When developing the VIB 170 BP, the main objective was to create a fairly compact column speaker with an extremely deep bass output, which is capable of reproducing the deepest regions of the audible frequencyspectrum. A common bassreflex housing can reach this aim only partly. Therefore, a very rare type of cabinet has been realized, at least when looking at fullrange-loudspeakers: A double-sided ventilated bandpass. In this layout, a woofer which is mounted on an inner separation wall, is operating on two bassreflex-tuned volumes, a larger one and a smaller one. By means of a subtle tuning of the two cavities, a linear frequency response down to 35 Hz (-3 dB) could be obtained with a housing of only 75 liters. Not until then, the sound pressure level starts to drop rather quickly. The lower cut-off frequency (-10 dB) is located around 24 Hz. Some very large bassreflex speakers are capable of reaching similar cut-off frequencies, but the SPL already starts dropping at much higher frequencies. This is why those kinds of loudspeakers sound less voluminous and deep.
Due to the exceptionally high excursion limit of the TIW 200 XS - 8 Ohm, the maximum obtainable sound pressure level is already physically tangible and more than sufficient even for large listening rooms.
Another design feature of the VIB 170 BP is the wide frequency range of the AL 170 - 8 Ohm. By means of a sophisticated crossover set-up, we have been successful in taking advantage of the outstanding acoustical properties of the AL 170 - 8 Ohm from 100 Hz up to 8 kHz. Not until then, the established ceramic tweeter KE 25 SC - 8 Ohm takes over to render the uppermost 1-2 octaves. By this layout, the widest part of the audible spectrum is reproduced by only one driver, which helps acoustical imaging and leads to a strikingly precise stage arrangement.
So how does such a fancy build sound like? Like the best of both worlds: The spatial precision and dynamic of a good fullrange driver, paired with the brute bass power of the TIW 200 XS - 8 Ohm in the bandpass cabinetand the silky, delicate treble of the excellent ceramic calotte.
At the same time, the whole loudspeaker plays all of a piece and acts absolutely neutral in terms of tonality. Moreover, not a hint of the often-cited "sponginess" of the bandpass principle could be observed, far from it: the low tones sound firm and massive, fully grown, thus becoming to many a much larger boxes.
All around, the VIB 170 BP can be said to be a felicitous loudspeaker, which combines the advantages of a high class fullrange speaker, a multiple way box and a strong subwoofer in one slim cabinet.
TIP: The low frequency part of the VIB 170 BP, without the tweeter and the midwoofer, and without the crossover network, makes a superb subwoofer to complement even large home cinema systems, single- or pairwise.
