Originally Posted by underminded999
So I went through the Speaker Forum and could not find any info. I was going to post this there, but it's really better suited here.
What are the pros and cons between the two? Obviously, there is a sound difference.
Horn-loaded speakers are also called "waveguide" speakers. Waveguide being new-speak for horn.
Your typical Dome speaker is mounted on a flat plate, which acts as a simple waveguide. It restricts the directivity of the dome to 180 degrees at low frequencies. At higher frequencies the side of the dome itself provides some additional directivity because the speaker's diaphragm diameter starts approaching 1/2 wavelength and cancellation reduces off-axis response.
Most horn speakers that are midranges or tweeters are composed of a compression driver and a waveguide. A compression driver is composed of a magnet and diaphragm assembly that looks quite a bit like a dome tweeter, but that is covered by a device called a phasing plug that gathers sound from all over the diaphragm and collects it into a tubular passage. The waveguide receives sound from the compression drivers tubular passage and guides the sound out into the room in ways that depend on the shape of the waveguide.
The waveguide helps match the acoustic impedance of the compression driver which produces highly concentrated sound, to the impedance of the room which receives dispersed sound. It's a kind of acoustic transformer.
Dome tweeters also produce concentrated sound but they make no effort to match the impedance of their diaphragm to that of the room so they are far less efficent.
There is a kind of intermediate kind of speaker that places a waveguide in front of a dome or cone speaker. While not quite as efficient as using a compression driver, the waveguide can have beneficial effects.
The big problem with waveguides is that their size is determined by the wavelength of the lowest frequency they handle so they have to be very large to be efficient at low frequencies.
The main benefit of the waveguide is that it can control the directivity of the speaker and provide many options. Wavegudes can control directivity to be wide, narrow, and different in the vertical and horizontal orientation. One benefit of controlling the directivity of a speaker is that you can use this control to prevent or reduce sound falling where it shouldn't and causing undesirable reflections.
If you use a dome or cone speaker as your baseline, the waveguide speakers have the advantages of better controlled directivity and the opportunity for greater efficiency.