Polyglass Subwoofers Manual
7
Polyglass Subwoofers Manual
We congratulate you on purchasing a Focal subwoofer, from the Polyglass range.
This product has been designed using the very latest technologies available; to ensure the quality
performance is to a very high standard. To gain the best results from your subwoofer, please
ensure you follow these recommendations. If not followed correctly any fault observed, may not
be covered by the guarantee.
Cables
For optimum performance the use of OFC cable (Oxygen Free Cable), to a sufficient thickness
(2.5mm²) is highly recommended. This is particularly important in the case of long cable lengths being
used in the installation. We recommend the use of Focal cables FC500 or FC700. Check with your local
Focal dealer for further advice.
Connecting up
Always check the polarity to the subwoofer, and that of the other speakers used in your installation.
The polarity is important to ensure the phase characteristics remain correct, otherwise a "loss" of
performance can result. The spring action input terminals are clearly marked red spot = positive (+) and
black spot = negative (-).
These subwoofers can be mounted in the traditional sense with the membrane on view externally, or
inverted mounting with the motor unit and its chrome back plate on display. Inverted mounting helps
increasing the volume for the given space available. When choosing inverted mounting the phase must
be inverted (thus swap the positive / to negative connections) so that the polarity is correctly observed.
Multi-subwoofer installations
To obtain a more powerful acoustic presence, we recommend the introduction of multiple subwoofers
for your chosen installation. Using multiple subwoofers, various series or parallel or combinations of
both can be used, but always check the specifications of the power source (amplifier) before attempting
any installation. It is worth remembering if low impedance of 2 or even 1 ohm is chosen an amplifier of
high quality should always be used for such installation.
Connections in parallel
Normally the terminal positive (+) on the subwoofer will be connected to the equally marked positive
(+) on the amplifier, and the terminal negative (-) on the subwoofer to the equally marked negative (-)
on the amplifier.
The Focal guarantee only applies if page 13 is
returned to us within 10 days of purchase.
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Polyglass Subwoofers Manual
Only on an inverted subwoofer installation is it normally necessary to invert the connections (-) and (+).
Calculation of the impedance is (Z), for the given impedance value nominal (R), is 4 ohms.
• 2 subwoofers : 1/Z = 1/R1 + 1/R2 1/Z = 1/4 + 1/4
Z= 2 Ω
• 3 subwoofers : 1/Z = 1/R1 + 1/R2 + 1/R3
Z = 1,33 Ω
Connections in series
Using multiples of subwoofers for such comprehensive installations, it is sometimes better to connect
them together in a series circuit. Using a low impedance load to the amplifier effectively ensures it will
work less hard. For connecting the subwoofers, they are effectively looped together in any series circuit.
Thus the positive (+) of 1st subwoofer will be connected to the positive (+) of the amplifier.
The negative (-) of the 1st subwoofer will be connected to the positive (+) of the 2nd subwoofer.
Then depending on how many subwoofers are to be included this looping will continue, until the last
(in this basic case the 2nd subwoofer), will have its negative (-) connected to the negative (-) of the
amplifier.
Calculation of the impedance is (Z), for the given impedance value nominal (R), is 4 ohms.
• 2 subwoofers : Z = R1 +R2
Z=4Ω +4Ω
Z=8Ω
Connections series and parallel, combined
Depending on your installation amplifier(s), subwoofer(s), various combinations of series and parallel
circuits can be used. The real advantage of doing this is to have a system with available power, but at the
same time to ensure the system impedance load is optimum for the amplifier(s) used.
Connection diagrams
Examples and configurations for various multiples of subwoofers:
2 subwoofers 21 V2 in parallel. Z = 2 Ω
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3 subwoofers 21 V2 in parallel. Z = 1,33 Ω
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Polyglass Subwoofers Manual
Adjustment of low cut off frequency
The cut off frequency of a subwoofer is normally in the region of 60 to 100Hz. This is always
dependent on the particular installation and listening position. A frequency of 80Hz is a good
compromise for effective bass compared to listening quality.
Enclosures
Focal offers 4 ready-to-use optimized enclosures. If you decide to ‘brew your own’, it is safest to go for a
bass-reflex type. This classic simple alignment usually give the best and most consistent results.
See page 12 regarding our proposals for the various volumes available per subwoofer.
Bass-reflex boxes
A bass-reflex system is more efficient than the closed box since some of the energy from the rear of the
cone is converted via the reflex port to add in phase with the main output. There is also a reduction of
cone travel at the tuning frequency, so this system can also give higher power handling. However, at very
low frequencies bass rolls off faster (24dB/octave). In simple terms, bass is louder, but not quite as deep.
You can make a reflex port from a piece of plastic pipe, or there are many flared ports custom designed
for loudspeakers that minimize turbulence (prevents what’s commonly referred to as chuffing).
Building an enclosure
The construction should always remain strong and rigid, to eliminate any unwanted resonances.
A good material such as MDF (Medium Density Fibreboard) will effectively ensure this is possible.
Choosing the correct thickness of MDF compared to the surface area decided, is also critical to ensure
the enclosure does not vibrate. For this reason the general thickness recommended is 19mm MDF. Any
loose components such as the internal connections and cables should always be fixed securely inside.
