Optical vs USB

[rueyloon]

hello

hi, I noticed that some amps offer the connection of either USB or Optical.
How does it differ ?

I understand that through USB I'll be using the DAC on the "receiver" end, so what about optical ? won't the signal be already processed by the "sender" ?

rgs
rueyloon

 

[m1abrams]

Quote:

Originally Posted by rueyloon /img/forum/go_quote.gif hello hi, I noticed that some amps offer the connection of either USB or Optical. How does it differ ? I understand that through USB I'll be using the DAC on the "receiver" end, so what about optical ? won't the signal be already processed by the "sender" ? rgs rueyloon

optical will still be digital so it still needs a DAC

 

[I3eyond]

What headphones will you be using?

 

[scootermafia]

Most people say that the optical output of a computer like my Macbook Pro sounds much better than the USB output. Both have to be converted from digital to analog. I only use a DAC accepting an optical input - I don't trust USB.

 

[krmathis]

Quote:

Originally Posted by rueyloon /img/forum/go_quote.gif hello hi, I noticed that some amps offer the connection of either USB or Optical. How does it differ?

Different interfaces and input connectors. Which also mean that the source will need to have a corresponding output option.

Quote:

I understand that through USB I'll be using the DAC on the "receiver" end, so what about optical ? won't the signal be already processed by the "sender" ?

It will use the DAC either way. As both USB and optical are digital, and need to be converted to analog.

 

[gadgetman]

2 more downers: (may be minor, depending on your setup)

1. USB consumes more CPU cycle than the optical out
2. You'd be using (some of the) USB bandwidth if you need to share it with USB drives and accessories.

 

[jonjungel]

In general, USB has much more jitter than optical. Jitter is random variation in the timepoint at which new data arrives. Correct data at the wrong time equals incorrect data at the right time, resulting in a lower signal-to-noise ratio. Stereophile has done many measurements on DACs with both USB and S/PDIF input, and USB has consistently worse jitter performance. Many results are available on stereophile.com.

A bit about jitter: Jitter - Wikipedia, the free encyclopedia

 

[vvanrij]

^ above statement and others are missing a very important point imo. The digital sound is already being converted to a optical one, and then needs to be 'received' by a optical sensor. The device (for instance soundcard) converting it into the 'optical' signal, is also quite capable of making errors etc. If you go through the usb, the data is transferred 'as is', and then being processed by your high-end dac

. Offcourse if you have a good SPDIF convertor, then this will have no effect.

 

[linuxworks]

Quote:

Originally Posted by jonjungel /img/forum/go_quote.gif In general, USB has much more jitter than optical. Jitter is random variation in the timepoint at which new data arrives. Correct data at the wrong time equals incorrect data at the right time, resulting in a lower signal-to-noise ratio. Stereophile has done many measurements on DACs with both USB and S/PDIF input, and USB has consistently worse jitter performance. Many results are available on stereophile.com.

that's not the ONLY opinion, though.

my view is that ALL usb dacs these days reclock JUST FINE. jitter does not exist on a usb cable. timing does NOT EXIST on a usb cable.

the dac is the master clock and IT determines jitter in the sound. not the cable, not the host, not the usb system, nothing on the pc determines clock. the usb device IS THE SOURCE.

so much misinformation.

USB AUDIO IS JUST FINE. it is not inferior to spdif. both are equivalent and both have local clocking to avoid jitter 'issues'.

stop arguing about theory that you probably don't understand. jitter on usb is a red herring.

 

[Quaddy]

Quote:

Originally Posted by jonjungel /img/forum/go_quote.gif In general, USB has much more jitter than optical. Jitter is random variation in the timepoint at which new data arrives. Correct data at the wrong time equals incorrect data at the right time, resulting in a lower signal-to-noise ratio. Stereophile has done many measurements on DACs with both USB and S/PDIF input, and USB has consistently worse jitter performance. Many results are available on stereophile.com. A bit about jitter: Jitter - Wikipedia, the free encyclopedia

the complete opposite is true.

you will always get a more analogue sound with USB, none of the harsh digital sound associated with optical/spdif, also it doesnt carrry the baggage of internal coding along with the music stream like spdif, so is more efficient with less overhead, which could manifest itself in jitter to some degree.

 

[vvanrij]

Yup, totally agree with this!

 

[wizia]

Is it true that USB can cause some performance troubles when using it through a computer? I mean, I will be using my HP for games as well so this is relatively important.

 

[linuxworks]

Quote:

Originally Posted by wizia /img/forum/go_quote.gif Is it true that USB can cause some performance troubles when using it through a computer? I mean, I will be using my HP for games as well so this is relatively important.

interrupts should be about the same.

to keep spdif 'going' and to keep usb 'going' is a wash. both are low speed 'easy boring yawn-able' protocols.

computers can keep 10/100 ethernet going and not break a sweat. usb audio or spdif is 1/10 the speed of THAT (or slower, even).

a pentium-2 computer could 'do audio' and not really even struggle.

don't worry

 

[chris_ah1]

TBH I've had more problems with USB than optical, especially on slower machines and laptops. USB at high cpu load does not work as nicely as optical and can crackle. I've never had a problem with optical...and that's in comparison to not just USB but also the pitiful digital out via flexijack of X-fi cards!

 

[linuxworks]

if you have interrupt problems, you have a mistuned system.

my laptop from 15 yrs ago (again, a pentium 2/700 machine!) can EASILY and with NO SWEAT keep usb happy and do other things. I don't game but we are not talking about that!

your system is messed up or you have too much bloatware.

or are you are running windows

its very possible to have misconfigured audio on windows.

try latest ubuntu and live cd just to TEST your hardware. I'm 99% sure you won't get crackly audio on linux with usb. that will prove its NOT the hardware and its entirely the broken o/s that is at fault, here.