These application examples use the TC15 HE with both voice coils in series. Power applied is 800 Wrms which is the maximum continuous power these drivers can handle. Peak power is in excess of 1600 Wrms.
The red curve is the TC15HE in a 5 cubic ft sealed box. Xmax is never reached for this combination. Equalizing will be necessary to obtain a flat response although one may observe that room gain needs to be taken into account for any given installation.
The yellow curve is the TC15HE in a 5 cubic ft vented box. A fourth order alignment, known to unload below the port frequency as will be shown in the Xmax plots below.
The magenta curve is the TC15HE in a 5 cubic ft vented box. A second order high pass filter is added, tuned at 20 Hz with a Q of 1.2. The result is protection for the driver below the tuning frequency (20 Hz) and a increase in the low frequency response without exceeding the maximum excursion of the driver.
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Above the acoustic on axis response when driven by 800 Wrms, both voice coils used. The graph below shows Xmax for this particular set up. Xmax for this driver is slightly above 23 mm, one way. Mechanical travel is about 28 mm. Observe the unloading below the port frequency for the TC15HE in 5 Cft vented without second order high pass filter.
Second application examples use the TC15 HE with both voice coils in series. Power applied is 800 Wrms which is the maximum continuous power these drivers can handle. Peak power is in excess of 1600 Wrms. Box size is 8 cubic ft, tuned to 20 Hz.
The green curve is the TC15HE in an 8 cubic ft sealed box. Xmax is never reached for this combination. Equalizing will be necessary to obtain a flat response although one may observe that room gain needs to be taken into account for any given installation.
The red curve is the TC15HE in an 8 cubic ft vented box. A fourth order alignment, known to unload below the port frequency as will be shown in the Xmax plots below.
The magenta curve is the TC15HE in an 8 cubic ft vented box. A second order high pass filter is added, tuned at 19 Hz with a Q of 1.2. The result is protection for the driver below the tuning frequency (20 Hz) and a increase in the low frequency response without exceeding the maximum excursion of the driver.
Above the acoustic on axis response when driven by 800 Wrms, both voice coils used. The graph below shows Xmax for this particular set up. Xmax for this driver is slightly above 23 mm, one way. Mechanical travel is about 28 mm. Observe the unloading below the port frequency for the TC15HE in 8Cft vented without second order high pass filter.
Building smaller boxes than 5 Cft with EBS alignment is often unpractical as the port length becomes prohibitive if one wants to avoid port turbulence and associated noise. Often a passive radiator or PR is the solution. The graphs below show one TC15HE in a 20 inch cube with 2 passive radiators. Internal volume is approximately 3.175 Cft assuming a wall thickness of minimal 1 inch. The passive radiator used in this model has a moving mass of 1400 grams, Sd is 0.083 m2, Xmax = 50 mm, Vas = 685 l and Cm is 700 uM. Two PR's are used at opposite sides to be able to "balance" the box. The PR system has active EQ (20 Hz HP2 with Q of 2) and is compared with the 6th order 5 Cft vented and 8 Cft vented boxes described in the preceeding paragraphs.
A fourth order 80 Hz low pass filter is used as in the other illustrations. The red curve is the passive radiator system and it can be seen that it compares favorably with the much larger 5 Cft vented box with active EQ. Similar response, much smaller box, no port noise, no organ pipe resonances. The Xmax plot is shown below. The Xmax of the PR system is actually more optimal than the excursion of the 5 Cft vented system. One and other could be improved by tweaking the HP2 filter's frequency
The graphs below show a comparison between a TC15HE in 3.2 Cft vented, tuned at 20 Hz, and the same box with dual 15" PR. Both systems are actively assisted with a HP2 filter with Q of 2.
Notice the port "organ pipe" resonance at 150 Hz for the vented system. There's a LP4 at 80 Hz in this simulation, this puts the organ resonance 20 dB down. The plot below shows the Xmax for both systems.
Applied power in both cases was 800 Wrms, both voice coils in series.
Copyright (c) 1997-2000, by Rudi A. Blondia, ALL RIGHTS RESERVED. Last update March 23, 2000.