AirPlay imposing low pass filter cutting off at 16,500 Htz?

[admin_exported]

Hi,

I've got an iPhone 4, iPad 3, and the new AppleTV and have been experimenting.

I got a spectrum analyser to measure a chirp I created which goes from 20 to 20,000 htz. When played on the AppleTV though my roksan amp and kef speakers, (both capable of way over 20,000 htz) the spectrum analyzer shows the frequency climbing as it plays all the way up to 20,000 htz which is what the chirp I created goes up to.

The problem is, when I did the same measurement while sending the track via AirPlay, it cuts off at 16,500 htz.

I'm assuming this is a limit imposed because transmitting those frequencies higher than 16.5khtz is deemed relatively pointless and bandwidth consuming...

I wouldn't be at all bothered about this limit, I don't listen to anything other than showing the mrs the odd youtube video via AirPlay, any serious listening is done by playing the content directly on the AppleTV from my library. I'm concerned about the limit all the sudden because I've seen some pretty high end looking kit becoming available for use exclusively with AirPlay.

http://www.whathifi.com/review/philips-fidelio-soundsphere-ds9800

These apparently work great with AirPlay but not so well when connected directly. Which sounds obtuse to me, but if people are starting to produce higher end reproduction equipment for use with AirPlay, surely the quality of AirPlay should be configurable too, to remove the LPF and up the bandwidth priority the audio stream is sent with, etc...

What do others think?

 

[Overdose]

If it is possible that there is a cutoff, 16.5KHz is a bit low, my hearing tails off around this point, but younger ears do better.

 

[shafesk]

These apparently work great with AirPlay but not so well when connected directly. Which sounds obtuse to me, but if people are starting to produce higher end reproduction equipment for use with AirPlay, surely the quality of AirPlay should be configurable too, to remove the LPF and up the bandwidth priority the audio stream is sent with, etc...

What do others think?

Well I think that some of the Airplay devices sound better through airplay than a line in device is because these things almost certainly have a dac built in, that dac may also be superior to an iphone/pad/pod. I don't think Apple is the kind of company who would allow customisation of such a proprietory thing. If you think about it, upping the frequency range of an airplay device would lead to greater instability due to higher bandwith processing requirements, having said that recent airplay devices also do video....surely an audio only airplay playback device should be able to use that part of the bandwith attributed to video to do audio only.

I do love airplay though, if I had to choose any form of wireless audio (God forbid) then airplay to me sounds better than any and I doubt other wireless devices can even touch 16 k themselves.