FOR MIXING TO DAT
your preferred mixing medium is DAT tape, here are
some important details that will assure the easiest mastering
session and therefore the best sound quality for
your finished product.
YOUR BLANK DAT
simply means to fast-forward & rewind a new blank tape before
recording on it. This will most often strip off any microscopic
particles on the tape surface that can cause glitches. This
is a recommended practice for any format of analog or digital
tape, either audio or video.
sampling frequency of an audio CD is 44.1Khz. If your DAT
is recorded at 48Khz, then a sample rate conversion has
to be performed in order to get the proper sampling frequency.
Although there are many good sample rate converters (such
as the HHB BitBox or Sonic Solutions SR Conversion
used by D.E.S.), none are totally transparent, and
you will lose some sonic detail by having to use this process.
be fooled into thinking that recording at 48khz will give
you a better high frequency response. In theory this may
appear to be true, but in reality the digital filters in
the D-to-A converter have a sharp cutoff at 20khz, so the
extra response is not realized in playback. Even so, any
extra high frequency brilliance gained by the higher sampling
rate would be negated by the sample rate conversion process.
are now 24 bit DAT machines, such as the Tascam DA-45HR
at D.E.S. If you have this capability, by all means
use it. However, most mastering houses will not invest in
a DA-45HR or other 24 bit DAT machines unless they become
widely used, so be prepared to have to take your machine
to the mastering house, or to pay for the rental of one.
you must be sure that your mastering house has full 24 bit
capability in order to realize the advantage of your 24
bit recording. Even if you mix to standard 16 bit DAT or
Audio CD-R, there is a HUGE advantage to mastering at 24
bit or higher resolution. Don’t be fooled by systems that
claim 24 or 32 bit "internal processing". Most
of these workstations cannot truly record or output a proper
24 bit digital signal; this is just a spec-sheet manipulation
to fool customers into thinking it is something it is not.
Most workstations will pass 18 bit at best.
We are moving into the brave new world of high-density audio.
The first high-density mastering system is represented in
Digital Editing Services' Sonic Solutions SSHD, which
will up-sample the incoming digital audio to 88.2khz (if
recorded at 44.1k) or 96khz (if recorded at 48k), and will
then down-sample to 44.1khz when burning the CD master disc,
DDP or DAT. We have not formulated an opinion yet as to
whether 48khz sample rate on the DAT would offer any advantage
in this case, but it is doubtful. However, as we move into
the new DVD-Audio and SACD formats, which will be 96khz/24
bit, it may be the case that 48khz is better for up-sampling
to 96k than starting from 44.1khz. Check back here for details.
YOUR DAT WITH A-TIME
(absolute time) is a time code that is recorded on the control
track of the DAT, and is read out in hours, minutes, and
seconds on the DAT's display. In order to get proper A-Time
on your DAT, two things have to happen:
must begin recording from the very beginning of the DAT
tape. Rewind to the beginning of the tape, put the machine
in record, and record silence up to the beginning of the
first mix on the DAT. This begins the A-Time process and
you will see the machine’s counter count up from 0:00. Whether
the DAT is recording silence or music, it is recording the
control track. Begin the first song after approx. 1 minute
(see next subject).
control track has to be continuous. If there is a break
in the control track, you will lose A-Time. A break in the
control track happens whenever there is unrecorded tape,
no matter how little, between tracks. Even a fraction of
a second of unrecorded tape will cause this.
most often happens when you stop recording on a blank DAT,
and then begin recording again from the same spot - the
machine will sometimes leave a little gap between the last
recording and the new one. This is why you may suddenly
lose A-Time half way through a DAT. There is a simple way
to prevent this; always let the DAT machine record several
seconds longer than necessary after you finish a song, then
when you are ready to mix the next song, back-cue the DAT
a couple of seconds, so you go into record/pause where silence
has already been recorded, and therefore there is a control
: If your DAT machine has a switch marked “Program Time”,
turn this off. This was a hi-fi feature that starts the
time counter over at 0:00 at the beginning of each song,
and defeats A-Time recording.
