During the recent "great recession", I spent most of my time over on the prosound side of things. Imo, there's a lot of validity to Mtrot's observation: "I'm beginning to think the ability of speakers to achieve that sense of dynamic "liveness" may be as or more important to a sense of realism than frequency response accuracy."
On the acoustics side, I take the word to mean unrestrained dynamic transients. Compression can come from amplifier clipping or loudspeaker thermal or mechanical limitations. I believe that the most common culprit in loudspeakers is "thermal modulation", a quick-onset compression that results from the near-instantaneous heating of the voice coil from a high-power transient.
On the psychoacoustics side, "slam" registers when a limbic system response ("fight or flight" startle) is triggered. It is a function of transient dynamics and raw SPL. If there's not much dynamic contrast, it doesn't come across as "slam". If there's good dynamic contrast but the sound pressure level is still soft, it doesn't come across as "slam".
From a loudspeaker design perspective, the solutions include high efficiency and/or large diameter (or multiple) voice coils. If a loudspeaker system is being pushed close to its RMS thermal rating on peaks, your peaks are softened and so is the emotion conveyed. If a loudspeaker system is just loafing along at fairly high SPL, it will deliver plenty of slam. That's why 5 watts into a 98 dB efficient speaker almost always sounds so much more lively than 200 watts into an 82 dB efficient speaker, even though "on paper" both are 105 dB capable.
Duke
dealer/manufacturer
On the acoustics side, I take the word to mean unrestrained dynamic transients. Compression can come from amplifier clipping or loudspeaker thermal or mechanical limitations. I believe that the most common culprit in loudspeakers is "thermal modulation", a quick-onset compression that results from the near-instantaneous heating of the voice coil from a high-power transient.
On the psychoacoustics side, "slam" registers when a limbic system response ("fight or flight" startle) is triggered. It is a function of transient dynamics and raw SPL. If there's not much dynamic contrast, it doesn't come across as "slam". If there's good dynamic contrast but the sound pressure level is still soft, it doesn't come across as "slam".
From a loudspeaker design perspective, the solutions include high efficiency and/or large diameter (or multiple) voice coils. If a loudspeaker system is being pushed close to its RMS thermal rating on peaks, your peaks are softened and so is the emotion conveyed. If a loudspeaker system is just loafing along at fairly high SPL, it will deliver plenty of slam. That's why 5 watts into a 98 dB efficient speaker almost always sounds so much more lively than 200 watts into an 82 dB efficient speaker, even though "on paper" both are 105 dB capable.
Duke
dealer/manufacturer