Golden Earring wrote: > > 2. Why do CD's, DVD's & Blu-Ray discs play from the inner available > radius outwards, when LP's (& 78's) work from the outside available > radius inwards? I presume that there is some engineering/practical > benefit from this inversion? While I don't know for sure, there are some obvious reasons that make engineering sense:
1. Optical discs: these spin at fairly high rates and any imbalance that causes wobbling can make life harder for the laser pickup servos. The degree of wobble will be much smaller at the centre of the disc. Unless the disc is long (ie. 70+ mins), starting at the centre means there is less liklihood of laser tracking failure. 2. Analogue records: distortion is greater towards the centre of the disc, because the constant angular rotation speed means that there is less linear space to contain the cut waveform. So it makes sense to start the cut towards the outer edge, so the minimum amount of the cut occupies the area where the distortion is greatest. Of course if you can calculate exactly how much space will be needed for the side, you could start the cut at the appropriate position so that the end of the side is close to the outer edge. And when you consider that many works (especially classical) tend to climax at the end, this would make sense - the most complex part of the waveform would be located where the distortion is at its lowest. (In fact I have a vague recollection that there have been records cut that way in the past). Transporter -> ATC SCM100A ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=106914 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
