Tower Speaker Reviews

All measurements shown were taken at a distance of one meter with the speaker grilles removed. The grilles did not roll off the high-frequency response progressively, but rather put ripples in the response, making it less smooth above about 2kHz. With the grilles in place, the most pronounced ripple dipped to –3dB at 4kHz.

The LR5's sealed enclosure was tuned to approximately 32Hz and its sensitivity measured 85dB/W/m. The minimum impedance was 2.97ohms at 70Hz; I would rate the nominal impedance at about 5ohms. The impedance magnitude never dipped below 5ohms above 170Hz; the speaker should be a relatively easy load to drive, as long as the amplifier is capable of handling loads at or slightly below 4ohms. The LR5's relatively low sensitivity should also be taken into account; really low-powered amplifiers need not apply. I would consider 100Wpc a minimum for an average-sized room at typical film playback levels; 200Wpc would not be out of line for larger rooms and challenging playback levels.

The frequency response of the LR5 is shown in Fig.1 (violet). This is the pseudo-anechoic response averaged across a 30° forward angle (+/-15°) in the horizontal, combined with the nearfield responses of the woofers. The LR5's averaged measured response is very smooth and flat—in fact, it's one of the best we have ever measured. A gentle plateau centered at about 1kHz could give the speaker a slightly forward character, but the elevation is small and the effect should be subtle. The off-axis response follows the on-axis result very closely up to about 6kHz, then rolls off slowly and gently. The speaker's effective lower limit (–10dB) is about 32Hz relative to its output at 100Hz.

Fig.1: Aerial Acoustics LR5, pseudo-anechoic horizontal response at 45° (red) and 60° (blue) relative to tweeter axis, measured at tweeter height.

The vertical responses in Fig.2 are good, particularly on or slightly below the tweeter axis. The dip at 15° above the tweeter centered at 3kHz suggests that you should listen to this speaker sitting down. The small tilt-back provided by the matching stands should eliminate this problem for any reasonable seated ear height.

Fig.2: Aerial Acoustics LR5, pseudo-anechoic vertical response at +15° (red) and –15° (blue) above and below tweeter axis.

The CC5 center speaker's characteristics are very similar to the LR5's. The center's impedance, sensitivity, cabinet tuning, and effective bass limit are essentially the same. The CC5's horizontal front response, derived and averaged as for the LR5, is shown in Fig.3 (violet). The on-axis average is very nearly as flat, as is the LR5's. The off-axis response is not as pristine as the LR5's, but the CC5's dips here are well-controlled, and the overall result is excellent for a horizontally configured center channel. Once again, the only type of driver configuration we have seen to date that will produce a respectable set of far-off-axis measurements in a horizontal center speaker is one in which the tweeter and midrange(s) are aligned vertically, as they are here.

Fig.3: Aerial Acoustics CC5, pseudo-anechoic horizontal response at 45° (red) and 60° (blue) relative to directly forward on the tweeter axis.

Nor is there much amiss in the CC5's vertical off-axis measurements (Fig.4), although, as with the LR5, you should listen at or just below the tweeter axis.

Fig.4: Aerial Acoustics CC5, pseudo-anechoic vertical response at +15° (red) and –15° (blue) relative to directly forward on the tweeter axis.

The rear-panel controls of the LR5 and CC5 affect the speakers' responses by a maximum of +/-1–2dB. The results shown in the curves presented here were taken with the controls set to their minimum, counterclockwise positions, which produced the flattest, smoothest responses.

These fine measurement results from two outstandingly well-engineered speakers are completely consistent with MF's enthusiastic listening results.—Thomas J. Norton