High frequency ringing sound when both external monitor and speakers are connected

[drjsway]

I searched the archives and I can't believe no one has mentioned this yet! This is a huge problem on both my Rev A and my new Rev B.

When you connect an external monitor and external speakers using the headphone output, there is a high frequency ringing sound coming out of the speakers. I've managed to live with it by turning the treble to minimum and keeping the volume low enough but at the expense of sound quality.

The strange part is, if you disconnect the monitor, the ringing sound stops. The problem only occurs if you have speakers and monitor plugged in at the same time. I've tried this on my Samsung monitor, my SONY TV, and my Panasonic audio receiver. The problem occurs with both Rev A and Rev B while my white MacBook and 2007 MacBook Pro all sound fine.

My theory is that because the ports are packed in so close, the audio output is getting interference from the Mini Display/Micro-DVI port. Is there anyone who is not experiencing this?

 

[justit]

I can also confirm this on the Rev B SSD. At the time I thought it was my Bose picking up something so I didn't think much of it. It was bothersome and I ended up turning the volume down.

 

[drjsway]

Did you find a fix or did you just turn volume down? This is a huge deal because it means no one can connect their MBA to a TV to watch a movie.

Anyone have a MBA without this problem?

 

[Cschweppe]

Yes i had and fixed the problem

I joined the forum after reading the post just to share this info... hah.

I am an audiophile and i use my macbook air to play my itunes through my audio system. I too noticed the high freq ringing. After disassembling my air thinking it was a hardware problem i realized exactly what you think is true.... it is the video signal not shielded well enough from the video and jumping to the audio output. I did however find a fix.... it will cost you about 20 bucks and is designed for car audio.

Pac SNI-1/3.5 Noise Filter

http://www.crutchfield.com/p_127SNI135/PAC-SNI-1-3-5-Noise-Filter.html?tp=1282&tab=review

I have tested it and the signal loss is VERY minimal. (less than a db at most frequencies)

 

[andrewp]

Ye I can confirm this too...However I had an old M-audio usb audiointerface that I used and got rid of the noise. But man, what a stupid mistake

 

[Cschweppe]

yep

Yep if you get your audio through the USB port in some way it will fix it. But i had to find something else since all my music and movies are on a usb drive... and i dont like the delay that my usb hub puts on audio when watching a movie....

 

[tubbymac]

Wow that is a sloppy mistake for Apple to have made. It probably didn't get fixed in rev B because not enough people knew about it.

 

[hybster]

I have it as well, rev. B.

As the displayport, usb and audio-out both reside on the same ribbon, it would be difficult to cut out the sound part of the ribbon in order to shield it. Could anyone try to pick up the audio directly on the audio board?
This way perhaps we could find out if the interference is at the ribbon or not. If it is before the ribbon, there is not a lot to be done. But (and most likely imo) if the noise only exist when using the ribbon connection, we could try to either cut up the ribbon or do some new wiring from the audio board.

Other ideas?

 

[Maven1975]

Same results with my 1.86 Rev. B. I feel bad for those with bad screens and this issue combined.

Im getting real tired of these issues.

 

[Maven1975]

I found a working in-store solution at RadioShack for $16.99. (Part # 270-054)

I hope Apple finds a solution with Revision C.

 

[obrecht]

Thanks

I have the same problem in my music classes. For the longest time I thought that the problem was in the AV cabinet—IT no doubt thought my "ringing" complaint was a little nutty. Now I'll need yet another wire connected so as to make this computer functional for the classroom.