Matt, For the most part I agree with your analysis. If the card is only making noise in the left channel then it seems more likely (to me anyway) that the card itself might be having problems. Bad clocking would presumably cause noise in both channels. Any reason to suspect it's gotten damaged? I have an M-Audio 2496 and I've never had any trouble like you're experiencing. I cannot remember. Did you say whether this machine is dual boot? Any problems with this specific card in Windows? It's my guess that the noise is not being caused by your PC environment unless you are having some sort of problem with either the power supply or the motherboard. Testing the card in a second computer would help identify that. Again, I've used one of these cards for years and never experienced what you are talking about. I'm sure if it was happening we would hear about this here all the time. - Mark On Fri, Apr 25, 2008 at 5:44 AM, Matt Garman <matthew.garman@xxxxxxxxx> wrote: > On Thu, Apr 24, 2008 at 09:43:33PM -0700, Mark Knecht wrote: > > > One, the crackling of my MAudio 2496. I'm just assuming that > > > the inside of my case has a lot of RF interference, so digital > > > coming out of the PC seems like a good way to get away from > > > that. > > > > Crackling is not caused by RF. That will cause non-linearity in > > the analog portion of the D/A which results in distortion of > > levels or 60 cycle hum, but hardly more than that. > > Just to be clear: are you saying that the crackling on my card > certainly doesn't have anything to do with electric noise in my > case, and/or power irregularities? > > > 1) Something in the audio chain, and it can be either analog or > > digital, is being over driven. Typically this is caused by > > different views of the proper strength of signals. It's often > > caused by folks thinking most of the time the song sounds better > > when it's turned up loud. My son composes in Acid Pro (as do I) > > and we're often finding mistakes within his mixing chain where > > little bits of distortion creep in. You should get VERY clear > > about how much headroom EVERYTHING in your signal chain has. Much > > of this hardware and software has almost none and hence you end up > > needing to be very careful about how you drive the signal through > > the chain. > > I usually think of the sound of over-driven circuits as "distortion" > rather than "crackling". (That comes from being an electric guitar > player, where, for example, the distortion from over-driven tubes is > desirable.) > > Either way, if something is being over-driven, wouldn't that imply > that certain types of sounds would be more likely to produce the > crackling than others? > > Also, wouldn't it happen on both the right and left channels? > > In my case, the crackling is on the *left* channel only (unless I > swap right and left on one end of the cable). Plus, the crackling > is random---it's not tied to any part of the music I'm playing. In > fact it sometimes happens during silent parts of the songs. > > It also occurs regardless of levels, either on my amp, in alsamixer > or in envy24control. I spent quite a while adjusting anything that > could be adjusted to see if I could stop the crackling. > > In fact it's more pronounced when levels are low---it does get > louder with increasing volume, but the music gets louder than the > crackling, so at sufficiently high volumes, I can almost drown out > the unwanted noise. > > > 2) The second most common cause of crackling, most especially I think > > with Linux audio users, is mismatching of sampling rates somewhere in > > the chain. Sending a 44.1K Signal across a 48K link, or sending it > > across a 44.1K link but the two ends being out of sync with each > > other. Ensuring that everything is properly clocked is an absolute > > requirement of doing digital audio. > > That seems more likely to me, but how do I test this? > > Also, why would this only cause crackling in one channel? > > ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
