- Published on 04 July 2012
Gallo Classico CL-4 Loudspeakers on the Bench
Measurements of the CL-4s were made using a Smith and Larson Audio Woofer Tester 2 impedance analyzer and audio data measured with a calibrated Earthworks M30BX microphone with a M-Audio Profire 610 audio interface and Spectra Plus FFT analysis software. Measurements were conducted at the end of the review period to avoid biasing the subjective conclusions.
Impedance measurements show a somewhat easier to drive load than the Reference 3.5 and Strada throughout the bass and midrange. The smith chart representation shows that the impedance remains within the factor-of-two impedance circle for the majority of the audio band, before running away in the treble. As with all Gallo products I've tested, the impedance of the tweeter varies by a large amount in both amplitude and phase. Luckily, since the tweeter demands so little current this is not a big deal for virtually all audio amplifiers. The characteristic impedance circles around 8 ohms, but it spends a lot of time near 4 ohms and below, as shown in the separate impedance magnitude and phase versus frequency plots. Gallo rates them as a 4 ohm load, which seems reasonable.
Total harmonic distortion plus noise (THD+N) was measured at 50 Hz, 1 kHz and 10 kHz with 100 dB tones. Absolute amplitude calibration was done at 1 kHz using a Radio Shack SPL meter. At 1 kHz, the distortion was a reason able 0.6%, similar to the other Gallo products I have measured in the past. At 10 kHz, the distortion increases slightly to 0.7%, a bit more than the 0.5% measured from the Reference 3.5. At 50 Hz, the THD+N was a significantly higher 4%. About 1% of this was noise from background I couldn't get rid of. Regardless, this is about twice the distortion level at 50 Hz than the other two speakers. Maybe this is why I believed the bass lost a bit of composure at high levels. At lower amplitudes, the issue disappeared.
Frequency response, measured from 20 Hz to 20 kHz was admirably flat, at least until room effects kicked in. I measured both at 1m using a single speaker and at the listening position using stereo white noise. I lost bass in my room at about 60Hz due to room suckouts, also seen in the measurements of the Reference 3.5s and Stradas. Without the ability to boost the bass with active control as with the Strada and 3.5, I wasn't able to get this back. The suckout in the room likely explains the higher THD+N number I measured at 50 Hz as well. The lower treble is a bit depressed compared to the upper treble and midrange, just like the Strada. Overall the frequency response measurements are not as good than the Reference 3.5, but certainly comparable to the Strada/TR3.