[Elecraft] external soundcards for digimodes

[Richard Kent]

Chris,
	Built on the motherboard type sound cards need to be checked before
using them for more than just listening. Many, but not all, are designed to
provide signals for "cheap computer" type speakers. This means that the
audio bandpass is pre-distorted to "match" these speakers. Often this means
a boosted bass and sometimes boosted treble. All Windows versions have some
control of this depending on the driver in use. However, sometimes this is
designed into the chipset and changing it in Windows makes it worse. 
	The other problem I have had is excessive noise. Power supply, chip
noise you name it. One that I measured barely made -40db noise floor. This
may not sound so bad, broadcasters are to make -60 min. for the entire
system. In this case the card is too noisy adding it to a system makes the
noise worse.
	Many third party "audiophile" type sound cards both internal and
external have flat response and noise floor well beyond -60db. Most have
better bypassing and dynamic range. Another difference could be that these
cards often sample out to 96K and some even higher sample rates, a benefit
if experimenting with SDR. Your software may not use the extra resolution or
the sample rate, but a card capable of better will generally do better even
in the lesser mode.

Good Luck
Richard Kent

My own interest in the K3 is principally (but not exclusively) the
digimodes. For that reason I was interested in the suggestion of Simon,
HB9DRV that there might be an operational gain in using a "better" sound
card than that on the PC motherboard. I don't know enough about computing to
make judgements, and it would help me (and others in my position) if more
knowledgeable and experienced folk on the list could offer advice on the
following questions.

Q1.    Does experience suggest that there can be an observable operational
gain in using a sound card different from that built into the PC?

Q2.    Which published technical specifications of a sound card are relevant
to digimode operation?

Q3.    On the basis of the answer to Q2, how does one judge whether one
sound card is "better" than another for digimode operation?

Q4.    Do list members have specific recommendations for cost-effective
external sound cards? (The sound card suggested by Simon costs around as
much in the UK as the 100W upgrade for the basic K3.)

73 Chris, MØPSK