tag:blogger.com,1999:blog-1016709139053396535.post8147951899867763317..comments2024-03-18T17:34:35.079+00:00Comments on A Smackerel of Opinion: Measuring Audio Quality with AudacityColin Ian Kinghttp://www.blogger.com/profile/06458723239721015750noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-1016709139053396535.post-56848736193678906522009-07-21T14:47:46.831+01:002009-07-21T14:47:46.831+01:00When I've got time I would like to repeat this...When I've got time I would like to repeat this for all the H/W I've got to sanity check things a little deeper. It is kinda weird.Colin Ian Kinghttps://www.blogger.com/profile/06458723239721015750noreply@blogger.comtag:blogger.com,1999:blog-1016709139053396535.post-46685880148845897402009-07-21T13:28:15.479+01:002009-07-21T13:28:15.479+01:00Those are weird symptoms.
One thing to try is to...Those are weird symptoms. <br /><br />One thing to try is to scroll way to one side on alsamixer and see if you've got "External Amplifier" enabled or disabled. I can imagine a cheap and cheerful headphone amplifier will distort like crazy, but OTOH it might be what you need to drive speakers. Pot luck, just try it.<br /><br />Another, if you have a surround sound capable mobo on a desktop, is to set the alsamixer switch that duplicates the main output on one of the surround outputs. This might eliminate something in the main output path that's blown up.Geekonoreply@blogger.comtag:blogger.com,1999:blog-1016709139053396535.post-30362830980431710462009-07-21T10:48:04.196+01:002009-07-21T10:48:04.196+01:00Geeko, yep, that sounds plausible for some hardwar...Geeko, yep, that sounds plausible for some hardware I've got. Unfortunately for this bit of hardware test 3 showed that the the low playback levels were next to useless, and the only way of getting something audible was to crank up the mixer volume level.<br /><br />As for test 2, I was seeing all sorts of harmonics even at 60% on the mixer, which was a little disturbing to see. As I was sampling a 440Hz tone at 44KHz I am not convinced I'm seeing distortion caused by high frequency clipping with too low a sample rate.Colin Ian Kinghttps://www.blogger.com/profile/06458723239721015750noreply@blogger.comtag:blogger.com,1999:blog-1016709139053396535.post-85717521111197998942009-07-21T09:13:11.033+01:002009-07-21T09:13:11.033+01:00I suspect what you're seeing is a consequence ...I suspect what you're seeing is a consequence clipping.<br /><br />http://en.wikipedia.org/wiki/Clipping_(audio)<br /><br />Audibly, it's that cracking sound you get when you wind up the playback volume to compensate for insenstive speakers.<br /><br />It isn't always a harmonic distortion - if you clip a high frequency, the harmonics are above half the sampling rate, so they alias down into the audible range in a most un-musical way.<br /><br />I try to keep my PC audio playback levels at about 70% on the mixer.Geekonoreply@blogger.com