Recording calibration tones onto DAT tape

     Whenever you have recorded, or are about to  record,  a
valuable DAT tape, especially one that may be played back on
a DAT deck and audio system other than those in our two stu-
dios,  you  should always include mid-range, bass and treble
calibration tones on the tape. Record  these  tones  at  the
beginning  or  end  of  your  tape,  separated  from program
material by at least 20 seconds, and include  a  _p_r_o_g_r_a_m  _I_D
number  at  the beginning of these tones so that they can be
cued up quickly.  You also may want dy  include  calibration
tones  on  compact  discs that may be played in concert hall
performances.

     The purpose of calibration tones is to assure that  the
amplified  DAC  output  level  of a playback DAT deck (or cd
player) matches very closely the output level of the deck on
which  the tape was recorded.  In addition, the three tones,
which should be identical in level, will identify any  prob-
lems  in  the equalization circuits of the playback DAT deck
(or cd player) and, if used, mixing console.

     The calibration tones can be created easily by  running
the script _m_k_c_a_l_t_o_n_e_s on one of the ECMC SGI systems.

_U_s_i_n_g _t_h_e _m_k_c_a_l_t_o_n_e_s _s_c_r_i_p_t

To create a soundfile called _c_a_l_t_o_n_e_s in your current  work-
ing  soundfile  directory,  using  the  recommended  default
values, type:
                    _m_k_c_a_l_t_o_n_e_s  _d_e_f_a_u_l_t_s

A stereo 44.1k soundfile consisting of 15 seconds each of  1
kHz,  10 kHz and 100 Hz tones at -18 dB will be created. For
more details and options for changing these default  values,
consult  the  online or hardcopy man page for the _m_k_c_a_l_t_o_n_e_s
script.  Also consult section 5 of the _E_C_M_C _U_s_e_r_s' _G_u_i_d_e for
more information.

After creating this soundfile, you can  digitally  copy  its
samples  to a DAT tape, or include it on a compact disc that
you master.  After copying the calibration soundfile samples
to  the  DAT tape or cd, play them back to make certain that
each tone registers exactly at the  correct  level,  without
any  drifting. The _w_o_r_s_t thing you can do is include inaccu-
rate calibration tones on a recording.

October 31, 1997
