Jeff Macaulay didn't get into electronics until he was 18. Like most people of his generation he had acquired a large collection of records but had nothing decent to play them on. Because of lack of funds he decided to roll his own equipment. Jeff’s first project was based around the then new IC amp. Plessey's SL403D. This was a 3W/channel device. It lasted about 10seconds before issuing the traditional cloud of smoke! Being intrigued enough to try his hand again, he thus entered the world of audio electronics. At this time he was afflicted with a long term health problem which meant he had literally years to learn how things worked. Eventually he started to design his own circuitry and to have these published. Since then Mr. Macaulay has regularly contributed audio projects to a variety of journals. Even after all these years there are still fascinating audio problems to solve, and new articles to write!
One of the problems in traditional speakers concerns the off axis response of the tweeter. The off axis response of a speaker is determined, essentially, by its diameter and the wavelength of the...