[James Tanner]

Hi All,

In the interest of further self education I purchased a Mac Pro Laptop and am playing around with Itunes. The Mac is limited to 96/24 output but Itunes is 44.1. The 'Digital Optical' output will give you 96/24.

Anyway, I just wanted to let everyone know that if you have the Bryston BR2 remote you can use the Previous, Next, Play, Pause and Stop buttons on the remote if your using the 'USB' or 'Digital' output from the MAC Pro into the BDA-1 External DAC to control your Playlist(s).

IMPORTANT:  If your using the Digital Optical Output off the Mac to the BDA-1 you have to leave the USB cable connected to use the Bryston Remote.

james

[Panelman]

James,

actually iTunes is not limited to 44.1 and will play 24/96. The iPod will not play high res files but iTunes does The Macbook Pro also outputs 24/96 through its USB port. See this link for more info on iTunes and the issue of matching the sample rate of the recording with the Audio Midi settings of the Macbook. Also the current version of iTunes is 8.0 which I read can handle 32 bit word depth but I don't now that for sure.

http://www.benchmarkmedia.com/wiki/index.php/ITunes-QuickTime_for_Mac

Sean

[James Tanner]

James,

actually iTunes is not limited to 44.1 and will play 24/96. The iPod will not play high res files but iTunes does The Macbook Pro also outputs 24/96 through its USB port. See this link for more info on iTunes and the issue of matching the sample rate of the recording with the Audio Midi settings of the Macbook. Also the current version of iTunes is 8.0 which I read can handle 32 bit word depth but I don't now that for sure.

http://www.benchmarkmedia.com/wiki/index.php/ITunes-QuickTime_for_Mac

Sean

Thanks -I will look into it.
So far I have choosen 96000/24 in the MIDI settings but I get this feeling the 44.1 is just being upsampled by the Mac because when you play a 44.1 file it indicates 96K on the BDA-1 even though its a 44.1 file.

james

[ian.ameline]

James -- that is correct -- on the mac, the Audio/Midi utility controls the bitrate/depth for the output devices. Applications feed their audio data into the system's Audio API, which then resamples (as needed) to the output rate/depth. If you want the mac to not resample, you have to go into the Audio/Midi utility and set the rate to match whatever file you are playing.

[James Tanner]

James -- that is correct -- on the mac, the Audio/Midi utility controls the bitrate/depth for the output devices. Applications feed their audio data into the system's Audio API, which then resamples (as needed) to the output rate/depth. If you want the mac to not resample, you have to go into the Audio/Midi utility and set the rate to match whatever file you are playing.

Hi Ian,

GEE's thanks for that - I thought it was me. I perferred the sound of the 44.1K file to the 96K file!

james

[James Tanner]

James -- that is correct -- on the mac, the Audio/Midi utility controls the bitrate/depth for the output devices. Applications feed their audio data into the system's Audio API, which then resamples (as needed) to the output rate/depth. If you want the mac to not resample, you have to go into the Audio/Midi utility and set the rate to match whatever file you are playing.

Hi Ian,

Does that go for the bit-rate as well or can you leave it at 2 channel 24 bit with a 44.1/16 bit file?

james

[ian.ameline]

If the bit rate matches, having additional bit depth on the output does nothing -- the extra bits are just stuffed with 0s. So I always leave the depth at 24 bits, and adjust the output sample rate as needed -- 44.1 for audio originating from CDs, 48 for pretty much everything else.


If the rate does not match, the extra bits on the output are a good thing -- (it's never a good idea to throw away precision)

[James Tanner]

Hi All,

Ya-know- I have been playing around with these computer playback systems over the last few months and I have this nagging feeling that due to the 'complications' of having to set specific settings etc. many people are actually listening to what they think are hi-res files and in fact are not?

The files are being manipulated by the playback software and hardware so it becomes suspect.

