Subwoofers

Gallo Strada 2 Speakers and TR-3D Subwoofers

ARTICLE INDEX

The Gallo Strada 2 Speakers and TR-3D Subwoofers On the Bench

I measured the Gallo Strada 2 and TR-3D with my M-Audio Profire 610 firewire audio interface, with a calibrated Earthworks M30BX microphone and Spectra Plus FFT analysis software. Electrical impedance of the Strada 2 was measured with a Smith and Larson Woofer Tester 2, calibrated with a 10 ohm 1% resistor.

Like the earlier Strada, the Strada 2 is not a particularly easy load to drive. In the critical low frequency regime where large currents are requested of the driving amplifier, the load is relatively benign. The magnitude of the impedance is relatively large, with phase angles that do not deviate by more than about 45 degrees from real. At high frequencies, as usual with Gallo speakers, the impedance goes a bit nuts. I measured an impedance as low as 1.2 Ohms at 20 kHz, albeit with an almost zero phase angle. At 10 kHz, the magnitude of the impedance is a more reasonable 5.4 Ohms, but with a capacitive phase angle of almost 70 degrees. With well-designed amplifiers, this challenging load should not be a problem.

Distortion was measured at 50 Hz, 100 Hz and 1 kHz. At 1 kHz, the distortion was an admirable 0.79%. This result is about 20% better than the 1% I measured for the original Strada. At 100 Hz, I measured a respectable 1.4%, but the distortion increased to 4.8% at 50 Hz. This is a typical number for a small subwoofer, but is considerably worse than the TR-3 I measured in the past. I am not sure why this is the case, but the measurement was done in a new house in a new room. At 50 Hz, room effects are considerable.

Frequency response measured at 1m shows very flat performance from 500 Hz up to 20 kHz, with obvious room effects kicking in below that. At the listening position, the measured response is excellent down to 40 Hz, with roll-off below that. Again, this is the room, not the speakers.