Sound Performance Lab 9737 HF-Adjust, HF-ADJUSTcontrol allows you to control the amount, Machine

The higher the DRIVE the more intense gets the saturation of the tape. While increasing the DRIVE value the output level may increase, too. Compensate for this by reducing the OUTPUT GAIN value (see 5) and monitor the OUTPUT LEVEL meters. The subjec- tively the perceived loudness will increase more dramatic than the actual PPM value!

Recommended values are 3 to 8 for the DRIVE-parameter which corresponds with +10dB to +15dB for the actual DRIVE LEVEL shown in the LED meter bar.

When booting the MACHINE HEAD the default value of the DRIVE parameter will be 0 in the LC-display. If you have “the perfect pitch” you can already hear slight saturation effects. To keep the handling of the MACHINE HEAD as simple as possible, it is necessary to provide a 1:1 level when activating the process for instant comparison between unprocessed and processed signal. Internally the MACHINE HEAD has to create a headroom – especially when processing full scale material – to compute the tape saturation algorithm. With a DRIVE set to ‘true 0’ you will loose 7dB headroom. As a starting position the DRIVE is there- fore set to 0 which is equivalent to +7dB of recording level. Therefore you also have negative values for the DRIVE para- meter. A ‘true’ 1:1 input/output setting is achieved by setting the DRIVE to -7dB and the INPUTGAIN to +7dB.

The corresponding level is displayed in DRIVE LEVEL PPM meters (see 8).

Practical values for the DRIVE are 3 to 8.

The paragraph besides offers some information on internal signal level management.

Above: original signal

Below: processed signal showing increased loudness

Both signals are normalized to 0dBFs.

Control Elements

The HF-ADJUSTcontrol allows you to control the amount of	4	HF-Adjust
high frequency damping or boosting. The control range is -6
(max. damping) to +6 (max boost).
The higher you saturate a real tape the more high frequency
damping takes place. With the MACHINE HEAD you can set the		Adjusting the high frequency
amount of damping independent of the DRIVE LEVEL. You can		damping effects
either use a strong damping effect with low saturation or the
other way around. This freedom is not offered by a real tape
machine.

On the other hand you can boost the high frequencies which simulates overemphasized harmonics e. g. due to improper calibration of the tape machine or differences in tape quality.

Machine Head 9