Any insight with the Berkeley Alpha DAC ..??

Dougmc wrote:
"As I understand it, quality computer audio systems bypass the sound card for conversion to SPDIF (and therefore for conversion to analog too) by taking the digital feed from the hard drive outside the computer. If this is so, why is it necessary to use a “high quality” sound card or any sound card at all?"

There are two ways to get audio data out of a computer:
1) using the audio software stack
2) using network - ether net/WiFi

#1 can output data three ways:

1) USB to S/PDIF converter
2) PCI bus using sound card or on-board logic with S/PDIF output
3) Firewire to S/PDIF converter

There is no direct S/PDIF from a computer. It must implement one of these three in order to get S/PDIF digital output. If it appears that these are "bypassed", it is because #2 is implemented on the motherboard. It is still there, not bypassed.

"Does the sound card perform some other functions that require very high quality parts or sophisticated design?"

Each of #1-#3 require high quality parts and low-jitter clocks to achieve good results.

Steve N.
Empirical Audio

Drubin - as for devices that use the audio stack in the computer, they are all the same in theory. However, the implementations and protocols used make some devices superior to others.

PCI cards are the worst because they rely on too much of the computer infrastructure, including the clocks and power system. Outboard converters, both USB and Firewire are generally better. However, there are good and poor chips available for both USB and Firewire, so it depends on the chip that was chosen for the converter, as well as the implementation.

By implementation I mean the Power System, PC board design, circuit design, cabling etc..

24/96 is supported on some USB converters/USB DAC's that use the TAS1020 chip from TI, as well as some Firewire converters. Only a couple of PCI cards support 24/192 at low quality, however they can be reclocked to provide high quality 24/192.

If you have to have 24/192, then a PCI card driving a reclocker is the best solution. If you are happy with 24/96, then USB is the best solution IMO.

Steve N.
Empirical Audio

Drubin - I dont like to comment on the performance of other companies products on the forums, so I will send you an email.

The Bryston DAC unfortunately uses one of the lesser TI chips, not one of the good ones. However, I am actually in talks with Bryston about them designing my OEM USB module into their DAC, so this could improve significantly. There are several other manufacturers already designing the module into their products and you will see some of these debut at RMAF in October.

The Berkeley DAC is evidently designed by the Pacific Microsonics team that designed the excellent D/A modules in the past. I'm sure that the D/A module is a good one, however I believe this is their first "system" product. Have not heard one yet.

Steve N.