Focal ACCESS SUBWOOFERS User Manual

Français page 7

We congratulate you on purchasing a Focal subwoofer, from the Access 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.

Access Subwoofers Manual

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 the enclosed guarantee card is returned to us within
10 days of purchase.

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.

Tel. [phone] - Fax [phone]

2

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 = 4 Ω + 4 Ω Z = 8 Ω

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

Access Subwoofers Manual

Examples and configurations for various multiples of subwoofers:

2 subwoofers 21 V2 in parallel. Z = 2 Ω 3 subwoofers 21 V2 in parallel. Z = 1,33 Ω

3

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

Access subwoofer were developed for vented box only. 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.

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.

Access Subwoofers Manual

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.

4

Access Subwoofers Manual

Recommended power ratings

Access 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

Impedance 4 Ohms 4 Ohms
Nominal power handling 200W 250W
Maximum power handling 400W 500W
Sensitivity (2.83 V / 1m) 92dB 94dB
Fitting diameter 9-1/8“ (232mm) 10-13/16“ (275mm)
Mounting depth 4-1/16“ (103mm) 4-11/16“ (119mm)

Parameters

25 A1 30 A1

2

Sd 339.79cm

510.71cm

Xmax 5.5mm 5.5mm
Fs 40.61Hz 37.4Hz
Qes 0.4 0.45
Qms 8.65 6.37
Qts 0.382 0.42
Vas 24.34 litres 52.97 litres
Re 3.35 Ohms 3.2 Ohms
Mms 102.35g 125.24g
Bl 14.79N/A 14.47N/A
Le 1.07mH 1.04mH

2

5

Access Subwoofers Manual

25 A1 - Vented enclosure
Frequency response

20 litres (0.70 cu. ft)

SPL (dB) 1W/1m

Fast and tight bass

25 litres (0.88 cu. ft)

Punchy and dynamic bass (best compromise)

30 litres (1.06 cu. ft)

Deep and articulate bass

Frequency (Hz)

20l 25l 30l 35l 40l
F-3 48Hz 42Hz 38Hz 38Hz 37Hz
Fb 53Hz 46Hz 46Hz 43Hz 42Hz
Boostmax. 2.5dB/65Hz 1dB/55Hz - 1.5dB/47Hz 1.5dB/46Hz

Calculating the internal volume

Internal volume calculation:
Vb = B x C x {D+(A-D)/2}

Internal

volume

A
B
C
D

25 A1
vents

20 l 25 l 30 l 35 l 40 l

1

300

330

370

370

380

237

9.33"

8x25

370

14.57"

370

14.57"

435

17.13"

237

9.33"

8 x 17

3.1x6.7"

3.1x5.9"

2

11.81"

300

11.81"

410

16.14"

190

7.48"

9 x 27

3.5x10.6"

(angled)

13"

330

13"

390

13.35"

210

8.27"

8x23

3.1x9"

14.57"

14.57"

14.96"

3.1x9.8"

1 - External sizes in inches and millimetres with sides of 19 mm thickness

2 - (Ø x L) in cm

370

14.57"

370

14.57"

490

19.29"

237

9.33"

8 x 15