of showing that there is a difference between stock & modified. I will not submit it to a test that nobody is willing to stand over & that has so many variables as I listed above.

My reluctance is because I don't believe the test has validity for al the reasons I mentioned. If people then accuse me of "having my bluff called" or being scared of the truth then I don't find them credible. If people keep pushing for this test & yet won't produce evidence of it's validity & then claim that I am dodging & avoiding, I distrust their credibility.

I have offered to provide units, preferably to somebody in EU (for customs reasons) to perform listening & eye pattern tests or indeed full blown jitter tests if they have the equipment. How these results translate into audible sonics is a whole can of worms & not something that anybody here has been able to provide examples of!

It seems that we have really not advanced any & those words were prescient!

 

[woodturner-fran]

No doubt Jocko is laughing his head off making snide comments about us all.... that would include all....

Look, Pano. you might as well lock this thread. Its gone nowhere for the last 20 pages.


This whole thing comes down to 2 sides of a fence.

Side 1. Measurements show everthing, it doesn't exist if its not on a scope
Side 2. measurements are useful, but I prefer to use my ears as well.


with all the bickering back and forth that follows those basic positions. Your ears are biased.... no, your measurements are rubbish and so on and so on and so on and so on and so on and so on and so on and so on and so on and so on and so on and so on and so on v v v v

oh, sorry forgot to keep pressing the ctrl....

An externally hosted image should be here but it was not working when we last tested it.

 

[SY]

Third side- anyone with even a shred of morality who is offering a gadget claimed to improve sound should have data (like controlled listening) to back it up.

 

[jkeny]

Third side- anyone with even a shred of morality who is offering a gadget claimed to improve sound should have data (like controlled listening) to back it up.

Ah, jeez, man just listen to the thing with a decent playback system & there's no doubt. Anybody who doesn't think it is worth the money gets their money back. Don't try talking about morality, SY - it's a bit too comical !

 

[SY]

I'm not the one hawking gadgets. If the effects are so obvious, let's see the listening test procedure and data rather than one anecdote after another, with more than a little defensiveness.