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0db or -8db




First thing to keep in mind is that db's stated is relative to something. If it
is not properly mentioned on the source documents what this something is, it is
basically worthless. If so, you make the rules, you decide how close to the
ceiling you wish to go. Even if stated properly it is so common with
misunderstandings that a second look is worthwhile. Keep in mind that any figure
as a lineup tone is permissible as long as it is stated to what it is referenced
to. I.e headtone x is -y db below reference/maxprogram level. 

In analog and digital recording there are two rules - know your noise floor and
know your headroom. Most of the time nobody knows. Same philospohy as a drunk
driver that cant focus on either left or right side of the road so he stays in
the middle and will eventually be surprised when the road turns.

If you receive a tape and you are obliged to make the best out of it suspecting
the references are weird then take your time to browse the material with a
peakholding peak measuring instrument. Find the peak(s) and match it to where
your own recording limits are less a suitable minimum headroom (which depends on
what media you are recording on). If you have available a good peak/dynamic
limiter it is permissible to set it to kick in in case you missed in the
browsing.

In Europe, VU's was long ago replaced by the EBU's program level indicator which
is an active peakinstrument. The red area is split into +3 and plus 6 db
indents. Normal program peaks are permitted to plus 3 but never to plus 6. I can
guarantee that using peak indicators versus "VU meters"  will give you more than
6 db better average distance to noisefloor. 

The Nagra instrument has its own ballistics, very different to VU response and
good for dialogue but weird for music. 

Forget volume unit meters (vu) they have no place in a modern facility,
particularly if you have  gone digital somewhere. VU meters, if built to true VU
spec's, are instrumenst intended for dynamic signals according to a ballistic
response that is carefully tailored to mechanical and electrical parameters of
the instrument and transmission path. VU meters have their origin in telephony. 

As David Tosh points out, you must know where your own system limits are, only
then can you introduce a minimum loss transfer. Even better, if you really go
about it you can get an analog chain capable of 110db dynamic range.   

Mike Reichel