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Re: 0db or -8db




        It warms my heart (and my ears) to hear Mr. Kreines and Mr. Reichel
remind us that analogue recordings can, and often do, sound better than
their digital counterparts.  Don't even get me started on valve vs.
solid-state audio electronics...

        While a field Nagra does have the normal limitations one would
expect from a low voltage device, I have found that noticeable distortion
occurs in the mic preamps long before it occurs in the record electronics.
This (as well as S/N ratio) is why most professional sound mixers use some
sort of external mixing board such as a Sonosax.

        My old Nagra 4.2 service manual instructs to set bias such that THD
returning from tape is 3% at 0VU.  This bias level obviously will vary with
the oxide being used.  In fact, when 3M 908 1/4" tape replaced the old
industry standard 808, many machines had to be electronically altered in
order to provide enough flux. Believe it or not, 3% distortion on a speaking
voice is scarcely objectionable, and correct me if I'm wrong, but I think
that the Nagra actually adds "predistortion" in order to lessen the effects
of tape oversaturation.  The Nagra, for it's day, boasted impressive
signal-to-noise specs if bias was matched to the tape being used.  It was
designed to record near the top of available headroom, with tape saturation
allowed and even encouraged within reason.  Remember, it's built for
recording voices withing a fairly limited dynamic range where you would
chase the level with a gain control, not an orchestra where you set the
gain, leave it, and wait for an 90dB spread.

        I have no idea why the Swiss decided to set the reference generator
at -8VU, but they did, and it means exactly that: 8dB below the 3%
distortion mark.  Note that the meter on a Nagra is called a modulometer,
with good reason.  In practice, probably half the recordings out there are
made on tape mismatched to the recorders. In post, I do the only logical
thing: preview a couple of scenes and set my transfer levels for reasonably
safe peaks.  

        Now if we could only get facilities out there spending two million
dollars on telecine bays to cough up more than ten bucks for audio baords! 


Sam Dlugach
Varitel/EDS, Los Angeles