Audio interface sending noise through USB

[CC Ricers]

I have a Lexicon Alpha audio interface that I use for recording samples and mixes from CDs, records, etc. Recently I tried to rip another one of my records to mp3 using Audacity on the Mac as usual, and I get some really loud distorted noise on the left channel. The right channel sounds fine, but quieter than usual.

I tried swapping USB ports and cables and still the same thing. Then I plugged my headphones into the headphone monitoring jack of the Alpha, and listened in while it's recording, and everything sounds fine there. Also, if I connect some audio cables from the Alpha's stereo out to the computer's line-in, it sounds okay there too, sans the quiet hiss you usually get from the line-in recording.

It seems like the USB port of the Alpha is somehow not working and sending in bad data to the computer. Is the Alpha messed up for good? Anything else I can try to isolate the problem?

[AMT]

Have you tried reinstalling / updating the drivers for the Alpha?

[SnappleMan]

First thing I would do is make sure your sources are not causing problems, then I would update the drivers, reinstall and see if you can flash the firmware of the unit. Then if all that fails, I'd declare it broken, and considering USB is a digital connection I don't think changing cables would solve your problem.

Possible causes for noise:

1. Input jack is fucked. Something may have happened to the jack to cause a loose connection or something else that would introduce noise into the recordings.

2. Preamp is fucked. If the unit has a preamp, that is. Or if it's made for high-z input like electric guitars, you may have damaged it by plugging in something that was not compatible or too hot and blew out a component inside.

3. Loose cables... seriously...

4. Electrical interference. Make sure the power going to all your music equipment and PC is as clean as you can get it. That means using surge protectors and power conditioners.

5. Faulty unit.

It's most likely gonna be 5.

[CC Ricers]

AMT, the Alpha has no drivers for the Mac. And if I can find that CD again only choice is to re-install Cubase LE and try that in place of Audacity.

Snappleman, I could try testing another sound source but it'll have to wait. The only cables I have for the Alpha's line in are 1/4" to XLR and only my mixer can use those at the moment.

These are the back connections it has:

Phono line outs are apparently working fine. If I connect a cable to the computer's line in and record using line in, it will sound great except with a hiss in quieter parts. I seldom use the 1/4" line outs.

I don't think the unit has a preamp- my mixer has one anyways. More likely I think the USB connector is messed up. That's the only place where the noise problems occur. Yeah, it's probably broken.