RECORDING THE FIRST MIX AT APPROXIMATELY ONE MINUTE ON THE
is going to be a problem with a DAT tape, most often it
will occur during the first thirty seconds of tape, where
problems may have occurred during manufacturing in spooling
or loading. Also, I have personally had to repair DATs that
have come loose from the spool, and in a case like this
you can count on loosing the first 10 seconds or so. Giving
yourself one minute of space gets you well into the “good”
tape. Also, it gives the mastering engineer plenty of room
to pre-roll to make sure all clocks have locked in and stabilized.
above in the A-'Time discussion, start recording silence
from the beginning of the DAT tape so Absolute Time is recorded
in the control track. Record silence to 1 minute 10 seconds
or so. Back-cue the DAT to 1:00, and go into record/pause
for the first track. The exact start time of the first track
is not critical - 0:58, 1:03, whatever - as long as you
are approximately one minute into the DAT.
BIG MISTAKE: I see it all the time; people who
start the first song at the very beginning of the DAT. They
mistakenly think that this space will directly translate
to the CD, and any extra space will show up before the first
song begins. The problem here is twofold.
as pointed out above, any tape problems or glitches in the
DAT tape itself usually occurs within the first few seconds,
so the beginning of the song is about 70% more likely to
contain glitches than if it were started at 1 minute as
it takes digital converters a couple of seconds to read
the control track off of the DAT and lock to the digital
clock, and until this happens, DAT machines will mute both
the analog and digital outputs. When the first song begins
at 1 or 2 seconds on the DAT, the attack of the first note
will invariably be chopped off on some DAT machines' playback
even though it may play on the machine that recorded it
SWITCH SAMPLING RATES
your DAT is recorded at 44.1k or 48khz, it should stay at
the same frequency all the way through. Some of the most
sophisticated digital processing gear that may be found
in a mastering room is VERY sensitive to sample rate changes,
and in some cases the gear will glitch and have to be powered
down, or even will be damaged. Also some processors will
pass huge glitches where the sample rate changes potentially
damaging monitor speakers.
BIG MISTAKE: If you accidentally switch sampling
rates part way through your DAT, what will compound the
problem is if the next mix begins immediately after the
sample rate changes. As I explained before, it takes about
a second or more for digital devices to lock & unmute
when they receive a new clock signal, and if a mix starts
too soon after a clock change, the beginning of the first
note will be clipped.
Even if your DAT doesn't switch sampling rates, the safest
thing to do is to let the DAT tape roll in record for a
few seconds before you begin the next mix. If you followed
our advice on keeping the control track continuous, you
also let the tape roll for several seconds after the previous
mix ended, and back-cued a couple of seconds before going
into record. This means that you will have at least 9 or
10 seconds between each mix. You do not need to be concerned
with the amount of time between mixes on your master DAT
or disc. The mastering engineer has total control over the
song spacing (and order) for the final master. Too much
time between mixes is much better than too little.
SURE YOUR DATS ARE PROPERLY ID'D
machines will automatically write ID's while recording,
but sometimes they will miss one, or write unnecessary ID's
because of noise. Go back and check your original master
and make sure that every track has an ID and that they are
properly numbered. Manually write ID’s where any were missed,
erase any erroneous ones, and renumber if necessary.
These manually-placed ID’s don’t have to be that accurate.
The mastering engineer will always back up and begin recording
into the editor several seconds before the beginning of
BIG MISTAKE: One of the things that I most hate
to see, and that happens way too often; a DAT with no A-Time
and mis-numbered or unnumbered ID's. Or the worst case possible:
no A-Time AND no ID's! This is a mastering engineer's nightmare.
TO TIPS & TRICKS
Sorry, that's all for now. Check back soon. Last updated 10/3/01.