normanstrong wrote:

"Stewart Pinkerton" wrote in message
...
On Thu, 16 Dec 2004 07:20:41 GMT, R wrote:

Stewart Pinkerton wrote in
:

On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews"

wrote:

"Arny Krueger" wrote in
news:QN2dnU2d2-ywhV3cRVn-
:

"R" wrote in message
. 1
I am looking for an sound card that features dual DA
converters in
parallel. Does anyone know of one?

Please explain more precisely what you mean.


Arny,

What I mean by parallel is that the data stream for one channel
feeds 2 dacs
at once and the resultant output of the dacs are tied together.
Many of the
high end CD players and D-A units use that circuit topology as it
lowers the
distortion levels.

You don't mean parallel, you mean a differential pair. Given that
distortion levels with conventional DACs can be 0.001% or less,
do you
think this is important?

I don't think i mean a differential pair. Wuld not a differential
pair be
2 dacs fed with the same source but one dac has it's invert pin
asserted?

Essentially yes, and this is a classic method of averaging errors
between the two DACs.

If the 2 DACs come from the entire universe of DACs then this will
probably work. But if they come from the same production run or, God
forbid, from the same wafer, the chances are excellent that both DACs
will have errors in exactly the same place--in the same direction.
You could get no benefit from averaging.

Not so. The differences are likely to be 'process related'. No 2 chips
from the same wafer are identical. The method is ( was ) valid.

Graham