On Friday 25 May 2007 02:48, Loki Davison wrote: > On 5/25/07, Ken Restivo <ken@xxxxxxxxxxx> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > On Sat, May 19, 2007 at 11:40:16AM +0200, Pieter Palmers wrote: > > > Pieter Palmers wrote: > > > >Ken Restivo wrote: > > > >>-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > > > >> > > > >>I plugged my spiffy new linux laptop into an amp tonight and used it > > > >>as an instrument with a band, using an M-Audio Axiom49 as a MIDI > > > >>controller. > > > >> > > > >>Not everything works yet on this new machine, but what I needed most > > > >>for tomorrow night's show (specimen, with a couple specialized > > > >>samples), worked fine. > > > >> > > > >>Except for the noise. The FA-66 was producing the most awful, buzzy, > > > >>glitchy digital background noise. > > > >> > > > >>I ran the following chain, and got horrible aliasing noise: Laptop -> > > > >> ExpressCard Firewire -> FA-66 -> SWR bass/keyboard amp > > > >> > > > >>The FA-66 is powered by its wall-wart, since the ExpressCard doesn't > > > >>power it (even though it is a 6-pin connector). > > > >> > > > >>My question is this. What's up with that awful noise? > > > > > > > >When googling around I found at least one other person having the same > > > >issue with the FA-66. > > > > > > > >I've noticed similar noise at some places with my QuataFire line > > > > out's. > > > > > > > >Some things to try: > > > >- unplug the power supply of the laptop (for test) > > > >- put a DI box inbetween the amp and the edirol (enable ground lift) > > > >- use another power supply for the edirol (preferably a transformer > > > >based one). > > > > > > http://docs.info.apple.com/article.html?artnum=86655 > > > > Thanks for your help! The USB M-Audio Audiophile exhibited the same noise > > problem. Then I unplugged the laptop's power supply and ran off of > > batteries, as you suggested, and there was blissful silence! > > > > The problem was the power supply. > > > > Any advice on brands/distributors of good *quiet* laptop power supplies? > > The cheap-ass "Delta Electronics" supply (19v, 3.6A) that came with the > > laptop obviously sucks, and the only other 19v laptop power supplies I > > have around here are only 1.8A. > > > > - -ken > > Have you tried groundlifting the power supply? Worked for me... until > i found a better solution, throwing out the laptop and getting a > desktop. ;) > > Loki A couple of thoughts Loki. Would an AC filter (such as on old computer equipment) resolve a problem like this ? Or perhaps one of those ferrite cores, like are on the monitor cable, and I see I have one on my webcam cable as well. I did see the ferrite core option suggested some time back when someone had interference showing up on sound output. Nigel. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo.cgi/linux-audio-user
