CLF Viewer – On-Line CLF Database
By Pat Brown
The CLF website now has an on-line database of CLF loudspeaker data. This article also discusses a new feature that has been added to CLF Viewer.
The CLF website now has an on-line database of CLF loudspeaker data. This will facilitate locating data for a particular model or type of loudspeaker. The database can be found at
http://www.clfgroup.org/files/index.php
Hint: Windows should configure the CLF Viewer as the default application for .CF1 and .CF2 files. This will allow on-line viewing of the data. This can be configured manually in Windows XP at:
Start/Control Panel/Folder Options/File Types
A New Option in the CLF Viewer
A new feature has been added to the CLFViewer. The polars can now be highlighted with markers showing the -6dB angles relative to on-axis. These can aid the observer in understanding how the beamwidth specification is determined. In cases where they are different on each side of the axial response (a common occurrence with some designs) the CLF Viewer takes the smaller of the two angles and doubles it to get the beamwidth.
The Bigger Picture
Most loudspeaker specifications are frequency-dependent. They are often displayed on two-dimensional plots with frequency as the independent variable. Such plots can be misleading for some specifications. A good example is the plot of beamwidth vs. frequency. Figure 1 shows this plot for the vertical radiation of a popular loudspeaker. Note the discontinuity at 500Hz. The polar plot for this 1/3-octave band is also shown, with the new -6dB option used to highlight the beamwidth limits.
When a loudspeaker’s response changes slowly over a large angle, a very small level change can have a profound effect on the beamwidth. This is because the software is trying to describe with one number something that is gradually changing. This can result in discontinuities in 2D plots. It must be remembered that modeling programs use the full-spherical data for calculations, not the 2D plots, and that the 2D plots represent ways of simplifying the description of very complex behavior. Such discontinuities can be further investigated by looking at the adjacent octave bands and the spherical balloons. Doing so may reveal that the coverage is actually very similar to that of the adjacent 1/3-octave bands. pb
