User manual SPL QURE

[. . . ] Manual Model 9738 Dual Channel Parametric Tube/LC Equalizer Qure Manual Model 9738 By Hermann Gier and Paul White Version 2. 2 - 1/1999 The information in this document has been carefully verified and is assumed to be correct. However Sound Performance Lab (SPL) reserves the right to modify the product described in this manual at any time. This document is the property of SPL and may not be copied or reproduced in any manner, in part or full without the authorisation of SPL. Limitations of Liability: In no event will SPL be liable for any damages, including loss of data, lost profits, cost of cover or other special, incidental, consequential or indirect damages arising from the use of the unit, however caused and on any theory of liability. This limitation will apply even if SPL or an authorised dealer has been advised of the possibility of such damage. SPL electronics GmbH P. O. [. . . ] In pre-mastering this circuitry garantees a reproducable sound for a long time. The WARM UP-LED (red) illuminates after the main power has been switched on. The in- and outputs of the tubes are de-coupled at 10 Hz with condensers of high voltage and capacity (1 microFarad/ 400 V/5 %) to minimize offset and humming noise. If the unit is already switched to active with the MASTER switch during the warm up period you will not hear any processing until the QURE switches to READY. Although you may not have done any equalization to the signal you will hear a little difference between the processed and the unprocessed signal because the tubes already produce a portion of their typical sound. MASTER 2 MASTER switches the QURE´s entire sound processing on or off. The MASTER function is a relay-hard-bypass function which links the input socket directly with the output socket to bypass all filters by pressing just one button. To increase operation reliability the QURE monitors the power supply´s primary and secondary voltages and switches automatically to hard bypass once certain tolerances have been exceeded (power failure safety). 10 The QURE features an IN control that enables you to set the level at which the QURE filters operate. To run the unit hotter set the level between the 0 dB-position and the clockwise position (up to +18 dB). This will result in a more intensely processed sound. Conversely, in order to achieve milder processing, set the level between the 0 dB-position and the counter clockwise position (up to -12 dB). 3 IN The IN control is followed by high (HF) and a low frequency (LF) cut filters with individual frequency controls. The HF/LF CUT ON is the hard-bypass switch for both filters. If the cut filters are not needed the HF/LF CUT ON switch routes the audio around this section to provide maximum audio quality when in bypass (LED is not illuminated). The HF CUT and LF CUT are usually used as a pair to provide control over the extremes of the audio spectrum. 4 HF/LF CUT ON The HF CUT filter is a 2nd order Butterworth filter defining the upper roll-off frequency the audio is to have. Fully counter clockwise the control is set to its starting position of 20kHz. Even if the HF/LF CUT filters are activated there is hardly any audible frequency limitation to the spectrum. Turning clockwise reduces the upper roll-off frequency until fully clockwise the minimum roll-off frequency of 2. 5 kHz is reached. Diagram 3 illustrates the frequency response curves for the highest roll-off (20 kHz) and the lowest roll-off frequency (2. 5 kHz). 5 HF CUT The LF CUT filter is also a 2nd order Butterworth filter defining the lower roll-off frequency the audio is to have. Fully counter clockwise the control is set to its starting position of 40Hz. Turning clockwise increases the lower roll-off frequency until fully clockwise the maximum roll-off frequency of 200 Hz is reached. Diagram 3 (page 12) illustrates the frequency response curves for the lowest roll-off (40 Hz) and the highest roll-off frequency (200 Hz). 6 LF CUT 11 Diagram 3: Frequency responses for the lowest (40Hz) and highest roll-off (200Hz). HF CUT: 20kHz to2. 5kHz LF CUT: 40Hz to 200Hz LF (Low Freq. ) Diagram 4: Frequency responses for the lowest (15Hz) and highest (365Hz) LF control setting at max. B/C and Q5 7 The low frequency control (LF) operates over more than four octaves. The center frequency can be varied between 15 Hz and 365 Hz. 12 The mid frequency control (MF) also covers more than four octaves. The center frequency can be varied between 200 Hz and 5 kHz. 8 MF (Mid Freq. ) Diagram 5: Frequency responses for the lowest (200Hz) and highest (5kHz) MF control value at max. [. . . ] The operational voltage of the tubes (275 V) is heavily smoothened and electronically regulated. The heating voltage (6. 3 V) is supplied by an individuell wiring within the transformer. Socalled »hum-trimmers« adjust the tubes´ heating voltage and minimize the hum voltages. Both inputs and outputs of the tubes are smoothened with condensers of high voltage and condenser values (1 microFarad/ 400 V/5%) to minimize offset voltages. All relays are operated via an individual voltage regulator and are therefore separated from the audio operating voltage. Extensive filtering and decoupling guarantee stable power and avoid audible changes such as a diffuse sound pattern. High voltage tube operation (275 volts) 21 Specifications Input & Output Instrumentation amplifier, electronically balanced (differential) transformerless Nominal input level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ]