Saffire Pro 10 - Hum with phantom power?

Discussion in 'Digital Audio' started by winstano, Mar 24, 2009.

  1. winstano macrumors regular

    Dec 17, 2005
    Hey guys, bit of a specialist question here, but thought I'd try anyway...

    Basically, I've invested in a load of home studio gear over the past week or so (graduated from uni nearly 2 years ago in Music Tech and never really followed it up, so decided to kick my rear into doing something!), and I've encountered a little problem.

    Basically, whenever I want to do some recording with a condenser mic, I get a really annoying hum around 100Hz, which I can only assume to be a ground loop. The annoying thing is that if it was a ground loop, wouldn't it affect everything else connected to the Saffire? (monitors etc?)

    Everything is currently in my room, which is on a separate circuit to the rest of the house, and removing all cable/Sky plugs and coaxial cables doesn't seem to do anything either. I've yet to test it on another circuit in the house, but it's a really annoying issue, as it basically means I can't do any recording with condensers!

    If I turn my monitor output up to full when there's nothing plugged in, there's a very very faint hum, but it's not noticeable on any recording as it's such a low level.

    If I turn Phantom Power on and don't plug a mic in, it's the same as above (ie, a very very very faint hum when turned up full), but as soon as I plug a mic in, it becomes borderline un-usable

    I've played around a little bit, and it appears that my iMac (G5) doesn't have enough juice in the firewire bus to power the Saffire on its own. However, my MacBook does, and this confirms it's definitely something to do with the power supply, as when I run it from FireWire it has no hum (even if I have to turn the input up a bit more than usual)...

    Any ideas?

    Thanks in advance :)
  2. BDjohnson macrumors newbie

    Sep 10, 2013

    Exactly the same problem here. Are there any workarounds? Have you solved the problem?
  3. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    Try this: Buy a stand alone phantom power supply box. Place this between the microphone and the audio interface. Then turn phantom power off at the interface.

    Or if you have the $$ just get an outboard microphone preamp and then run that to the line-in on the audio interface. Tell yourself you wanted the compressed/limiter to be analog anyway to justify the cost.
  4. BDjohnson macrumors newbie

    Sep 10, 2013
    Thanks. The phantom power supply is worth a try.
    A preamp is no solution for me because I allready got one which comes in via s/pdif. I want my condenser mics to work with the saffire in a drum- and band recording set up...
  5. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    If the power supply fixes the problem then you know the audio interface's built-in phantom power is defective. Get it fixed. Perhaps the "balance" is not perfect between pins 2 and 3?

    One other idea, I've been fighting hum also with a video mic. I found two of my XLR cable have the shells conected to pin-1. I think this is wrong. If the chassis and shell needs to be grounded the connection should be made inside the device or the microphone, not in the cable. I cut the connections. It was not a 100% fix. Just one more thing to think about. I am NOT talking about "ground list" that is what you disconnect pin-1. This is the shell to pin-1 connection. Ground list might be the last thing to try but I doubt it would do anything in your case.

    All that said, you will know a lot more after experimenting with a phantom power supply.

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