18
The QURE ON switch puts a coil/condenser/resistor filternet-
work (LCR) into the tube output stage.This network is integrated
into the coupling path of the tubes and reacts on the dynamic
reponse of the input signal changing THD spectra and phase
responses. It sounds similar to a ‘closed shelving bandpass’
frequency response, but with a time frame in which harmonics
are newly created or become more present in close relation to the
dynamic response of the source material.
Diagrams 13 and 14 show how the harmonic content is altered
of a period of 30 seconds. Diagram 13 shows a standard sweep
from 1kHz to 4kHz within that time frame and the corresponding
harmonical spectrum. Diagram 14 shows the treated signal with
the QURE circuitry. The comparison shows, although both
diagrams represent a linear frequency response, that the harmo-
nical structure after the QURE treatment is enhanced,new harmo-
nics have been created and existing harmonics show a more
stable response. Also, so-called ‘cross-harmonics’ (between the
main harmonics) are more intense. What cannot be seen are the
effects on phase response.
How to use the QURE circuitry
By activating the QURE circuitry the overall output level raises
inevitable by +2 dB. There are two ways to compensate for this
effect.
1. Activate the QURE circuitry (Press QURE ON) which lets the
output level raise by about 2 dB. Use the mid-range filter (MF) to
cut harsh or annoying frequencies with a medium or broader
bandwidth to achieve a linear frequency response. Use the QURE
control to select the frequency range.With the SHIFT QURE switch
you can jump from a high frequency range (2 kHz-6 kHz) to a
lower frequency range (400 Hz-2 kHz).
2. Activate the QURE circuitry (Press QURE ON) which lets the
output level raise by about 2 dB. Turn the OUT control counter
clockwise and compensate for the level increase.
The QURE potentiometer changes the frequency response and
produces a fresh and silky top-end and a mid-range free of shar-
pness and harshness.
Especially vocals gain clarity and presence. They seem to step
right in your face while at the same time the dimensionality of the
music is getting bigger.This sound pattern is achieved by simulta-
neously influencing THD spectra and phase responses.
The QURE potentiometer changes the center frequency of
processing from 2kHz (counter clockwise) to 6kHz (clockwise).To
process a deeper frequency spectrum use the SHIFT QURE switch
(see 15).
Integrating a coil/condenser/
resistor filternetwork (LCR)
into the signal path
Tips on using the
QURE circuitry
14
QURE
