Universal Audio Ampex ATR-102 Manual page 402

Figure 129. The calibration controls for Studer A800
HF Record EQ HF (High Frequency) Record EQ is provided to make up for common residual
HF loss due to Bias optimization and system filtering. It is used to tune HF con-
tent into the incoming signal prior to the tape non-linearity. The control pro-
vides a continuous "boost filter" gain and affects saturation characteristics.
Note:
Repro) are for tape playback only.
HF Driver Bias Bias is defined as an oscillator beyond the audible range applied to the audio
at the record head, allowing for adjustment of the record behavior. Ideal bias
voltage settings provide maximum record sensitivity and low distortion. Inten-
tionally overbiasing is a common technique especially for "tape compres-
sion" of drums, giving a warmer, gently saturated sound. Underbiasing can
also be used to add distortion and other nonlinear responses, similar to gate
chatter or cold solder joints; extremely low voltages may even cause audio to
drop out entirely. Bias voltage, HF Record EQ, and fixed Emphasis EQ (CCIR,
NAB, AES) work together to provide a linear response to the recorded signal.
Sync/Repro EQ Sync and Repro Playback EQ Controls are available for tape playback cali-
bration. They affect the signal coming out of the tape circuitry.
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This filter is prior to the tape record circuit, while the other EQs (Sync,
- 402 - Chapter 45: Studer A800