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New Apple TV is NOT bit perfect


freemanzhu

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Just got the new Apple TV by FedEx today. I had been using an Airport Express (the newer 802.11n model) as a music server pulling Apple Lossless files from iTunes on my computer, and I intended for the Apple TV to take over this function (in addition to its other functionality). However, I was dismayed after some investigation that, not only is the new Apple TV not bit-perfect, its digital audio output is audibly flawed.

 

First, the bit-perfect part. The Airport Express is bit perfect as long as volume is set to maximum. I've tested this myself; when the Airport Express plays a DTS-encoded WAV file, my receiver's DTS indicator comes on and I hear music, indicating that the Airport Express is bit perfect. (As soon as I lower the volume even one notch, there's nothing but static, because the calculations required to perform digital volume control get in the way of bit perfect.)

 

Playing the same file through the Apple TV connected to the same receiver, I get nothing but static regardless of volume. I read on another forum that the Apple TV converts all audio to 16-bit/48KHz; presumably it's that conversion that precludes bit perfect. By the way, I turned off sound effects in the Apple TV, and it's still the same, no bit perfect.

 

So, the Apple TV is not bit perfect, but does that matter for the sound quality? AirPlay (formerly AirTunes) offers an easy way to do an A/B between the bit-perfect Airport Express and the non-bit-perfect Apple TV. By setting iTunes to output to both simultaneously, I'm able to do an A/B comparison simply by switching inputs on my receiver. My initial impression was that the two sounded pretty much the same even if one was not bit perfect. But then I noticed a slight click, almost like a tapping sound, in certain passages in piano recordings with the Apple TV but not the Airport Express (it's almost like the clicking sound you might hear through a digital receiver or processor when switching between inputs, but softer). I did have to listen closely, with headphones (AKG K702), and in a quiet environment, but it's consistently observable and repeatable in the exact same places in those recordings. I haven't tested with other recordings to see if the Apple TV does the same thing, but having observed the same flaw with two different piano recordings, it's clear that the Apple TV's digital audio output is flawed.

 

Anyway, I hope this information helps those out there looking for the Apple TV to do music duty. Stick to the Airport Express, at least for now.

 

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@freemanzhu: Slightly off topic, but can I ask what playback software you are using to play dts encoded wavs (aside from appletv of course!)? My next question is this: I just found a beta version of xbmc that appears to be bit perfect and change sampling rates automatically (can't confirm this as I don't have a DAC that would show what's coming out). So my question is if I am hearing a DTS encoded wav being played back without the static (and all 5 channels although its PCM-my receiver does decode DTS in movies but I get PCM on the mac side for audio. On the PC it shows DTS on the receiver go figure!) does this mean that I have some transparency happening and that it is indeed bit perfect? I've experimented with higher res files and while my hearing suggests that it is outputting in these frequencies it can be sometimes hard to tell. Thanks for your time and/or expertise if you can answer these for me!

 

Macbook Pro 2010->DLNA/UPNP fed by Drobo->Oppo BDP-93->Yamaha RXV2065 ->Panasonic GT25 -> 5.0 system Bowers & Wilkins 683 towers, 685 surrounds, HTM61 center ->Mostly SPDIF, or Analog out. Some HDMI depending on source[br]Selling Art Is Tying Your Ego To A Leash And Walking It Like A DoG[br]

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Chris, you are speaking solely about the optical digital connection, correct??? Most folks using an AppleTV are using the HDMI connection, I'm curious if you perceived the same thing with HDMI.

 

I own the new AppleTV, but have only used it for video/photos/movies stuff, I prefer my PWD/Bridge for a myriad of reasons.

 

Thanks!

-Brian

 

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Ugh. It is really disappointing that Apple seems to consistently underwhelm in the audio realm. The first Airport had great jitter measurements according to Stereophile. The more recent ones have such bad jitter that some DACs have trouble locking onto a Toslink signal. And the hiss out of my Macbooks headphone output is an undending source of frustration.

 

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No hiss at all from the new Apple TV. My Bel Canto DAC lock the signal perfectly.

I'm using a Silflex glass cable. This made a huge difference comparing plastic optical cables. I don't know about the jitter, I can't measure, but as I said the overall performance are great, for the price.

 

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hey - I just got myself a 160GB appletv. I don't know how to measure the bitperfectness and jitter?

But I like the usability and remote capabilities with an ipod touch.

