Focal POLYGLASS SUBWOOFERS, SUBWOOFERS POLYGLASS User Manual

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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.

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.

The Focal guarantee only applies if the enclosed guarantee card is returned to
us within 10 days of purchase.

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.

Focal-JMlab® - BP 374 - 108, rue de l'Avenir - 42353 La Talaudière cedex - France - www.focal-fr.com

Due to constant technological advances, Focal reserves its right to modify specifications without notice. Images may not conform exactly to specific product.

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2

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.
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

Polyglass Subwoofers Manual

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

3

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 = 2Ω 3 subwoofers 21 V2 in parallel. Z = 1.33Ω

Polyglass Subwoofers Manual

2 subwoofers in series. Z = 8Ω 4 subwoofers in series/parallèle. Z = 4Ω

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.

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Polyglass Subwoofers Manual

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 below regarding our proposals for the various volumes available per subwoofer.

Vented boxes

A bass-reflex system is more efficient than the sealed 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 vent port from a piece of plastic pipe, or there are many profiled vent 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.

Calculating the internal volume

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

Internal
volume

A

B

C

Dv

27 V1
vents

33 V1
vents

40 V1
vents

1

2

2

2

15 L

0.53cu.ft.

11"

280

11"

280

3/16

14

360

1/16

7
180

3/4

13/16

2

"x9

7 x 25

"

"

20 L

0.71cu.ft.

11
300

11

300

16

410
7

190

3/4

"

2

"x9

7 x 25

30 L

40 L

50 L

450

440

440

260

"x15

11/16

5/16

5/16

1/4

"

"

"

"

3/4

"

60 L

2.12cu.ft.

11/16

17

450

5/16

17

440

7/8

20

530

1/4

10

260

3/4

2

"x15

7 x 40

"

"

"

"

3/4

"

1.06cu.ft.

1.41cu.ft.

3/4

2

9/16

14

370

9/16

14

370

1/4

19

490

5/16

9
237

"x9

7 x 23

"

"

"

"

1/16

1.77cu.ft.

17

17

17

10

"

3/4

2

7 x 40

3/4

9/16

14

"

370

3/4

9/16

"

14

"

370

1/8"

15/16

14

"

380

7/16

5/16

"

9

"

237

13/16

3/4

13/16

"

2

"x9

"

7 x 25

3/4

1/16

2

"x9

"

7 x 23

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Polyglass Subwoofers Manual

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.

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.

Technical characteristics

27 V1 33 V1 40 V1

Cone 20.5cm 26cm 33,5cm

Sd 330.06cm

Xmax 6mm 7.5mm 7.5mm

Fs 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

2

530.93cm

2

881.41cm

2

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/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)