Damping material (foam etc) covering all the internal walls of the enclosure, will further ensure it is free
from unwanted resonances. It is imperative that your custom designed subwoofer enclosure remains
securely mounted at all times to the vehicle.
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Polyglass Subwoofers Manual
Calculating the internal volume
Volume
interne1
A
B
C
D
15 L
11"
280
11"
280
143/16"
360
71/16"
180
30 L
40 L
50 L
60 L
113/4 149/16"
300
370
113/4 149/16"
300
370
161/8 1415/16"
410
380
77/16" 95/16"
190
237
149/16" 1711/16"
370
450
149/16" 175/16"
370
440
191/4" 175/16"
490
440
95/16" 101/4"
237
260
1711/16"
450
175/16"
440
207/8"
530
101/4"
260
2 x9
2 x9
Events2 2 x9
27 V1 7 x 25 7 x 25 7 x 25
2 x9
2 x9
Events
33 V1
7 x 23 7 x 23
2 x15
2 x15
Events
7 x 40 7 x 40
40 V1
3/4"
Internal volume calculation: Vb = B x C x {D+(A-D)/2}
1 - External sizes in inches and millimetres with sides of 19 mm thickness
2 - (Ø x L) in cm
20 L
0.53cu.ft. 0.71cu.ft. 1.06cu.ft. 1.41cu.ft. 1.77cu.ft. 2.12cu.ft.
13/16"
3/4"
13/16"
3/4"
13/16"
3/4"
1/16"
3/4"
1/16"
3/4"
3/4"
3/4"
Recommended power ratings
Polyglass subwoofers are already highly efficient, with improved sensitivity. Therefore, their use with
amplifiers will produce comfortable listening pleasure.
However used in a more high-end system, with more powerful amplification, the audio quality will
be greatly improved. It is very important to check that rated power of the amplifier is suitable to the
subwoofers. Otherwise they may distort, or possible damage could occur.
Always consult the owners manual of the principal source (head unit/amplifier), to ensure the power
rating is compatible. A safe guide is to ensure the maximum power of the amplifier is not greater than
the nominal power of the speakers.
Warning!
The improved power handling has allowed Focal subwoofers to play at very loud sound volumes.
For this reason, we recommend caution be wisely applied, especially during long listening periods.
Excessive volume levels of more than 110dB can cause permanent hearing damage.
Guarantee
All Focal loudspeakers are covered by guarantee drawn up by the official Focal distributor
in your country. Your distributor can provide all details concerning the conditions of guarantee.
Guarantee cover extends at least to that granted by the legal guarantee in force in the country where
the original purchase invoice was issued.
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3/4"
Polyglass Subwoofers Manual
11
Technical characteristics
27 V1
Cone
Sd
Xmax
Fs
33 V1
20.5cm
40 V1
26cm
33,5cm
530.93cm
881.41cm2
6mm
7.5mm
7.5mm
330.06cm
2
2
39.01Hz
25.25Hz
26.84Hz
Qes
0.510
0.360
0.510
Qms
3.470
3.440
4.620
Qts
0.445
0.326
0.459
Vas
21.43 liters
91.79 liters
165.66 liters
Res
19.73 ohms
31.92 ohms
29.89 ohms
Mms
118.87g
171.36g
231.60g
Bl
12.87N/A
15.88N/A
15.90N/A
Le
23.20mH
58.48mH
38.37mH
Re
2.9 ohms
3.34 ohms
3.3 ohms
Parameters
27 V1
33 V1
40 V1
Impedance
4 ohms
4 ohms
4 ohms
Max. Power
500W
800W
800W
Nom. Power
250W
400W
400W
Sensitivity (2.83V X 1m)
90dB
92dB
93,5dB
Fitting diameter
9-3/16”
(233mm)
11-5/16”
(287mm)
13-5/16”
(351mm)
Fitting depth
5-1/8”
(130mm)
6-1/4”
(158mm)
7-5/16”
(185mm)
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Polyglass Subwoofers Manual
12
Frequency response
27 V1
SPL (dB) 1W/1m
Vented enclosure
15 liters (0.53 cu. ft)
F - 3 = 46Hz / Fast and tight bass
20 liters (0.71 cu. ft)
F - 3 = 40Hz / Punchy and dynamic bass
30 liters (1.06 cu. ft)
F - 3 = 33Hz / Deep and articulate bass
Frequency (Hz)
33 V1
SPL (dB) 1W/1m
Vented enclosure
30 liters (1.41 cu. ft)
F - 3 = 40Hz / Punchy and dynamic bass
40 liters (1.77 cu. ft)
F - 3 = 36Hz / Deep and articulate bass
Frequency (Hz)
40 V1
SPL (dB) 1W/1m
Vented enclosure
50 liters (2.12 cu. ft)
F - 3 = 43Hz / Punchy and dynamic bass
60 liters (2.83 cu. ft)
F - 3 = 40Hz / Deep and articulate bass
Frequency (Hz)
Polyglass and Focal are trademarks of Focal-JMlab
BP 374 - 108, rue de l'Avenir - 42353 La Talaudière cedex - France - www.focal-fr.com
Tel. 00 33 4 77 43 57 00 - Fax 00 33 4 77 37 65 87
®
®
®
Due to constant technological advances, Focal reserves its right to modify specifications without notice. Images may not conform exactly to specific product. ©Focal-JMlab-SC-050304/1
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