[Elecraft] what soundcard for K3 and Mac

[Walter Underwood]

This list was updated in 2018. 

http://www.telepostinc.com/soundcards.html <http://www.telepostinc.com/soundcards.html>

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Oct 31, 2021, at 11:54 AM, Joe Subich, W4TV <lists at subich.com> wrote:
> 
> 
>> What I haven’t quite figured out is how important is this really is
>> to weak signal digital decoding.
> 
> Low noise in a sound card is important to weak signal decoding in two
> ways:
> 
> 1) you want the inherent noise floor in the sound card to be 10 to 15
>   dB *LESS* than the minimum - receiver noise + "antenna" - noise.  On
>   VHF with a very quiet receiver the receiver noise can be quite low.
> 
> 2) high noise level in a sound card directly subtracts from the dynamic
>   range (ADC clipping - noise floor).  With a high noise floor, strong
>   signals either overflow the ADC or the receiver AGC must reduce gain
>   with moves the weak signals below the (higher) noise floor.
> 
>> After testing, I settled on a Sound BlasterX G5 model SB1700 which 
> > tested at about -120dB noise level.
> 
> -128 dB relative to what?  A quality 16 bit sound card has a theoretical
> dynamic range of 97dB - a quality 16 bit card (low noise) will produce
> about 90 dB dynamic range in practice.  A 24 bit sound card has 144 dB
> theoretical dynamic range but a practical 24 bit sound card will produce
> maybe 115 dB dynamic range but to take advantage of that dynamic range
> the sound card (any audio preamps and the ADC) need to operate with a
> supply voltage greater than the typical 3.3 or 5 V USB supply.  A 24 bit
> sound card with a 5 V (USB) supply will be lucky to achieve 100 dB
> dynamic range.
> 
> 73,
> 
>   ... Joe, W4TV
> 
> 
> On 2021-10-31 10:41 AM, SteveL wrote:
>> Dave,
>> This interest caught my eye awhile back:
>> http://members.chello.at/oe1mww/sound-card-check/ <http://members.chello.at/oe1mww/sound-card-check/>
>> I’ve tested several of the inexpensive (<$10) nameless USB sound card dongles using his method and saw a wide variety of noise floors - however significantly higher than a name brand USB card.  After testing, I settled on a Sound BlasterX G5 model SB1700 which tested at about -120dB noise level.  How does this compare?  My nameless sound dongles noise level tested -70 to -90dB - a big difference.
>> What I haven’t quite figured out is how important is this really is to weak signal digital decoding.
>> Steve
>> aa8af
>>> On Oct 30, 2021, at 10:49 PM, David Christ <radioham at mchsi.com> wrote:
>>> 
>>> Yes this has been bead to death previously. Jim Brown made a number of suggestions in a paper from 2014.  However the market has changed.  Those models are all discontinued and those manufacturers' follow ons are much more expensive and have features that are not needed for sound card modes.  Any offerings of these older models seem to be coming from overseas.  The $100 and under market seems to be dominated by mystery brand dongles which are a gamble.
>>> 
>>> So can any one recommend a tried and true sound card interface for use between an K3 (without a sound card) and a MacBook Pro (which has no mike or line in jack)?  I would like to hear from people who have actually the unit, not just speculation.
>>> 
> 
> 
> ______________________________________________________________
> 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
> Message delivered to wunder at wunderwood.org