[LAU] hardware - Intel CPUs

[Gene Heskett]

On Wednesday 16 April 2014 08:44:15 david did opine:

> On 04/15/2014 03:17 AM, Len Ovens wrote:
> > On Tue, 15 Apr 2014, James Mckernon wrote:
> >> On Mon, Apr 14, 2014 at 2:06 AM, Len Ovens <len at ovenwerks.net> wrote:
> >>       I would realy like to stay away from having to use a USB or FW
> >>       audio IF. In fact I would like to be able to continue to use my
> >>       delta 66 for as long as I can before I spend more money :)  The
> >> 
> >> Thanks for the useful info in your post. Just to be clear on this
> >> part: are
> >> you saying you don't want to switch to USB/FW solely because you want
> >> to keep using your delta 66, or because you have some definite
> >> preference for
> >> PCIe over USB/FW devices? If the latter, I wonder why?
> > 
> > USB in audio is limited. Getting clear USB ports interrupt wise is not
> > easy. Audio can not be on a hub or share it's usb with anything else,
> > but many new MB have no mouse or kb port so the USB is already being
> > used for that much. The real reason though, is latency. With the pci
> > the latency can be 1/4 what it can be in USB or FW. That is the
> > lowest seeting jack for USB or FW is 64/2, but I can run the d66 at
> > 16/2 with no problem on a well tuned system. This does make a
> > difference for live work. I know that 64/2 seems like very good
> > latency (it is) but remember that the card then adds another ms in
> > each direction as well as the stage distances on top of that. That is
> > the time it takes the sound to reach my ear after going through the
> > computer as a processor and then through the air to my ear. Maybe
> > that is still not worth worrying about... but even with 30 feet of
> > cord and no digital delay, I can hear the delay from my playing to
> > the sound reaching my ear.
> 
> Interesting. What is the difference between speed of sound in air and
> the speed of electricity through a cable?

Sound is nominally 720 miles per hour. Rather leisurely IOW.
A perfect cable is C speed, 258 times faster.  But cable (coaxial) actually 
range in speeds between 66% of C for home usable cables, to around 98% of C 
for 9" diameter high power broadcast stuff, C being 186,272 miles per 
second in a vacuum.  Thats 298,035.2 kilometers per second for the metric 
folks here.

> I think the lowest I've had my UCA-202 (USB 1.1) card work at was around
> ~3msec latency (on a USB2 port) with a Debian RT kernel just fooling
> around (no other RT optimizations on this 2.4GHz i7 laptop). I've had
> Yoshimi problems when latency gets too low on my stock kernel. And when
> I first tried Zyn, it had problems at much higher latencies than Yoshimi
> did at the time.
> 
> But I haven't done much music stuff with my new laptop.


Cheers, Gene
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