Allen&Heath 21 Series - Manual (Page 15)

12
All that has been said about the balance between added noise
and added clipping distortion applies to the other parts of
a console system not just the preamp. This is why the faders
show a zero '0' calibration point from which to work as a
start for level balancing and why PFL switches are provided
on the output faders as well as on input channels. In each
case you can see the signal level at that point in the system
and correct your gain and level control settings to preserve the
original sound quality.
Tape and tape meters
The audio world rightly gets excited about new developments
in tape manufacture that provide lower distortion at
existing signal levels or lower noise from the tape itself
and occasionally both at the same time. Noise reduction is
expensive and some systems need great care in use if other
signal degradations are to be avoided.
Do not assume that a signal faithfully reproduced at your
console output, nicely beating the meters to 0VU, will come
back off-tape so sweet. In the same way that audio amplifiers
h a v e limitations on performance so do tape and tape deck
amplifiers.
Start with a must and make it a habit.
Use a 1kHz tone generator if available, music synthesiser
or FM radio tuned to inter-station noise to feed the console
outputs and adjust for 0VU meter readings, check that yourmonitor
section is selected for output monitor (stereo), not tape monitor.
On the tape machine select input monitor and adjust the record
level for 0VU reading. Record a few minutes of tone. Switch
the tape machine to replay monitor and the console monitor
section to tape monitor status. Replay the tape tone.
Provided your tape machine is reasonably well calibrated the
meters will show the tone replay level to be 0VU. On the
console check that the meters show 0VU and adjust the output
level controls of the tape deck if necessary. The console