ed@plx.UUCP (04/03/87)
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? I hope not... -ed-
north@apple.UUCP (04/04/87)
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. -- Don North Apple Computer, Inc. Advanced Development Group UUCP: {voder,nsc,dual,sun,ucbvax!mtxinu}!apple!north CSNET: north@apple.CSNET {{ Facts are facts, but any opinions expressed are my own, and do not }} {{ represent any viewpoint, official or otherwise, of Apple Computer, Inc.}}
pozar@hoptoad.UUCP (04/07/87)
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? >I hope not... > It doesn't. It samples at 44.1KHz, but the sampling word is 8bit instead of 14 or 16. The S/N is around 40 to 50db. Noisy... For the poop on the II, read this months BYTE.
grr@cbmvax.UUCP (04/07/87)
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? >I hope not... > >-ed- Ed, old buddy, the Amiga D/A's are 8-bit *linear* with a 6-bit volume control. You can view this as floating point if you wish, but it's quite different from the exponential converters used on some "noise generator" class chips. The Mac II can manage a 44KHz sample rate, but it can't handle the 14-16 bits normally considered as CD quality. The Amiga is nominally limited 8 bits, with a 28.8 KHz, but by playing games with the multiple channels and volume controls you can get another bit or two and get some rather impressive dynamic range. If you are willing to dedicate the processor to sound generation you can directly drive the sound channels to achieve >> 44KHz sampling rates. (a little snip-snip on the low-pass filter helps here). Still, 16-bit resolution at 44KHz would be nice, but one has to comtemplate the noise floor in the personal computer environment, especially when using on-chip converters. I haven't seen/heard the Mac-II yet, but I have seen Bob Hoover demonstrating his Mimetics/Soundscape stuff. Pretty nice... -- George Robbins - now working for, uucp: {ihnp4|seismo|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@seismo.css.GOV Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)
elwell@osu-eddie.UUCP (04/08/87)
Another thing to take into account regarding the sound quality of the Mac II is that (according to the manual on my desk) the DAC can operate in both linear mode and u-law compression mode, which gives it much better dynamic range. This really improves the subjective quality of the sound. -=- "The greatest warriors are Clayton Elwell the ones who fight for peace." Elwell@Ohio-State.ARPA --Holly Near ...!cbosgd!osu-eddie!elwell
michael@m-net.UUCP (Michael McClary) (04/15/87)
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 | AUDIO: (313) 973-8787 Michael McClary | SNAIL: 2091 Chalmers, Ann Arbor MI 48104
eacj@batcomputer.tn.cornell.edu (Julian Vrieslander) (04/21/87)
In article <1191@m-net.UUCP> michael@node.UUCP (Michael McClary) writes: >Talk was that someone (do I hear any volunteers?) will probably >do a 16-bit add-on shortly... National Instruments has already announced NuBus boards for the Mac II that will do 12-bit d-to-a and a-to-d at rates up to about 100 ksamples/ sec. One of their techies told me that another board is in the works that will do dual-channel a-to-d and d-to-a at 16-bits and at sampling rates up to 48k. He claimed the board would have anti-aliasing filters and some other goodies which I can't remember. I would guess that a number of such products will be announced before the year is out. -- Julian Vrieslander (607) 255-3594 Neurobiology & Behavior, W250 Mudd Hall, Cornell University, Ithaca NY 14853 UUCP: {cmcl2,decvax,rochester,uw-beaver,ihnp4}!cornell!tcgould!eacj ARPA: eacj@tcgould.tn.cornell.edu BITNET: eacj@CRNLTHRY