mike86325 Posted December 15, 2014 Share Posted December 15, 2014 I'm thinking about buying a longer USB cord (16 ft as opposed to our 6 ft one), but wondering if this might introduce any latency. I know that USB extenders, hubs, etc have a tendency to cause latency or other issues, but I'm wondering if just having a longer cable will be OK. If anyone has already given this a shot please let me know. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
pfsmith0 Posted December 15, 2014 Share Posted December 15, 2014 I use a very long cable as well for the SPDIF connection and noticed no latency. Time delay thru a cable is roughly 2ns/ft or less, so latency due to cable delay will be negligible. The biggest problem will be whether or not your system can drive a cable that long. It should if it meets spec. 1 Quote Link to comment Share on other sites More sharing options...
pianoguyy Posted December 15, 2014 Share Posted December 15, 2014 of course a longer cord will cause delays. everybody knows this. The question is -- how much delay. As pfsmith said, 2ns/ft. Does it really matter? Quote Link to comment Share on other sites More sharing options...
joel_brown Posted December 15, 2014 Share Posted December 15, 2014 No change in latency. We're talking a difference of nanoseconds, which is well below anything humanly detectable. Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted December 15, 2014 Share Posted December 15, 2014 As long as the USB interface still works, you are fine. You will eventually reach a length where it is no longer reliable. USB is a packet interface so latency is not purely a function of wire length. Additional latency will not be an issue with a longer cable. Quote Link to comment Share on other sites More sharing options...
BucF16 Posted December 15, 2014 Share Posted December 15, 2014 John Petrucci would notice it... Quote Link to comment Share on other sites More sharing options...
pianoguyy Posted December 15, 2014 Share Posted December 15, 2014 John Petrucci would notice it... so would an audio tape if you were recording it. Quote Link to comment Share on other sites More sharing options...
Rewolf48 Posted December 16, 2014 Share Posted December 16, 2014 Tell John to move his head 0.0000135" closer to the speaker then. Quote Link to comment Share on other sites More sharing options...
BillBee Posted December 16, 2014 Share Posted December 16, 2014 Haaaaa haaaaaa love it! :P Quote Link to comment Share on other sites More sharing options...
silverhead Posted December 16, 2014 Share Posted December 16, 2014 Tell John to move his head 0.0000135" closer to the speaker then. I trust you used the speed of sound, not light, in this calculation? Also, perhaps John should wear a neck brace to avoid whiplash during this manoeuvre. ;-) Quote Link to comment Share on other sites More sharing options...
Rewolf48 Posted December 16, 2014 Share Posted December 16, 2014 :) Sound travels 1,129 ft/s (Wikipedia) which is 13.548 inches per millisecond, roughly varying with pressure, temperature and humidity. Millisecond to nanosecond is divide by 1,000,000. 2ns/foot as pfsmith0 says is a typical speed for a electromagnetic wave down a conductor (which is between 40% and 70% of the speed of light) So my figure is only for the delay of 1ns caused by an additional 6" of cable, but I was rushing a bit. The 16' chord is 10' longer than the 6' chord so adds a 20ns delay, which is the equivalent of moving the head just 20 x 0.0000135 = 0.00027 inches further away. Yes, technically the extra cable length does increase latency, but by an amount that would only be noticeable when examining the waveforms on an oscilloscope (sound at 1K has a wavelength of over 1'). I practice we are talking digital sound, and at 96K sample rates each sample covers 0.0000104167 of a second, and 20ns is 0.000000020, so you would need over 5000' of cable to delay the signal by even 1 sample. Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted December 16, 2014 Share Posted December 16, 2014 USB input delay is swamped by the digital processing of it. All of this BS here applies to analog signals. Quote Link to comment Share on other sites More sharing options...
BillBee Posted December 16, 2014 Share Posted December 16, 2014 But this one goes to 11. :ph34r: Quote Link to comment Share on other sites More sharing options...
Rewolf48 Posted December 16, 2014 Share Posted December 16, 2014 USB input delay is swamped by the digital processing of it. All of this BS here applies to analog signals. The discussion is about potential latency from a longer USB cable which like all communications signals carries an analogue signal that encodes the digital signal. There is no such thing as a 1 or a 0 over a bit of wire, there are voltage thresholds over and under which the voltage being received is interpreted as being a 1 or a 0. As I said at the end, you have to go over 5000' before you get a single audio sample of delay and I'm not carrying that cable in my gig bag. Quote Link to comment Share on other sites More sharing options...
BucF16 Posted December 20, 2014 Share Posted December 20, 2014 John Petrucci hears notes before they're even played. https://www.youtube.com/watch?v=23i8BzhxCy8 Quote Link to comment Share on other sites More sharing options...
Brazzy Posted December 20, 2014 Share Posted December 20, 2014 The discussion is about potential latency from a longer USB cable which like all communications signals carries an analogue signal that encodes the digital signal. There is no such thing as a 1 or a 0 over a bit of wire, there are voltage thresholds over and under which the voltage being received is interpreted as being a 1 or a 0. As I said at the end, you have to go over 5000' before you get a single audio sample of delay and I'm not carrying that cable in my gig bag. That's a long run for a cable. What is that just short of a mile. Lol Quote Link to comment Share on other sites More sharing options...
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