[600MRG] Important info for rigs and accessories with built in USB audio interfaces

[sbjohnston at aol.com]

In my work with Windows computers for digital audio production recording in recent years I've noticed some weirdness with external USB sound input/output devices - sometimes the record inputs have *waaay* too much gain as though it is expecting a microphone level signal.  Very frustrating when you want to feed in a line-level signal.


 
 It seemed like some Windows versions did not show the problem and others did, but I didn't keep track of troublesome systems.  Now I've heard from several sources that the Texas Instrument chipsets used for most of the USB audio devices inside these accessories definitely could have this trouble when used with a Windows computer running Vista, Windows 7, and Windows 8.  XP should not be a problem. 
 
 Unfortunately lots of ham radio equipment that provides a USB sound interface for computer connections will have this same issue - here are some examples of ham equipment using these TI chips:
 
     Icom transceivers with built in USB Audio
     Kenwood rigs with built in USB Audio
     Yaesu rigs with built in USB Audio, as well as the SCU-17 Interface
     Signalink USB interfaces
 
 Here's a video that describes the situation and a workaround - thanks to KD9DAL...
 
 https://www.youtube.com/watch?v=guH0NMRRTAo&wide&hd=1
 
 The workaround presented in the video involves switching the recording input to two-channel mode - then the input is expecting a line level signal.  Unfortunately this change may not "stick", requiring you to do it again each time the rig or computer is restarted, or even after some time sitting idle.  The interaction between the chips, the driver software and the later Windows operating systems seems to make it default back to microphone level mode.
    
   
    
 
    
   
   Steve WD8DAS
 
 sbjohnston at aol.com
 http://www.wd8das.net/
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