[Elecraft] OT - sound cards

[Erik Basilier]

Dave, "decent quality" may be a somewhat subjective concept. Without the
software noise reduction in the computer, the microphone recordings sound
very good, except for that noise which is noticeable in pauses. With noise
reduction on, the situation is reversed: Low noise during pauses, almost
like a noise gate, but artifacts during words. To be more precise about the
artifacts, I don't notice a great deal of reduction in higher audio
frequencies as has sometimes been observed in radios' noise reduction
algorithms, but mostly a metallic twang, similar to "robot speech" in an old
sci-fi movie, which is most obvious at start of recording and at the end of
words, where the speech signal level is close to zero. (This is all using
the standard Sound Recorder that comes with Windows 7.)

 

The KX3 I/Q outputs may for all I know have sufficient levels that they can
feed the sound card's line input. That input doesn't necessarily have the
same noise problem as does the microphone input; I have never tried the line
input on this rather new PC. To clarify, when I referred to past digital
mode usage, it was not on this computer but on either an older desktop or on
the old laptop. As I recall from the small number of qso's using the laptop,
the results may have been inferior on receive compared to the old desktop,
which had a mid-level brand name PCI soundcard. 

 

I don't think it fair to expect Elecraft to somehow guarantee that a user
who wants to make use of the KX3 I/Q outputs will get optimal results with
all computers' sound cards. For starters, most laptops obviously won't do
the job without an external soundcard, since they don't have stereo inputs.
I would expect that a good internal sound card will do a better job than
most motherboard-integrated "sound cards", and that a good external one will
perform best, even if one doesn't need a high sampling frequency for a given
application.

 

I would not assume that the noise performance of the microphone input is
determined by the quality of the sound chip, but that the layout of the
card, as well as decoupling and isolation components play a significant role
in preventing sub-millivolt noise signals from entering the signal chain at
some point before digitization. 

 

 

73,

Erik K7TV

 

>If you can't even make decent quality voice recordings, you have something
else wrong.  Unless it is simply defective, even the cheapest sound chip out
there isn't going to act like you describe.

 

And what exactly do you think the I/Q outputs of the KX3 are going to be
using?

 

Dave   AB7E