Couple of quick comments from someone who does a fair amount of re-issue
mastering from material that has been "Domain Transferred" as part of
collections.
1) Don't normalize levels. spend the time to get the levels right on the
transfer. Gain staging is your friend. I regularly see stuff that was
transferred at peak levels of -12 to -18 then normalized. While in the
digital domain the process is pretty transparent, it is in the analog
domain that there is a problem. The analog noise floor of converters is
usually somewhere around -100 and typically has an audibly different
character when compared to the analog noise from the tape machine. When you
add 12 to 18 dB of gain the noise floor becomes audible. It's really not
that hard to get the peak levels into the top 6 dB. Get a good quiet
attenuator to adjust the levels feeding the converters. This stuff is
really not rocket science.
2) Get to know the safe operating levels for your equipment. We've
calibrated out converters for the past 30 years to +18dBu=0 dBFS. We tend
to use professional equipment and test the devices to see where the device
clips. Most professional analog gear has at a minimum peak level of +22
before clipping. Many Semi pro and consumer devices are incapable of
getting to +18 without clipping or distortion. You need to find out where
your equipment clips and leave the appropriate headroom. Again, gain
staging is your friend.
3) Operating levels for tape machines are all relative. (Unless calibrating
for Noise reduction). It's the same if someone calibrates to 185 and peaks
at +3 an the VU or 250 and peaks at 0 VU. On tapes without tones it is
most important to get the azimuth correct. Calibrate level and EQ to the
MRL and then align the azimuth for peak high frequency on the tape to be
transferred. Equalization can be corrected later with very little
degradation. For folks dealing with tapes from the EU, learn to hear the
difference between NAB and CCIR.
These are just a couple of my pet peeves. I could go on for hours.
I'll step off my soap box and let the conversation continue.
All the best,
Mark Donahue
Soundmirror, Inc.
Boston, MA
On Fri, Oct 19, 2012 at 12:48 PM, Tom Fine <[log in to unmask]>wrote:
> Richard made a bunch of good points here. Henry, I definitely think you
> should make sure to absorb everything Richard said.
>
> Regarding normalized levels across an archive, I don't even think it's
> feasible unless one had a real-time RMS analizer/gain control running as
> people listened to archive material. Since there may well be a huge range
> of program dynamic ranges within a single archive, I think the net-net
> would be overall "softer" sound requiring good amplifications for listening
> stations (something like any of the new generation of very-loud-capable
> pro-sumer headphone distribution amps would do the trick). Something like a
> college music library, for instance, would the equivilent of a classical,
> rock and jazz FM station. I know that some college and NPR FM stations have
> just that kind of content, but my experience listening to them is that the
> compromise processing is disappointing for all music types. And that's
> really what we're talking about with an archive-wide "level normalizing
> system," the equivilent of FM processing, at least in regard to gain
> control and dynamic range control.
>
> Regarding postings about levels from Richard and Shai, I'm not about to
> argue for less-conservative levels in a 96/24 world, so go with their
> guidelines. I should probably rethink my own rather "hot" levels. If I were
> doing more aggressive DSP or making original wide-dynamics recordings, I'd
> have to bring all the gains down a few notches. The hot levels are probably
> hereditary. One of my father's favorite sayings was that VU meters are "a
> guide, not a rule." He would always monitor off the tape and go by his
> ears, rarely looking at meters. I always tell people putting up old Fine
> Recording tapes on modern solid-state machines to take the "0 VU" tone down
> -2 so you don't run into headroom problems. Ampex 350's had a lot of
> headroom before they'd get fuzzy. By the way, the "hot" levels were pretty
> standard practice in US studios back in the day, in order to both eke out a
> couple more dB of s/n from the brown-oxide tapes of the day and also to
> provide an already-hot master to cut loud singles for AM radio play. In the
> classical world, it was a way to use maximum headroom to reduce the hiss
> floor on the finished record. None of this is necessary in today's 24-bit
> world, so I'd say go with the conservative levels and normalize after
> you've done all the DSP you plan to do. I stand by the idea that it's a
> generally good idea to normalize at -1dBfs peak.
>
> -- Tom Fine
>
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