Kanex HDMI adapter audio adjustment

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Level 1

59 points

Kanex HDMI adapter audio adjustment

I set up a Mini connected to a 26" Sony LCD in my kitchen. The computer and cable box live in the cabinet below the TV and the wires pass through a conduit in the wall to keep it neat. To minimize the amount of wire that I had to fish through the conduit I got the Kanex Mini Display Port to HDMI with USB Audio adapter. Two HDMI cables and a small wire for the IR repeater are all that I have in the conduit.

Everything works very well so far with one exception. Changing the audio on the Mini does not affect the audio going to the TV. I was not expecting this but found a review online that referred to this issue so I thought it was normal. I wrote to Kanex and the response from their support said that the audio should be adjustable on both the USB and Digital audio models and they issued me an RMA.

Does anyone have any experience with this adapter? Their support could be wrong (it wouldn't be the first time tech support gave me some bs) or perhaps I should just get a replacement. I also have the option of getting the Digital Audio version of the adapter ($10 more). Last option would be to get a cheaper display port to HDMI adapter and fish two RCA cables through the conduit for audio. That would be cheaper but more of a hassle since the HDMI cables are pretty thick and the conduit is cramped already.

Thoughts?

Thanks.

Macbook Pro, Mac OS X (10.6.2)

Posted on Jan 20, 2010 10:58 AM

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Answer 1

BSteely

Level 5

7,643 points

Jan 20, 2010 9:44 PM in response to Ian Keller

Can you explain the below comment in a little more detail?

Changing the audio on the Mini does not affect the audio going to the TV.

When you say changing the audio on the mini, do you mean you are going into Sound preferences on the mini and selecting USB as the port through which audio should pass? If that is a correct statement, then what do you mean by "does not affect the audio going to the TV"? Do you mean the TV receives no audio, therefore no sound is coming out of its speakers?

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Answer 2

Dah•veed

Level 9

66,667 points

Jan 21, 2010 6:12 AM in response to Ian Keller

Adjusting the audio, do you mean turning the volume up and down?

BTW, Monoprice has your digital version for only US$49.99.

Dah•veed

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Answer 3

Jan 21, 2010 6:33 AM in response to Ian Keller

If you are referring to changing the volume on the Mac mini and this not resulting in a volume change on the TV (via the Kanex Digital HDMI adapter) then this is normal and correct behaviour.

With the Kanex Digital HDMI adapter, the Mac is outputting audio via the digital TOS-Link connection, and should in most cases be merely passing through unaltered the digital audio from your video file or DVD. With digital signals, the volume is actually part of the analogue waveform that has been encoded as digital data, volume changes actually involve changing the analogue waveform of the sound, and as you as in this scenario are passing a digital signal there is no access to the analogue waveform to allow modifying it to change the volume.

So how do TVs receiving audio via (digital) HDMI change the volume you might ask. Well I am glad you asked 😉 they are able to do this because like all devices actually playing sound they need to and do convert the digital signal to analogue before playing it. This is done by a device generally referred to as a DAC - Digital Analogue Converter see http://en.wikipedia.org/wiki/Digital-to-analog_converter once the TV has converted the signal to analogue it can then modify the waveform to alter the volume.

What might be worth considering, is that if you are currently using the Apple Remote to control the volume on the Mac mini, you could instead get a Logitech Harmony Remote and program it so that navigation/playback commands are the same as the Apple Remote, but the volume commands are not and are instead the same as your TV remote. Therefore you can press play/pause etc. and this will control your Mac but when you use volume up/down/mute this controls the TV (or AV receiver).

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Answer 4

Dah•veed

Level 9

66,667 points

Jan 21, 2010 7:19 AM in response to John Lockwood

However, John, if you read his post he is not using the digital version. He has the analog version.

Dah•veed

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Answer 5

Ian Keller Author

Level 1

59 points

Jan 21, 2010 7:34 AM in response to John Lockwood

Sorry, that was unclear - I should have written "changing the volume on the mini" has no effect.

I suspected this was normal as I've read that elsewhere. However, the response from Kanex was that this is a defective unit. When I rephrased the question to reconfirm they responded: "Yes, the volume should be adjustable with both the USB and Digital audio adapter. Thank You, Kanex Live Tech Support"

I came to this forum with the hunch that they don't understand their own products. John Lockwood's response refers to the Digital Audio signal, but would the same be true of the audio over USB? I have USB Soundsticks attached to another computer and that is adjustable so changing the volume over USB must be possible. The question is whether the Kanex USB Audio adapter supports that.

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Answer 6

Dah•veed

Level 9

66,667 points

Jan 21, 2010 7:37 AM in response to Ian Keller

Ian, I think that you will find that the USB connection is purely to power the adapter. It is not functioning for either audio or video.

Dah•veed

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Answer 7

Ian Keller Author

Level 1

59 points

Jan 21, 2010 8:00 AM in response to Dah•veed

David.Austin.Allen wrote:
Ian, I think that you will find that the USB connection is purely to power the adapter. It is not functioning for either audio or video.

Dah•veed

That's true of the Digital Audio version of this adapter, the USB connection is strictly to power the device. But for the USB audio version that I have you must select "USB Sound Device/USB Type" for audio output. There are only two connections, USB and Mini DisplayPort, so the audio must be USB.

For what it's worth, I'd never heard of Kanex before they announced this adapter. Their website has undergone a lot of improvement in the last couple of months and they've now started using different product names. The device I have used to be called the Mini DisplayPort to HDMI with USB Audio Adapter. It's now called the Kanex iAdapt 20. I suspect this is all in an effort to seem like they have their act together for Macworld, though an educated tech support department would serve me a lot better.

Message was edited by: Ian Keller

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Answer 8

Jan 22, 2010 2:50 AM in response to Dah•veed

David.Austin.Allen wrote:
However, John, if you read his post he is not using the digital version. He has the analog version.

Oops. Reading the USB audio version specs, I certainly interpret them as supporting USB analogue audio and therefore implying volume control should be possible. While their information does not state it, it is in theory possible to run digital audio over USB and this then would like the TOS-Link version not be volume controllable.

I intend to get the TOS-Link version but I am awaiting stock to arrive here in the UK.

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