The KLH Model Three occupies a specific and deliberate place in the modern loudspeaker landscape. It is a two-way, sealed-box bookshelf that traces its DNA directly to the acoustic-suspension designs Henry Kloss helped bring to prominence in the late 1950s. For the experienced listener, the Model Three is interesting precisely because it refuses the shortcuts that a ported box would offer, and instead commits to the tighter, more disciplined bass and low-distortion character that a sealed enclosure delivers. This deep dive breaks down the engineering choices, the drivers, the crossover, the cabinet, and the specifications, and explains what each of them means when you sit down to listen.
Design Philosophy and Enclosure
What is acoustic suspension, and why does KLH use it?
Acoustic suspension is a fully sealed cabinet design in which the trapped air behind the woofer acts as a spring that controls the cone's motion, and KLH uses it because it produces very tight, accurate, low-distortion bass that stays clean at high volume. In a sealed box, the compliance of the enclosed air adds to the mechanical suspension of the driver, so the restoring force on the cone is dominated by that air spring rather than by the surround and spider alone. The practical result is exceptional control over cone excursion, which lowers distortion and yields deeper extension from a smaller cabinet than a vented alternative of the same volume would manage. The trade-off, and it is a real one, is slightly lower sensitivity, because you are asking the amplifier to work against that air spring. This is why the Model Three rewards a capable amplifier, and it is the single design decision that most defines how the speaker sounds. KLH helped popularize this approach decades ago, and it remains the backbone of the brand's voice.
Why does a sealed box roll off differently than a ported one?
A sealed box rolls off more gently at the low end, at roughly 12 dB per octave, compared to the steeper 24 dB per octave slope of a ported design below its tuning frequency. This matters for two reasons. First, the gentle slope means the Model Three's usable bass often reaches lower in a real room than the raw number suggests, because room gain fills in below the corner frequency and blends smoothly with that shallow rolloff. Second, the sealed alignment produces better transient behavior and tighter group delay, so kick drums and bass lines start and stop with more precision. You give up a little of the ported box's mid-bass emphasis and headline extension figure, and in exchange you get bass that is more honest and more controlled.
The Drivers
What is the woofer made of, and why does it matter?
The woofer is an 8 inch pulp-paper cone mounted in a die-cast aluminum frame with a reverse-roll suspension, and the material choices matter because they prioritize damping and control over flash. Treated paper pulp is light and inherently well-damped, meaning it converts unwanted resonant energy into heat rather than ringing and adding coloration. KLH voices this material for a natural, uncolored tone, which is a deliberate aesthetic rooted in the brand's heritage. The die-cast aluminum frame provides a rigid, non-resonant platform that keeps the motor structure stable under load and avoids the flexing that a stamped-steel basket can exhibit. In a sealed acoustic-suspension design, that rigidity is not cosmetic. It ensures the alignment between the cone, the air spring, and the motor stays consistent at high excursion.
What does the reverse-roll suspension do?
The reverse-roll rubber surround controls cone motion precisely and lowers distortion by orienting the roll of the surround to better manage the way the cone travels. In a conventional surround, the geometry can introduce subtle asymmetries in how the cone moves inward versus outward. Reversing the roll helps keep excursion linear across the cone's travel, which is especially valuable in a sealed box where the air spring is already loading the driver heavily. The payoff is lower distortion at the frequencies where a large woofer moves the most air, and cleaner reproduction as you push the volume.
What kind of tweeter does the Model Three use?
The Model Three uses a 1 inch aluminum dome tweeter, and the metal dome is chosen because it is light and rigid, which yields extended, detailed treble. A dome that is stiff relative to its mass behaves as a rigid piston across most of its operating band, pushing breakup modes up and out of the audible region rather than letting them color the midrange and lower treble. The result is high-frequency reproduction that reaches to 20 kHz with clarity and air. Aluminum's rigidity gives the top end its detail and speed, and the Model Three pairs it with a control that lets you tailor its balance to your room, which brings us to a KLH signature feature.
Tuning and the Crossover
What does the Acoustic Balance Control do?
The Acoustic Balance Control is a 3-position switch on the speaker that raises or lowers the high-frequency level in small steps, letting you tune the treble to your room and taste. This is a genuinely useful tool rather than a gimmick. Rooms with hard floors, glass, and minimal soft furnishings tend to sound bright, and a live room can make even a well-behaved aluminum dome feel forward. Dropping the high-frequency level a step tames that. Conversely, a heavily damped room full of carpet, drapes, and upholstery can sound dull, and nudging the level up restores air and presence. The control is a KLH signature carried over from the original Model Five, and it means you can adjust the speaker to the space instead of rearranging the space around the speaker.
Where does the crossover split the signal, and why there?
