Recording 12+ analog channels on a PC at 192KHz/24-bit. Is..

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In article <1121729937.613803.161970@g14g2000cwa.googlegroups.com> tpatsch@gmail.com writes:

> All of this said, I'm not sure resolution isn't a consideration.

Oh, it certainly is. What most of us think is NOT a consideration is
recording at 192 kHz sample rate. That's sample rate and not
resolution. While in theory, they're not related (you need only
infintessimally more than one sample per half-cycle of the highest
frequency in order to reconstruct the waveform with perfect accuracy)
intuitively, having a couple more samples to average out errors surely
couldn't hurt.

But there are some component performance issues that are present with
real world components today that prevent really accurate performance
at 192 kHz. While there are certainly some 192 kHz converters that
sound better than some 96 kHz converters, it would mostly be your
imagination at work if you thought that the best 192 kHz converter
sounded better than the best 96 kHz converter. Dan Lavry has a paper
on his web site that you might find stimulating:

http://www.lavryengineering.com/documents/Sampling_Theory.pdf

> Have any of you out there who've said no difference recorded large
> scale projects at extremely high resolution and A/B'd them with lower
> resolution versions?

I can't imagine how a valid experiment like this could be constructed.
You could send the same analog audio sources simultaneously to one set
of 192 kHz converters and to another set of 96 kHz (or lower)
converters, record the outputs of both, use the same mix parameters to
mix both, and compare the mixes, but:

- You would have recorded with two different A/D converters. Even if
both were the same make and model, simply switched to different
sammple rates, you still have no guarantee that they're actually
operating identically other than the number of samples they
generate per unit time.

- Mixing (assuming "mixing in the box" here) may not work the same
for two different sample rates. You're adding (nominally) twice as
many samples for each time interval, so rounding errors may make
the mathematical results different.



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On Tue, 19 Jul 2005 01:38:57 +0200, tpatsch wrote:

> Ahhhh... And the crazy friend surfaces!!!!! And I do indeed hear the
> holes in swiss cheese.... Woohhhaaaaaaaa!!!!!
....
> Resolution sort of became the focus of this discussion. Probably my
> fault.
....

The question posted was:
| He needs to record 12 or more _analog_ channels simultaneously on a PC
| at 192KHz/24-bit.
....
| It seems to me that the PCI bus and/or the IDE bus would present an
| insurmountable bottleneck.

The answer was clear: for modern PC hardware this 10MByte/sec datastream
is no problem, but the need for 192/24 is not very clear.

> But after recording a track I tend to apply multiple filters (high pass,
> compression, limiting, etc). It makes no sense to me from a
> computational standpoint that greater resolution during filter
> applications does not minimize error at the final dithering stage.
....

The endpoint for a recording are always ears. Ears have their limitations,
so to record sound there is no need to do much more than these
limitations.

24 bits makes life easier, but there are queastions about the need. Some
say the 96 dB of 16 bit sampling already is more than enough. More samples
might help to get better results from algorithms, some say that if 44.1/16
is more than enough for the end result, it is good enough for algorithms
too if the algorithms are good.

To avoid problems, with current posibillities of technology, 24/96 could
be a good choice. There seems to be no extra benefit in 192/24. So most
answers contained a question about the "need" for 192/24.

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com

 

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<tpatsch@gmail.com> wrote:
>
> Have any of you out there who've said no difference recorded large
> scale projects at extremely high resolution and A/B'd them with lower
> resolution versions? Do you know for certain that artifacting isn't
> minimized overall?



A quick Google search of this group will answer that question for you.

I've never gone as far as doing a "large scale" project at hi-res, but
I've done some test sessions comparing 48k to 96k. My opinion was that
if there was any difference (and I couldn't even say for sure there
was), it was so small as to be insignificant. The weight of the guitar
pick would make more difference.

I understand the reasoning behind capturing at higher resolutions, but
I'm also familiar with the concept of overkill. At some point, the
extra storage space and processing overhead requirements totally swamp
any theoretical benefit.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

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