Gradient SW-63 Subwoofer
for
QUAD ESL-63
INSTRUCTION
MANUAL
DESCRIPTION
The SW-63 differs from other subwoofers in that it relies on dipole operation. Most subwoofers are bass reflex
loaded, which gives them an isotropic radiation pattern (omnidirectional) at low frequencies. This type of
radiation pattern is impossible to integrate with the dipole pattern of the ESL.
Adding the subwoofers is easy. In addition to the SW-63:s one only needs one extra stereo power amplifier, two
pairs of RCA (or XLR with the balanced one) cables and one pair of speaker cables.
BENEFITS OF THE SYSTEM
* The subwoofer is acoustically perfectly integrated with the QUAD because it relies on dipole operation like the
QUAD
* Dynamic, well controlled bass reproduction down to 28Hz (-3dB)
* Adjustable bass level enables perfect room/taste matching
* The system is able to go 10 dB louder than the ESL-63:s by themselves
* The reduced low frequency strain on the ESL-63 results in a more accurate and cleaner midrange reproduction
* The QUADs are placed on top of the SW-63:s so there is no need for stands. The SW-63 raises physically the
acoustical centre of the ESL to optimum listening height.
* Free choice of amplifiers. The SW-63 is an easy load and it is possible to choose either 16 ohm or 4 ohm
nominal impedance depending on the gain and the current/voltage capability of the amplifier.
* The active crossover includes a subwoofer mono switch. Mono operation reduces excessive cone excursions
when playing warped LP records.
* Certain recordings may sound slightly harsh on the ESL:s. The crossover unit also includes an upper midrange
attenuation switch. Attenuation is at maximum 0,5 dB or 1,0 dB.
* A small drawback: There are two acoustic centres in the system instead of one, but the subjective acoustic centre
remains at the center point of the ESL-63, because of the low crossover frequency.
GUARANTEE
This subwoofer system is guaranteed against any defect in material and workmanship for a period of twelve
months from the date of purchase.
Within this period we undertake to supply replacement parts free of charge provided that failure was not a result
of misuse, accident or negligence. Labour and carriage costs are not covered unless by local agreement.
This guarantee is void and inapplicable if the subwoofers have been subject to inputs in exess of the maximum
rating or inputs from an unstable or clipped amplifier or have been subject misuse or abuse (result of which would
be burned voice coils or other mechanical damage).
SERVICE
If servicing is required the unit should be returned to the supplier, to the distributor or to the manufacturer.
UNPACKING
The subwoofers are packed in two cartons. One of them also includes the active crossover unit, eight spikes, an
allen key and the Instruction manual. Loudspeaker and interconnect cables are not included. The AC-adapter
needed for powering the crossover unit is supplied by the local SW-63 distributor (in those countries not using
220-240 V and European 2-pin socket). Packing should be retained in case the subwoofer needs to be returned
for service.
INSTALLATION
SW-63 subwoofer is dimensioned to suit the present ESL-63 fitted with plastic feet. In this case the height of the
ESL bottom trim is more than 83 mm from the base. When installed on the subwoofer the ESL63 should stand on
its own feet and there should be a small space between the ESL bottom trim and the subwoofer front grille and
side walls.
Where QUAD ESL-63s are fitted with cork feet (the height is less than 83 mm) they should be replaced by
furniture feet of greater height (or any other suitable feet). If you are going to use spikes with your subwooters it
is recommended that you first check the placement of speakers and then fix the spikes before installing the ESLs.
Tilting is possible with spikes. When installing, first remove the subwoofer top trim (back of the unit) to fit the
ESL-63 on the SW-63 top level. Raise the ESL and place it on the subwoofer. Fix the top trim. 'tighten the nuts
(not too tight) with the allen key provided. The system is now ready for speaker wiring.
AMPLIFIER REQUIREMENTS
The SW-63 is a very easy load for any power amplifier. The sensitivity of the'SW-63 is comparable to that of the
ESL-63. Consequently the power demand is similar to that of the ESL-63. The recommended amplifier power is
50-250 W / ch / 8 ohm.
BASIC SETUP OF THE ESL-63 & SW-63 SYSTEM
The system consists of program sources, preamplifier, crossover unit, two power amplifiers, one pair of ESL-63s
and one pair of SW-63 (see fig. 1). basically it is possible to use any power amplifiers in the system.
