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Help with noisy USB audio interface

paulraphael

paulraphael

Apr 13, 2006
624
302
Brooklyn
paulraphaelson.com
Disclosures
If you heard me play, you'd stop reading what I write.
#1
I've been losing my mind trying to troubleshoot this. Maybe one of you geniuses can help.

I'm using an E-MU 0202 USB-2 interface on my computer (PowerMac G4, OSX 10.4.11). I'm using it more for music playback than for recording.

I get noise that ranges from the ocasional buzz and zap to loud backround crackle. Sometimes it even degenerates to total distortion, which repairs itself if I turn the device off and on.

Here's some troubleshooting I've done:
1) replaced the E-MU device. The store that sold it to me assumed it was defective and sent a new one. No change.
2) replaced the USB-2 card. Things got worse!
3) replaced the USB-2 cable. No change.
4) tried different outputs on the device (line out to stereo, line out to powered speakers, headphone out). No change.
5) compared to the Mac's built-in audio. This is almost perfect, although once in a great while I hear a buzz or zap. Of course, sound quality is low.

Any thoughts?

This audio interface draws its power from the USB port. There's no option for a separate power supply. I'm wondering if dirty power from the computer's power supply might have something to do with it. If this sounds likely I may try a powered USB hub.

Thanks for any brainstorming.
 
#3
I don't think that's it. From what I gather, the only issue with USB resources if if you don't have the bandwidth available. At that point the port will just shut off.

I have these problems even if I'm not using any other USB devices (the keyboard and mouse, which use insignificant bandwidth, are on the computer's built-in port, not the USB-2 card that powers the audio interface).
 
#5
Did some more troubleshooting. Proximity to monitor, computer, wireless stuff, etc. isn't the issue.

I hooked the unit up to another power Mac, and the problem went away. So it seems to be an issue with the computer.

I'm wondering if it could have to do with dirty power from the computer's power supply. I may try plugging the unit into a powered USB hub, but i'd have to buy one ... does this sound like a reasonable idea?
 
#8
It's more than likely a driver issue and how the computer is handling them. I get a similar issue if I don't get a clean reboot (ie. after a fresh cold boot or crash). Creative makes great devices, but their drivers are terrible. Try another set of drivers or a clean restart (not a shut down/restart). I really can't be certain on this due to pc vs mac issue. But their drivers usually tend to be the culprit in most situations.
 
#9
yamark said:
i found that my issue came from my laptop power cord
Click to expand...


Glad ya found it. And now that you say what it was, I've seen similar on the forum for the company that makes my firewire interface.
By power cord, you mean that when the laptop is plugged in to A/C voltage it creates the interference but running off the battery it doesn't? Rather than something was/is physicaly faulty with the power cord?
 
#11
paulraphael said:
I don't think that's it. From what I gather, the only issue with USB resources if if you don't have the bandwidth available. At that point the port will just shut off.

I have these problems even if I'm not using any other USB devices (the keyboard and mouse, which use insignificant bandwidth, are on the computer's built-in port, not the USB-2 card that powers the audio interface).
Click to expand...

- Did this card come with the audio interface?

- Does your G4 have USB 2.0 ports?

- Which PowerMac G4 do you have?

- The USB audio interfaces I've seen all call for a fast G4 (or better) with built-in USB 2.0 ports.
 
#12
It's not a card, it's an external interface that connects via USB-2. It works fine hooked up to the same usb-2 card in a different computer.

The computer that's having problems is a dual 1.25ghz machine (it works fine in the other machine which is only 500 mhz).
 
#14
How does a ground loop isolator work? And does it do somethring different from the ground lift switches on the unit itself (they have no effect)?

By replacement power supply I'm assuming this includes a powered USB hub, which I'm thinking about trying. I don't believe they're all expensive.
 
#15
paulraphael said:
It's not a card, it's an external interface that connects via USB-2. It works fine hooked up to the same usb-2 card in a different computer.

The computer that's having problems is a dual 1.25ghz machine (it works fine in the other machine which is only 500 mhz).
Click to expand...

Hmm... Invalid Link Removed The last & fastest of the OS 9.2.2-bootable Macs. Nice machine! :)

Have you tried your USB card in different PCI slots? (The ol' card shuffle is sometimes what it takes to get things working.)

Which make & model of USB PCI card do you have?

Are you using other PCI cards as well? If so, you may be straining the power budget for your Mac's PCI bus thus starving your USB card.

Are you running your Mac in dual processor mode? If so, that may be causing the problem.

EDIT: Is your Mac's firmware up to date? If not, then check Apple's Web site for a newer version whose description may indicate that it was aimed at resolving a PCI bus issue. (It's a long shot...)

--------

Sorry for all these questions, but often troubleshooting amounts to eliminating the 99 things which aren't the cause in order to find the one which is.
 
#16
I'll try a different PCI slot ... hadn't thought of that. If that doesn't work, I'm getting a powered USB adapter and crossing fingers.

MIJ-VI said:
Hmm... Invalid Link Removed The last & fastest of the OS 9.2.2-bootable Macs. Nice machine! :)

Have you tried your USB card in different PCI slots? (The ol' card shuffle is sometimes what it takes to get things working.)

Which make & model of USB PCI card do you have?

Are you using other PCI cards as well? If so, you may be straining the power budget for your Mac's PCI bus thus starving your USB card.

Are you running your Mac in dual processor mode? If so, that may be causing the problem.

EDIT: Is your Mac's firmware up to date? If not, then check Apple's Web site for a newer version whose description may indicate that it was aimed at resolving a PCI bus issue. (It's a long shot...)

--------

Sorry for all these questions, but often troubleshooting amounts to eliminating the 99 things which aren't the cause in order to find the one which is.
Click to expand...
 

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