Robin,
What difference do you hear?
Without launching off into audiophile rambling about 'inner detail' and 'timbre'. The dpa just sounded more realistic, detail was easier to hear and transients (i.e. drum strikes) had more impact whilst the squeezebox sounded muffled in comparison.
That sounds like classic symptoms of jitter - smearing of the transients.
> I'd have no qualms about trying to discern the
differences in a double blind test and I'd be pretty damn confident that I'd
be able to get a statistically significant result telling the two apart. To
give myself a bit of leeway with hyperbolae - the difference was like night
and day. The fact that 4 of us were in total agreement (even though the
tests were sighted and we all have wildly different tastes in music and
systems at home) should give some clue as to the magnitude of the
difference.
Have you got anyway to measure jitter? If so, you may be in a position to perform an experiment to keep Phil happy :)
Something like this:
1. Measure jitter from Squeezebox 2. Measure jitter from the dpa 3. Perform double-blind testing between the two sources
I'd be very interested to hear about the results of such an experiment.
Erm, mp3s are lossy so they will inevitably sound "worse". How are you comparing?
I'm not actually talking about sound quality here - flac/pcm still has the legs on mp3 (just at 320 but it's a tough call at that bit rate). As I said before my dac has low and high quality locks - one for high jitter signals which isn't very picky and can lock onto pretty much any standard digital signal you throw at it. There is also a higher quality lock which will only 'XLOCK' if the signal received is low enough jitter / high enough quality. Mp3's and the transports tested all 'XLOCK'ed. Flac / pcm's do not. This is 100% verifiable and consistent and not subject to any subjectivity - I can post pics somewhere if you like.
So, you're saying that the SB digital out is different for flac vs. mp3, and that your dac will only XLOCK onto mp3s (and the output from your other transports)? That is certainly interesting information. Can you measure the jitter in the output when playing mp3s vs playing flac/pcm?
I've got to say, the Tent clock chip upgrade looks very appealing. I'm planning an upgrade to my Art DI/O (4 x ALWSR PSUs: +/-15V, +5V digital and +5V analogue) and I might slip a clock chip upgrade in too.
Let me know how you get on.
I'm going to be borrowing a prototype alwsr psu specifically designed for the squeezebox in the near future. I'm not sure how big a difference it will make as I feel a psu will mostly benefit the analogue output stage. I tried a monarchy dip reclocking device but this made little or no difference so it looks like the tent clock will be my next thing to try but the casing issue makes things difficult.
Yeah, you need to pull the guts out of the SB and mount it in another case if you're doing this level of modification.
I haven't decided exactly what I'll be doing, but one option is to build the SB and the digital stage of my Art DI/O into a new chassis, along with several ALWSR (I'll need five, or six if I add a Tent clock!)
That's on the back-burner right now until after I've moved house/changed jobs. I'm going to work for Farnell so I'll great access to components :)
R. -- http://robinbowes.com
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