BASIC SETUP
QUAD QUAD
ESL-63 ESL-63
SW-63 SW-63
+ - - +
POWER AMPLIFIER
FOR ESL-63
+ - + -
L/R POWER AMPLIFIER
FOR SW-63
L/R
ACTIVE CROSSOVER AC
ADAPTOR
L/R
PREAMPLIFIER
PROGRAM SOURCES
FIG. 1
1. The power amplifiers are similar
Just hook up the system as in fig. 1.
2. The power amplifiers are not similar
Power amplifiers can be phase inverting or non-inverting. In order to get the correct phasing between the ESL-63
and the SW-63 it is important to determine which is the case. If this data is not obtainable, please do the
following test:
- connect the system as in fig. 2
- adjust the balance between the channels
- switch the preamplifier to mono and listen to music. If the sound is coming exactly from the center point
between the speakers, the phase behaviour of the amplifiers is identical (as in the QUAD 306 & 606 or QUAD
405 & 303). If the sound comes from an undefined direction, one amplifier is inverting and the other noninvertig
(as in the OUAD 405 & 306).
PHASE TEST FOR AMPLIFIERS
WHEN DIFFERENT AMLIFIERS ARE USED
QUAD QUAD
ESL-63 ESL-63
- L + - R +
POWER AMP I POWER AMP II
L IN R IN
OUT
L R
PREAMPLIFIER
PROGRAM SOURCE
FIG. 2
With identical phase amplifiers, use the wiring exactly as in fig. 1.
In the case of nonidentical phase behaviour, the + and - speaker wires of one amplifier (both channels!) must be
interchanged at either the amplifier or the speaker end.
If one of the ampfiers is more powerful than the other it is recommended to connect it to the ESL:s.
THE INPUT/OUTPUT PHASING OF SOME QUAD AMPLIFIERS
MODEL 606 306 405 405-2 303 QAII
PHASE NON NON INVERT INVERT INVERT NON
SUBWOOFER PHASING
Each subwoofer should be connected to its appropriate amplifier output so that the two pairs of wires are
connected in the same way, to ensure that the subwoofers operate in phase. The input terminals are colour-coded
to facilitate this.
USE OF 4 OHM OR 16 OHM SETTING IN THE SW-63
The normal subwoofer setting is 16 ohm.
If the amplifier you are using with the SWs has significantly less nominal output power capability than another
amplifier but can give lots of current, you can try the 4 ohm setting. This will increase the sound pressure level of
the SW's by 6dB. In this case reduce the level with the SW level control of the crossover unit.
SW JUMPER SETTINGS:
4 ohm 0-0 0-0
- +
16 ohm 0 0-0 0 (normal setting)
- +
HUM PROBLEM
In cases where more than one of the mains powered units in the system are grounded to the mains earth there may
occur hum caused by the the ground loop. In this case check that only one of the units is earthed.
LOUDSPEAKER PLACEMENT
The Quad ESL-63 & Gradient SW-63 combination will give good results when positioned in a similar way as the
ESLs alone. The combined system is easier to position in a room than normal omnidirectional speakers.
Especially in acoustically difficult rooms the system will produce more satisfying sound than more room
dependent loudspeakers.
To get optimum results it is recommended to follow the suggestions given here.
Basics
The loudspeaker in a room always excites standing waves and causes room reflections. How these phenomena
affect the sound depends on the location of the speakers and the listener.
A dipole system
The Quad & Gradient combination is a dipole radiator. This means that the speaker system is radiating sound
both to the front and rear in a similar way. The radiating pattern is that of a figure eight. This gives some benefits
over normal speakers. Normal omnidirectional loudspeakers (closed or vented box) give rise to standing waves in
all directions. However a dipole radiator excites standing waves mainly in one direction only. It also generates
less room reflections. Thus the room colourations remain minimal. With proper placing it is possible to achieve
smoother and better sound reproduction than with standard omnidirectional systems.
Elimination of the first wall reflection
A dipole system has features that are quite unique. For instance the backward radiation which is in opposite phase
in relation to the forward radiation can be used for your benefit. If the distance between the speakers and the front
wall is similar to that of the listener and the back wall (fig. 3 a), the first wall reflection will be eliminated. This
phenomenon smoothens the response. Best results are obtained when the distances are one third of the room
lenght (1/3) (fig. 3 b). This placement is especially preferable in the case of a hard wall behind the speakers.
Side walls
Another feature of a dipole radiator is the way it radiates sound to the sides. The sound radiation to these
directions is minimal. This means that the speakers can be placed near the side walls without deterioration of the
sound.
