Small Monitors vs. Large Speakers: What Really Happens Inside a Speaker Cabinet?#
Have you ever looked at tiny studio monitors and thought: “How on earth do they produce that much bass?” Manufacturers know how to make a response graph look “magically” flat — but in acoustics, there’s no such thing as magic. There is only physics. Below is an accessible explanation of why cabinet size matters, where that heavy bass in small boxes really comes from, at what cost, and when a bass-reflex design helps — and when it does more harm than good.
Physics ripples, marketing smooths it out#
Sound is made of waves — oscillations of air molecules. The lower the frequency, the longer the wavelength. With the speed of sound being around 343 m/s, a 50 Hz wave is about 6.86 meters long. A “quarter-wave” (¼ λ) is roughly 1.72 meters — and that’s a great intuitive rule: if you want to reproduce the lowest frequencies reliably, the size of the acoustic system (cabinet volume, diaphragm diameter, etc.) should keep a reasonable relationship with a quarter of the target wavelength. In other words: bigger usually means better — especially in the low end.
Why?#
When a driver plays high frequencies at a given amplitude, its diaphragm moves quickly but with small excursions. When reproducing low frequencies, it moves slower but with much greater excursion. Large excursion means a large volume of air being pushed (both into the room and into the inside of the cabinet). The air trapped in the cabinet acts like a spring — it compresses and resists the diaphragm’s movement. That’s exactly why the smaller the enclosure, the higher the system’s resonance frequency.
How “big bass” is created in a small box — 4 tricks and their side effects#
To make a small cabinet produce a big low end, a few tricks are used. Each of them improves the amplitude response curve, but hands you the bill later — in time-domain behavior and distortion.
1. Bass-reflex (port)
The movement of air inside the cabinet creates a resonance in the port — tuned by the designer to extend the low-end rolloff. The side effect is increased inertia of the diaphragm, which in the lowest band leads to group delay. The smearing of transients and time-domain distortion is just as powerful as the bass gained by this design.
2. Passive radiators
Often perceived as “more refined” than ports due to the lack of port turbulence — no audible chuffing or other artifacts. However, it’s still a resonant system with compromises in the time domain.
3. Drivers with very high excursion (Xmax)
In a small box, a lot of air has to be displaced, so the diaphragm travels far. This increases nonlinear distortion (suspension elasticity, BL force factor vs. excursion) and intermodulation distortion (IMD).
4. EQ correction - DSP
Sure, you can flatten the amplitude curve this way — but you can’t cheat time-domain physics. Boosting the low end means more excursion, less dynamic headroom, and worse impulse response.
Conclusions#
A flat amplitude-frequency response graph at a single SPL level in an anechoic chamber does not guarantee that musical material (variable loudness, transients, complex spectra) will sound accurate. That’s even more paradoxical considering that in the “studio monitor” segment, bass-reflex constructions dominate today (e.g., the famous yellow-cone monitors) — while in the past, sealed enclosures like Yamaha NS-10 or Auratone were the standard. Not because older engineers didn’t know how to tune ports like we do today, but because true professionals prioritize monitoring accuracy, transient control and time coherence (smooth ~12 dB/oct rolloff, less sensitivity to placement).
Today, the entry barrier to music production has dropped: anyone can produce music in a bedroom and expects “full” bass from a tiny box. So the market rewards bass-reflex, passive radiators, and DSP — solutions that deliver a “wow effect” for casual users.
The moral is simple: choose your tool for your task. If your priority is control and time-domain fidelity — go for a sealed enclosure. If you need maximum bass out of a one-liter box — knowingly accept the compromises of bass-reflex.
Subjectively#
Personally I believe that in modern music, it’s often the lowest frequencies that create groove and bounce — and as we know, the rhythm section lives and dies by its transients. Taking that into account I can’t imagine consciously giving up precise monitoring of those transients — especially if I’m working on the material, not just enjoying it.