Transient Response Effects
A speaker with poor transient response will store energy, releasing it after the initial musical transient has passed. This causes a loss of detail and obscures important musical information. Also associated with poor transient response is a narrow-band resonance, which can emphasize specific notes.
When listening for the low-frequency transient accuracy of a speaker, it will be useful to utilize a broad variety of recordings. Try playing a rock or jazz group, and listen to the interplay between the drummer and the bassist. Is it easy to distinguish the kick drum from the bass, or is there a blurring of low-frequency detail caused by the speaker's time-smear?
To listen for narrow-band low frequency resonances, use a recording with the bass line played by a synthesizer. As you listen to the bass line, are the individual notes of equal level, or are some of them more prominent than others? Electronic instruments can be more useful for this test since acoustic instruments have resonances of their own which can hide flaws in the speaker, unless you are intimately familiar with the instrument and the recording. Similarly, an electric bass that has been recorded by miking its speaker/amplifier will exhibit the resonances of its speakers, which are inevitably considerable, masking defects in the loudspeaker under evaluation.5
5There is a technique known as "direct injection" where the signal from an electric instrument is connected directly from the amplifier to the recording console, bypassing the speakers. In this instance, an electric bass will prove to be a consistent low-frequency source. The difference between direct injection and miking of the speaker/amplifier is easily audible with high-quality speakers.