I got raked over the coals at CES this year for preferring the sound of  many of the recordings played using 44.1 files to some of the hi-res files supplied - I stand exonerated - as always believe your ears - THE DEMO IS EVERYTHING!

james

[James Tanner]

If the bit rate matches, having additional bit depth on the output does nothing -- the extra bits are just stuffed with 0s. So I always leave the depth at 24 bits, and adjust the output sample rate as needed -- 44.1 for audio originating from CDs, 48 for pretty much everything else.


If the rate does not match, the extra bits on the output are a good thing -- (it's never a good idea to throw away precision)

[James Tanner]

If the bit rate matches, having additional bit depth on the output does nothing -- the extra bits are just stuffed with 0s. So I always leave the depth at 24 bits, and adjust the output sample rate as needed -- 44.1 for audio originating from CDs, 48 for pretty much everything else.


If the rate does not match, the extra bits on the output are a good thing -- (it's never a good idea to throw away precision)

Hi Ian,

Why 48?

james

[Watson]

Ya-know- I have been playing around with these computer playback systems over the last few months and I have this nagging feeling that due to the 'complications' of having to set specific settings etc. many people are actually listening to what they think are hi-res files and in fact are not?

The files are being manipulated by the playback software and hardware so it becomes suspect.

You're absolutely right. But the situation is even worse than that, because on a lot of machines (e.g. Windows XP and its infamous "kmixer") even if you get the sampling rate right, the operating system can still munge the audio data. There is, for example, no way to get clean audio data out of iTunes running on Windows XP, except in certain unusual hardware combinations, thanks to the mysteries of kmixer.

This is why the Squeezebox (and the Airport Express) are so nice... you actually get clean transport data, even if it does have moderately high jitter, without having to muck about with issues you really shouldn't have to and probably don't realize you need to. Macs are fine too provided you stick to CD audio. Anything higher res than 44.1kHz means you have to know what you're doing.

[Sasha]

Hi All,

Ya-know- I have been playing around with these computer playback systems over the last few months and I have this nagging feeling that due to the 'complications' of having to set specific settings etc. many people are actually listening to what they think are hi-res files and in fact are not?

The files are being manipulated by the playback software and hardware so it becomes suspect.

I got raked over the coals at CES this year for preferring the sound of the many of the recordings played using 44.1 files to some of the hi-res files supplied - I stand exonerated - as always believe your ears - THE DEMO IS EVERYTHING!

james

That is why I do what professionals do, Lynx card, XP, ASIO, end of story, no any kind of gizmos. You are in full control of output.

[Sasha]

Ya-know- I have been playing around with these computer playback systems over the last few months and I have this nagging feeling that due to the 'complications' of having to set specific settings etc. many people are actually listening to what they think are hi-res files and in fact are not?

The files are being manipulated by the playback software and hardware so it becomes suspect.

You're absolutely right. But the situation is even worse than that, because on a lot of machines (e.g. Windows XP and its infamous "kmixer") even if you get the sampling rate right, the operating system can still munge the audio data. There is, for example, no way to get clean audio data out of iTunes running on Windows XP, except in certain unusual hardware combinations, thanks to the mysteries of kmixer.

This is why the Squeezebox (and the Airport Express) are so nice... you actually get clean transport data, even if it does have moderately high jitter, without having to muck about with issues you really shouldn't have to and probably don't realize you need to. Macs are fine too provided you stick to CD audio. Anything higher res than 44.1kHz means you have to know what you're doing.

There is nothing mysterious about kmixer or XP, just use correct hardware and software, what professionals have been doing for ages. ASIO has been developed by Steinberg long time ago and works perfectly, bypassing all the intermediary layers of operating system. This is the ONLY correct way of doing PC based audio at present time.

[ian.ameline]

Why 48 James? Because almost everything other than CDs are mastered at 48khz, 24 bits (pretty much every movie you get on DVD etc) only hi-res downloads are 96/24 -- and I have a very small number of those.

The SRC4392 in the BDA-1 does a better job upsampling then the audio system on the mac does in software. It could be better choice of algorithm in the 4392, it could be the mac using single precision floats for the resampling (they would need double precision float to match the 28 bit fixed point that the 4392 uses), or it could be some combination of the two.

