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From: michael@m-net.UUCP (Michael McClary)
Newsgroups: comp.sys.mac,comp.sys.amiga,rec.audio,rec.music.synth
Subject: Re: Mac II D/A resolution
Message-ID: <1191@m-net.UUCP>
Date: Wed, 15-Apr-87 15:15:45 EST
Article-I.D.: m-net.1191
Posted: Wed Apr 15 15:15:45 1987
Date-Received: Sun, 19-Apr-87 18:08:04 EST
References: <585@plx.UUCP> <597@apple.UUCP>
Reply-To: michael@node.UUCP (Michael McClary)
Organization: McClary Associates, Ann Arbor, MI
Lines: 40
Keywords: 16-bit?
Xref: mnetor comp.sys.mac:2581 comp.sys.amiga:3847 rec.audio:1346 rec.music.synth:683

In article <597@apple.UUCP> north@apple.UUCP (Donald N. North) writes:
>In article <585@plx.UUCP> ed@plx.UUCP (Ed Chaban) writes:
>>I've heard conflicting reports about the MacII's D/A resolution.
>>Would anyone at Apple care to set me straight?
>>
>>How can you say the Mac II  delivers CD audio quality with only 
>>8-bits of resolution?  Exponential D/A converters A'la Amiga?
>
>The one DAC in the Mac II sound chip is only 8 bits; it is time multiplexed
>via a S/H for two channel (stereo) operation.  The sample rate can be either
>Macintosh compatible at 22.26kHz, or CD compatible at 44.1 kHz.  The sound
>quality is 'very good', but it is not strictly 'CD quality', because of the
>lower resolution of the DAC.  However, you won't believe how good only 8 bits
>can sound until you hear it in person.

I'm not associated with apple, but let me add a comment or two (partly
hearsay).

I heard the Mac II and talked to some of the developers at the Symposium on
Computers in the Performing Arts this weekend.  Story was the sound system
was originally supposed to be 16-bit, but got cut down to 8, which is why
the confusion between what was heard and what will be delivered.

Because the resolution is compromized but the sampling rate is not, the
effect on the sound is mainly quantization noise, most noticible as
distortion when the passage is getting quiet, such as at the end of a
fade-out.  Talk was that someone (do I hear any volunteers?) will probably
do a 16-bit add-on shortly, and meanwhile the onboard can be used as a
slightly noisy studio monitor for fast preview during composition.  Also,
the sound software handles larger samples, even if the chip does not, so
once the hardware is available it should be useable with no more than a
trivial patch.

Meanwhile, you can use it to "charge" the keys of sampling-reconstruction
synthesizer keyboards (such as those from E-MU), or ship data to other
system with full-width D-As.

  "I've got code in my node."	| UUCP:  ...!ihnp4!itivax!node!michael
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