Bass extension is the one spec on this site that tells you what a speaker physically cannot do. It’s also the one manufacturers state most loosely. This page explains the two figures we publish and why we don’t trust the one on the box.
The Problem With “Frequency Response: 40 Hz - 20 kHz”
That claim is meaningless without a tolerance. Every speaker produces something at 40 Hz - the question is how much quieter it is than the midrange, and at what volume it stops being clean.
A useful figure always has two parts: a frequency and how far down it is. That’s what -3dB and -10dB mean.
The Two Numbers We Publish
Bass extension (-3dB) is the point where output has fallen 3 dB below the speaker’s average level. That’s roughly half the power and the conventional definition of where a speaker “stops”. This is the conservative, honest number. 99 speakers here have it.
Bass extension (-10dB) is where output has fallen 10 dB - clearly quieter than the rest of the sound, but still audible and still contributing. 346 speakers here have it, which is why it’s the figure you’ll see most often in our rankings.
They can be an octave apart on the same speaker. A speaker with an F3 of 67 Hz and an F10 of 42 Hz is not contradicting itself - it’s rolling off gradually. The KEF LS50 Meta is exactly that, which is why its entry says it doesn’t meaningfully play below 50 Hz in-room despite an F10 in the 40s.
When you compare two speakers, make sure you’re comparing the same figure. A manufacturer quoting -10dB against a competitor’s -3dB looks better while being worse.
What The Numbers Sound Like
Rough anchors for the frequencies you’ll see in these rankings:
- 80-100 Hz - no real bass. Most small pocket speakers.
- 60-65 Hz - bass is present but thin; kick drums lack weight. Top of the small class.
- 50-56 Hz - satisfying with most music. Best of the medium class, comparable to a 5.25” bookshelf speaker.
- 44-48 Hz - you feel it a little. Best of the large class, comparable to a 6.5” bookshelf.
- 35-43 Hz - genuinely deep; a floor starts to move. Best boomboxes, comparable to an 8” tower.
- Below 32 Hz - subwoofer territory, and where movie content lives.
Why Room Gain Changes All Of This
A speaker’s measured extension is not what you hear. Below the frequency where a room’s longest dimension stops supporting a full wave, the room reinforces bass at roughly 12 dB per octave. In a small room that can add most of an octave of usable extension for free.
This is why a sealed subwoofer’s gentle roll-off often measures flatter in a real room than a ported one’s steeper cliff, and why buying enormous output for a small room is mostly wasted. Both arguments are worked through in the subwoofer buyer’s guide and how room acoustics affects speakers.
For Subwoofers, Use A Different Number Entirely
Extension says how low a subwoofer reaches, not how loud it plays there - and for subwoofers, loud is the point. That’s what CEA-2010-A measures, and it’s what orders our subwoofer rankings. See CEA-2010-A explained.
Where To Look Next
Every speaker’s extension figures are in its spec table. Each size class ranking states what the best in that class achieves - small, medium, large, boombox - and the portable buyer’s guide uses them to explain why size is the decision you can’t buy your way out of.
Last Updated August 07, 2026