Crossover-63
HIGH END
CROSSOVER UNIT
FOR
GRADIENT
SW-63 SUBWOOFERS
Instruction Manual
Congratulations for your purchase of the Gradient Active Crossover. It is intended to use with
the Gradient SW-63 subwoofer & QUAD ESL-63 combination.
We recommend you to read this manual entirely to fully utilize the high performance of your
speaker system.
BRIEF OPERATING INSTRUCTIONS
1. Connect right (R) and left (L) channel signals from the signal source (line out) or the preamplifier
(pre out) to the crossover (input / balanced input).
2. Set the BALANCING SWITCH according to the input used, i.e. to the BAL position when XLR-input
is used and to the UN position when RCA input is used.
3. Connect the right (R) and left (L) channel bass signals (LOW FREQ OUTPUT (XLR) or OUTPUT
UNBALANCED / LOW (RCA)) to the amplifier feeding the subwoofers.
4. Connect the right (R) and left (L) channel high frequency outputs (HIGH FREQ OUTPUT (XLR) or
OUTPUT UNBALANCED / HIGH (RCA)) to the amplifier feeding the QUAD electrostatic
loudspeakers.
5. Connect the left and right loudspeaker cables from the bass amplifier to the corresponding binding
posts of the subwoofers.
6. Connect the left and right loudspeaker cables from the high frequency amplifier to the
corresponding binding posts of the Quads.
7. Make sure that the connections are tight.
8. Turn the BASS CONTROLS / LEVEL knob of the crossover to halfway position and increase the
volume from the preamplifier.
9. Adjust the bass level according to your taste by the LEVEL knob.
10. The speaker system is now ready for fine tuning.
SYSTEM DESCRIPTION
Gradient SW-63 subwoofer system with a pair of Quad Electrostatics is a dipole loudspeaker system
you can freely make your own choice of power amplifiers.
Signal coming from a sound source or a preamplifier is fed to the active crossover. There it is divided
into two parts and equalized to correct the properties of a dipole bass system.
For the bass section it is recommended to use solid state amplifiers because of their low output
resistance at low frequencies. For the Quads (over 110 Hz) valve amplifiers will do as well.
Active Dipole correction
The low frequency response of an open baffle will roll off at 6 dB per octave. This is
ruled by Mother Nature. Thus the subwoofers will need equalization.The lower limit is set to reach to
20 Hz, -3dB.
Other benefits
The woofers are directly connected to the power amplifier giving the best possible control over the
cone excursion.
Similarity of amplifiers
If the amplifiers in use are of similar brand and type you can skip the following.
Amplifiers can be either non-phase-inverting or phase-inverting. When the speaker is powered by two
amplifiers it is essential for correct phasing to know what is the case. Most modern amplifiers are noninverting and different models of one brand most probably similar in this respect.
It is easy to find out what is the case using a simple test setup where the Quads are powered by two
amplifiers as follows.
1. Connect the HIGH FREQ OUTPUT´s left channel of the crossover to the input (line in / left) of the
first amplifier. Connect the left channel loudspeaker cable to run the upper part of the left channel
Quad.
2. Connect similarly the HIGH FREQ OUTPUT´s right channel of the crossover to the input (line in /
right) of the second amplifier. Connect the right channel loudspeaker cable to run the upper part of the
right channel Quad.
3. Play a record with a soloist, adjust the balance and check if the soloist is singing or playing in the
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