Rotating Woofer-Port and Cabinet Simulation

It is straightforward to extend our computational model to include the rotating woofer port and wooden cabinet enclosure as follows:

• In [191], it is mentioned that an AM ``throb'' is the main effect of the rotating woofer port. A modulated lowpass-filter cut-off frequency has been used for this purpose by others. Our measured data will be used to construct angle-dependent filtering in a manner analogous to that of the rotating horn, and this ``woofer filter'' runs in parallel with the rotating horn model.

• The Leslie cabinet multiply-reflects the sound emanating from the rotating horn. The first few early reflections are simply handled as additional sources in Fig.3.12. We can extend the impulse-response-component separation algorithm of §3.4.7 to the case of superimposed early reflections in the impulse response. (Preliminary results are promising.)

• To qualitatively simulate later, more reverberant reflections in the Leslie cabinet, we feed a portion of the rotating-horn and speaker-port signals to separate states of an artificial reverberator (see Chapter 2). This reverberator may be configured as a ``very small room'' corresponding to the dimensions and scattering characteristics of the Leslie cabinet, and details of the response may be calibrated using measurements of the impulse response of the Leslie cabinet. Finally, in order to emulate the natural spatial diversity of a radiating Leslie cabinet in a room, ``virtual cabinet vent outputs'' can be extracted from the model and fed into separate states of a room reverberator.

In summary, we may use multiple interpolating write-pointers to individually simulate the early cabinet reflections, and a ``Leslie cabinet'' reverberator for handling later reflections more statistically.

---

Order a Hardcopy of Physical Audio Signal Processing

Previous: Separating Horn Output from Base Leakage
Next: Miscellaneous Effects

---

written by Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.