Tower Speaker Reviews

All measurements were taken with the speakers' grilles removed and, except as noted, with the tweeter-level controls at 0dB and the boundary control (C30) in the stand-mounted position. For logistical reasons, the measured samples were different from the samples used in the listening tests.

The impedance of the F30 indicates that its ported cabinet is tuned to about 23Hz, with a minimum impedance of 2.9ohms at 540Hz. We would rate the nominal impedance at about 5ohms, with the impedance magnitude remaining just below 4ohms from 45 to 112Hz. Any well-designed amp capable of working into a 4ohms load should have no trouble driving the speaker. My experience with the modestly rated Outlaw receiver (though in a small room) backs this up. The F30's sensitivity measured 85dB/W/m.

The pseudo-anechoic response of the F30 at tweeter height, averaged over a 30° forward horizontal angle and combined with the nearfield responses of the woofer and port, is shown in Fig.1 (violet). A true anechoically flat speaker measured in this way normally exhibits a slight positive bump in its response curve around or just below 100Hz. The fact that the F30 does not suggests that its bass response has been tailored to compensate for normal room gain. The bass holds up strongly to 30Hz (about -6dB; -10dB at 26Hz). The overall response is remarkably smooth and flat out to 20kHz, with only a modest dip of 1-2dB between 1.5kHz and 4kHz.

Moving off-axis horizontally (Fig.1), the inevitable high-frequency rolloff is very well controlled, even at 60° (blue). Smooth off-axis response is one of Revel's primary design goals; the F30 measures up to that standard.

Fig.1

Fig.2 shows the same averaged horizontal front response (violet), plus the vertical responses taken at +15° (red) and -15° (blue) relative to the tweeter. The suckout centered at 3kHz in the +15° response, and the smaller dip at 4.3kHz at -15°, suggest that the speaker will sound best when the listener's ear height is on or near the tweeter axis. I would avoid conducting a serious audition of the F30 while standing up.

Fig.2

The Revel C30 center-channel's cabinet is tuned to about 46Hz, with a minimum impedance of 2.8ohms at 435Hz. A reasonable rating for the nominal impedance would be 4ohms, though the speaker dips slightly below that value from 90 to 650Hz. The phase of the impedance is highly capacitive from 50 to 70Hz, but the relatively high impedance magnitude in this region (greater than 5ohms) and the rapidly falling input (when the speaker is highpass-filtered for use with a subwoofer) at these frequencies should make this a non-problem. The sensitivity measured approximately 89dB/ W/m above 500Hz.

The measured front horizontal response of the C30 center-channel, taken on the tweeter axis and averaged in the same manner as described above for the F30, is shown in Fig.3 (violet). The effective bass extension is approximately 50Hz (-10dB), but this comes with a rather significant dropoff in response across most of the bass region. Using the output level at 500Hz as the reference point, the response is down by nearly 8dB at 160Hz, recovers a bit at 80Hz, then drops off at lower frequencies, as might be expected. The response tapering could be deliberate, though it looks as if the woofers (which operate below 280Hz) are operating at too low a level. I was not overly conscious of this response anomaly in the listening tests, though it may account for both the slight leanness I observed in the system and the fact that the Ultima Voice center-channel, when substituted into the system, produced a noticeably warmer, fuller sound.

Fig.3

The top-of-monitor setting of the C30's boundary control actually increased the speaker's output by 1-2dB in the 80-400Hz region. The C30's response will actually be slightly flatter with the control in this position. (I didn't audition this setting; the measurements were, as always, made after the listening tests; and intuitively, this setting should reduce the mid- and upper-bass response to compensate for the boundary re-inforcement provided by the nearby cabinet and screen.) The flush-mounted setting produced virtually the same results as the top-of-monitor, except for about 1dB less output from 300 to 400Hz.

The off-axis responses (Fig.3), while not as smoothly matched to the on-axis curves as with the F30, are still remarkably linear for a horizontally configured center-channel. The measurements verify the superiority of a 3-way center-channel over the usual 2-way, woofer-tweeter-woofer design; there is no midrange or low-treble suckout in the response, even at an off-axis angle of 60° (blue).

The changes in response as we move above and below the tweeter axis (Fig.4) indicate that the response will be best at or slightly below the tweeter axis. If the C30 is mounted below a projection screen and well below ear height, it should be tilted up slightly (the optional stand does this automatically)—or mounted upside down! If mounted atop a big-screen TV, it could be tilted down slightly, but since the response at 15° below the tweeter axis is still very good, that may not be necessary.

Fig.4

The action of the tweeter-level controls on both the F30 and the C30 were also measured at the +1 and -1dB positions. The controls operated above 2kHz, and, within a tolerance of about 0.2dB, provided the specified boost and cut.

Apart from the unusual dip in the C30's response through the bass and lower midrange, the performance figures turned in by the F30 and C30 are hard to fault.—TJN