Crackling audio

I have a Mac Pro 5,1 with AMD 580 RX graphics card running Mojave and FCPX 10.4.7. In FCPX there are no problems with audio. Outside of FCPX is a different story. If I am looking at a video on youtube, or listening to a song on iTunes, or anything else, the audio crackles. The audio sounds fine if I listen to the internal speakers. I am monitoring audio with an older Alesis MasterControl surround interface that is connected via firewire. Like I said previously, Audio is fine inside
FCPX, so I know its not a loose or faulty cable.

Since the Alesis is 11 years old and the driver for it is pretty old, I would suspect that is the culprit. But why does the audio sound great inside of FCPX?

Anyone have any thoughts?

Thanks,


Mike

Could be several factors. I'll respond in more detail soon.

I'm guessing you forgot.

Hi Mike, Welcome to the forums.
If I understand you correctly, you experience audio crackle anytime you use the Alesis Control interface, but not if using internal speakers or inside FCPX. Also that it does not matter the source of the audio including iTunes or other audio files?? But is it fine playing audio while using the interface via FCPX??
What about wired headphones directly to computer?
If it only occurs with the Alesis interface, then that pretty much isolates the issue to your interface. While it could be the "drivers" or a software/firmware issue(are you up to date?), it could also be as simple as a bad cable, dirty connections at ports, or it could be that a circuit component could be going bad like a capacitor/resistor/power supply chip. If swapping the cable and cleaning the ports does not fix the issue, very possible interface is going kaput and would need internal board level repair. Sometimes this could be a bad solder connection on the Alesis internal board. Unfortunately, board level repairs can be expensive, but might be worth it. OTOH, it is 11 years old.
Can you borrow a different interface to test? If a different interface does have the issue, I would then suspect a chip inside the computer itself that is going bad. If a different interface especially a surround sound device, also shows the same behavior, then I would suspect that the issue is in computer, but that FCPX is sending the signal to a different component for processing that bypasses the faulty chip.

Hope this Helps, Greg

Hi Greg. Thank you for your reply. I have figured out the problem. It's not the Alesis or the Mac Pro. I was using a Magic Trackpad via bluetooth. I had heard that bluetooth can have a problem with certain devices. I turned off bluetooth and the problem disappeared. I use the Magic Trackpad in concert with my Wacom. I guess I will have to give up the trackpad or find another way to use it.

Hey Mike
Thanks for posting your solutions, that helps everyone.
There are known issues with USB3 and Bluetooth. But are you using USB3? Did you add a card? MP5.1 had only USB2.1. Have not heard about this issue using USB2 devices.
Before giving up completely on your Trackpad, you might try to move the trackpad around your desk and see if it improves reception. USB3 frequencies can radiate and cause interference but is very subject to distance and direction.
Good Luck and Happy Editing
Greg