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2004-07-21, 17:48
> -----Original Message-----
> From: discuss-bounces (AT) lists (DOT) slimdevices.com
> [mailto:discuss-bounces (AT) lists (DOT) slimdevices.com] On Behalf Of Sean Adams
> Sent: 22 July 2004 00:26
> To: Slim Devices Discussion
> Subject: [slim] How does lossless work?
>
>
>
> > Interesting stuff.
> >
> > Is there any change of getting hold of a circuit diagram of the
> > squeezebox as I'm interested in experimenting with some mods
> > (primarily analogue output
> > stage) ?
> >
>
> Sure, here it is. Please also get the mas35x9 data sheet from
> micronas.
> This is mostly the same as their reference schematic but you
> should study the data sheet to see the capabilities of the
> chip. Also see mas35x9.pm in our source code to see what
> features we're using. There are quite a few features we don't
> use that might be of interest, for example mixing another
> analog source in with the audio via the geekport. One fun
> project might be an FM tuner controlled by i2c that uses this
> mechanism.
>
> If you want to connect a different DAC you can do so using
> the SOC, SOI, and SOD pins. Note that two of these pins are
> easily accessible at the 74HC125. The other pin unfortunately
> is not brought out but if you are extremely agile with a
> soldering iron, it is quite possible to solder directly onto the chip.
>
> Legal C.M.A: this does not imply any license to implement
> this design for any purpose. Just sharing it so you can hack on it.

Thanks for this.

However, there doesn't seem to be all that much to hack as the chip does
everything! I was at least expecting an op-amp output stage or something!

You mention hooking up a FM tuner controlled by i2c; what would be really
cool would be a DAB radio controlled the same way. I've got no idea how to
go about doing that!

Actually, what would be better is a DAB radio solution that plugs into my
Linux server somehow (USB/Firewire?) and that streams digital audio out the
the squeezebox and can be controlled from both the slimserver web interface
and from the squeezebox.

Thanks again,

R.

seanadams
2004-07-22, 07:53
> However, there doesn't seem to be all that much to hack as the chip
> does
> everything!

Indeed, there's not too much to hack. That's why I suggested an
alternate DAC as one of the few interesting things one could do.

> I was at least expecting an op-amp output stage or something!

Yep - already integrated in the DSP, but I suppose you could add one.
Eg for higher line outs or more headphone power.

Notice everything here is driven off GND & 3.3V so that determines max
analog output level of 3Vpp, and the series caps on the output knock
out the DC. If you added a split power supply you could drive op amps
+/- directly to the filter. That might be a better output stage.

Graham Ridgway at home
2004-07-22, 16:08
thanks for all the answers re lossless. I will hopefully soon get the new
Naim DVD player accompanied with a Naim AV2 processor. This will provide a
D2A conversion from the PCM stream for hopefully pretty high quality sounds.

Are there any gotchas here that would stop the lossless PCM getting to the
D2A converter in the AV2 or problems that anyone forsees with things like
jitter?

Graham

PS I know this may spark a "what's the point" debate (as it did before) but
let's not go there as there is no point other than satisfying senseless
audiophile curiosity!! :-))

John Gresty
2004-07-23, 03:27
Hi Graham,

If it's possible, I'd suggest trying/testing your set-up before you buy. I
stream PCM directly to my hi-fi DAC through the Squeezebox, but my DAC is
unable to lock at 44.1kHz to the signal. I should point out that I seem to
be in a very tiny minority in experiencing this problem - see this month's
conversation titled "Squeezebox PCM sample rate support". It may be worth
you picking up previous list contributions by Simon Turner and Mark Bennett
(e.g. "External DACs" in March 2004) - these helped assuage my fear of
gotchas. My disappointment is that my external DAC happily syncs at 44.1kHz
to the digital signal provided by a (relatively cheap) M-Audio Sonica USB
audio card connected to a laptop! :-(

Good luck!
JohnG.

----- Original Message -----
From: "Graham Ridgway at home" <graham (AT) ridgworld (DOT) com>
To: "Slim Devices Discussion" <discuss (AT) lists (DOT) slimdevices.com>
Sent: Friday, July 23, 2004 12:08 AM
Subject: [slim] How does lossless work?


> thanks for all the answers re lossless. I will hopefully soon get the new
> Naim DVD player accompanied with a Naim AV2 processor. This will provide
a
> D2A conversion from the PCM stream for hopefully pretty high quality
sounds.
>
> Are there any gotchas here that would stop the lossless PCM getting to the
> D2A converter in the AV2 or problems that anyone forsees with things like
> jitter?
>
> Graham
>
> PS I know this may spark a "what's the point" debate (as it did before)
but
> let's not go there as there is no point other than satisfying senseless
> audiophile curiosity!! :-))
>
>

Graham Ridgway at home
2004-07-23, 14:13
thank John, I will try to try before I buy! Although the AV2 is coming
anyway (probably!).
GRaham
----- Original Message -----
From: "John Gresty" <jgresty (AT) ntlworld (DOT) com>
To: "Slim Devices Discussion" <discuss (AT) lists (DOT) slimdevices.com>
Sent: Friday, July 23, 2004 11:27 AM
Subject: [slim] How does lossless work?


> Hi Graham,
>
> If it's possible, I'd suggest trying/testing your set-up before you buy.
I
> stream PCM directly to my hi-fi DAC through the Squeezebox, but my DAC is
> unable to lock at 44.1kHz to the signal. I should point out that I seem
to
> be in a very tiny minority in experiencing this problem - see this month's
> conversation titled "Squeezebox PCM sample rate support". It may be worth
> you picking up previous list contributions by Simon Turner and Mark
Bennett
> (e.g. "External DACs" in March 2004) - these helped assuage my fear of
> gotchas. My disappointment is that my external DAC happily syncs at
44.1kHz
> to the digital signal provided by a (relatively cheap) M-Audio Sonica USB
> audio card connected to a laptop! :-(
>
> Good luck!
> JohnG.
>
> ----- Original Message -----
> From: "Graham Ridgway at home" <graham (AT) ridgworld (DOT) com>
> To: "Slim Devices Discussion" <discuss (AT) lists (DOT) slimdevices.com>
> Sent: Friday, July 23, 2004 12:08 AM
> Subject: [slim] How does lossless work?
>
>
> > thanks for all the answers re lossless. I will hopefully soon get the
new
> > Naim DVD player accompanied with a Naim AV2 processor. This will
provide
> a
> > D2A conversion from the PCM stream for hopefully pretty high quality
> sounds.
> >
> > Are there any gotchas here that would stop the lossless PCM getting to
the
> > D2A converter in the AV2 or problems that anyone forsees with things
like
> > jitter?
> >
> > Graham
> >
> > PS I know this may spark a "what's the point" debate (as it did before)
> but
> > let's not go there as there is no point other than satisfying senseless
> > audiophile curiosity!! :-))
> >
> >