Computer sounds carried through USB cable into audio interface and speakers

[porcupinetree]

Hi guys,

After doing a fair bit of troubleshooting, I've realized that the sounds produced inside my mid-2011 21.5" iMac (power supply, circuits, etc.) are being transmitted through my hi-speed USB 2.0 cable into my audio interface (Roland Octa-Capture), and out my powered speakers (KRK Rokits). I hooked up my Macbook (much older model), and the sounds go away, with everything else being the same.

Has anyone else had this issue? If so, how did you get around it? I've heard that using a powered USB hub can fix this, and I also know of optical USB extenders that may do it (although they cost more than the interface itself, which is pointless). I also believe there are some galvanic isolators out there, but from what I know, they only support up to full speed (12 Mbps) USB and not hi-speed (480 Mbps).

Your help and insight would be much appreciated! The sounds are driving me nuts. Each time a page loads, I move the mouse, etc. I hear the corresponding sound in the form of hisses, crackles, squeals and the like.

Thanks!

 

[PTravel]

A couple of thoughts:

1. Get a USB cable with a ferrite bead. The bead should help sync any leaking signal that may be finding its way into the audio circuits.

2. It might be a ground loop through which high-frequency signals are leaking. Is everything plugged into the same AC line? If so, try a ground lifter (get at any hardware store). Ground loops usually result in 60 Hz hum, but I suppose they could provide a signal path as well and ground lifters are cheap.

3. You might have a bad piece of hardware. Have you tried moving the Octa-Capture somewhere else? Routing the cables differently?

 

[porcupinetree]

Hi,

Thanks for the input.

1. Get a USB cable with a ferrite bead. The bead should help sync any leaking signal that may be finding its way into the audio circuits.

Tried this, but no effect at all unfortunately.

2. It might be a ground loop through which high-frequency signals are leaking. Is everything plugged into the same AC line? If so, try a ground lifter (get at any hardware store). Ground loops usually result in 60 Hz hum, but I suppose they could provide a signal path as well and ground lifters are cheap.

Haven't tried this yet, but I've ordered an EBTech Hum X unit, which is kind of like a ground lifter, but not quite. It just filters the ground, but keeps the actual ground connection. People have sworn by it. Let's see how that goes.

3. You might have a bad piece of hardware. Have you tried moving the Octa-Capture somewhere else? Routing the cables differently?

I'm pretty sure I have a bad piece of hardware - and that is the iMac. I did effectively try moving the Octa-Capture somewhere else. As I mentioned in my original message, I kept everything the same (i.e. Octa-Capture, USB cable, speakers, etc.), but instead of hooking up the USB to the iMac, I hooked it up to my Macbook running on battery. In other words, the computer driving my Octa-Capture, speakers etc. was now the Macbook, and not the iMac. All the sounds stopped, and it was just fine. When I hook up the iMac again, it starts all over. I talked to Apple Care, and I've set up an appointment for a repair on Friday. I think it's the power supply unit in the iMac. Will keep you posted on how things go.

Thanks!

 

[Armistice]

Are you related to Porcupine Tree the band?

Does Steven know you've taken a life of your own and are posting on teh interwebz?

Sorry, can't help with your problem BTW...

 

[captainbeyond79]

Just turn your computer sounds off. I have the Steinberg CI2 interface, and the second I plug that USB cable in...everything goes through it. My computer sounds, itunes, windows media player. It effectively routes everything that was coming out of my speakers through the audio interface. I don't know macs well but in Windows if you go into audio properties, there should be a drop down menu where you can toggle whether your mixer is controlling volume on your internal audio card, or volume/settings on your audio interface. I'm not sure what kind of sounds are being routed through, but just go into properties of audio and shut off computer noises, blips and bleeps, and boops out of the OS. You should be able to select no sounds.

I know I'm not talking Mac, but I hope this helps anyway.

One more thing with hisses/crackles pops is there any chance there is an internal microphone in the iMac that might be picking things up?
I know when I'm using like ASIO4all I have to go into the ASIO plugin and disable the onboard microphone on my laptop otherwise it picks up room noise.
Check in ASIO or your audio settings what you have for input channels.

 

[porcupinetree]

Hi guys,

Armistice - I wish I was in that band! Unfortunately, I'm far from it, but I'm a huge fan!

captainbeyond79 - Maybe I didn't explain well enough. It's actually ground loop noises that are being carried through the USB, and not ding/ting kinda OS sounds - i.e. not system sounds. So putting it in "no sounds" mode wouldn't help in this case, since it's internal hardware EMF/EMI type sounds that are being picked up by the USB, which is almost acting like an antenna. I suppose it's the equivalent of sounds made by the internal fan, hard drive whirring, etc. which can't be shut off by a soft menu. Hope that clarifies it.

In any case, as I mentioned in my previous post, I found this little gadget online which I was able to purchase from Amazon: EBTech Hum X Hum Eliminator (weird, it won't let me post the URL, even though it did in the previous post! But Google it).

I received it in the mail yesterday. Plugged my iMac into it, plugged it into the power outlet, and no more weird computer noises! So yes, definitely a ground loop issue. I have Apple Care, so I will be taking it in for them to check out any ground loop issues, but for now all's well. If anyone else has a similar issue, give it a shot.

 

[PTravel]

In any case, as I mentioned in my previous post, I found this little gadget online which I was able to purchase from Amazon: EBTech Hum X Hum Eliminator (weird, it won't let me post the URL, even though it did in the previous post! But Google it).

I received it in the mail yesterday. Plugged my iMac into it, plugged it into the power outlet, and no more weird computer noises! So yes, definitely a ground loop issue. I have Apple Care, so I will be taking it in for them to check out any ground loop issues, but for now all's well. If anyone else has a similar issue, give it a shot.

That's good to know. I have one that I used to knock out some hum in a power amp, but it never occurred to me to suggest it for your problem. Glad your problem is fixed, and happy that this handy little device is so useful.