Firewire 800 noise really annoying!

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Level 1

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Firewire 800 noise really annoying!

Hi, I recently upgraded from an iMac 17" intel (Late 2006 model), to an all new iMac Late 2009 Intel core 2 duo, 3.06GHz, 8GB Ram. VERY NICE!

My only issue is this:

My old iMac I used to run my recording studio with, mainly connected to my Mackie Onyx 1220 firewire desk, (Firewire 400).
Since the new iMac only comes with 1 Firewire 800 socket, I had to but a 400 - 800 lead.
Now I get really bad background hum all the while through my main studio monitors, that I didn't get any background hum with my old iMac.

Is there anything anyone can suggest to cure this, of is it just a Firewire 800 thing?
Do I need to buy a REALLY expensive Firewire 400 to 800 lead or a Firewire 800 to 400 adapter?

I'm using a deoxygenated, gold plated Firewire lead at the moment, it cost £30!

Please help.

Late 2009 iMac 21.5" 3.06GHz 8GB Ram 1TB HDD, Mac OS X (10.6.2)

Posted on Jan 8, 2010 2:12 PM

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Answer 1

Jan 8, 2010 2:50 PM in response to rpl16a

It's not like an analog RCA cable. It's digital data being transmitted, not an audio signal. As long as the connection is secure, there should be no difference. It is either working or it's not working. As long as the connection is good, I don't think a "deoxygenated, gold plated Firewire lead" will make any difference in the sound quality.

Is there any way to connect regular headphones to that FireWire device? If you connect something like iPod earbuds to the FireWire audio device output, do you still hear this hum?

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Answer 2

Slicecom

Level 2

295 points

Jan 8, 2010 3:20 PM in response to rpl16a

This is a known issue (by Apple users, not by Apple themselves). The new iMac's cause all sorts of ground loop issues. The best solution is plugging your iMac in through an Ebtech Hum X. You can also just pull the ground pin out of your iMac's power cord but thats not very safe. Other solutions include power conditioners or I've also found plugging my USB audio interface through a powered USB hum eliminates the noise.

Another random observation I made is the noise disappears when the CPU is under heavy load. Weird.

See some related threads here:

http://discussions.apple.com/message.jspa?messageID=10857870

http://discussions.apple.com/message.jspa?messageID=10748818

http://discussions.apple.com/message.jspa?messageID=10748807

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Answer 3

rpl16a Author

Level 1

0 points

Jan 9, 2010 4:26 AM in response to Slicecom

That's great. However. I'm in the UK and can't find anything like that over here. Also, Can't order from the USA because 110 Voltage and Plug pins are different.

I hope Apple solve this problem soon.

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Answer 4

Mar 26, 2010 9:20 AM in response to rpl16a

I'm in the same boat, UK and can't find anything like a Humx. This is really ******* me off now, I've been learning Logic Pro 9 now for the last 4-5 months but the consistent hum is killing me, I can't get any mastering done like this. Apple need to sort this out asap or i'm considering dumping my Imac and Logic for my old PC and Ableton.

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Answer 5

Apr 13, 2010 10:39 AM in response to rpl16a

Still no info for us UK users then?

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