Sound Performance Lab 9737 manual Quick Start, Analogue Tape, Press ACTIVE. LED illuminates

All controls are in the start-off positions:

INPUT GAIN 0,	DRIVE 0, HF-ADJUST 0,
OUTPUT GAIN 0,	TAPE SPEED 15

1.Press ACTIVE. LED illuminates.

2.Increase the DRIVE-value to saturate the “virtual” tape. Set DRIVE to about 6. If the output level increases, use the OUTPUT GAIN control to compensate for the increase.

3.If more saturation is wanted, it may be necessary to reduce the INPUT GAIN slightly to prevent clipping.

4.Use the HF-ADJUSTcontrol to create the typical high frequency damping effect (negative values) or increase the high frequencies and harmonical content (positive values).

Quick Start

Input

Record Equaliser

High frequency

Bias Current

Playback	Output
Equaliser

Erase	Record	Playback
Head	Head	Head

Magnetic Tape:

Hysteresis Curve

Analogue Tape

Recording Signal Flow

The audio signal that passes the input electronics of an analogue tape machine is first processed by the recording equalizer. The high frequencies are boosted to compensate for the level loss of those frequencies during magnetization and to improve the signal to noise ratio.

A high frequency bias current is afterwards added to the signal to linearize the non linear hysteresis transfer curve of the magnetization.

The recording head converts the current of the input signal into a magnetic field. The field magnetizes the magnetic particles on the passing tape. This process is physically complex and non linear. Hysteresis curves lead to the typical saturation effect and to the effect of short wavelength losses.

The playback head converts the magnetic field of the passing tape back into current and voltage. The playback equalizer has a normed frequency response (e.g. CCIR/NAB) which makes the overall freqency response flat and compensates for the additional boost in the recording equalizer.

Machine Head 7