Objective-Fi Optical Networking & SFPs

[fas42]

7 hours ago, cat6man said:

 

So let me put down a friendly challenge.  In the interest of being 'objective' and not 'subjective' in this sub-forum, how about a sub-sub-group interested in getting to the bottom of this technically and not just acting like my old 'arrogant PhD' colleagues who already knew all the answers (but had oversimplified the situation and therefore hadn't formulated the problem accurately)?

 

This will be my last shot at trying to see if anyone else is interested in approaching this in a similar manner to my current way of thinking.  I'm not interested in debating  philosophy of testing and will not reply to such.  Anyone want to try to figure out what is going on here?

 

 

Go for it ... 🙂.

 

The overall answer for "what is going on" is that electrical noise from a variety of sources internal and external to the rig impacts the analogue areas of the replay chain; just enough to be audible - this was true 3 decades ago, and is just as true, still, right now. Doesn't matter that the music player is "right over there, way, way from the sensitive stuff!!" ... nasty stuff gets around with the greatest of ease, and your challenge, should you choose to accept it 😝, is to track down and nail every last one of these pathways for the SQ to be degraded by interference mechanisms.

 

The precise, technical explanation for what's going on in a particular setup would be handy to know - but ultimately far less important than knocking the relevant interference pathways on the head ... 😉.

[fas42]

6 hours ago, cat6man said:

 

i accept!

 

and while the precise technical explanation may be hard to elucidate, why isn't the result measurable at the DAC output?

whatever the exact mechanism may be........

 

is it our inability to measure transient and/or peak distortions at a low enough level?

 

What matters is what our ears hear - the tiniest, tiniest variation in electrical activity is guaranteed to make the output of a DAC change to some degree; measuring something happening there is highly likely useless in terms of explaining what our minds are perceiving. And the next complication is that integrated playback systems no longer have a DAC to measure - a digital speaker has that part of itself buried inside. The only useful method is to capture what the speaker is producing, and compare before and after versions of its output.

 

Until very recently we had no decent mechanism to do that comparison ... luckily our able member Paul, @pkane2001, has created some software clever enough to sync the two microphone recordings, and hopefully show something useful. I did an exercise some years ago, examining a YouTube video of a percussion group playing, and a supposedly high end rig reproducing an earlier recording of the same piece - sounded very different, and it was trivially obvious why in the waveforms: the treble of the speaker output was miles from being right ... there are no mysteries, if you look at the right things, 😉.