Princeton University  

 

Loudspeaker Directivity

An Ongoing Experimental Survey

Research Sponsored by the Sony Corporation of America

 

Here at the 3D3A Lab we have a well invested curiosity about Loudspeaker Directivity, and so we have been collecting data on individual speakers tested within our Anechoic Chamber, we find it that learning more about Loudspeaker Directivity is essential to improving the 3D Audio experience.

What is Loudspeaker Directivity?

Loudspeaker Directivity is the extent to which loudspeakers beam the sound towards the listener instead of broadcasting it in all directions around the room. Loudspeaker Directivity is the single most important loudspeaker property for 3D audio with crosstalk cancellation (XTC), since room reflections directly degrade the level of crosstalk cancellation. There is a very high correlation between loudspeakers with high directivity and high XTC levels.

What is the Directivity Index?

The Directivity Index is defined as the difference between the on-axis curve and the sound power curve, which means that the higher the "DI" value, the higher the degree to which the speaker's sound has a forward bias - directivity. For example, a DI of 0 dB shows that the speaker's sound radiation is omnidirectional - Radiates in every direction. The larger the DI, the more directional the loudspeaker will be towards the reference axis (our 0° Frequency Response).

Below we have ranked all the speakers that have currently been measured here at the lab by their Horizontal Directivity Index. With the first one being the most "directive" and the rest in descending order. The speakers in the archive section are NOT ranked in this way.

Sanders Monitor

Manufacturer website not available

Directivity Ratings and Data

Horizontal directivity index: 8.29 dB
Vertical directivity index: 9.32 dB
Directivity index: 15.2 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Sanders Model 11

Manufacturer website

Directivity Ratings and Data

Horizontal directivity index: 7.50 dB
Vertical directivity index: N/A
Directivity index: N/A

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity

 

Unavailable

King's Audio

Manufacturer website not available

Directivity Ratings and Data

Horizontal directivity index: 6.22 dB
Vertical directivity index: 8.58 dB
Directivity index: 12.63 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Fisher STE-720

Manufacturer website not available

Directivity Ratings and Data

Horizontal directivity index: 6.16 dB
Vertical directivity index: 6.59 dB
Directivity index: 8.29 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

KEF LS50

Manufacturer website

Directivity Ratings and Data

Horizontal directivity index: 4.25 dB
Vertical directivity index: 4.06 dB
Directivity index: 5.28 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Ascend CBM-170

Manufacturer website

Directivity Ratings and Data

Horizontal directivity index: 4.21 dB
Vertical directivity index: 4.72 dB
Directivity index: 6.17 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Dynaudio Xeo 3

Manufacturer website

Directivity Ratings and Data

Horizontal directivity index: 4.18 dB
Vertical directivity index: 4.14 dB
Directivity index: 6.02 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Monsoon MM-1000

Manufacturer website not available

Directivity Ratings and Data

Horizontal directivity index: 4.06 dB
Vertical directivity index: 6.45 dB
Directivity index: 8.10 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Polk Audio 5JR

Manufacturer website

Directivity Ratings and Data

Horizontal directivity index: 3.56 dB
Vertical directivity index: 3.35 dB
Directivity index:4.83 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Gradient Helsinki 1.5

Manufacturer website

Directivity Ratings and Data

Horizontal directivity index: 3.42 dB
Vertical directivity index: 5.99 dB
Directivity index: 5.49 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

Monsoon MM-700

Manufacturer website not available

Directivity Ratings and Data

Horizontal directivity index: 2.75 dB
Vertical directivity index: 4.52 dB
Directivity index: 6.98 dB

View directivity index plots
Download directivity data

Horizontal Directivity


Click on the plot for more

Vertical Directivity


Click on the plot for more

ARCHIVES
Horizontal Directivity
Vertical Directivity

1. Sanders M11 (Electrostatic)

 

Unavailable

2. Quad ESL 57 (Electrostatic)

 

3. Janzen ZA2.1 (hybrid electrostatic)

 

4. GedLee Nathan (Waveguide/Dynamic)

 

5. Tannoy Definition DC6i (Concentric/Dynamic)

 

6. Manger Sidekick (Single bending wave transducer)

 

7. Genelec 8030a (Dynamic)

 

8. Spendor SA1 (Dynamic)

 

9. Ascend Acoustics CBM-170 (Dynamic)

 

 

Notes on the measurements: The directivity measurements were carried out in the anechoic chamber of the 3D3A Lab using a B&K Microphone Type 4189 placed 1.6 m ± 0.1 m from the loudspeaker being tested, for desktop speakers we used a distance of 0.8 m ± 0.05 m, and at the same height as that of the center of the loudspeaker's tweeter. The loudspeaker was placed on a rotation stage, which was turned by increments of 5 degrees.

The data reduction and plotting were carried out using custom software developed at the 3D3A Lab. By default, we used a 1/24 Ocatve Smoothing value applied to our frequency response curves prior to plotting the data. For some speakers only Horizontal data was taken, this did not affect their ranking as we used the Horizontal Directivity Index as our rating scale. The ripples that are seen at lower frequencies (around 100 Hz) are due to the nature of our Anechoic Chamber here at the 3D3A Lab.

These measurements have been taken by Lukasz Mosakowski, Tim Matchen, Joe Tylka, Rahulram Sridhar, Tony Jin, and Gianfranco Colombi under the direction of Prof. Choueiri.

If you know of any loudspeakers that may have particularly high directivity please inform the 3D3A Lab. We will try to acquire these loudspeakers and measure their directivity.