[Paul Spencer]
Some of these terms will apply to other areas, but this glossary is specifically intended for the subwoofer section.
Please feel free to add to this list. If you find words in any of the articles in this section, add them even if you don't know what they mean.
Note: Individual words have their own wiki page and can be linked in any wiki page entry
* room gain: where a room has solid boundaries and is not open, it will provide bass boost below a certain point, determined by its dimensions.
* Shroeder frequency: this is where the acoustics of a room transition from modal to the geometric region. Above the Shroeder frequency (typically 200 Hz), sound travels as waves; below this their wavelength approaches the dimensions of the room and they form
standing waves where maxima and minima form
room modes which can be seen as peaks and dips in the frequency response.
* fb: this is the frequency at which a box has its F3, its tuning point
* F3: this is the frequency at which the frequency response drops by 3db
* fs: free air resonance - the frequency at which the driver has an impedance peak in free air; often a vented box will use this as the tuning point.
* Linkwitz Transform: a custom designed eq circuit which is designed to lower the F3, dial in the desired Q and remove the hump in the upper end of the bandwidth that can be added by using a box that is undersized. This is how many commercial subs achieve 20 Hz extension in a small box.
* Q factor: this is a number which represents damping; a sealed sub with a Q of 0.707 will have a known roll off and a size determined by its TS parameters; a Q of 0.5 is "critically damped" and is considered an amount of damping which gives a good transient response, although it is quite large.
