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View Full Version : Digital out, audio quality and volume control



Andrew Lucas
2003-12-18, 02:52
>>Using the analogue outs its fine, the staging is as it should be.
>>
>
>The analog outputs are driven internally from the exact same pcm bitsream
>as the s/pdif output. So if the analog outs sound okay, and you believe
>that jitter is the problem, then it must be happening in transmission, not
>generation (clocking), of the signal. Try listening carefully for any
>difference between the optical and coax outputs - it may be that the signal
>is being distorted due to a lengthy run over the coax.
>

Coax is is around 1m, optical 1.5m. I wouldnt have thought these lengths
were an issue, good quality interconnects also.

I suggested jitter but perhaps not, could still be a bad box but it really
does sound like the speaker cables on one side have been reversed but only
when I use the squeezebox, could you have flipped the bitstream to one
channel by accident someplace? This would cause this problem.


>>Also, if the squeezebox is configured to fixed level on the digital outs,
>>the difference in volume on the analogue outs between setting 11 and
>>setting 10 is enormous, is this deliberate?
>
>No, it's not deliberate - we know we need to adjust the curve for that
>mode. I was actually going to suggest that you experiment with the fixed
>s/pdif level. This bypasses the digital volume matrix, which will have no
>effect on jitter but does ensure that the data going out is the same as
>what you'd get from a CD player (assuming a PCM source, of course).
>

OK, tried this though, same result.



>>That's strange, maybe you have an S/P-DIF Sync/jitter problem?

Although I tried other sources into the same processor and these worked
fine, I do have a stand alone DAC which I will try also just to be sure.

>>BTW was the source file PCM or a file type that supports fully independent
audio channels?

WAV's, FLAC's, MP3's all the same....used different rippers, different
encoders...open to suggestions and please feel free to send me test files if
you like.

Thanks
Andy

seanadams
2003-12-18, 12:02
> it really does sound like the speaker cables on one side have been
> reversed but only when I use the squeezebox, could you have flipped
> the bitstream to one channel by accident someplace? This would cause
> this problem.
>

Interesting... It's not possible, AFAIK, for us to have accidentally
inverted a channel. However, we could do this if we wanted to for PCM
streams. I can check this here - will get back to you. In the mean
time, I suppose the obvious thing to try would be reversing on of the
speaker connections and seeing if it sounds better.

BTW you can test this easily with a low frequency test tone.

kevin
2003-12-19, 12:17
I did some testing on this last night and could discern no audible
difference between the coax S/P-DIF outputs on my Rotel RCD-971 and my
Squeezebox. Also FYI I had the volume control set to digital and the
volume on the Squeezebox at max.

The staging sounded identical (to me anyhow) on both devices--to the
point that after 30 minutes of back-and-forth between the Squeezebox
playing WAVs and the CD player playing the original disc, I could no
longer remember which input was which on the processor.

One thing of note here, though... To my ears, while the Squeezebox
S/P-DIF and Rotel S/P-DIF outputs sounded identical to me, the analog
output on the Rotel sounded very different. So we need to make sure
we're comparing apples to apples. S/P-DIF to S/P-DIF using the same
DAC in the same configuration...

Andy, could you tell us more about your system setup? As well as
volume settings in the server's player settings?

Thanks,
Kevin P.

On Dec 18, 2003, at 11:02 AM, Sean Adams wrote:

>
>> it really does sound like the speaker cables on one side have been
>> reversed but only when I use the squeezebox, could you have flipped
>> the bitstream to one channel by accident someplace? This would cause
>> this problem.
>>
>
> Interesting... It's not possible, AFAIK, for us to have accidentally
> inverted a channel. However, we could do this if we wanted to for PCM
> streams. I can check this here - will get back to you. In the mean
> time, I suppose the obvious thing to try would be reversing on of the
> speaker connections and seeing if it sounds better.
>
> BTW you can test this easily with a low frequency test tone.
>
>

kevin
2003-12-19, 15:06
I didn't really expect it to... But I wanted to make sure that the
imaging didn't sound any different as reported earlier on this thread.
Come to think of it, I probably should have checked the analog as
well...

Regards,
Kevin P.

On Dec 19, 2003, at 2:25 PM, Rob Studdert wrote:

> On 19 Dec 2003 at 11:17, Kevin Pearsall wrote:
>
>> I did some testing on this last night and could discern no audible
>> difference between the coax S/P-DIF outputs on my Rotel RCD-971 and my
>> Squeezebox. Also FYI I had the volume control set to digital and the
>> volume on the Squeezebox at max.
>
> Out of interest why would you expect it to sound different?
>
> Rob
>

Rob Studdert
2003-12-19, 15:25
On 19 Dec 2003 at 11:17, Kevin Pearsall wrote:

> I did some testing on this last night and could discern no audible
> difference between the coax S/P-DIF outputs on my Rotel RCD-971 and my
> Squeezebox. Also FYI I had the volume control set to digital and the
> volume on the Squeezebox at max.

Out of interest why would you expect it to sound different?

Rob