Effect of Loudspeaker Directivity Compared with In-room Measurements

We know loudspeakers sound different, we also know they can measure different – both in the lab, and in-room. But what if they seem to measure quite similar – and still sound very different. Is there something hidden in those measurements, that we missed?

Installing the new speakers

A living room with no acoustic treatment other than thin panels in the ceiling, quite lively acoustically. We compare some good, traditional speakers to the new full-range controlled directivity type.

After adjustments for level and bass-system integration, we can sit down and listen. And it sounds different. But when we look at the measured frequency responses, they are quite similar – they should sound the same?

Frequency response at listening position – green trad speaker, brown new Cd speaker
1/12 smoothing, so we can see what is going on – green trad speaker, brown new CD speaker
Separated traces – green trad speaker, purple new CD speaker

More listening

The new controlled directivity speakers gives a different presentation, where soundstage and the instruments within are perceived as much more precise and accurate, while they also maintain or improve their natural size. Clarity and definition is much better.

These are the first initial impressions. This was set up for demo purpose in a private home, for the owner to try out over some period of time in the coming days.

We go deeper into what has been measured

If we look at the decay profile, we see that the speakers actually do measure different – the controlled directivity speaker has more even and smoother decay, and early decay is more attenuated – trad speaker on left:

Decay 40ms profiles – trad speaker left, new CD speaker right
Decay 40ms 1/3 smoothing – trad speaker left, new CD speaker right

Ignore below 100Hz, as there is a lot of noise below 30Hz in some of the measurements, and we also did some small adjustments to the bass-system, crossover is 120Hz.

Spectrum plot reveals same behavior – trad speaker on left:

Spectrum – trad speaker left, new CD speaker right

Update: Added spectrum plot with 60dB scale:

Spectrum 60dB scale – trad speaker left, CD speaker right

The controlled directivity speaker has more frequency linear decay, it is smoother with less pronounced resonances, and early decay is faster.

We can see differences in group delay, especially in the low midrange – trad speaker on left:

Group delay – trad speaker left, new CD speaker right

And here is how those controlled directivity speakers measure in one of my rooms, actually the “bad room” – with same scaling on graphs:

F205 in the media-room, decay 40ms and spectrum

Quite a huge difference, but the sound in this room compared to the previous more live one has much of the same character – open, defined, large soundstage. Which shows that it is difficult to predict exactly how something sounds, looking at measurements alone, because how it looks on a graph does not necessarily correlate well to how we hear.

Conclusions

  • Frequency response alone does not fully describe the sound we hear
  • Analyzing decay profile reveals differences attributed to speaker radiation patterns
  • Measurements can be used to compare – which one of 2 is better
  • Controlled and more narrow directivity distributes the sound better across the whole room, and greatly improves soundstage accuracy and size
  • Controlled directivity reduces negative effects of less than perfect room acoustics

Comments or want to discuss this article? Then you can use the discussion thread on the forum: https://www.kvalsvoll.com/blog/kvalsvoll-design-audio-forum/topic/effect-of-loudspeaker-directivity-compared-with-in-room-measurements-2/

Update: Several new graph pictures posted in the forum thread.