Maintaining Audio Quality in the Broadcast Facility 2011 - Orban

in the Broadcast/Netcast Facility 65
C) Excite the record amplifier of the master recorder with pink noise, spot frequencies,
or swept tones.
D) Adjust the azimuth of the master recorder’s record head, by observing the
mono sum from the playback head.
Pink noise and a real-time analyzer are most effective for this.
If the traditional Lissajous pattern is used, use several frequencies, and
adjust for minimum differential phase at all frequencies.
E) Set the master recorder’s VU meter to monitor playback.
F) Record your secondary standard alignment tape on the aligned master recorder.
Use an audio oscillator to generate the spot frequencies. Immediately after
each frequency is switched in, adjust the master tape recorder’s record
gain control until the VU meter reading matches the compensated
meter readings calculated in step (B).
Your homemade tape should have an error of only 0.5dB or so if you
have followed these instructions carefully.
“Sticky Shed Syndrome”
Tape manufactured from the 1970s through the 1990s (particularly by AGFA, Ampex,
and 3M) may suffer from so-called “sticky shed syndrome.” When played, the
tape sticks to the guides of the playback machine and severe oxide loss may occur.
The generally accepted cure is to bake the tape at 130� F (54� C) in a convection
oven. One recommended device is the Snackmaster Pro model FD-50 made by
American Harvest 19 . Don’t use the oven in a household stove or a microwave oven.
Baking time ranges from about 4 hours for ¼" tape to 8 hours for 2" tape, although
it's not critical. You can't over-bake unless you leave the tape in for a day or so; if
you under-bake and the tape is still gummy, you can bake it more. After you shut
off the heat, leave the tape to cool down to room temperature before attempting
to play it.
A baked tape should be playable for about a month, although this depends greatly
on the ambient humidity. Although many tapes can be re-baked as necessary, this is
not always true; baking has risks 20 . It is important to make a high-quality digital archive
of the tape on its first pass through the playback machine after baking. This
19 (800 288-4545; www.americanharvest.com). Model FD-50 is no longer being manufactured.
However, American Harvest still makes similar products, which we have not evaluated.
20 Bill Holland, “Industry’s Catalog at Risk – Archived Tapes could be Lost to Binder Problem,”
Billboard Magazine, June 5, 1999. (This article is not available on line unless you subscribe to
Billboard’s online service, so a local library may be the best way of getting it.)