This is the second part of a series of four short posts about the speaker's sound dispersion and its major influence on the sound experience in the living room.

Frequency measurements of SA2K, directly from the front and gradually out to 60 degrees from the axis. One of the few weaknesses of SA2K was its directivity. The speaker loses sound pressure between 1000 and 3000 Hz as you gradually move away from the speaker's axis and out to the side.

The sound dispersion of a loudspeaker results from the relationship between the wavelength of the given frequency reproduced by the loudspeaker, the geometry of the loudspeaker cabinet, the physical design of the loudspeaker units, the position of the crossover filter(s) and their edge steepness(es). It is, in other words, a complex quantity.

This means that deep bass tones - which have long wavelengths - are radiated in a spherical shape around the entire speaker. So it doesn't matter if you're sitting in front of, behind, above or below a speaker if you want to hear a deep tone. The sound is radiated evenly all around.

It's a different story when it comes to the highest and finest notes of sound, where the wavelength is shorter than the diameter of the membrane that reproduces them. Here, the physics of the speaker means that the sound is emitted almost like a laser beam, where you'd rather be sitting directly inside the beam to hear the sound.

All tones between the deepest (spherical) and highest ("laser beams") are radiated with a greater or lesser directivity. A loudspeaker unit becomes progressively more directional the higher the frequency it is required to reproduce, and it can generally be said that the larger the loudspeaker unit, the poorer its sound dispersion at the high frequencies.

Better than its predecessor. With its waveguide on the tweeter, the Q113 Evolution has better control of its directivity.

It's acoustic craftsmanship

Conversations about Loudspeaker Q113 are sometimes about topics such as active speakers, electronic crossovers, etc., and whether we should put some electronics in the speaker and take the project to the next level of technology.

I rarely disagree with people who advocate active speakers, and I certainly don't think you should be blind to a future where built-in electronics can make everyone's speakers a whole class better. But I also have a point for the technology-hungry, because several of the things we work on in Speaker Q113 can in no way be fixed with a batch of electronics.

The sound dispersion of the speaker cannot suddenly and magically occur if it is not already in the speaker's DNA. The same goes for edge reflections and many of the other things we've worked on here. There is no technological cure that can reset the need to do the job properly, master the basic disciplines, perform the tedious routines and be meticulous.

Only then will it be interesting to reap the rewards of a higher level of technology. By the way, I expect a passive Q113 to sound somewhat better than many of the active speakers on the market, when just put together with a good amplifier. But let it be said: an active Q113 could be a wild ride! Well, the craftsmanship still comes first.

Want to know more?

I recommend you read this white paper by American Earl Geddes. In the paper he concludes that the acoustic challenges of loudspeakers can only be solved acoustically, not in any other way. That's really water on my personal do-it-yourself-first mill.

Earl Geddes also concludes that if you require constant directivity from a 2-way speaker, there is no way around a waveguide (or something similar) for the tweeter, combined with a low crossover frequency. That's exactly what we've come up with in the story of Speaker Q113. Read more at Earl Geddes. These are good vitamins for the inquisitive.