[LAU] Awful noise out of FA-66

[Ken Restivo]

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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?

Tonight's workaround was to unplug the FA-66 from the amp, and plug it in only for the few bars at the end of the one song where I need to trigger the samples, and then unplug it again.

The laptop's power supply is grounded (three-prong) but the FA-66's wall-wart isn't. I thought of trying to ground the FA-66 to the power strip's ground, but then I noted that:

	1) This doesn't sound to me like 60-cycle hum, though it has a little bit of that too (bummer I didn't think to record it and post it). It's digital noise, and I'm not sure grounding would help.

	2) I have no guarantees that the club I'm playing at tomrrrow night will have a decent ground. I've been in some that have pretty sketchy electrical systems. 

Alas, I'm borrowing this amp, and I don't have an amp anymore, I play through my stereo. The FA-66 sounds amazing through the stereo. So this means that I don't have the ability to duplicate the problem at home.

I didn't think to try my Audiophile USB interface, because the FA-66 is much "higher end" and I didn't expect the lower-end interface to be immune to this problem if the higher-end one has it.

However, a possibly-related problem is that the FA-66 has really low-level line outputs. I notice this when playing through my stereo too, but I didn't think much about it until now. But maybe it is related? 

Anyway, I'm not much of an audio engineer, so I figured I'd ask here, in case someone's been through this and fixed it.

- -ken
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