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Discussion Starter · #1 ·
Hey guys. I have been looking at the Kanex iAdapt 51 adapter for a few weeks now and am curious as to what you guys think about it.

http://www.kanexlive.com/products/item.aspx?id=3495


If you read the description it says that it supports 5.1 Uncompressed LPCM audio.


This confuses me. I have read all of the FAQ's on their site and it says that the only function of the USB cable is to supply power to this unit. So what we are left with is an adapter that combines an optical audio cable and mini displayport cable into a single HDMI cable.


It has always been my understanding that an optical audio cable is not capable of sending uncompressed audio. How is this adapter able to take the same audio signal out of the mac yet convert it so that it is playing 5.1 uncompressed audio??


If this were possible, I would think that just using a standard optical audio cable should be able to send uncompressed 5.1 but it doesn't.


I know the plug on the other end is going to be HDMI which does support uncompressed audio... but it is still coming through the included optical cable before it gets to the adapter.


I would love to be able to play uncompressed audio from my mini when watching movies, and this seems like an incredible adapter, but I'm skeptical on how it can perform the functions that it claims it can.


If anyone has any insight on how this is possible or any experience with this adapter and would like to offer their "opinion" on the quality and functionality I'd greatly appreciate it.


Thanks guys!

Scott
 

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That adapter has been out for maybe 6 months already, Scott.

Quote:
If you read the description it says that it supports 5.1 Uncompressed LPCM audio

They're lying.

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It has always been my understanding that an optical audio cable is not capable of sending uncompressed audio. How is this adapter able to take the same audio signal out of the mac yet convert it so that it is playing 5.1 uncompressed audio?

It can't.

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I know the plug on the other end is going to be HDMI which does support uncompressed audio... but it is still coming through the included optical cable before it gets to the adapter

Right, best you can get is what optical permits, compressed audio like DD 5.1 and DTS 5.1, definitely not "uncompressed 5.1 channel audio" like Dolby TrueHD or DTS-HD Master Audio. Use this only if for some reason you don't want to run an optical cable to your AVR or just want to run a single HDMI cable direct to your HDTV.
 

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Discussion Starter · #3 ·
I would agree with everything you said based on logic. That's why I posted the question because I wanted to understand how it was possible.


The only hang up that I have is that this device was shown at the Mac World convention as a working device. I know that logically I do not understand how it's possible but at the same time I think a company falsely advertising a product for 6 months would have been forced to stop selling the product or correct the advertisement to reflect that it indeed does NOT support uncompressed audio as they claim.
 

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Quote:
The only hang up that I have is that this device was shown at the Mac World convention as a working device.

Well, it does work for most Mac users in most situations, it just works with DD 5.1 and DTS.

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I think a company falsely advertising a product for 6 months would have been forced to stop selling the product or correct the advertisement to reflect that it indeed does NOT support uncompressed audio as they claim.

Well, now you're getting into gray areas of language, words used intentionally to mislead, and the different ways one might interpret the language on their website.


If you go back and look at caches of the original website and the product press releases that all the stupid bloggers out there merely parroted on their websites, Kanex not only mentioned uncompressed LPCM but also specifically stated DTS-HD and Dolby True HD support. Lots of sheep quickly pre-ordered the devices, first the "miniDP + USB" model, assuming audio would be handled by USB, later they found out that the "miniDP + USB" only model didn't support digital audio at all over USB--since OS X doesn't support it over USB--and later that the "miniDP + USB + optical audio" model didn't support audio over USB at all, that it was for bus power only. So, eventually Kanex changed the language on their website, removed the specific mentions of DTS-HD and Dolby TrueHD and deleted blog entries and a bunch of posts from users complaining about the deception and who wanted their money back. Kanex itself didn't know what its own devices would or would not support in OS X, its users had to complain and tell them.


Now, with this re-launch of something called the "iAdapt 51" the only misleading line in question is "Supports uncompressed 5.1 channel audio such as LPCM."


Well, I hate to say it, but this is probably technically correct. How? The DisplayPort spec (and miniDisplayPort presumably) supports 8-channel uncompressed LPCM--so what Kanex is really saying is that their device supports what DisplayPort supports. Since it's up to each manufacturer to decide which aspects of the full spec to implement, Apple gets to decide whether or not to implement the DisplayPort spec completely and allow uncompressed LPCM through it--and so far they haven't. But as far as Kanex is concerned, that's not their problem.


Unfortunately, someone hoping for this support is gonna read the product blurb and excitedly misinterpret that language the way they want to misinterpret it.


In reality, the Kanex device supports uncompressed LPCM only "if" a particular computer manufacturer enables its miniDP to pass uncompressed LPCM, otherwise you're limited to the optical bandwidth.
 

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Discussion Starter · #5 ·
You are the man!!! That makes perfect sense! I know that I saw their website specifically mention DTS-HD and TrueHD but then I couldn't find it a couple days later.


As far as the mini DisplayPort supporting the audio, is this something that Apple has disabled through the OS that could potentially be "unlocked" by Apple later through a firmware update or maybe could potentially be hacked? Or is it a hardware limitation in the port itself?
 
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