Re: [LAU] Awful noise out of FA-66 -- SOLVED

On Friday 25 May 2007 02:48, Loki Davison wrote:
> On 5/25/07, Ken Restivo <ken@email-addr-hidden> 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@email-addr-hidden
http://lists.linuxaudio.org/mailman/listinfo.cgi/linux-audio-user
Received on Fri May 25 20:15:01 2007