On The Graph And To The Ear
We were surprised. The 3151 was capable of attaining very high sound levels for its category and available power. This is not a miracle, as we'll see, but a conscious decision by the manufacturer.
Maximum volume level: 112 dB SPL
The response of the 3151 as measured shows a particular profile generally known as "physiological," with emphasis on the treble and bass compared to the midrange, which, in short, gauges the familiar "loudness" effect. But in general the linearity is quite good. Above all we noticed a lack of extreme bass. The subwoofer is centered on approximately 120 Hz - a relatively high frequency - with regular attenuation below that frequency. Clearly Altec has chosen to sacrifice the sub-bass (which any system that's small in size and low in power has trouble with) on this model and emphasize volume above all, as we noted above.
Response fitting a "physiological" profile, with a lack of sub-bass
While the curve is classic for a small subwoofer, the frequencies are higher than usual, with the best output at 120 Hz.
At first contact, we appreciated the system's good behavior when we fed it a musical program. Reproduction was clear and dynamic. The volume level possible without audible distortion was fairly high, which will certainly be appreciated. However, you don't get much bass, and sub-bass is just not there. The two are obviously related. So depending on your musical tastes and what you're looking for in a system, you may or may not appreciate the 3151.
In home cinema mode, the out-front presence of the highs gave a pleasant impression of definition, but the lack of sub-bass limited the reproduction of certain soundtracks- particularly that of "major motion pictures," which are heavy on the explosions and other earth-shattering noises... But overall, the result is very good. Above all if you don't compare with systems that are more generously endowed in the subwoofer department. In fact, Altec's choice of putting volume level ahead of extended response is not an absurd one, and you may well prefer somewhat limited bass to distortion that rips your ears off if you like it loud but can't afford a high-end system.