The other thing that could be happening is when driving their optical toslink output at 96khz, there might be more jitter -- any or all of these could conspire to make the 44.1 sound better to you. I expect that the only time 96 would sound better is with an actual sound file at 96/24.

-- Ian.

[James Tanner]

Why 48 James? Because almost everything other than CDs are mastered at 48khz, 24 bits (pretty much every movie you get on DVD etc) only hi-res downloads are 96/24 -- and I have a very small number of those.

The SRC4392 in the BDA-1 does a better job upsampling then the audio system on the mac does in software. It could be better choice of algorithm in the 4392, it could be the mac using single precision floats for the resampling (they would need double precision float to match the 28 bit fixed point that the 4392 uses), or it could be some combination of the two.

The other thing that could be happening is when driving their optical toslink output at 96khz, there might be more jitter -- any or all of these could conspire to make the 44.1 sound better to you. I expect that the only time 96 would sound better is with an actual sound file at 96/24.

-- Ian.

Thanks Ian - good info.

james

[Watson]

There is nothing mysterious about kmixer or XP, just use correct hardware and software, what professionals have been doing for ages. ASIO has been developed by Steinberg long time ago and works perfectly, bypassing all the intermediary layers of operating system. This is the ONLY correct way of doing PC based audio at present time.

I agree, ASIO is one of the best ways of doing PC audio, but that means you can't use iTunes or Windows Media Player, which don't support ASIO.

Kmixer is a complete mystery to everyone. The only way to figure out if you have a setup that kmixer doesn't touch is by doing experiments with specific software/driver/hardware combinations. There's no way to predict in advance. Which is one of the reasons the pros switched to ASIO long ago.

[werd]

Hi All,

Ya-know- I have been playing around with these computer playback systems over the last few months and I have this nagging feeling that due to the 'complications' of having to set specific settings etc. many people are actually listening to what they think are hi-res files and in fact are not?

The files are being manipulated by the playback software and hardware so it becomes suspect.

I got raked over the coals at CES this year for preferring the sound of the many of the recordings played using 44.1 files to some of the hi-res files supplied - I stand exonerated - as always believe your ears - THE DEMO IS EVERYTHING!

james

O .... and i always thought DEMO was short for demolition.hehe

[James Tanner]

Hi All,

In the interest of further self education I purchased a Mac Pro Laptop and am playing around with Itunes. The Mac is limited to 96/24 output but Itunes is 44.1. The 'Digital Optical' output will give you 96/24.

Anyway, I just wanted to let everyone know that if you have the Bryston BR2 remote you can use the Previous, Next, Play, Pause and Stop buttons on the remote if your using the 'USB' or 'Digital' output from the MAC Pro into the BDA-1 External DAC to control your Playlist(s).

IMPORTANT:  If your using the Digital Optical Output off the Mac to the BDA-1 you have to leave the USB cable connected to use the Bryston Remote.

james

Well so far the Mac Pro laptop playing the Itunes (AIFF) through optical sounds better on my Quad 2905 system than Windows playing Itunes.

james

[WGH]

I agree, ASIO is one of the best ways of doing PC audio, but that means you can't use iTunes or Windows Media Player, which don't support ASIO.

An interesting experiment that costs less than $100 would be to see if using the M-Audio Transit optical output improves the sound. M-Audio wrote its own ASIO drivers.

I use the Transit for my computer based home theater because it can also output a true AC-3 5.1 Dolby Digital signal, unfortunately my AVA Insight DAC does not have an optical input and the Technics SH-AC500D digital surround processor is too low-res for any meaningful comparison.

In Windows, set the default output device to the M-Audio Transit and listen to iTunes and WiMP using the ASIO drivers.



Wayne 

[Watson]

In Windows, set the default output device to the M-Audio Transit and listen to iTunes and WiMP using the ASIO drivers.

As far as I know, there is no way to get iTunes or WMP to use ASIO.