Recording Handbook - Hol.gr
Recording Handbook - Hol.gr
Recording Handbook - Hol.gr
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2.Getting Your Sound On Tape<br />
Until recently, "Analog" was the only kind of recording available to most musicians. The wide availability<br />
of DAT recorders, Alesis ADAT 8-tracks, Tascam DA-88 8-tracks and hard disc recorders like the Emu<br />
Darwin, Akai and Vestax machines have forever changed that situation. Still, the process is the same even<br />
though there are different technical considerations and format specific issues to address.<br />
a. The Analog <strong>Recording</strong> Process<br />
Analog recording devices use a plastic tape coated with magnetic particles moving across a magnetic<br />
recording head at a constant speed to record and playback. There is always an "erase head", first in the<br />
tape path, to erase and re-align the tape particles before they hit the "record head". In the "two-head"<br />
machine there is one head for both recording and playback. The "three-head" design features one head<br />
dedicated to recording, the "sync head", and another for playback, "the repro head". Professional machines<br />
have three heads.<br />
There is a limit to the intensity of the signal that the tape particles can actually absorb and reproduce. The<br />
two parameters that interact to maximize the tape's ability to correctly record and playback are "tape<br />
speed" and "bias". At a faster speed, there is more tape area for a given signal, i.e. more tape particles to<br />
record. Most professional analog multitrack recorders run at 30 ips (inches per second). "Bias" is a process<br />
that was discovered by accident. It was found that when a high frequency signal, 100 Khz or so, much<br />
higher than human hearing, was recorded along with the normal signal, the magnetic particles did a better<br />
job of recreating the higher frequencies.<br />
It is a complicated process and there are lots of things to go wrong! The tape machine must be<br />
mechanically and electronically aligned to very fine specifications. First, to ensure that it physically<br />
handles the tape gently during shuttling, rewind and fast forward. Although tape formulations have<br />
improved <strong>gr</strong>eatly over the years, mechanical problems can damage the tape by stretching or wrinkling it.<br />
There is no error correction for this! Treat your tapes with care and respect. Other problems include loss of<br />
particles off the tape, called shedding, speed fluctuations which produce "wow and flutter" and improper<br />
tape to head contact.<br />
Furthermore, the electronics have to record the input signal and play it back faithfully. This is where tones<br />
on your master tapes becomes so important. They are required to properly align the electronics in the tape<br />
machine so when you work at different studios, your tape sounds like you remembered. When all these<br />
parameters are aligned correctly, you stand a good chance of hearing back a reasonable facsimile of what<br />
you recorded previously.<br />
b. The Digital <strong>Recording</strong> Process<br />
The digital recording process is far simpler mechanically, but much more involved electronically. The<br />
input signal is sampled 1000's of times per second and each acoustic slice is given it's own digital number,<br />
consisting of 0's and 1's. Theoretically, the "analog-to-digital converter" (ADC) recieves the analog input<br />
and converts it into a stream of numbers and conversely, the "digital-to-analog converter" (DAC) reverses<br />
the process.<br />
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