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Old 06-08-2008, 07:48 PM
Ralf Mardorf
 
Default Anyone using a HDSP9632 at 96K ?

John Rigg wrote:
> There are a couple of reasons why 96kHz can sound better.
>
> Most audio ADC chips use an incorrectly implemented decimation
> filter to convert the single bit oversampled data from
> the sampling stage to multibit PCM. If you check any of the
> common ADC data sheets you'll see a stopband spec for the
> filter of about 0.55 x sample rate, a clear violation of
> sampling theory. This allows a small amount of aliasing to occur
> on high frequency signals, and increasing the sample rate shifts
> the problem to a higher, less audible frequency range. Correctly
> designed converters like those from Lavry or Prism don't suffer
> from this, but are very expensive.
>
> The other reason is that non-linear DSP like compression
> or limiting introduces harmonics, which will also produce aliasing
> of high frequency signals. A higher sample rate reduces (but doesn't
> entirely eliminate) the aliasing.
>
> In practice, these effects are often not noticeable enough to
> put up with the disadvantages of doubling the data rate, but YMMV.
>
> John

Thank you John

this is very interesting. When I worked at Brauner years ago, we checked
out Crystal DSPs and after that we stayed completely analogue. When I'm
talking about digital, I'm only thinking of homerecording. I don't know
how it's today in professional studios. I'll test 96KHz next time I do
homerecording. Until now I guess there are some reasons that speaks for
44,1KHz when doing homerecording. Homerecording people are using mixing
consoles with op-amp chips, lousy speakers etc. ... I'm speaking for my
own equipment ... it seems to be better to record in CD quality from
the beginning on, because I think it will be easier doing the mastering,
when you always here the quality it will be in the end. The better
quality of 96KHz (and more bit) might be unable to hear, because of all
that phasing done by op-amp chips etc., until now I only noticed a
difference between 44,1KHz and 48Khz for my home equipment. I have to
say that I'm using an Envy chip and a Behringer mixing console, that
might be different for people using a Neve. I think most people using
Linux will do it for homerecording and not for professional recording,
but I'm not up to date.

Cheers,
Ralf

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Old 06-09-2008, 05:50 AM
Quentin Harley
 
Default Anyone using a HDSP9632 at 96K ?

HDSP9632 does not suffer from the problems itself, as it is merely an
ADAT dataport with some smart DSP's implemented on-bord. Ok, not
entirely - it does have two analog ports, but the main mode of operation
remains ADAT. You would have to look at the data sheets of the actual
capture device to make an educated decision.

96k sounds better. It is common knowledge that 44.1k does not carry
enough bandwidth to represent the full sonic range undistorted... but
there are only a hand full of guys that can actually hear the
difference. The trade-off is a rapidly filling hard drive, especially
in a 16ch or more live session, of two hours or more!

Your choice...

Ralf Mardorf wrote:
> John Rigg wrote:
>
>> There are a couple of reasons why 96kHz can sound better.
>>
>> Most audio ADC chips use an incorrectly implemented decimation
>> filter to convert the single bit oversampled data from
>> the sampling stage to multibit PCM. If you check any of the
>> common ADC data sheets you'll see a stopband spec for the
>> filter of about 0.55 x sample rate, a clear violation of
>> sampling theory. This allows a small amount of aliasing to occur
>> on high frequency signals, and increasing the sample rate shifts
>> the problem to a higher, less audible frequency range. Correctly
>> designed converters like those from Lavry or Prism don't suffer
>> from this, but are very expensive.
>>
>> The other reason is that non-linear DSP like compression
>> or limiting introduces harmonics, which will also produce aliasing
>> of high frequency signals. A higher sample rate reduces (but doesn't
>> entirely eliminate) the aliasing.
>>
>> In practice, these effects are often not noticeable enough to
>> put up with the disadvantages of doubling the data rate, but YMMV.
>>
>> John
>>
>
> Thank you John
>
> this is very interesting. When I worked at Brauner years ago, we checked
> out Crystal DSPs and after that we stayed completely analogue. When I'm
> talking about digital, I'm only thinking of homerecording. I don't know
> how it's today in professional studios. I'll test 96KHz next time I do
> homerecording. Until now I guess there are some reasons that speaks for
> 44,1KHz when doing homerecording. Homerecording people are using mixing
> consoles with op-amp chips, lousy speakers etc. ... I'm speaking for my
> own equipment ... it seems to be better to record in CD quality from
> the beginning on, because I think it will be easier doing the mastering,
> when you always here the quality it will be in the end. The better
> quality of 96KHz (and more bit) might be unable to hear, because of all
> that phasing done by op-amp chips etc., until now I only noticed a
> difference between 44,1KHz and 48Khz for my home equipment. I have to
> say that I'm using an Envy chip and a Behringer mixing console, that
> might be different for people using a Neve. I think most people using
> Linux will do it for homerecording and not for professional recording,
> but I'm not up to date.
>
> Cheers,
> Ralf
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> 64studio-users mailing list
> 64studio-users@64studio.com
> http://lists.64studio.com/mailman/listinfo/64studio-users
>


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