Phase Technology 7T Speaker System Review

Phase Technology’s 7T loudspeaker was specifically designed for use in home theater installations. The company says that in such a setting the 7T’s precise imaging and soundstage allow it to be used, at least initially, without a center-channel speaker (normally an important component of a good home theater system).

A two-way system, the 7T has an 8-inch polypropylene-cone woofer operating in a ported enclosure and crossing over (at an unspecified frequency) to a 1-inch soft-dome tweeter. The tweeter rim is surrounded by an absorbent ring to minimize diffraction and enhance imaging accuracy. The system’s impedance is given as 8 ohms and its overall frequency response as 40 Hz to 20 kHz +3 dB. With a rated bass response down only 3 dB at 40 Hz, the system is said to be usable without a subwoofer. For optimum results, of course, both a center-channel speaker and a subwoofer are desirable in a home theater installation (Phase Technology manufactures compatible speakers of both types). The 7T’s sensitivity is rated as 90 dB, slightly higher than the average speaker.

The speaker’s cabinet weighs about 45 pounds and has rounded edges, presumably to reduce edge diffraction. The tweeter is near the top of the front panel, with the woofer just below it and the port near the bottom. A black cloth sleeve covers the entire exterior of the cabinet except for its wooden base and top plate, which are finished in black or oak. The top plate is easily removed in order to roll down the sleeve, which is retained by Velcro snaps. The input connectors—multiway binding posts that accept dual banana plugs, stripped wires, or lugs— are recessed into the bottom of the speaker so that the cabinet presents a finished appearance on all visible surfaces.

The measured room response of the Phase Technology 7T, using a sweeping warble-frequency sine wave, was impressively uniform, with an overall level variation of ±4 dB from 60 Hz to 20 kHz. The close-miked woofer response was equally noteworthy, within +3 dB overall from 40 Hz to 1.1 kHz. The port’s contribution was dominant below 45 Hz and extended to our 20-Hz lower measurement limit.

The speaker’s composite frequency response (an artificial construct from the room and close-miked bass-response measurements that indicates the potential frequency-response capability of a speaker rather than its actual performance in any specific room) was among the widest we have measured, ±3 dB from 20 Hz to 17 kHz except for a 4-dB dip in the 10-kHz region. Measurements with a swept one-third-octave random-noise signal made on the speaker’s axis and 45 degrees off-axis showed a divergence between the two above 4 kHz, with the off-axis response down by 6 dB at 10 kHz and 15 dB at 20 kHz relative to the on-axis response. Quasi-anechoic MLS frequency-response measurements confirmed the essential features of the room measurements.

The speaker’s impedance reached its minimum of 5.5 ohms at 28 and 140 Hz. There was a bass peak of 16.7 ohms at 53 Hz and a broad treble peak of 21 ohms at 1.8 kHz. Above 400 Hz the impedance remained well over 8 ohms.

Sensitivity measured 89 dB sound-pressure level (SPL) at 1 meter with a 2.83-volt input, close to the rated 90 dB. With a drive level of 3.18 volts (equivalent to a 90-dB SPL), the woofer distortion from 50 Hz to 2 kHz ranged between 0.6 and 1.4 percent, averaging about 1 percent. It increased to 5 percent between 20 and 30 Hz. These are rather low distortion levels.

The speaker also had ample power-handling ability. Driven by a single-cycle sine-wave burst at 100 Hz, the woofer was able to absorb 920 watts (the clipping point of the test amplifier) without damage or audible indications that its woofer’s suspension limits were being exceeded. At that level, the output waveform was distorted but not severely clipped. At 1 and 10 kHz the amplifier clipped (at respective power levels of 360 and 730 watts) before the speaker showed signs of distress.

In listening tests, the Phase Technology 7T lived up to the manufacturer’s claims in full measure. The sound-stage and spatial imaging were as good as we have heard in our listening room, and the system’s frequency balance was exceptional. The absence of unnatural boom or chasteness in the upper bass and lower midrange was striking, especially in view of the speaker’s claimed (and measured) extended bass response.

When listening for enjoyment (as opposed to evaluation) to most compact or moderately priced speakers, we normally use a pair of subwoofers to fill in the (usually) missing deep-bass range below 40 Hz. But with the Phase Technology 7T, the only times the subwoofers made an audible improvement were when we played a few CD’s of pipe organs and pure-tone test discs at frequencies below 32 Hz. For listening to most music adding a subwoofer to a pair of 7T’s would be gilding the lily.

There are a number of very good speakers in the 7T’s price range, but few can challenge its combination of spatial accuracy, wide-range response, and attractive appearance. We agree with Phase Technology that it could do a fine job all by itself in a home theater system, and in a music-only system as well. Phase Technology’s 7T is one of the best buys in today’s speaker market.

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