I think she's making perfect sense

DVD-Audiobahn

New DVD-Audio music releases and talk about the latest players.

In Reply to: Who in their right mind would believe what you say anyway, Teresa? . . . posted by Martin419 on August 21, 2005 at 05:21:19:

Martin, you've laid claim to having an engineering background. Change out of your DuaDisc cheerleader uniform for a few minutes and try to think like an engineer.
Earlier you brought up to Christine >>mechanical reliability analyses and statistical correlation; MTBFs, FMEAs etc..<< Let's talk about that.
MTBF is an average, typically determined through prior experience and estimates based on typical usage.
FMEA is a predictive analysis based on the system's intended use.
Once you take a device outside of its design envelope, MBTF and FMEA are pretty much useless!
As an example - the motor in my Yamaha racebike contains many parts, most of which have MTBF ratings based on typical usage. I expect that FMEA (or something similar) was performed in order to determine spares allocation and the like, but again, this would be based on typical usage! Yamaha warrants the motorcycle to be reliable in a typical-usage situation.
The way I use the motorcycle is far from typical. Since it is a race machine, I run the motor near redline (for maximum power output) almost constantly. I am not exceeding the tolerances, in that I do not exceed maximum rpms allowed, but since I am running it near maximum tolerance at all times, it is not typical usage so MTBF means NOTHING! Since I am pushing the motor as hard as it can be pushed without exceeding tolerance, I expect things to wear out more quickly, go out of tune, lose efficiency. This means I am frequently doing maintenance and replacing parts that would not have worn as quickly if I were using the product at less than maximum tolerance. To that end, Yamaha does not warrant the motorcycle when it is used under race conditions.
So - the disc players we have today were designed for a typical usage scenario of CDs and DVDs which are at, or very near, the specified 1.2mm thickness. MTBF is based on this. Any FMEA would be based on those design parameters. There is a maximum tolerance of 1.5mm for disc thickness, but since it is maximum, there would not have been an expectation that many discs would reach maximum. In the opposite, in fact - a close-to-1.5mm disc would tend to be a rarity prior to DualDisc.
Now comes DualDisc, with a MINIMUM specification of 1.42mm, up to 1.5mm maximum. I'll be generous and assume for discussion purposes that there are no longer any discs that exceed the 1.5mm maximum.
1.42-1.5mm is within the tolerance range, but it's MAXIMUM. Feeding a player designed for 1.2mm discs a steady diet of discs at maximum tolerance is outside the typical usage scenario, which means, just like the situation with my racebike, that MTBF becomes meaningless, and any predictions based on a FMEA would be useless.
Again, just like my racebike situation, it's reasonable to assume that regularly running the player at or near its maximum tolerance may cause parts to wear out more quickly, cause alignments to drift, and create maintenance or replacement situations that might not have occurred if the player hadn't been regularly run at maximum. Given this quite reasonable assumption, player manufacturers are well within their rights to say that they will not warrant the players if the players are used in this manner.
So, until the player manufacturers have had the opportunity to do long-term testing, and FMEA with new parameters, Teresa is absolutely correct - you are incurring risk by playing DualDiscs.
BTW, if you think that the DualDisc consortium did long-term player reliability testing (as opposed to simply testing for a minimum playback compatibility level on various players), then YOU are the one smoking something, and you should put the pipe down.

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Topic - Picture of Panasonic replacement spindle motor kit - Christine Tham 18:27:36 08/12/05 (53)

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