Bookshelf Speakers

Anthony Gallo Acoustics Reference Strada Speakers and TR3 Subwoofer

ARTICLE INDEX

In Use

The second area of strikingly better performance was the clarity and retrieval of detail the Stradas offered. The Reference 3.1s are very good speakers in this regard, competing with planar speakers in their speed and clarity thanks to their crossoverless design. The Stradas push that quality up another notch. This was not an area that revealed itself on just a few recordings. On everything I listened to, I was able to hear deeper into the recording, like some obscuring background noise was gone. Where I had to strain to hear detail with the 3.1's the Stradas presented the detail clear as day. A prime example of this is the now defunct record label EM:T's 1994 album 2294 by British ambient group Qubism. This album's sound is characterized by layers of subtle sampled and synthesized sounds that can be easily smeared together or lost. The detail and clarity of the Stradas was only bested by my Denon AH-D7000 headphones.

The Stradas also clearly excelled in their ability to produce accurate timbre, offer a wide stereo sweet spot, and offer fatigue free frequency extension from 22 Hz up past 20 kHz, but were not as obviously superior to the Reference 3.1s than the first two qualities I discussed. There is only one area where the Reference 3.1s might be a bit better than the Stradas, at least in my system, and that is bass performance. The Stradas can play every bit as deep as the 3.1s in my room, and offer excellent tonal quality and plenty of volume for even the most bass heavy music (like Daft Punk's Human After All). They give up something in bass slam, impact and perceived speed. I think this is because my He-man Emotiva XPA-1s are not able to exert their iron fisted control over the bass drivers.

In the Strada system, only the subwoofer amp is driving the subwoofer. In the Reference 3.1s, the 500W into 8 ohm XPA-1s are driving the speaker full range, and have the assistance of the Gallo Reference SA subwoofer amplifier to drive the second voice coil. Given this level of firepower running the 3.1s woofers, its no wonder the 3.1s can offer a ridiculous level of bass slam, speed and agility. The fact that a single TR-3 was able to do so well with the Strada system is actually very surprising to me. This outcome is dependent on the fact that I have XPA-1s as my amps. With an amp with a more typical level of power, I would bet the Strada/TR-3 combo would come out on top. With the TR-3 in the middle of the Stradas, I didn't miss the lack of stereo bass, but a second TR-3 located with each Strada would provide stereo bass and additional bass output which might be welcome in a larger room.

Measurements

I measured the impedance of the Gallo Stradas using a Smith and Larson woofer tester. Presented as impedance vs. frequency and phase angle vs. frequency plots, we can see wide variation in the real part of the impedance from about 3.3 ohms at about 140 Hz to as high as 34 ohms at 4.2 kHz. Phase angle is typically moderately inductive, but has excursions to very capacitive at around 100 Hz and above about 5 kHz. Viewed on the Smith chart, the Stradas clearly deviate from an easy to drive 8 ohm load. This is the penalty for their crossoverless design. There's no circuitry there to moderate the load presented by the drivers, and they go nuts a bit around their resonant frequencies. Amps that have trouble driving capacitive loads won't like the Stradas, but fortunately this is not an issue with pretty much all modern amps.

I measured distortion and frequency response of the speakers using a calibrated Earthworks M30BX microphone, a Roland Edirol UA-101 24-bit 192 kHz USB sound interface and a PC running PHS SpectraPlus FFT analysis software. Absolute level was set to 100 dB (A weighted) at 1m and at 1 kHz using the ubiquitous Radio Shack battery powered SPL meter. Note this process only calibrates the y-axis of the plots, and does not effect the measured frequency response or distortion measurements in any way.

Distortion was measured on the tweeter axis at a distance of 1m from the loudspeaker. The THD performance of the Stradas is excellent, besting the Reference 3.1 (even in the bass) by about 50%. While not as stupendously low as the Legend Tikandis or the Thiel 3.7s I have tested in the past, the sub-1% THD at 1 kHz and 10 kHz is still very respectable. At 1 kHz, the second and third harmonics are about equal in level and dominate the THD measurement, as you would hope. The TR-3 delivers only 1.5% THD with a 50 Hz tone, again with low order harmonics dominating the measured value.

The in-room frequency response again shows very good performance, with no non-room related problems. The first plot below was measured at 1m from the speaker with the microphone on axis and at tweeter level. The suckout at about 120 Hz is a room related feature. Bass response is good down to close to 20 Hz. The tweeter level is a bit tipped up above 7 kHz, but this is an effect of measuring on the tweeter axis. The next plot shows the frequency response at the listening position. Tweeter response is smoother and bass response flatter down low. The treble is still a little high, but only by 3 dB or so. The suckouts at 180 Hz and 40 Hz and the peak at 60 Hz are room effects.