External clocks and lag?

[Mister Crash]

If an external clock is hooked up to a transport + DAC system, how much lag is introduced by the external clock reclocking the data? In other words, if an external clock is in place, and there is a disc is playing in the transport with the display showing 04:30 (exactly), is the music that comes through the speakers/headphones the same as the music that would be coming through if the external clock was not there and the transport showed 04:30 (exactly)? If not, about how much lag does the clock add? Any ideas?

 

[nick_charles]

Quote:

Originally Posted by Mister Crash /img/forum/go_quote.gif If an external clock is hooked up to a transport + DAC system, how much lag is introduced by the external clock reclocking the data? In other words, if an external clock is in place, and there is a disc is playing in the transport with the display showing 04:30 (exactly), is the music that comes through the speakers/headphones the same as the music that would be coming through if the external clock was not there and the transport showed 04:30 (exactly)? If not, about how much lag does the clock add? Any ideas?

If you have another component in the link i.e

Transport.......clock.....DAC instead of
Transport.......DAC

Then you have two things adding a lag. One is the effect of the extra cable and you can calculate this from the speed of electrical propogation and the length of wire. The second is how the clock deals with the signal it gets. One of the members here audioengr (Steve Nugent) runs Empirical Audio. I think he makes reclocking devices, you could ask him. My guess is that it depends on how much data is buffered.

 

[Herandu]

The length of the track of 3:40 on the display won't change. That's the duration of the track. It has nothing to do with reclocking.
If your DAC need an external clock to operate properly and accurately, then consider getting a better DAC. My Rolex is not as accurate as my Timex, so I don't use the Rolex when timing accuracy is an issue.

 

[Mister Crash]

The reason why I asked this question is because I use my DAC for more than just my audio system. I play a fair number of video games, many of which are timing-sensitive (Beatmania, Pop'n Music, Guitar Hero, etc.). I currently run the digital output from my game systems into an external DAC. As it stands right now, there are no issues with my timing in these games. However, if my TV had even one frame of lag (~30 ms), my timing would end up being wildly off. I learned this when I went shopping for HDTVs and brought my game system with me. Of the ten HDTVs I tried out, only two had small enough lag for me to consider buying them.

Currently, I am looking into upgrading my source, and am considering the possibility of using a transport/DAC/clock combination. I will still run my games through the DAC, but wasn't sure if I could take advantage of the clock as well. If the clock introduced lag of more than a millisecond or so, then it wouldn't make sense for me to try to use it with the game systems (though I would still want to use it with the transport).