The crossover hands off from woofer to tweeter at 1,500 Hz, a frequency chosen to let the 8 inch woofer cover the midrange while handing off before it begins to beam and before the tweeter is pushed too low. An 8 inch cone starts to become directional as its radiating wavelength approaches its diameter, so crossing over at 1,500 Hz keeps the woofer operating where its dispersion is still even. At the same time, 1,500 Hz is comfortably above the region where a 1 inch dome tweeter would be strained by excursion demands, so the tweeter operates in its clean, linear band. This is a classic, well-reasoned two-way crossover point that balances dispersion, power handling, and driver integration.
Reading the Specifications
What does a sensitivity of 88 dB mean in practice?
A sensitivity of 88 dB in-room (85 dB free-field, measured at 2.83 V and 1 m) means the speaker produces that sound pressure level from a standardized drive signal, and it tells you how loud the speaker plays for a given amount of power. The two numbers describe two different measurement conditions. The free-field figure of 85 dB is measured without room reinforcement, while the in-room figure of 88 dB reflects the boundary gain you actually get when the speaker is set up in a listening space. Acoustic-suspension designs tend to sit a touch lower on sensitivity because of that air spring load, which is exactly why a robust amplifier helps the Model Three sound its best. This is not a speaker that needs coddling, but it will reward clean power with dynamics and effortless volume.
What do 6 ohms nominal and a 3.7 ohm minimum tell me?
A 6 ohm nominal impedance with a 3.7 ohm minimum describes the electrical load the speaker presents to your amplifier, and it tells you the amp needs to be comfortable delivering current into a moderately demanding load. The nominal figure is a representative average, while the 3.7 ohm minimum is the dip the amplifier will actually see at certain frequencies. That minimum is low enough that you want an amplifier with a stable power supply that does not fold under current demand, though it is not an exotically difficult load. Most competent integrated amplifiers and receivers rated for 6 ohm or 4 ohm operation will drive the Model Three without complaint. The takeaway is to favor amplifiers that specify their power into lower impedances rather than only into 8 ohms.
How much amplifier power should I use?
KLH recommends 30 to 150 watts, which gives you a wide and forgiving window for amplifier matching. The lower bound of 30 watts is enough to drive the speaker to satisfying levels in most rooms, given the sensitivity, while the 150 watt upper figure indicates the headroom the Model Three can absorb before you risk overdriving it. Because the sealed design stays clean at high volume, feeding it ample clean power lets those low-distortion dynamics shine, particularly on bass transients where the woofer is working against the air spring. There is little risk in aiming toward the upper half of that range, provided the amplifier is delivering clean watts rather than clipping.
What does the 46 Hz to 20 kHz frequency response imply?
The frequency response of 46 Hz to 20 kHz (plus or minus 3 dB) tells you the speaker reproduces the full treble range and reaches genuinely deep bass for a sealed bookshelf. The 20 kHz top end confirms the aluminum dome extends to the limit of human hearing. The 46 Hz bottom end is the more remarkable figure, because it represents real low-bass extension from a compact sealed cabinet, and thanks to the gentle sealed-box rolloff and room gain, useful output typically continues below that corner in practice. This is a full-range presentation for most music, and many listeners will not feel a pressing need for a subwoofer unless they chase the lowest organ pedals and cinematic effects.
Cabinet, Placement, and Lineage
Why does the cabinet and its riser base matter?
The cabinet matters because a sealed acoustic-suspension design depends on an airtight, non-resonant enclosure to make the air spring behave predictably, and the included slant-riser base further improves the presentation. The Model Three measures 19 by 12.25 by 10.5 inches and weighs 29 lbs each, rising to 28.25 inches tall and 36 lbs with the riser base fitted. That mass and the sealed construction help suppress cabinet resonances that would otherwise smear the sound. The slant-riser base is an angled plinth that tilts the speaker back slightly, which time-aligns the drivers at ear height when the speakers sit low, and adds stability. It is offered in English Walnut, Nordic Noir, and West African Mahogany finishes.
How should I place the Model Three in my room?
Place the Model Three on stands or the riser base with the tweeters near ear height, and use its proximity to walls together with the Acoustic Balance Control to dial in the tonal balance. Because it is a sealed design, the Model Three is more forgiving of near-wall placement than a rear-ported speaker, since there is no port to load or chuff against a nearby boundary. Moving it closer to a wall will reinforce the bass through boundary gain, while pulling it into the room tightens and lightens the low end. Once the physical placement is set, use the high-frequency switch to fine-tune the treble to the room's liveliness.
Where does the Model Three sit in the KLH lineup?
The Model Three sits as the compact acoustic-suspension bookshelf within a range that includes the larger Model Four, the floorstanding Model Five, and the flagship Model Seven. Each shares the sealed-box philosophy and the Acoustic Balance Control heritage that traces back to the original Model Five. As you move up the range, you gain cabinet volume, driver count, and in the case of the Model Seven, a dedicated sealed sub-enclosure that isolates the woofer from the midrange along with a more demanding 4 ohm load. The Model Three distills that same engineering into a bookshelf format, making it the entry point into the acoustic-suspension sound for listeners who want the KLH character in a compact package. All of it is backed by a 10 year warranty, a reflection of the build quality and the confidence behind this revived American loudspeaker heritage.