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Anthony Gallo Acoustics Reference Speakers

Part II

January, 2007

Chris Groppi

 

I like the futuristic styling of the Reference 3.1s, as does my wife, so we preferred to have them on display. I also like the smaller apparent size of the speaker without the grille. The Reference 3.1 is not a large speaker, which is one of the things that make it attractive to me. It stands only 36" tall and is a mere 8" wide by 14" deep, but its pillar and separate enclosure design make it seem even smaller.

The back slanted MDF pillar, combined with longer spikes in the front of the base help to time align the system. As mentioned earlier, the Reference 3.1s use almost no crossover. The only crossover in the speaker is a low pass filter used to limit the high frequency extension of the woofer to 125 Hz. Neither the midrange nor the tweeter use a crossover, instead relying on the acoustical properties of the enclosure and driver to define their bandpasses. This design minimizes the negative effects of the crossover on the musical signal. Crossovers are filters, and are therefore purely reactive circuits.

Reactance is a way to describe energy storage in an electrical circuit. Its counterpart, resistance, describes the dissipation of energy in a circuit. Resistance just turns electricity into heat, and does not affect the time response of a speaker, but reactance is a completely different kettle of fish. In changing the frequency response of a speaker, a crossover stores up energy and then releases it over time. It is the fundamental nature of the crossover that it will alter the time response of a speaker. While the crossover-less design of the Reference 3.1s does not eliminate reactance above 125 Hz (the drivers themselves present a reactive load), the design goes a long way towards a time coherent system without the use of complicated electronics in the signal path. Their sensitivity is a modest 88 dB/w/m. While likely not in the single digit wattage SET amplifier regime, the Reference 3.1s should be fairly easy to drive with most solid state or tube amplifiers.

As I alluded to before, the two pairs of binding posts on the Reference 3.1s are not for bi-wiring, but for a novel version of bi-amping that can extend the low frequency performance from a respectable 34 Hz to a stupendous (for a 47 lb 36" tall loudspeaker) 22 Hz. The 10" woofer in the Reference 3.1 is a dual coil driver, meaning that there are two independent voice coils attached to the driver inside a single magnet. One of these voice coils is driven via the top pair of binding posts with the full range signal through the low pass crossover, as in a traditional speaker. The bottom binding posts drive the second voice coil directly, and are meant to be used exclusively with an outboard subwoofer amplifier and crossover. With this second amplifier and crossover tuned properly, the speaker's low frequency response can be extended by almost a full octave. It is essential, however, that this subwoofer amplifier be equipped with a low pass crossover, otherwise the amp will attempt to drive the woofer with a full range signal, resulting in terrible performance above the woofer's 125 Hz maximum design frequency.

The Gallo Reference 3 S.A. amplifier was designed specifically for this mission, although it can be used to drive any non-powered subwoofer as well. The output power level is 240 watts RMS x 2, and it offers one of the most complete set of adjustments available to properly tune the performance of the Reference 3.1 woofers or separate subwoofers.

The crossover frequency is continuously adjustable from 40 Hz to 180 Hz. The phase is also continuously adjustable from 00 to 1800 for the left and right speaker independently. Gain controls are independent for left and right speakers, making tuning for oddly shaped rooms of asymmetric speaker positioning possible. Both low level (RCA) and high level (five-way binding post) inputs are available, as well as a low level "subwoofer" input which bypasses the crossover controls for use with the bass management features of a surround sound processor. The amp is also bridgeable to mono with 650 W available into 4 ohms.

The very solidly built rack mountable unit weighs in at 42 pounds. An unobtrusive thermostatically controlled fan passes air over internally mounted heat sinks, and both a signal sensing option and remote trigger allow the amp to be automatically turned on if desired.

The Reference AV Center Channel Speaker is a new addition to the Gallo line, bringing the high performance of the Reference 3.1 to a home theater application. The speaker is built on the same model as the Reference 3.1, combining four of the 4" carbon fiber midrange drivers in their independent spherical enclosures with a modified version of the CDT II ribbon tweeter.

The two outer drivers are used as woofers, with low pass crossovers that limit their operation from 55 Hz to 100 Hz. The center pair of drivers is used full range as in the Reference 3.1, with the high frequencies limited to 3 kHz acoustically.

The CDT II tweeter has had its horizontal dispersion limited to 1200. The five drivers are mounted on an aluminum cross-member, housing the binding posts and electronics. A perforated metal grille covers the drivers. While this grille is removable, the speaker is meant to be used with the grille on at all times. This speaker can be directly mounted on the wall below a flat panel display, or used with an optional stand. This cast aluminum stand is very sturdy, and allows adjustment of the speaker for vertical tilt. The loudspeaker is built to the same very high standards as the Reference 3.1, using the same drivers, sub-enclosures, binding posts, and construction techniques. It makes an excellent visual compliment to the 3.1s, while not taking up a huge amount of space, as do many other center channel speakers of this performance and price class.

Click Here to Go to Part III.

Copyright 2007 Secrets of Home Theater & High Fidelity

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