PowerBook Soundcard Bit Depth

[.:*Robot Boy*:.]

Hi,
Since getting my PowerBook in February, I've been listening to a lot of music from the internal soundcard (as opposed to one of the Digidesign soundcards at my disposal). I know it's not ideal, but sometimes it's just easier to plug your headphones in and get on with what you've gotta do, rather than having cables everywhere and having to mess around with the atrocious Digidesign CoreAudio Manager.

So, does anyone know what the limitations of the internal soundcard are? According to AppleHistory.com, the PowerBook headphone jack is capable of 16-bit at up to 48KHz, however, in my System Profile I see this:

Formats:
PCM 16:
Bit Depth: 16
Bit Width: 16
Channels: 2
Mixable: Yes
Sample Rates: 32 KHz, 44.1 KHz, 48 KHz
PCM 24:
Bit Depth: 24
Bit Width: 32
Channels: 2
Mixable: Yes
Sample Rates: 32 KHz, 44.1 KHz, 48 KHz

The main reason I'm asking is that I often have to listen to 24-bit .wav files in Quicktime (due to the fact that iTunes won't even add them to my library). So... is Quicktime simply converting to 16-bit on the fly? Or is this internal card actually capable of playing back 24-bit files? And if so, why will iTunes not add 24-bit files to my library? Isn't iTunes, uhhh, 'built' on top of the Quicktime 'playback engine'?

Also, I've never come across the term 'Bit Width' before. Can anyone explain what it is and how it relates to audio?

Tim.

 

[motulist]

I could be wrong, but as I understand it, it truncates 24 bit to 16 bit during playback through the soundcard. The difference between truncation and conversion is just one of maximum possible quality. But truncation for most human beings in non critical listening applications sounds exactly the same. Meaning unless you're mixing an album through the soundcard (which you probably shouldn't do anyway) then it won't make a difference. Or at least that's what I've been lead to believe, I could be wrong.

 

[.:*Robot Boy*:.]

I could be wrong, but as I understand it, it truncates 24 bit to 16 bit during playback through the soundcard.

Yeah, I thought that might be the case . I'm not really doing any critical stuff, just listening to rough mixes that I've bounced from Pro Tools. I know it's easy to dither and bounce at 16-bit... I just don't like bouncing at 16-bit, just in case the mixes I'm bouncing end up getting used for something in the future.

Ha. It's really just laziness on my part, I guess I'll just keep bouncing at 16-bit and 24-bit for now ( which takes forever if you're bouncing a whole record, due to the fact that Pro Tools has to bounce in real-time )... it's just annoying being tied to external hardware in order to monitor at 24-bit.

Thanks.

Tim.

 

[WinterMute]

All audio out the headphone jack is 16-bit 44.1/48Khz (depending on source) the soundcard dithers the bitrate up or down and converts the sample frequency on the fly.

The internal audio processors in the PowerBook will handle 24-bit, but will only play them back through a 24-bit enable interface (Digi M-box, 002 etc.)

Bit width may refer to the processor path, not the audio, but it's not a standard audio nomenclature.

For headphone listening it's OK, but not great, there are too many PSU issues in laptops for clean audio out the headphone jack, and you'd better have a mains powered interface for serious audio too, USB and Firewire powered interfaces don't have the supply rails for the dynamics or the frequency response.

This is why the M-box mic amps suck so badly, but sound OK iin the Control 24...

 

[.:*Robot Boy*:.]

This is why the M-box mic amps suck so badly, but sound OK iin the Control 24...

*sigh* I know what you mean ... but the M-Box is really nothing more than a Pro Tools dongle . I'm not really a fan of any Digidesign hardware, but I adore Pro Tools.

Anyway, I'm reasonably happy with the tradeoff between sound quality and convenience when it comes to listening to records on my PowerBook - it's nice to be able to lie on the couch with my Grados and compare mixes using iTunes. The problem is that the audiophile in me that wants to know what's messing with my audio before it hits my eardrums!

Tim.

 

[WinterMute]

*sigh* I know what you mean ... but the M-Box is really nothing more than a Pro Tools dongle . I'm not really a fan of any Digidesign hardware, but I adore Pro Tools.

Anyway, I'm reasonably happy with the tradeoff between sound quality and convenience when it comes to listening to records on my PowerBook - it's nice to be able to lie on the couch with my Grados and compare mixes using iTunes. The problem is that the audiophile in me that wants to know what's messing with my audio before it hits my eardrums!

Tim.

It's a bitch really, I'm lucky to have HD at my disposal pretty much all the time now, but I still have the M-box at home, I use an Amek PurePath pre into the line in on the M-box, which doesn't sound too bad, better than the internals anyway.

I'm going to take a look at the M-powered version of LE with the 18/14 M-audio box, it's better than the 002 rack by some way I think.

Signal path is a bit of an obsession isn't it, too many years running studio sessions I guess...