Yamaha Audio Master Mode on CDR

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MRehorst

Member
2002-05-17 8:48 pm
Recent Yamaha CDR drives (CRW-3200, CRW-F1, etc.) have what they call Audio Master Mode in which they claim to reduce jitter by lengthening the pits and (or?) lands on the disc. This is supposed to produce a better sounding audio CD copy. The recording process is slowed to 2X, and the capacity of the disc is somewhat reduced (consistent with longer pits/lands). Can anyone who knows about these things explain why lengthening the pits and/or lands would reduce playback jitter?

Thanks,

MR
 
Well... the general idea is that with longer lands/pits it is easier for the player to decide if a land is really a land and not a pit (and vice versa of course).
This improves the laser S/N especially with the CDR / old player combination. Older CD players (before 1994) where not designed to read CDR. They can play them, but the fact that a CDR reflects back only 80% of an original CD to the laser may introduce errors.
A Greek magazine that tested a Yamaha home writer said that the trick really works, and in some cases it can give a copy with better quality than the original (especially if the original CD is scratched)...
 

MRehorst

Member
2002-05-17 8:48 pm
I was under the impression that the pick-up detects transitions, not the actual pit/land. Since the data rate coming off the disc must remain more or less constant, the disc must spin slightly faster than normal to play back an audio master mode CD. Is there some reason why spinning a little faster would reduce jitter?

MR
 
the "laser" does pick up just transitions... but since its such a microscopic amount, it sometimes doesnt know if its a transition or not, because of small cd vibration or even a slight bend or blemish in the cd... this is one way jitter occurs. so, yamaha makes the pits bigger so its easier to tell a transition. this reduces jitter. so the "laser" has to do less work.

MRehorst said:
I was under the impression that the pick-up detects transitions, not the actual pit/land. Since the data rate coming off the disc must remain more or less constant, the disc must spin slightly faster than normal to play back an audio master mode CD. Is there some reason why spinning a little faster would reduce jitter?

MR
 

MRehorst

Member
2002-05-17 8:48 pm
cowanrg said:
the "laser" does pick up just transitions... but since its such a microscopic amount, it sometimes doesnt know if its a transition or not, because of small cd vibration or even a slight bend or blemish in the cd... this is one way jitter occurs. so, yamaha makes the pits bigger so its easier to tell a transition. this reduces jitter. so the "laser" has to do less work.


You're talking about an error- missing a transition or detecting one wen one is not there. Jitter is a matter if the timing of the transitions, i.e. the physical location of the transitions.

I'm thinking maybe by lengthening the pits/lands you're allowing the control electronics in the burner to more accurately place the transitions. It would be easy to believe if the pits/lands were made 10X longer, but what is actually done seems like such a small difference that it's hard to imagine it having much effect on the jitter.

MR
 

MRehorst

Member
2002-05-17 8:48 pm
promitheus said:
Sounds logical so far from you guys said.
I have another question that cam up now.

If the pits and lands are a little bit longer how does the cd change the speed of the reading process? Or is this a stupid question because this is automatic in CD player ?

CD players adjust speed continuously as the disc is played in order to get a constant data rate streaming off the disc. The data is recorded at a fixed density on the disc. That means that when data is read from the inside edge the disc has to spin faster than when it is read from the outside edge. So the disc starts rotating fast and slows down as it is played.

MR
 
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