Pls confirm that it is very good, otherwise I won't be able to sleep well tonight, if I sleep at all LoL

 

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  • 2 weeks later...
Guest hifichip76

Hmm. I have both Apple TV's-new one and 160gb. I have not expereinced any clicking or static, even when listenining with AKG 701's.

 

I use them through the Time Capsule. I have them both hooked up through theri optical audio outs (one to a DAC and the other to my receiver). I thought it was bit-perfect, at least with losless cd files (ALAC). No?

 

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The Apple TV is NOT bit perfect, but I really don’t care!

The output quality is incredible good, thanks also to my Bel Canto DAC 3.5bv jitter elimination circuit.

I did a test a couple of days ago, comparing my Apple TV (2010) with my iMac27" with HiFace and Amarra 2.0.

The Apple TV looses the match, but not by much. The lower end was less impacting and the overall sound was a bit thinner then the Mac, but it is something I can live with. I can say that the Apple TV sound 96% of Mac with HiFace and Amarra, and this is a stellar result in my opinion.

The only disadvantage on the Apple TV is missing Hi Res output, but I hope in the future, when Jobs will open to third part applications, something may change.

 

 

 

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  • 4 weeks later...

I was convinced that resampling to 48k is bad, given that there are so many efforts like asio etc. It must be bad.

However, I just realized that I do not know the reason why 44.1 to 48 is that bad? Since 48 > 44.1 there should not be any loss in fidelity. All I can think of is that it might be a cpu intensive task and therefore general purpose OS like windows may not be able to do justice to this. So it may just be OS/ processor dependent thing?

Or is 44.1->48 itself is a bad thing?

 

I now have both old and new appletv. old one is set to make music, new one was just unpacked last night so still in the waiting.

 

Something strange is happening with my speakers. I am not yet able to find out the reason. They keep making strange noises (like they do on when you turn a dusty vol pot) - but constantly, even when no part is moving. I am trying to debug it but get limited time with the setup.

 

 

 

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.....its just not bit perfect, that's all. Several well known DACs upsample as their norm.

 

Benchmark media, makers of the venerable DAC1, have conducted tests that have shown that the upsampler within iTunes (NOT coreaudio) on the Mac is very good, too:

 

http://www.benchmarkmedia.com/wiki/index.php/ITunes-QuickTime_for_Mac_-_Setup_Guide#Overview:_iTunes-QuickTime

 

The DAC1 also resamples everything to 110 Khz. 44.1Khz data goes up and 192 Khz goes down.

 

CD

 

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  • 5 months later...
  • 7 years later...
On 12/1/2010 at 10:32 AM, Codifus said:

.....its just not bit perfect, that's all. Several well known DACs upsample as their norm.

 

Benchmark media, makers of the venerable DAC1, have conducted tests that have shown that the upsampler within iTunes (NOT coreaudio) on the Mac is very good, too:

 

http://www.benchmarkmedia.com/wiki/index.php/ITunes-QuickTime_for_Mac_-_Setup_Guide#Overview:_iTunes-QuickTime

 

The DAC1 also resamples everything to 110 Khz. 44.1Khz data goes up and 192 Khz goes down.

 

CD

 

 

The above is a good point - also note the posts near the top refer to the TV2, and the TV3 may be different.

 

There are reports of differences in SQ on the web; and memory and the processor differ between the 2 models.

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12 minutes ago, Ralf11 said:

Yes, video also.

 

Stick with AT3 then. Useful device.

 

13 minutes ago, Ralf11 said:

There is a previous thread on here about the TV3 and the conversion of 44.1 to 48 -- the gist of it is I see no reason why that would harm SQ.

 

but I'm open to new information

 

As I mentioned in one of the other threads:

 

"up and down-sampling are forms fo DSP.

 

Keeping in context of the Apple TV 3 specifically, I have no idea if it's up-sampling of 44 to 48kHz is regarded as good or bad or whatever.

 

But if you like the internal DSP your DAC does (if it does DSP - which DAC?) then you MAY not want the bits messed with, before they arrive at your DAC's input.. depending on your personal preferences (what your ear/brain system likes).

 

Maybe it makes no difference to your ears? That's a good problem to have (good for your wallet...)

 

Please note I'm very careful not to claim definitively what sounds good/better/best... AirPlay multi-room audio (from a Mac iTunes Server) got me through years of music enjoyment (well before I got onto Roon), so I'd never put anyone down using AirPlay."

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