[reemas]

are there any specs available on the audui output quality of the powerbooks? specifically the headphone out port? i have the 1.67 pb 15".

also, there are two ports, one is headphone out, and the other i'm not sure. can someone let me know what that port is for?

[PrOeliuM]

http://www.apple.com/powerbook/specs.html

Audio

* Audio line in (minijack) (12- and 15-inch models)
* Headphone out (minijack) (12- and 15-inch models)
* Combined optical digital input/audio line in (minijack) (17-inch model)
* Combined optical digital output/headphone out (minijack) (17-inch model)
* Built-in stereo speakers with midrange-enhancing third speaker (12-inch and 15-inch models)
* Two built-in stereo speakers (17-inch model)
* Internal omnidirectional microphone

I'm guessing you mean the line-in. I don't know about the quality of the headphone out.

[tooki]

The developer note goes into more detail:

Sound System
The 24-bit stereo audio circuitry provides sound input through the built-in microphone, the audio line in port, the USB port; and sound output through built-in stereo speakers, a midrange-enhancing speaker, and a headphone port.

All audio is handled digitally inside the computer, including audio data from the optical drive and devices connected to the USB and FireWire ports. Sound data is converted to analog form only for output to the internal speakers and the headphone out.

The sound circuitry handles audio data as 44.1 kHz 24-bit samples. If audio data sampled at a lower rate on another computer is played as output, the Sound Manager transparently upsamples the data to 44.1 kHz prior to sending the audio data to the sound circuitry.

The 15-inch PowerBook G4 can record sound data from the built-in microphone, an audio CD, the audio line in, or a USB audio device. For each sound input source, sound play-through can be enabled or disabled. Sound data from digital sources is converted to analog form for output to the speakers and the headphone out port.

Sound Inputs
The sound system accepts inputs from the following sources:

*the built-in microphone
*the audio line in port
*a CD or DVD in the DVD-ROM/CD-RW Combo drive
*a CD or DVD in the DVD-R/CD-RW SuperDrive
*a digital audio device connected to a USB or FireWire port
*sound signals from the communication (modem) slot

The microphone preamp has a dedicated analog input channel in the sound circuitry; the other inputs send digital data. The analog input can be set for play-through or recording. The digital inputs can be selected or mixed by the sound circuitry.

The computer also accepts digital sound data from the Combo drive, SuperDrive, or from devices connected to the USB or FireWire ports. Sound data from those sources can be sent to the sound system to be converted to analog form for output to the speakers and the headphone out port.

Built-in Microphone
The built-in microphone is located in the middle of the left speaker grille. The sound signal from the built-in microphone goes through a dedicated preamplifier.

Audio Line In
The audio line in is a 3.5 mm mini jack located on the I/O panel on the side of the computer. The audio line in accepts line-level stereo signals and a stereo miniplug-to-RCA cable adapter for connecting stereo equipment to the computer.

The audio line in signal connections are

tip: audio left channel
ring: audio right channel
sleeve: audio ground
The audio line in has the following electrical characteristics:

*maximum input signal amplitude 2 Vrms (5.65 Vpp), +8 dbu peak
*input impedance 30 kilohms
*channel separation greater than 60 dB
*recommended source impedance 2 kilohms or less
*ground noise rejection greater than 40 dB
*frequency response 5 Hz to 20 kHz, +0.0, –0.5 dB
*distortion below –80 dB
*signal to noise ratio (SNR) greater than 90 dB A-weighted

Sound Output
The sound system sends sound output signals to the built-in speakers and the external headphone out port.

Headphone Out Port
The headphone out port is located on the left side of the computer. The jack accepts a standard stereo mini-plug.

The stereo audio signals at the jack is configured to drive a pair of low-impedance stereo headphones. External powered speakers may also be connected to the headphone out port.

The audio signals on the headphone out port have the following electrical characteristics:

*output impedance: 16 ohms each channel
*minimum recommended load impedance: 32 ohms each channel
*maximum level: 1.5 V rms (4.4 V P-P)
*signal to noise ratio (SNR) greater than 100 dB A-weighted
*total harmonic distortion (THD) 0.03% or less

Internal Speakers
The computer has three internal speakers: one on either side of the keyboard and one beneath the keyboard for mid-range enhancement. The computer turns off the sound signals to the speakers when an external device is actively connected to the headphone out port and during power cycling.

tooki

[reemas]

ah. thanks!