Advent Legacy III Loudspeaker System

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The Advent Legacy III is a two- way floor-standing speaker system using a 10-inch woofer and a 1-inch soft-dome tweeter with magnetic-fluid damping. The woofer is unusual in having a dual voice coil that enables the system impedance to be set at either 6 or 8 ohms by means of a toggle switch on the back of the cabinet near the input terminals.

The manufacturer recommends using the 6-ohm setting when the amplifier is driving a single pair of speakers, since that will deliver the system’s maximum sensitivity (efficiency). If two or more pairs of speakers are driven in parallel, as they might be in a multiroom installation, for example, the 8-ohm setting lightens the load on the amplifier.

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The Legacy III’s cabinet is made of ¾” particle board covered with black textured vinyl, with a solid pecan top plate and base trim. The front is covered by a removable black cloth grille. The woofer, operating in a sealed enclosure, is at the midpoint of the front grille, with the tweeter above it, near the top of the front panel. The input connectors, spring clips de signed to accept only wire ends, are recessed into the rear panel, together with the impedance switch.

Advent’s specifications for the Legacy III include a bandwidth of 40 Hz to 23 kHz, sensitivity (6-ohm setting) of 90 dB sound-pressure level (SPL) at 1 meter with a 2.83-volt input, and a crossover frequency of 2.5 kHz. The woofer’s resonant frequency is given as 50Hz, ±5Hz.

Our room-response measurements showed relatively flat output from 100 Hz to about 1 kHz and another flat range from 1 to 20 kHz at a 4-dB lower level. The close-miked woofer response was flat within I dB from 55 to 170 Hz, sloping down gently above that frequency to —3.5 dB at 800 Hz. Below 60Hz, its response fell off at 12 dB per octave, to —5 dB at 40 Hz and —9 dB at 30 Hz.

Close-miked response measurements of a 10-inch cone are invalid above a few hundred hertz, where its dimensions become comparable to the wavelength of the radiated sound. It was nonetheless possible to splice the close-miked and room-response measurements to form a believable composite response curve. It showed relatively uniform output (2.5 dB overall variation) from 50 Hz to 1 kHz, where there was an abrupt downward step of 4 dB, and a ±2-dB variation from 1.2 to 20 kHz. The tweeter’s horizontal dispersion over a 45-degree angle was good, with on- and off-axis outputs diverging by about 2 dB at 5 kHz, 4.5 dB at 10 kHz, and 16 dB at 20 kHz, which is reasonable for a 1-inch dome tweeter.

We also made a number of quasi anechoic response measurements, using the MLS (maximum-length sequence) program of the Audio Precision test system. These showed the abrupt drop in output above 1 kHz, with an amplitude of 3 to 6 dB, that appeared in the room curves, but did not match their smoothness at higher frequencies.

The system’s sensitivity varied from a high 92 dB to a rather low 86 dB, depending on the setting of the impedance switch. Our tests revealed that the shape of the impedance curve altered dramatically between the two switch settings. The shape of the nominally 6-ohm impedance curve was like that of many speakers, with a bass- resonance peak of 23 ohms at 48 Hz and a broad minimum of less than 4.6 ohms between 100 and 200 Hz. There was a broad rise to 14 ohms at 1.5 kHz and a drop to just under 6 ohms at 20 kHz. In contrast, the 8-ohm setting gave a much more uniform curve, varying between 7 and 13 ohms over the full audio range.

It is hard to generalize about the audible effects of these differences, except to note that in some unusual cases the combined effect of an amplifier’s internal impedance and the speaker-cable resistance can imprint the shape of a speaker’s impedance curve on the system’s frequency response, for better or worse. From that standpoint, the more uniform impedance with the 8-ohm setting would seem to be preferable.

We measured woofer distortion at an input of 4.5 volts (equivalent to a 90-dB SPL at the lower sensitivity). From a maximum of 9 percent at 20 Hz, the distortion dropped to 1.5 percent at 35 Hz and remained between there and 2 percent up to 900 Hz.

The woofer absorbed a single-cycle 1-kHz burst input of 550 watts before the driving amplifier overloaded, with out audible complaint from the speaker. At 100 Hz, the cone bottomed noisily (but without damage) at a 1,000-watt input, and at 10 kHz, the amplifier reached its limit of 1,050 watts into the impedance at that frequency without evidence of distress to the speaker.

But measurements do not unambiguously define the sound of a speaker (in fact, they can tell you almost every thing you want to know except how it sounds). For that, you have to listen.

The Advent Legacy III is unquestionably an excellent value for its price. It is a good-looking speaker, well finished, and its overall sound was balanced and musical. All the other loudspeakers we had on hand during our tests were more expensive than the Legacy III, and though it didn’t out class any of them, it didn’t come off a clear second to most of them either.

The Legacy III had the deepest low- bass output we have heard from currently available speakers in its price range, or from many at considerably higher prices. It delivered honest, sole-tickling bass to somewhere under 40 Hz (my best guess is the low 30’s). Nor has the rest of the audio range been neglected. I had to keep reminding myself that the speaker costs only $450 a pair.

The one weakness we found in the Legacy III’s performance was a noticeable boxiness imparted to the voices of male radio announcers, especially apparent in an A/B comparison with a somewhat costlier speaker that happened to be particularly free of this type of coloration. In fairness, I should say that the Legacy III shares this quality with many other speakers we have tested, in all price ranges.

It is rare to find a two-way speaker with a 10-inch woofer and a 2.5-kHz crossover frequency. It is difficult, if not impossible, to obtain a seamless transition from a relatively large woofer to a small tweeter at that high a frequency, but it is also impractical to work such a tweeter down to a significantly lower frequency. That design dilemma almost certainly accounts for my criticism. On the other hand, the large woofer helps the speaker achieve its fantastic bass performance. There is no free lunch—compromise is al ways necessary—but not too many speakers in this price range will give you the overall performance and the handsome appearance of the Advent Legacy III.

“John, I believe the price of that speaker is twelve thousand dollars a pair, not twelve million.”


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Updated: Monday, 2016-09-19 21:38 PST