DAMPING
X a MATERIAL
X
a
X a
Fig. 3 a) Fig. 3 b) fig. 3 c)
Back wall influence
One of the benefits of a dipole radiator is that the sound is open and airy and at the same time phenomenally
accurate and three dimensional. However if placed too close to the back wall (<. 1 m) two things will happen.
The bass output will decrease which makes the speaker sound thin and lacking in bass. The minimum distance for
good bass is about 1 meter.
A very close back wall will cause some colourations in the mid band. Also in this case the recommended distance
from the back wall is about one meter or more. The speakers can be situated even nearer (60 cm) if the wall is
acoustically treated with damping material. Two pieces of sound absorbent material of the speaker size are
enough (fig. 3 c). This will improve the mid frequency clarity but does not affect the bass response.
Symmetry
In order to create a good stereo imaging it it always recommendable to place the speakers in a room with
symmetry to the nearby boundaries (walls).
Best locations
The best locations in different rooms vary. Using the above mentioned suggestions it is possible to find the most
satisfying result. It is also useful to know that the QUAD ESLs give best results when angled to the listener.
CROSSOVER UNIT CONTROL FUNCTIONS & CONNECTIONS
* SW LEVEL: Subwoofer level control. Adjustment range is +/-l0 dB. If the gains of the SW and ESL power
amplifiers are equal and the subwoofers are wired for 16 ohm connection, 2 o'clock position is recommended as a
start point.
* SW MODE: Subwoofer stereo / mono switch. Mono position is recommended when playing warped LP
records.
* MID ADJ: With this switch you can attenuate upper midfrequencies by 1,0 dB (1) or 0,5 dB (11). This may be
of benefit with some less than optimal multimike recordings and / or in compensating for less than ideal listening
rooms. In OFF position the frequency response remains unaltered.
* SW OUT: Signal to SW power amplifier. Output impedance is between 1... 3 kohm depending on SW level
control position.
* ESL OUT: Signal to ESL power amplifier. Output impedance is 1 kohm.
* IN: Signal from preamplifier. Input impedance is 22 kohm.
* 15-20V AC: Power supply connector. Accepts also 18-24 V DC. Polarity has no meaning.
SPECIFICATIONS
SW-63 SUBWOOFER UNIT
Impedance: selectable, nominal 16 or 4 ohm
Radiation pattern: dipole
Drive units: 2 pcs 300 mm long throw dynamic drivers
Max. input voltage: thermal limit 90 V program when 16 ohm selected,
mechanical limit depends on frequency
Amplifier
recommendation: 50 ... 250 W / 8 ohm
Weight: 18.5 kg
Dimensions: W 660 mm; H 475 mm; D 285 mm
System height: 1325 mm (with ESL-63)
ACTIVE CROSSOVER UNIT
Input impedance: 22 kohm
Output impedance:
-ES output: 1 kohm
-SW output: 1...3 kohm depending on SW level control
THD: less than 0.03% any output with input voltage 500 mV (80 Hz -15 kHz)
Signal to Noise ratio: better than 105 dB, A-weighted, any output, referred to 500 mV,
SW level control in mid position
Crosstalk attenuation: better than 65dB at 15 kHz
Crossover frequency: 110 Hz
Filter slopes
- ESL high pass section: second order
- SW low pass section: third order
- SW high pass section: second order
Voltage gain
- input to ESL output: on passband ca. 0 dB
- input to SW output: depends on frequency, adjustable +/- 10 dB
Operating voltage: 15 - 20 V AC / 18-24 V DC
Current consumption: ca. 35 mA (75 mA, balanced)
Dimensions: Width 182 mm; height 50 mm; depth 130 mm (plus connectors & controls)
Weight: 700 g (900 g, balanced)
OVERALL
Lower cutoff frequency: -3 dB point at 28 Hz
Crossover frequency: 110 Hz, low pass acoustical slope of second order
SUPPLIED ACCESSORIES
AC-adapter Mascot type 8310, 230 VAC - 16 VAC / 220 mA, Plug 3630; (www.mascot.no)
eight spikes with nuts, eight pads, 5 mm allen key, instruction manual
Gradient Ltd
Levysepänkatu 28 D
04440 Järvenpää
Finland
Tel. +358 9 2917875
Fax +358 9 2916730
www.gradient.fi
e-mail: info@gradient.fi
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