At 10:04 AM 9/23/2005, andy kolovos wrote:
>A friend visited me last week and, being the total losers that we 
>are, the topic of our conversation eventually ranged to A/D 
>conversion and digital file input to a PC.  We were talking around 
>the benefits of using a quality outboard A/D unit that feeds a 
>digital audio signal into a quality PCI card versus using an quality 
>outboard A/D that feeds the digtial signal in via USB or FireWire.
>Thing is, no one I've asked has been able to give me a clear 
>explanation of the benefits and drawbacks either way.
>I can imagine at least one--outboard DAC-to-PCI can input an AES 
>signal--and can guess at a couple others, but I'm curious to get 
>people's opinions, especially since most people in the field and the 
>best practices out there always instruct in the use of a DAC-to-PCI 
>setup.  Specifically, is the DAC-to-PCI approach just a hold over 
>from a time when that was the only way to go?  What are the benefits 
>over quality USB/FireWire input devices?

Hi, Andy,

I think your analysis is correct. Let's briefly follow what RME in 
Germany has done. I use that as an example because I have the first product:

The RME Multiface has 8 analog I/O and an ADAT I/O (8 more channels 
at up to 48 ks/s, 4 at 96 ks/s) plus SPDIF I/O and an analog monitor 
out for 18 channels in and 20 channels out or 38 channels. It uses a 
dedicated PCI card that connects to the outboard unit via a FireWire 
cable, but is not using FireWire protocol. I have two of these (with 
two PCI cards installed) You can have up to three for 24 tracks. 
There is also a PCMCIA card interface available, turning a laptop 
into an 8-channel recorder. THis product is about 3-4 years old.

This is a year-old (more or less) product that has a total of 56 
channels and connects to the host PC via a FireWire 800 interface. It 
has 10 analog inputs (including four with mic pres) and 10 analog 
outputs. It also has two ADAT inputs/outputs and an SPDIF I/O. You 
can probably use three of them with FW800 connections (it can also 
connect to FW 400 with loss of throughput) although they suggest 
disabling the ADAT ports when you do that. The manual is available on 
the above page and page 90 of the manual describes bus loading.

Oh, both do MIDI as well.

So, with RME (who I consider to be an excellent but not esoteric 
supplier of PC interfaces--Steinberg also rebadges the Multiface--I 
have one of each flavour) we can see a progression from a dedicated 
PCI card to a FW 800 interface. As both sound cards and PCs 
stabilize, I think using standard interfaces makes sense. The 
dedicated PCI cards are more expensive than a standard PCI card, by the way.



Richard L. Hess                           email: [log in to unmask]
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