Re: Headphone Jack GS

[spector@vax2.concordia.ca (Mitchell Spector)]

In article Erick Wagner <wagnere@netcom.com> writes...
>
>It's definitely mono on the ROM 00 and 01 machines.  I remember
>someone once mentioning that the ROM 03 had stereo on the
>headphone jack but I don't have access to a ROM 03 at this time to
>check it out.

	No version of the Apple IIgs (of the two existing motherboard
revisions) supported stereo output from headphone jack. However, the
Ensoniq 5503 DOC chip built-in to every IIgs, does in fact support 
stereo (Left/Right channel) output. Apple just never "bridged" the
signal from the chip to the headphone jack, though luckly they designed 
the system so that stereo signal could be tapped. The molex connector
on the motherboard provides both sound input and output, which is where 
a stereo card or audio digitizer comes in.

	Stereo cards such as the SuperSonic, SonicBlaster, Audio Animator,
GStereo, SoundMeister and others do _not_ create stereo, they just tap
the existing stereo signal that's essentially built-in to your IIgs. The
same applies with sound digitizing. The Ensoniq also has a DAC (Digital
to Analog Convertor) and ADC (Analog to Digital Convertor) that allows
you to capture and playback real-world sound at 8-bit resolutions. 
I believe the Audio Animator used it's own ADC to get higher quality 
digital sampling, but all other cards didn't do much beyond simple I/O
(and filtering) for the what was already built-in the IIgs. Had Apple
continued support for the GS, they could have easily added stereo
output to the headphone jack and an audio-in jack with microphone (a la
Mac LC).

	Another interesting note: the Ensoniq chip supports up to 8
independant stereo channels, although all existing stereo cards and software
only support up to 2 channels. In otherwords, you could connect eight stereo 
speakers (ie, two in front, two in middle, two in back, one above and one 
below) and create some really interesting stereo surround effects! :-) And 
the bonus is you wouldn't need certain mind alternating substances or an 
overly active imagination to get 3-D sound! ;-)

Mitchell Spector
m_spect@alcor.concordia.ca / spector@vax2.concordia.ca