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WS 13 BF 8 OHM

13 cm (5") HiFi low-midrange driver with 25 mm voice-coil, elastic rubber surround and coated paper cone. Due to balanced frequency response and high efficiency suitable as woofer and low-midrange driver.
Technical Data
Amplitude & Impendance Frequency
Rated power 40 Watt
Maximum power 60 Watt
Nominal impedance Z 8 Ohm
Frequency response fc - 6000 Hz
Mean sound pressure level 88 dB (1 W/1 m)
Excursion limit 16 mm
Resonance frequency fs 51 Hz
Magnetic induction 1 Tesla
Magnetic flux 390 µ Weber
Height of front pole-plate 5 mm
Voice coil diameter 2.5 cm
Height of winding 1.1 cm
Cutout diameter 13.1 cm
Net weight 0.7 kg
D.C. resistance Rdc 5.4 Ohm
Mechanical Q factor Qms 2.65
Electrical Q factor Qes 0.61
Total Q factor Qts 0.5
Equivalent volume Vas 12 l
Effective piston area Sd 85 cm2
Dynamically moved mass Mms 8 g
Force factor Bxl 5.2 T · m
Inductance of the voice coil L 0.76 mH

Used in / Accessories:


Subwoofer satellite arrangements are becoming ever more popular amongst those who simply do not have room to place large-scale speakers or who are unwilling to have large items of furniture around, but who do not wish to go without the enjoyment of powerful, low-range bass. Since low-frequency sounds below 100-150 Hz cannot be located by the human ear, only one subwoofer cabinet is required. The difficulty here is the combination of left- and right-channel low-range frequencies into a single loudspeaker. An uncompromising solution to this is an active crossover unit, which has a corresponding effect on costs. Special loudspeakers with completely separate voice coils make a simple construction of the subwoofer crossover unit possible. If you are intending to use normal bass speakers, a smart trick will solve this problem and kill two birds with one stone: the compound principle. With this arrangement, two bass speakers are screwed together in such a way that they are acoustically coupled via a small air volume. This produces a loudspeaker with two separate voice coils. Despite the relatively small volume in the chamber, very low frequency extremes are achieved. When connecting up the woofers, remember to transpose the polarity on one of them as otherwise the two speakers will be working against each other. In order to ensure the satellite speakers are perfectly matched to the subwoofers, they are vented, too. This enables the volume to be raised at lower frequency ranges. At around 3,000 Hz the ferrofluid-filled textile DTW 95 NG 8 Ohm takes over. A characteristic of this dome tweeter is the "smooth" high-range treatment. If more brilliant high-range frequency output is required, the DSM 25 FFL 8 Ohm with its metal cone can be substituted without altering the crossover unit.


The FILOU is a D'Appolito configuration designed as a shelf-mounted speaker, but thanks to its excellent bass reproduction, can also be free-standing. It is based on the vented cabinet principle. The bass to mid-range is covered by two WS 13 BF 8 Ohm speakers. The extremely small moving mass coupled with the powerful driver and the rounded overall concept of this 13cm driver makes it possible to use it as a mid-range unit. At about 2,600 Hz, the two mid-bass units working in parallel are reduced and the DT 94 8 Ohm dome tweeter linked up. The FILOU is characterised mainly by its powerful and accurate bass reproduction and, due to the high efficiency level, lively, bubbly music reproduction. Its excellent sound distribution characteristics contribute to spatial clarity and good positioning with music. Thanks to the relatively high efficiency rating coupled with good power handling capabilities, louder volume levels can be easily achieved with no sound distortion. As long as the overall cabinetvolume is retained, the unit can be built slightly wider and shorter (e.g. width: 230 mm, depth: 300 mm).


Well designed 2-way speakers with excellent mid-bass speakers and equally good tweeters can work wonders in terms of their spatial qualities and localisation. One of the reasons for this is certainly that the a large, absolutely critical frequency range (up to around 4,000 Hz) is covered by a single loudspeaker driver. In other words, there is only one soundsource and no possibility of interference or loss from an intermediate crossover. In addition, the narrow baffles in such speakers tend to have a positive effect on omnidirectional sound distribution and the intended related characteristics.
The SKYLINE is indeed a 3-way combination, but, in contrast to usual practice, with a very low cut-off frequency between the low- and mid- to low ranges (here around 300 Hz). This keeps the cone still, but the system still manages to produce sufficient low-range bass. In a sense, the SKYLINE is nothing more than a 2-way speaker with a subwoofer.
The WS 13 BF 8 Ohm is one of the few mid-range cone drivers, that produces a completely linear frequency response across the entire transmission range up to 5 KHz. If the SKYLINE is placed in a room with at least moderately good acoustics, the exact positioning of the instruments or voices is immediately noticeable. Even if the listener is not in the ideal central listening position between the speakers, the SKYLINEretains its precise positioning characteristics.

AK 14.20

Cover cap for midrange drivers which require an enclosed air volume of their own. For 10 cm, 13 cm and 17 cm midrange drivers. Half-round shape avoids resonances.

KM 80

Ring-shaped magnets for the compensation of the stray magnetic field (magnetic shielding). The ring has to be glued on the rear pole-plate (e. g. with Pattex), reducing the stray magnetic field to a minimun, allowing speakers positionings of 20 cm apart from TV or computer screens.Suitable for: AL 130 8 OHM; AL 130 A 8 OHM; AL 130 M 8 OHM; AL 170 8 OHM; AL 170 A 8 OHM; DMR 35 8 OHM; DSM 25 FFL 8 OHM; DTW 8.12 NG 8 OHM; DTW 95 NG 8 OHM; G 25 FFL 8 OHM; WS 13 BF 8 OHM

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