"Slam"--what is it, is it really accurate?

I put this question under speakers because I assume "slam" is mostly a function of the speakers, but perhaps a certain level of amplification is required. The only places I have experienced slam is listening to certain demos at audio shops, and some live music. Most speaker demos I have heard over the years did not produce slam.

So, what mostly accounts for a system producing that "slam" you can feel in your chest? Is it that certain speakers are "voiced" with a mid-bass hump that causes it? Do they EQ the signal to produce it? Do they employ super powerful amps?

Secondly, how accurate is slam? How much of a goal in speaker selection should the ability to produce slam be?

The reason for the questions is that I am getting close to being in the market for new main speakers. My current amp is a McCormack DNA 1, BTW. Thanks for any info!

Kiddman wrote,

"Remember that in real life the SPL of individual drums being hit reasonably hard (slam would imply more than soft gentle drumwork) is going to be over 100db. Well over. Most speakers simply don't have the ability to convey music that loud without a lot of distortion. Most audiophile speakers just won't do it."

Kiddman, you must be kidding.
Not kidding. You can't get realism in slam without playing it near the levels you hear it at live. Bring a sound level meter to live events, you won't believe the SPL peaks.

I'm not advocating playing at those levels constantly at home. But, if you want to see if your system can have the slam of a drum like you heard it live you have to play it back at that level. Then you will know if the perceived lack of slam is due to your system or just the fact that you are playing it much lower than real life.

Course, that assumes you want a system to sound real. My experience is that most audiophiles don't go hear live music and are just chasing some idea of what they think it should sound like.
I agree with Martykl. My experience coincides with his. I do feel slam is a real part of some live music. I like a system that can give a credible rendition of slam.

An example would be really hearing the "kick" in the kick drum.
Yes, you feel the wave hit your body with a nice kick drum shot when you are near it, with no amplification. I would call that "slam". Same with the floor tom, which is actually a lower frequency than a kick drum.
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.