Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

audio jack issue

L

Link00seven

macrumors regular
Original poster
Mar 6, 2008
133
1
NYC, USA
Hello,

I have a couple of questions. I just purchased a stereo audio cable (the red/white plugs) so I can plug my macbook pro into my yamaha sound system. Since the MPB has a 3.5mm headphone jack, I used an adaptor to plug in the LR audio into that jack. The problem is that when I plug it in, I get a weird noise (we've all heard it...I just can't explain what it is, the like, bzzzzzt noise) and it doesn't go away. Using the same cables and 3.5mm jack on my iPod, however, works fine. Using regular headphones in my MPB works fine too. So whats the problem? Do I need a certain 3.5mm jack to use the stereo cables into my MPB?

Thanks.
 
adapters like that can cause noise try and find a red/white rca to 3.5 mini all in one cord
 
Find the cable. Being a sound engineer, adapters can just be terrible. I've seen people hooking up 3 or 4 adapters and the sound integrity just plummets. Get a cable, it'll be more sturdy and sound much better.
 
Sounds like a grounding issue to me

As an engineer, I don't think the adaptors are the problem, considering output from your ipod doesn't cause it. Many amps, especially when connected to other electrical equipment, sometimes don't hold the same ground voltage as the output device (i.e. the computer) due to the resistances in the device leading to ground. Since the ground of the computer and amp are different, and tend to vary over time slightly, this offset is amplified and creates the buzz you hear. Try finding a ground wire on the amp (it's a green wire or screw connection) and ground that to the mains power supply. Make sure the computer and amp are connected to the same surge protector so that the grounding between each is as close as possible. Differences in ground connection can introduce small resistances that can affect the quality of the sound. Hope this helps.

One addition, other electrical devices can interfere as well through electromagnetic radiation from cabling, or simply from the device itself. Try to separate the cabling of your TV and other devices from the cabling of your sound system and computer.
 
This is weird. Since my Yamaha system as a 3.5mm jack that will accept input signals (and I use the macbook pro's 3.5mm output) I picked up a cable that would do that and its the same problem. However, the noise only occurs when I have devices plugged into the USB ports, or my monitor plugged into the DVI port. Otherwise it doesn't do the bzzzz noise. How can I get the proper equipment that will let me plug this MPB into my sound system? It's almost like I need a better shielded cable.

I could use an optical cable, but all the optical ports on my sound system are used already and getting true 5.1 audio out of my laptop isn't a concern.

Edit: I read through your post leo, and you say the problem is that I need to run a ground wire from my receiver? I haven't had this problem before now and as I described it only gets the noise when I have other cables connected to the laptop such as the DVI or USB. I don't understand why this is happening nor do I really understand what I need to do to fix it.
 
Keep the wires leading from your DVI and USB away from the sound cables. It wouldn't hurt to coil the sound cables around a pencil or something larger, this may decrease interference if that is in fact the problem. If this doesn't help then the DVI and USB devices may be inducing current fluctuations that are affecting the sound leads inside the computer, which you will not be able to do anything about.
 
Hmm its some interference somewhere along the line. I used the same RCA audio cables and adaptor to go from my laptop directly into the HDMI analog sound inputs that my TV has and then use a DVI-HDMI cable for video and that all works perfect. (Although I wish Mac OSX had a nice way to use ONLY an external monitor.)

The problem lies when I use my Yamaha sound system. Somewhere something isn't grounded nicely.
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back