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In the Forum: Off Air Audio
In the Thread: How to record FM broadcasts.
Post Subject: Re: Computer digital storagePosted by jtavan on: 11/6/2005
Romy,
I've been storing all my digital music on a computer located fairly far
from the audio system for quite some time now. You've brought up a few
issues that are worth discussing.
1) Storing the digital stream - I assume you mean either (both?) from
audio extracted from CDs and audio captured by an ADC from FM or LP
source. For the former, you simply use proper software and hardware to
extract the audio from your CDs. I use a Plextor Plexwriter Premium
CD-RW drive plus their "Plextools" software package. This combination
has proven to give me reliable, repeatable digital audio extraction
without errors. The interface is bad, but it is fast and reliable. The
alternative is Exact Audio Copy, which is slow and reliable, with a
marginally better interface. For the latter, recording from ADC, you
will need a digital interface card for your PC, the ADC, and some
software to do the capture. Alternatively, if the ADC has a Firewire
port, you can use that instead of a digital interface card. If using a
digital interface card (probably something on the order of a Lynx AES16
or RME DSP9652), you will most likely end up using AES/EBU
digital over (perhaps long) runs of cable, because that seems to be the
format most frequently supported by AD converter boxes. Additionally,
you may wish to run a BNC cable with wordclock synchronization between
the ADC, the interface card, and (possibly) your DAC. In fact, you
might even want to experiment with a standalone clock generator, like
the Apogee Big Ben, to provide this wordclock. For software, there are
any number of solutions for the Windows platform, and any should work.
At the high end, there's stuff like Steinberg's Wavelab. Lower end,
tools like Goldwave will also be just fine for simply capturing the
bits and storing on disk.
2) Storage format - lossless compression works fine. FLAC is generally
what I'd recommend. It is bit-perfect, allows tagging of files with
metadata, and it's fast and easy to compress and decompress.
3) Optimization of music PC - There are a lot of options here. I
definitely agree about keeping a noisy switching PC power supply off
the power rails of your audio system. Also, keeping an acoustically
noisy PC away from the audio system is to be desired. I've tried a
couple things so far. First, I had a silent (or very nearly silent) PC
with no fans whatsoever sitting in the audio rack. It ran off a noisy
external supply AND had a noisy DC-DC converter internally AND held the
PCI sound card RIGHT above the noisy motherboard, though. It wouldn't
have been difficult to replace the external supply and DC-DC converter
with a multi-voltage linear supply, but silencing the (admittedly
small) noise made by the hard disk would have been difficult. Network
booting to windows requires third party software in which I didn't want
to invest. Right now, I am using a small clock radio-like device called
a Squeezebox to stream music off a server in another room. This device
has a good quality transport for streaming music to a DAC, but won't
help in the other direction. Thus, my next approach is going to be an
AD/DA box in the audio rack, connected to the server in another room by
long cables. Lynx Studio claim that they can drive 500 feet of cable at
192kHz - should be sufficient. At this point, the server hardware
doesn't matter, it can be as noisy as it needs to be, as it's in a
different room and on a different power circuit.
4) Quality of AD vs DA - It seems reasonable to assume that a designer
of an ADC and DAC product will have consistent design priorities.
Whether this will translate to similar sound is uncertain. I would
certainly not expect similar subtle tonal nuances to be shared between
models - the circuits are different enough.
I can't claim to be an expert in this subject, but this basically sums
up what I've been playing with recently. Hope it helps.
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