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Julian Alden-Salter
2005-02-28, 15:46
Having done a number of comparisons between various cd transports (dpa,
arcam) and the squeezebox into my dac using the same digital interconnect
I'd be interested to know peoples thoughts on what is causing the clear
differences heard if not jitter. Power supplies have been mentioned and to
an extent I would agree that they make a difference. Another theory I've
heard is that somehow interference / noise is being transferred from some
transports to the dac and thus causing degradation to the sound. Anyone got
any alternatives?
The thing that doesn't really make sense is that flacs (pcm / wavs) have a
worse digital output than mp3's. I'm wondering if this is an internal rf
noise issue as something will have to be working harder to process more data
than with mp3's - or perhaps not. The thing I like about the tent xo3 is
that it doesn't just feed a high quality clock to the decoder but it also
corrects the spdif output after decoding. There is another board by a
company called trichord which does a similar thing but it's more expensive.
The biggest problem that I've got at the moment is how to fit the extra
gubbins inside the squeezebox. I guess I'd have to re-box it but finding
something that's a suitable size is difficult.
Cheers

Julian.

JJ
2005-02-28, 16:02
----- Original Message -----
From: "Julian Alden-Salter" <julian.alden-salter (AT) ntlworld (DOT) com>
To: "'Slim Devices Discussion'" <discuss (AT) lists (DOT) slimdevices.com>
Sent: Monday, February 28, 2005 3:46 PM
Subject: [slim] Modifying squeezebox clock


> Having done a number of comparisons between various cd transports (dpa,
> arcam) and the squeezebox into my dac using the same digital
> interconnect
> I'd be interested to know peoples thoughts on what is causing the clear
> differences heard if not jitter. Power supplies have been mentioned and
> to
> an extent I would agree that they make a difference.

That would likely be just another source of jitter.

> Another theory I've heard is that somehow interference / noise is being
> transferred from some transports to the dac and thus causing degradation
> to the sound.

I'd like to see some measurements of RFI, both for the wired and wireless
versions of the SqueezeBox. I'll bet it's particularly high in the
latter.

> Anyone got any alternatives? The thing that doesn't really make sense is
> that flacs (pcm / wavs) have a worse digital output than mp3's.

I dunno. We don't know what the Squeezebox is doing with PCM streams, but
there's no reason to think there should be a difference for the signal on
the S/PDIF out. Something's definitely going on and it doesn't sound
good.

> I'm wondering if this is an internal rf noise issue as something will
> have
> to be working harder to process more data than with mp3's - or perhaps
> not.

That's sounds plausible, though it shouldn't be from a CPU load
standpoint, as the processor shouldn't have to work as hard in decoding
the pcm stream. More likely it's in the network end of things.