HDMI funny business?

[ohwell]

I'm running into the some odd scenarios with the basic goal of trying to get my 11" MBA to work with any TV to play audio and video.

External displays:
- Dell 23" monitor SP2309W
- Samsung 40" UN40B7000 TV
- Samsung 55" UN55D7000 TV

Adapters:
- monoprice.com Mini DisplayPort to HDMI Adapter - (old) video only
- monoprice.com Mini DisplayPort to HDMI Adapter - (newer) video + audio

Laptops (all connected to external display without using power adapter):
- late 2010 11" MBA
- late 2010 13" MBA (wife's laptop)
- mid 2010 15" MacBook Pro (work laptop)

Scenarios
* 11" + video-only adapter + 23" monitor: video only works - OK
* 11" + video-only adapter + 40" TV: video only works - OK
* 11" + video-only adapter + 55" TV: video only works - OK

* 11" + video/audio adapter + 23" monitor: MBA detects display #2, but no output to the monitor (using power adapter didn't make a difference) - NOT OK
* 11" + video/audio adapter + 40" TV: video & audio works on TV- OK
* 11" + video/audio adapter + 55" TV: MBA detects display #2, but no output to the TV - NOT OK

* 13" + video/audio adapter + 55" TV: video & audio works on TV- OK

* 15" + video-only adapter + 23" monitor: video only works - OK
* 15" + video/audio adapter + 55" TV: video works on TV- NOT OK, TV doesn't show up as audio output option for some reason

If anyone has any thoughts to why the 11" outputs video + audio using the newer monoprice adapter to the 40" TV but not to the 23" monitor or the 55" TV, please let me know.

Much appreciated!

 

[gnasher729]

If anyone has any thoughts to why the 11" outputs video + audio using the newer monoprice adapter to the 40" TV but not to the 23" monitor or the 55" TV, please let me know.

With HDMI, you need a certain signal quality to work. You get signal degradation from the output of the MacBook, from the adapter, the cable, and the connector on the TV. And you need a better signal for higher resolution.

It could be that the second connector had more signal degradation than the first one, and the 55" and 23" TVs had worse connectors than the 40", and you just found an unlucky combination that didn't work. (Doesn't mean there is any fault with the other TVs; it could be that the adapter is just very bad, so a TV that is only 50% better than it needs to be doesn't work, but one that is 90% better works).

 

[ohwell]

@gnasher729

Thanks for the additional insight.

I just thought I had eliminated some of the variables by having the same TV manufacture/resolution, the same MBA video card, and the same adapter manufacture.

FYI, the cable is a high-speed one from monoprice.com.

Lucky me, I'll probably try some more external displays and/or other adapters.

 

[TooSmooth]

I am using the audio/video HDMI adapter from monoprice. I just used it to watch a movie today and it worked flawlessly delivering the movie in 1080p and also sending over the DTS audio track.