Klipsch R-40M Review

The number that matters: 91 dB

Klipsch publishes 91 dB sensitivityfor the R-40M, qualified on their own spec sheet as an in-room figure measured at 2.83 V into half-space. On a small bookshelf speaker that is a high number, and it is the single most consequential specification on the sheet.

Read the qualification honestly: an in-room, half-space measurement flatters a speaker relative to a full-anechoic one, so treat 91 dB as a figure to compare against other Klipsch models rather than as a laboratory absolute. Even discounted, it sits well above the class.

Sensitivity is how loud a speaker plays for a given electrical input, and the arithmetic is unforgiving in a useful way: 3 dB of extra sensitivity is worth a doubling of amplifier power. A typical competitor at 86–87 dB needs roughly twice the amplifier for the same volume. An 85 dB speaker needs four times.

What that buys you in practice:

• A cheaper amplifier does the job.A 25–30 W integrated amp drives these to volumes most people never reach at home.
• You stay out of clipping. The commonest way to kill a tweeter is an underpowered amplifier pushed past its limit. High sensitivity keeps the amplifier working well inside itself.
• Budget shifts to the source.If the speakers do not force you into a large amplifier, the money can go into the turntable and cartridge instead — which is where it does more good.

This is also why the R-40M appears in our amplifier-and-speaker pairings as the middle recommendation: it makes a modest receiver behave like a bigger one.

What a Tractrix horn is doing

The tweeter is a 1-inch aluminum dome, but it is not firing directly into the room. It sits behind a 90x90 square Tractrix horn— a flared waveguide with a specific mathematical profile. Klipsch describes the Next-Generation horn as having larger outer dimensions than the one it replaces, which is their stated reason for claiming directivity control across a wider band of frequencies.

A horn does two things. First, it acts as an impedance match between the small, stiff tweeter diaphragm and the large volume of air in the room, which is where a large part of that 91 dB sensitivity comes from. Second, it controls dispersion: the “90x90” means the horn is designed to spread sound across roughly 90 degrees horizontally and vertically and not much beyond.

Controlled dispersion is genuinely useful in a small or reflective room, because less high-frequency energy is thrown at the side walls and ceiling to arrive back at your ears late and smeared. It is also why Klipsch speakers reward being aimed at the listening position rather than pointed straight down the room.

The cost is that horns sound different. More immediate, more forward, and to some listeners harder than a conventional dome. Klipsch’s Linear Travel Suspension is their answer to that — a low-mass Kapton suspension intended to reduce distortion in the tweeter’s movement. Whether the result reads as “detailed” or “bright” is a genuine taste question, and we have not heard this pair, so we are describing the design rather than pronouncing on the sound — see how we pick.

71 Hz: the honest limitation

Klipsch publishes a frequency response of 71 Hz – 21 kHz ±3 dB. The number to look at is the 71.

A four-inch woofer in a small cabinet cannot move enough air to produce deep bass, and no amount of engineering changes that. Below 71 Hz the output falls away. In musical terms, that is the bottom of a bass guitar’s range and most of what a kick drum contributes below its attack.

Two honest readings of the same fact. On one hand, plenty of music lives entirely above 71 Hz and the R-40M will play it complete — and a small box that does not attempt deep bass often sounds tighter in the upper bass than one that tries and fails. On the other, if you listen to electronic music, hip-hop or organ recordings, you will notice what is missing and you should either buy a larger speaker like the ELAC B5.2 or Q Acoustics 3030i or plan for a subwoofer.

The cabinet, the woofer and the ports

The woofer is a 4-inch spun-copper TCPcone — thermoformed crystalline polymer, which Klipsch says it borrowed from the Reference Premiere line for its steeper cone angling and added ribbing. The copper color is Klipsch’s long-running visual signature rather than an acoustic property.

The cabinet is MDFin a textured wood-grain vinyl finish, at 11.7 by 5.8 by 8.5 inches and 7 lbs each, and it is bass-reflex via rear-firing ports. That port placement is a real constraint rather than a detail: a rear-ported speaker shoved against a wall gets a boomy upper bass, so leave a few inches behind them or accept the coloration.

Nominal impedance is published as 8 ohms compatible, which makes these an easy load, and the crossover sits at 1,770 Hz. Any amplifier rated for 6–16 ohms or 4–8 ohms will drive them without complaint, and that includes the inexpensive stereo receivers with phono inputs in our amplifier roundup.

Setting them up for vinyl

Three things matter more than usual with a horn-loaded speaker:

1. Toe them in. Controlled dispersion means aiming matters. Point each speaker at the listening position rather than straight ahead, and the stereo image tightens noticeably.
2. Get the tweeters near ear height. The vertical dispersion is also about 90 degrees, so a speaker on a low shelf firing past your knees is throwing its treble at the floor. Stands or a shelf at seated ear height.
3. Keep them away from the turntable.This applies to every speaker in a vinyl system but especially to efficient ones, because they will be producing more sound pressure for the same amplifier setting. Speaker energy reaching the plinth becomes acoustic feedback — see troubleshooting.

Who should buy them

Buy the R-40M if you are building a separates system on a real budget and want the amplifier to be the cheap part; if your room is small; or if you value detail and immediacy over low-end weight.

Buy the ELAC Debut B5.2 instead if you want more bass extension and a more relaxed balance for the same sort of money, accepting that you will need a bit more amplifier. Buy a powered pairinstead if you would rather not own an amplifier at all — the trade is set out in powered vs passive.