ABSTRACT
Before we leap into the fascinating world of time domain filters, we will take a quick look at some of the physical methods used for delay compensation. These are shown in two-way loudspeaker form in Figure 10.5. Clearly it is best to mount the drive units as close together vertically as physically possible to minimise the path difference, but loudspeaker manufacturers do not appear to always do this, possibly because of the aesthetic drawbacks of two drive units that look “crammed together.” Possibilities are:
1. Tilting the front baffle. This compensates the delay for a listener on the horizontal axis. The problem is that the drive units will have been designed for optimal performance on the drive-unit axis, and now you are listening to off-axis output. This method is relatively cheap to manufacture, but people are used to having the front of a loudspeaker facing them directly, and as a result there is a general feeling that it looks wrong. It may compensate for the horizontal offsets (though for it to work with a three-way system you will have to have the three acoustic centres in a straight line, which may not be easy to arrange), but only reduces the effective vertical offsets slightly.
