Garageband and USB interface woes

I've been using Garageband and my Lexicon Alpha USB interface for a few years now, and I've recently run into trouble.

I changed from a Macbook Air to a refurbished Macbook Pro earlier this year, and have had little trouble using my USB interface in Garageband (primarily to record a bass guitar). Now I've come across a strange problem where I only get this really harsh staticy hissy noise instead of my bass guitar. I changed out the USB cable once, and that seemed to work, but now nothing seems to be working. I tried it on my old Macbook Air and it worked perfectly, so I don't think it's the USB interface that's the problem. I've tried different audio cables, USB cables, I've tried restarting my computer, updating software, etc. I even tried Audacity to see if it was a problem with Garageband. The same thing happens. Harsh staticy hissing noise that resembles a screaming robot.

Is it my computer? I figured it might be since my old Macbook Air worked perfectly with the interface...any ideas?

Is it my computer? I figured it might be since my old Macbook Air worked perfectly with the interface...any ideas?

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It sure sounds like it might be the input interface of the refurbished MacBook Pro. Where did you buy the MacBook Pro from? And do you have another machine besides your MacBook Air that you can try?

Interesting. There's another thread running right now that comments on static type noises from USB (while using iTunes.) You don't mention your OS. Are you running Sierra, perchance?

KevinJS said:

Interesting. There's another thread running right now that comments on static type noises from USB (while using iTunes.) You don't mention your OS. Are you running Sierra, perchance?

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No, I'm running El Capitan.

OK. That kills my hypothesis then. I wondered if Sierra had damaged USB digital sound output but in your case it hasn't had the opportunity.