Bill Unruh wrote: > On Wed, 26 Jul 2006, Thomas Hood wrote: > >> I'm using a Realtek ALC850 >> http://www.realtek.com.tw/products/products1-2.aspx?modelid=2003101 on >> an http://www.asrock.com/PRODUCT/775Twins-HDTV.htm, so I guess it's >> not the STAC9708/11 issue. >> >> Incidently noise levels on this thing are appalling -- you can hear >> noise just by moving the mouse, although the tests on this page >> suggest otherwise: >> http://www.ixbt.com/mainboard/epox/rmaa/9npa3j-alc850.htm >> > > The inside of a computer case is probably the worst place in the world for > any low noise electronics. There is so much radiation in there of all > frequencies thatit is astonishing that sound cards can produce any low > noise signal at all. > >> I assume that this could be due to a bad analogue stage on my >> motherboard's particular implementation, as I imagine Realtek, just >> supply a chip(?) and the motherboard manufaturer supplies the rest. >> > > Not just the analog but the whole electronics. designing a board so that > all the radiation from all of the other parts of the computer do not > pollute the sound signal is tough and is far more than just the chip. > > >> I will try reducing the level when I return home on Thursday. >> >> Thank you for the suggestions, >>
Exactly, the Codec itself just converts what it receives into digital values. The problem is the analog pre-amps etc. that happen before the signal reaches the Codec. I have a PCI sound card with an analog input that is true 20bit accurate. It has a 24bit codec, but the pre-amp circuitry can only manage 20bits. This is currently the best possible of any audio equipment in the industry. Now, 20bit accurate is extremely accurate and low noise. So, it is achievable on a PCI card. The problem is that hardly any motherboard manufactures take even simple steps to make the mic input less noisy. Your noisy mic is probably only giving you about 8 bits of real sound, even though the codec probably says it is 24bit. From what I can tell, the cost of improving the mic input on motherboards would be a zero cost item in hardware terms, but manufacturers just don't seem to care, and therefore don't spend any time even trying to improve it. James ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
