D’Appolito: superior spatiality in stereo music reproduction?

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D’Appolito: Voodoo or genius?

Speaker design according to the theories of Joe D’Appolito promises superior spatiality in stereo music reproduction and is practically impossible to realize. Aural Sculptures come closer to the ideal than ever before.

A D’Appolito configuration in speaker enclosures is the configuration of two woofers vertically in a line around a tweeter. When certain other criteria are met, this method succeeds in producing a particularly stable stereo sound, which gives the listener an exceptionally three-dimensional listening experience.

Unfortunately, implementing the physical configuration of the theoretically perfect D’Appolito in speaker enclosures is very difficult to achieve in practice:
The usual crossover frequencies to the tweeter of between 1,500 and 3,000 Hertz would require a maximum distance between the center axes of the surrounding woofers of 15 or 7.5 cm. This design is not feasible for conventional loud speaker drivers and the result here is always an approximation in the best case.

3BE Product Highlights featured article Dappolito driver arrangement 2
This is certainly not a speaker enclosure according to D’Appolito. The rest is probably a matter of taste.

Important criteria for brilliant sound

In fact, two woofers can be found in a configuration above or below a tweeter in many high-quality speaker enclosures as well as other less high-quality ones. However, here it is not appropriate to speak of a “D’Appolito configuration”. The crossover frequencies are too high overall and the distances between the woofers are sometimes ridiculously large. Moreover, the two woofers are often controlled differently, e.g. by using one of the two woofers only for low bass amplification.
Also the theoretically correct design of the crossover is – at least in low-budget designs – extremely rare due to the relatively large number of high-quality components that are required. The experience of many listeners who mistakenly associate the D’Appolito principle with combinations such as this is therefore disappointing.

3BE Product Highlights featured article on Dappolito driver arrangement 1
Aural Sculptures speaker configuration – here a longitudinal section through the front section.

The multi-faceted sound of Aural Sculptures

We were able to achieve a comparatively rare approximation of a true D’Appolito speaker during the Aural Sculptures developmental phase. The construction distance between the woofers and the crossover frequency from the identically driven woofers to the tweeter are both extremely low. Together with the advantages offered by the shape of the enclosure and a special crossover design, this combination actually provides an almost tangible three-dimensional configuration of musical instruments and voices. The obvious minimization of so-called masking effects that accompanies this was even more fascinating to our test listeners. An Aural Sculpture allows you to discover the finest details and modulations of individual musical instruments or vocals, even in polyphonic and rich soundscapes. It’s no wonder our listeners demand more and more spectacular “music” over the course of the sessions…

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Bernd Marsch
Bernd Marsch
Bernd is a graduate engineer with an additional long-time career in business controlling and managing director plus founder of 3BE. Music has always been his passion, and now he is in the fortunate position to pump up the volume with professional excuse. At 3BE, Bernd cares for general management and quality of sound.