OT: S/N-Ratio measurment - help

[Martin Czech]

:::Don't forget the dirt that comes from the powersupply. 
:::Digital and analog GNDs must meet at the edge connector, not at the mains
:::GND terminal, some manufacturers don't even include on card regulators, etc. 
:::(Look for a computer with star-grounding and linear PSU ;->) 
:::Best thing to do would be to power the card from an extra linear PSU, or
:::via a DC/DC convertor. And I wish they would float the in/outs, I get
:::groundloops everytime I plug something into a soundcard.

The manufacturer must earth the chassis to protective earth, and as
ISA bus cards are made that way they are, signal ground is protective
earth then. A nice groundloop which is not improved by the fact that
a PC is a HF sender, i.e. the whole chassis jumps up and down with
the clock and it's subharmonics and other bands, since the connection
to protective earth works for dc, not for these transients.

I'd like to test one of my audio transformers with my friend's PC,
I guess much of the noise will go away then. Other problems
may come up then, low frequency impedance and response?

I think the useable cards contain only the ISA interface and optical
connectors to an external ADC box, with seperate supply.
This way very high quality is available today.

Isn't there any optical/coaxial SPDIF interface card on the market.
It think so. Combine it with your portable DAT, or maybe a second
hand DAT with broken mechanics (ADC still working), a lot more
fun for the money.

Removing any kind of noise out of recordings is such a sh*t that
allmost any effort is worth to avoid it right from the start.
Been there and suffered a lot from *quick and dirty* recording.


m.c.