Gradient Crossover-63, SW-63 Owners manual

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

middle (in-phase) or if the signal is coming from unidentified direction (out-of-phase). You can easily
check this if you have a test disc with so called phase test.
If the system now sounds in-phase the amplifiers are similar and can be connected
as described in the BRIEF OPERATING INSTRUCTIONS.
However if the sound is out-of-phase the amplifiers are not similar in phase behavior. In this case do
as follows:

- reverse both loudspeaker cables of one amplifier and only at the amplifier end (plus to minus and
minus to plus, both channels). Now the signals from both amplifiers to loudspeakers are in-phase.

THE CROSSOVER

The crossover designed by Gradient and manufactured in Denmark is carried out following the best
High End principles. The layout of parts and printed circuits made of high quality components are
situated in a solid metal housing so that both external and internal magnetic and electrical
interferences are eliminated. For instance the power supply is positioned far away from the small
signal sections. The components used have passed the golden ear designer´s test, to mention only
Burr-Brown´s operational amplifiers.

Controls

All controls are found from the left side of the back panel under the text BASS CONTROLS (see Fig.

1).

Bass level control (1)

The level of the signal feeding the bass amplifier can be adjusted continuously by a knob marked
LEVEL by +/-10 dB. According to the personal taste and listening room acoustics the bass is easy to
adjust. Once found the correct balance, there is little need for further adjustments.

Stereo/mono switch (2)

When paying warped LPs the cartridge tone arm system may give rise to high level subsonic
frequencies which cause excessive cone excursion and take a lot of unnecessary power from the
amplifier. Mono operation of bass channel will eliminate this.

Q-value adjustment (3)

The crossover is equipped with a three position switch adjusting the Q-value of the bass response. It is
up to the listener’s taste whichever position gives the best personal result.
The effect of this switch is shown in Fig. 2.
Position HIGH gives the flattest response reaching to 20 Hz, -3 dB. In position LOW 20 Hz is
attenuated by 10 dB and in position MEDIUM by 6 dB.
Terms fast and slow bass are often used by experts when speaking about the quality of bass. Fast
refers to LOW and slow to HIGH position.
The effect of the Q value is easily noticed when listening to records with "bass transients". Such
records are numeral, here two popular ones:
* Eagles: Hell freezes over, track 6 (Hotel California), Geffen 424 725-2 or GED 24725
* Ein Straussfest, track 1 (Explosions Polka). Erich Kunzel & Cincinnati Pops Orchestra, Telarc CD­80098

Connections

The crossover is equipped with both balanced (XLR) and unbalanced (RCA) connections to suite
every audio system. If long cables are necessary it is recommendable to use balanced lines which
guarantees the most interference-free signal transfer. Desired type is selected by the BALANCING
SWITCH. It is also possible to use both types of connections in a mixed configuration. In this case the
position of the Balancing Switch is selected according to the type of the input signal: position BAL with
XLR connectors and position UN with RCA connectors.

Inputs (4 & 6)

A program source or a preamplifier equipped with RCA connectors is connected to the RCA inputs of
the crossover marked INPUT / LEFT & RIGHT and equipments with XLR connectors to the XLR
inputs marked BALANCED INPUT / RIGHT & LEFT.
The position of the BALANCING SWITCH is set according to the input connectors used: UN (RCA) or
BAL(XLR). When position UN is selected the pins 3 of the XLR inputs are grounded.

Outputs for power amplifiers (7, 8, 9, 10)

Balanced signals to the amplifier running the upper parts of the loudspeakers are taken from XLR
connectors marked HIGH FREQ OUTPUT / RIGHT & LEFT.
Unbalanced signals are taken from RCA connectors marked OUTPUT UNBALANCED HIGH (LEFT &
RIGHT).

Balanced signals to the amplifier running the bass sections of the loudspeakers are taken from XLR
connectors marked LOW FREQ OUTPUT / RIGHT & LEFT.
Unbalanced signals are taken from RCA connectors marked OUTPUT UNBALANCED LOW (LEFT &
RIGHT).

How the XLR pins are connected

In this crossover unit the pins of the XLR connectors are connected according to the IEC-268 standard
which nowadays is most frequently used. The connection is as follows:

-pin 1 = ground

-pin 2 = signal +

-pin 3 = signal ­Some older amplifiers use reversed system (pins 2 and 3) which inverts the phase. Happily no danger
is taking place. See point Similarity of amplifiers.

AC mains connection (11) and mains switch (12)

The crossover unit can be set either to 230 V or 115 V. The factory setting is marked on the back
panel and on the shipping carton. The fuse to be used is as follows:

- 315 mAT (315 mA, slow) / 230 V

- 630 mAT (630 mA, slow) / 115 V

Use always the correct type.
The fuse holder is located in the body of the mains connector (11).
Because of the low power consumption the crossover can be constantly powered.

TECHNICAL SPECIFICATIONS

Active crossover

Amplification: 6 dB (bal) / 0 dB (unbal)
Input impedance: 40 kohm (bal) / 20 kohm (unbal)
Output impedance: 150 ohm (bal) / 75 ohm (unbal)
Bass level adjustment: +/-10 dB
Crossover frequency: 110 Hz for SW-63 & ESL.-63 system
Dimensions, WHD: 430 x 108 x 390 mm
Weight: 9,6 kg

Gradient Ltd

Levysepänkatu 28

04440 Järvenpää

Finland
Tel. [phone]
Fax [phone]

www.gradient.fi

[e-mail]

FIG 1

FIG 2