tls Wrote: 
> It can't possibly have anything to do with "power line conditions" since
> the power input to the Squeezebox is DC, not AC.  "Power line
> conditions" impacting time sync is -- and I do know a little bit about
> this, since one thing I used to do for a living was design digital
> carrier circuits for a telco -- something that went the way of the
> dinosaur with the General Electric 60Hz electromechanical alarm clock
> many of us had by our bedsides as kids. ;-)
> 
> I'm more than a little surprised that the units can't keep tight sync
> over the course of a song.  They have an accurate oscillator of more
> than sufficient frequency available to drive the digital output -- if
> they didn't, it would have fierce bit sync problems, bad enough to be
> audible as glitches.  Perhaps the digital output IC they use doesn't
> expose this clock to the rest of the system, or perhaps the rest of the
> hardware design doesn't allow its use to keep frames in sync during
> playback.
> 
> Temperature variations would make sense except that my two units are in
> adjacent rooms.  Basically, I have to ask "just how crappy are the
> system clocks on these devices, anyway?" since you'd need a *really*
> bad oscillator to slip by half a second over the course of a few
> minutes, which is what I'm seeing.


Ah, good point about the power-line stuff.  I'm not an electrical
engineer so I really am not able to comment any more about this
intelligently.  I agree that the slippage seems surprising.  It'd be
interesting to hear from Sean on the matter.

Here's a crazy thought--are you running different VU effects on the two
units?  I wonder if the processor load could have anything to do with
it?  I don't have any idea how these things are designed or programmed
at a low level, so someone more knowledgable than I might come along
and be able to definitively say that there's no way for the processor
load to affect the audio data being output.  But as a lay observer it
seems like a potentially plausible explanation.


-- 
azinck3
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