I also think multi-sub deployments are more likely to be less punchy as sub count goes up.
I think rooms mask this phenomenon, especially small ones. Bigger the room, the less the masking.
Tactile feel that is more in the mode of steady vibration, like hair tingling, pants flapping, or chest resonating......multi-works just fine ime.
But punch, the hit in the chest, the bass drop that sends loose beers cans flying, comes from a strong vector...which is usually easiest to obtain from a single sub cluster.
Over the last dozen years I've amassed a near ridiculous amount of subwoofer power. (I wanted to partner with some folks for live sound, but found I don't like the late night hours gigs often require.)
Anyway, I've built a lot of subs...sealed, reflex, front-loaded horns...and bought a few more. I've compared then indoors and out, in single, stereo, and multiple sub fashion.
Subs definitely have a directional punch ime. And with multiples it's a vectored punch.
Heck, even a single reflex sub has a directional punch, depending on where the ports are in relation to the cone.
I've built double 18" subs with the ports surrounding the drivers in the front baffle like typical, with ports firing to to floor, with a slot port facing outward between two opposed drivers facing each other clamshell style, and drivers in a 90 degree frontal angle with a large port below them. They all hit a little different, and it's almost track by track which sub will hit hardest on it. (They are were tuned maximally flat to within a few Hz, using the same 18" BMS drivers.)
Anyway again, I know this thread is really in reference to home audio rooms, but it don't think it takes that big of a room, to feel the hit difference from a single sub (with balls) vs multi-subs (also with balls).
You can have a system that does really well but it's the room that surely brings every bit of complexity to the matter, having in mind what
@j_j says about velocity and pressure in recent discussion.
It has been my experience that certain strategies can be beneficial for the overall performance and in some cases you should even be careful what you wish for. The overall shape of the wavefront is what may be worth to look into, also having ports or not in the equation may sound and feel very different.
My setup is stereo bass and I've shared some measurements in other threads, but here I would like to focus on the correlated signals, especially ones that may produce the punch you describe. In room front wall and floor bounce must be considered along with wavelengths, room dimensions, where the system and MLP is positioned, etc. It's about how the energy is distributed along the way. Luckily bass is slow and can be manipulated, room gain as well.
Here are some initial measurements from setup and alignment that to me looked deceiving:
- close field, subwoofer cone level, mains ported (no smoothing):
Some colors of that:
Same setup, ear level, 3,5 meters distance:
Which translated into the room that wants to ring forever:
Comparing step response of this and that:
I thought I can do better with regards to time and phase alignment, group delay and all that, so I did:
Again close field, sub cone level:
This looks a bit better:
Unfortunately, this at MLP this was even worse, at which point I started thinking in terms of what amount of energy and at what time can I put it into the room, without making it collapse. This was not about punch, nor trouser flapping, plenty of that, but the room simply could not handle it. Even though there's not much very low frequencies at ear level, all the sub bass was accumulating underneath my seating position, wanting to bring the house down at higher SPL. I've shown measurements of that elsewhere.
Next thing I've done is try and get rid of the ports and this is how it now looks like, with some EQ:
- Close field, sub cone level:
Now, the MLP, ear level:
And how the room behaves now:
I think this deserves a bit of zoom in:
It's slow and predictable distribution of room gain that reaches 6dB louder at MLP that is pretty much frequency independent, caveat being that it comes about 12 ms later. The energy that bounces around is now more predictable, with moments of almost total silence, and then in bounces again but loses pressure more rapidly and more importantly, in similar fashion within modal frequencies as well. Room no longer does what it wants.
The step response of this and that is complicated, to say the least:
And If I clean this up a bit, this is what it does on average at MLP:
How the room behaves seems to be in correlation of where the peak energy level is, so it corresponds to that room dimension in between the system and listening position. The wavefront shape is such that low frequencies can seemingly fit into the room and bounce rather than stand at similar spacing that again corresponds to that 12 ms sound has to travel.
All I can say about how it sounds (and feels like) is that there's plenty of time for localization and neural stream separation, also for auditory compression mechanism to do it's thing. Sense of spaciousness is never confused or masked by that, all important quick bass drops (punches and kicks) or mono centered signals of longer duration. Perhaps
@j_j could comment on how do we perceive order vs disorder in low frequencies and how various mechanoreceptors in the body are involved, that would be interesting.
Maybe my math is wrong so I am willing to hear your explanation.
