Emu XL-7 & MP-7 User's Group

hi

i used to have an XL7 now an XL1 -turbo

what i don't understand is why the SPdif digital out has such a low 
output.

also if you want to sample sounds off it is it best to use the 
Digital output and then normalize or should you just sample off the 
analogue "Main outs"?

thank you kindly

Quick lesson on digital audio math:

One full scale 16 bit sound = 16 bits.
Two full scale 16 bit sounds = 17 bits.
Four full scale 16 bit sounds = 18 bits.
128 full scale 16 bit sounds = 23 bits.

Difference in volume bewteen 16 bits and 23 bits = 42dB.

Essentially what all this means is that a 128 voice sampler needs to
have 42dB of headroom to ensure that no digital clipping occurs. 
However, if you record the S/PDIF output, normalizing will *ALWAYS*
sound cleaner and be more high-fidelity than recording the analog
mains.  Always, always, always; no exceptions.  The same digital signal
that goes to the S/PDIF jack is the same one that goes to the D/A
converters.  It's not like there's a separate "gain-reduced" version
that goes to S/PDIF.  D/A then back through A/Ds NEVER improves
fidelity (though it may color the sound which may or may not be a good
thing).

--- rajah_patel <rajah_patel@...> wrote:
> why the SPdif digital out has such a low output.
> 
> is it best to use the Digital output and then normalize
> or should you just sample off the analogue "Main outs"?


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What if my S/PDIF cable is dirty though?

rEalm



However, if you record the S/PDIF output, normalizing will *ALWAYS* sound 
cleaner....






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--- vibesart <vibesart@...> wrote:
> Great post Aaron. Given this neccesary situation w/re to headroom,
> does this mean that (presuming a 16 bit D/A) the "low level"
> S/PDIF signal is not a full 16 bits  - i.e. like 8-12 bits or
> something, given that level corresponds directly to bit depth in
> digital audio?

I think the S/PDIF is 20 bit, but I don't really recall.  It might be
24 bit, and it might depend on the S/PDIF / AES Pro setting in the
global menu.

> Is the D/A in the XL7 16, 20 or 24 bits?

24 bit, but converters never achieve the accuracy of their input.  Even
the best converters out there get about 18-20 bits resolution
(106-118dB SNR) and that's not even counting THD.

-Aaron

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--- vibesart <vibesart@...> wrote:
> Great post Aaron. Given this neccesary situation w/re to headroom,
> does this mean that (presuming a 16 bit D/A) the "low level"
> S/PDIF signal is not a full 16 bits  - i.e. like 8-12 bits or
> something, given that level corresponds directly to bit depth in
> digital audio?

I think the S/PDIF is 20 bit, but I don't really recall.  It might be
24 bit, and it might depend on the S/PDIF / AES Pro setting in the
global menu.

> Is the D/A in the XL7 16, 20 or 24 bits?

24 bit, but converters never achieve the accuracy of their input.  Even
the best converters out there get about 18-20 bits resolution
(106-118dB SNR) and that's not even counting THD.

-Aaron

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