[Mehve]

Quote:

Originally Posted by Andrew_WOT /img/forum/go_quote.gif This noise is the result of ground loop, USB cable in spite of toslink creates electrical connection between computer and external USB audio device, depending on that device PSU implementation that may close the ground loop. Two prong cheater adapters, ground loop isolators or even better Hum-X solve this problem completely.

Are you talking about a DAC getting its data via toslink, but power via USB? I wouldn't think any decent DAC would settle for anything less than getting its power from the wall.

 

[Andrew_WOT]

Quote:

Originally Posted by Mehve /img/forum/go_quote.gif Are you talking about a DAC getting its data via toslink, but power via USB? I wouldn't think any decent DAC would settle for anything less than getting its power from the wall.

No, I was talking about USB used to feed data, some DACs (e.g. Pico) take power from USB too. But regardless there is an electrical connection (ground) between two that makes ground loop to close. Toslink on the other hand is dielectric and breaks that circuit.

 

[Mehve]

Quote:

Originally Posted by Andrew_WOT /img/forum/go_quote.gif No, I was talking about USB used to feed data, some DACs (e.g. Pico) take power from USB too. But regardless there is an electrical connection (ground) between two that makes ground loop to close. Toslink on the other hand is dielectric and breaks that circuit.

That's what I would say too. But the way your earlier post was phrased, you made it sound like a toslink connection still had an electrical connection between the devices, which didn't make much sense to me.

 

[Duggeh]

Quote:

Originally Posted by Andrew_WOT /img/forum/go_quote.gif This noise is the result of ground loop, USB cable in spite of toslink creates electrical connection between computer and external USB audio device, depending on that device PSU implementation that may close the ground loop. Two prong cheater adapters, ground loop isolators or even better Hum-X solve this problem completely.

How does a mechanical hard drive create a ground loop?

 

[audioengr]

Quote:

Originally Posted by plonter /img/forum/go_quote.gif i have a question: what about jitter..? does usb jacks (and usb interface in general) produce more jitter than optical or coaxial ? if the answer is yes, than reducing the jitter amount to minimum (with cables or with certain computer/motherboards configurations, can improve the sound in computers.

There will be small differences in jitter from a PCI card outputting S/PDIF versus USB interface on a given computer, but it will probably be dominated by the overall clock jitter of the computer. There is probably more difference from one type of computer to the next.

Different USB ports will often have differences in latency depending on the internal controller structure and hierarchy, but usually the jitter is about the same IME.

Steve N.
Empirical Audio

 

[Duggeh]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif There will be small differences in jitter from a PCI card outputting S/PDIF versus USB interface on a given computer, but it will probably be dominated by the overall clock jitter of the computer. There is probably more difference from one type of computer to the next. Different USB ports will often have differences in latency depending on the internal controller structure and hierarchy, but usually the jitter is about the same IME. Steve N. Empirical Audio

Could we please see the measurements you have behind those claims and the context in which they were taken?

 

[Andrew_WOT]

Quote:

Originally Posted by Duggeh /img/forum/go_quote.gif How does a mechanical hard drive create a ground loop?

This is not what was said. The ground loop is created by USB connection to external audio device, mechanical drive just makes noise that gets picked up via that loop.
Some basics on ground loop

 

[gevorg]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif Different USB ports will often have differences in latency depending on the internal controller structure and hierarchy, but usually the jitter is about the same IME. Steve N. Empirical Audio

Why should we care about minor changes in latency? We're not recording audio here, just listening.

 

[Currawong]

Quote:

Originally Posted by gevorg /img/forum/go_quote.gif Why should we care about minor changes in latency? We're not recording audio here, just listening.

If makes a difference to your system that's important to you, then you should care. If that doesn't matter to you, then you shouldn't care. Simple.

 

[gevorg]

Quote:

Originally Posted by Currawong /img/forum/go_quote.gif If makes a difference to your system that's important to you, then you should care. If that doesn't matter to you, then you shouldn't care. Simple.

Important not to have a ~1ms delay before your song start? Computer Audio must have achieved a new highpoint in performance if there are people who "care" about these things.

 

[audioengr]

Quote:

Originally Posted by gevorg /img/forum/go_quote.gif Why should we care about minor changes in latency? We're not recording audio here, just listening.

Latency differences can cause pops and ticks or even stalls, even when using Async USB interface or Firewire interface.

Steve N.
Empirical Audio

 

[Duggeh]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif Latency differences can cause pops and ticks or even stalls, even when using Async USB interface or Firewire interface. Steve N. Empirical Audio

Could we please see the measurements you have behind your claims and the context in which they were taken?

 

[shamu144]

Duggeh, since you seem so knowledgeable, would you mind sharing with us your protocols and scientific measurements to come up with your conclusions ?

 

[Duggeh]

I didn't make conclusions based on testing. I stated facts. The USB spec sheets are freely available here. All devices make to work to those specifications are USB compatible. Those not made to compatible spec may have issues. I will not reiterate my previous points regarding compatibility. The issue relating to single bus power, as was patently obvious from my post, came from my own personal experience with a particular situation.

Additionally, I am not a MOT in the business of selling cables. Empirical Audio are. As such, claims made should be substanciated, if there is no evidence for claims made by manufacturers then those claims, from any company, scientific though they may often sound, are no different that claiming that their product is superior because it uses magic dust harvested from the wings of organically grown pixies.

Please don't miscontrue me. I'm not trying to slander what has been claimed. But it is a claim that is best served by some means of verifiction.

 

[Duggeh]

Quote:

Originally Posted by Andrew_WOT /img/forum/go_quote.gif This is not what was said. The ground loop is created by USB connection to external audio device, mechanical drive just makes noise that gets picked up via that loop. Some basics on ground loop

Ah, with you. I got the wrong end of the stick.

Quote:

Originally Posted by Andrew_WOT /img/forum/go_quote.gif This noise is the result of ground loop, USB cable in spite of toslink creates electrical connection between computer and external USB audio device, depending on that device PSU implementation that may close the ground loop. Two prong cheater adapters, ground loop isolators or even better Hum-X solve this problem completely.

Is this is the same ground sharing problem which is causing potentially catastrophic problems because of the bad design of the Ray Samuels portable Amp/DAC. You get hum on interconnection because of the ground loop, same as you can end up with DC into the voice coil of a headphone from an amp out?