Bass, Baby, Bass
Bass is visceral and immediately impressive. It’s the frequency that hits you in the chest and rattles the plates in the cabinet. It’s also why audio brands over decades focused so much energy on products that produce LOTS of bass. But it’s important to know that impressive and accurate are not the same thing; and when it comes to bass reproduction, that distinction matters more than most people realize.
Our approach to bass at KLH Audio is informed by the Acoustic Suspension design, which was once the dominating speaker design on the market. If you’ve read our marketing materials before, you’ll know our founders invented the Acoustic Suspension approach we still use today. It produces bass that’s deep, punchy, accurate, and less affected by room dynamics than bass reflex designs.
However, speaker design—like fashion—goes in and out of style. While sealed cabinet (Acoustic Suspension) design was once the de-facto standard, ported speakers (bass reflex) flooded the market for years. People were wooed by the amount of bass that came out of ported speakers, making them especially effective on retail store floors. Now, like the baggy clothes of yesteryear, sealed cabinet design is once again in vogue. As people shift their buying habits online, and aren’t as swayed by the showmanship of retail store bass magic, they’re realizing that bass accuracy is more important to them.
The thing is, not many people make Acoustic Suspension loudspeakers anymore. And we’re certain no one makes them as well as we do at the prices we offer. If you’re interested in dipping your toes deeper into the well of bass, read on:
The Ported Promise — and Its Fine Print
As we previously mentioned, most speakers on the market today are ported, meaning they have a hole—the port—through which air moves in and out. This design is also referred to as “Bass Reflex”. Manufacturers tune the port to a specific frequency to augment bass output, which translates to bass that sounds LOUD.
Think of bass reflex a bit like the pipes on a Harley-Davidson. Some of you may know Harley actually patented its iconic low rumble, tuning the exhaust pipes to resonate at a very specific frequency. As it happens, it sounds enormous at exactly that note. But ask a Harley to play anything above or below that frequency, and it just doesn't have the same magic. Ported speakers work similarly.
If a speaker designer tunes a port to hit hard at 40–45 Hz, it will. But, below that tuning frequency range the two apertures in the system—the woofer and the port—start working against each other. The bass diminishes and deteriorates, introducing sound that isn’t native to the music, or worse: distorted.
Ported designs also mean less woofer control. In a ported speaker, which allows air to move freely in the cabinet, the woofer cone also moves more freely. This sounds like a good thing, but freedom has consequences. When the cone moves further than it should thanks to an especially beefy note, it takes longer to return to its neutral position. This causes a slight delay, causing subsequent bass notes to start slightly out of place. It's a subtle form of distortion, but it's there, and it accumulates across every note in a bass line.
The Sealed Difference: Physics!
In a sealed enclosure, the air trapped inside the cabinet acts like a natural spring. This produces a constant, precise counterforce and ensures the woofer cone returns to its zero position faster after every excursion. Faster return means the next note starts exactly where it should. This is what we mean by accurate bass.
Sealed speakers also don't chase a tuning frequency sweet spot since there's no port to boost a narrow frequency band. Instead, the speaker produces consistent, controlled output across a range of bass frequencies. It doesn’t produce artificial bumps and you only hear what was recorded, not what the cabinet was tuned to emphasize.
Per our lead engineer Kerry Geist, there's an engineering adage worth repeating here: if it moves, it distorts. If you can produce the same amount of sound with less woofer movement, you'll do it more accurately. That's the sealed speaker argument in a single sentence. Larger woofer diaphragms move less per stroke than smaller ones, which is why our Model Seven's 13-inch woofer isn't just about being louder, it’s about bass clarity.
Origins - Why Ported Speakers To Begin With?
Here's something most people don't think about: when bass reflex speakers became popular in the early 1970s, they were arguably filling a gap left by the recordings of that era. Music from the '60s and early '70s was often recorded with limited low-frequency depth. The soundstage was narrow, the bass was thin and a ported speaker that boosted the low end made everything sound a little more alive. The unfortunate truth is it wasn't fidelity; it was a useful correction for the recording medium's shortcomings.
Modern recordings are a different story entirely. Today's producers and artists across every genre are now making deliberate, sophisticated use of the full low-frequency spectrum, extending well below 50 Hz (we’re looking at you, Finneas). The artificial embellishment a ported speaker offered in 1972 is unnecessary today, and some might say it actually gets in the way. You don't want your speaker adding bass that isn't there. You want it to reproduce what is.
Our job, as KLH sees it, isn't production. It's reproduction. The difference matters.
Bass Differences From Big Speakers, to Small Speakers
So, what will you notice if you get something small like the Model Three, vs something large, like the Model Seven? Every speaker in the KLH Model Series—Model Three, Five, and Seven—is a sealed Acoustic Suspension design, optimized for its specific cabinet volume and woofer size. Think of the speakers as a one cubic foot (Three), one-and-a-half cubic foot (Five) and two-and-a-half cubic foot (Seven) wooden boxes, each tuned to perform at its best within those size constraints.
It’s easiest to describe the distinction between these models using numbers to tell the story: at 45 Hz, right in the heart of the bass register, the Model Three delivers a maximum output of 101 dB. The Model Five hits 106 dB. The Model Seven reaches 111 dB. That's a 10 dB difference between Model Three and Model Seven. This doesn’t just sound like "a little more bass”, it sounds like “woah”. As a matter of fact, a 4 dB increase is enough to literally double perceived bass output. When you buy a bigger speaker, you’re paying for bass that hits harder and stays clean at higher volumes.
There's an important nuance we want to drive home here: the advantage of a larger sealed speaker isn't just that it goes deeper or louder. It's that it plays with the same purity at high volumes that a smaller speaker manages only at moderate ones. Headroom isn't about maximum volume, it's about how cleanly you get there.
Bass is Fickle — Less So with KLH
One last advantage that rarely gets the attention it deserves: room placement. Ported speakers are sensitive about where you put them, because rear-facing ports interact unpredictably with nearby walls. If you put ported speakers too close to walls or corners, the bass becomes boomy and smeared. This is because the port essentially amplifies room problems rather than your music.
Sealed speakers don't have that problem (to a certain extent). The Model Series was designed to be used in imperfect environments, since most of us don’t have dedicated listening rooms with acoustic panels and a perfectly symmetrical floor plan. Without a rear port to worry about, the speakers are more forgiving of placement, and the wide baffle on the larger models is engineered to keep sound energy projecting forward rather than bouncing off the back wall and muddying the image.
Bass That Earns It
To be clear, ported speakers aren't bad. In the right context, with the right music, in the right room, they are compelling. But "more bass" and "better bass" are genuinely different things and understanding that difference is the whole point of this monologue.
If anything we hope you leave this blog feeling more educated about sealed and ported cabinet design. Obviously we’re partial to the former, given that’s the design we invented. But sound—like fashion—are subjective choices, and while we can always point people in the direction we think will serve them best, ultimately they choose their own destiny.
