[Elecraft] OT - sound cards

[Joe Subich, W4TV]

Eric,

Sound facilities integrated on computer main boards - both "desk" and
laptop systems - are notorious for noise issues.  Mainboard designers
simply do not have the experience in keeping signal lines "clean" and
doing the level of bypassing/decoupling necessary to maintain power
supplies clean enough for audio (analog) signals.  They have gotten
sloppy since the digital domain is much more forgiving of "low level"
noise.

Fortunately or unfortunately depending on one's point of view, the
sloppy audio practices are a primary reason that external audio devices
tend to provide a much higher level or performance today.  That has not
always been the case and some PCI/PCI-E sound cards go to extraordinary
lengths to clean up the power supply to avoid the problems.

73,

    ... Joe, W4TV



On 1/9/2012 10:50 AM, Erik Basilier wrote:
> 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
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>