--- title: "Balanced Armature vs Dynamic Driver IEMs Explained" description: "How a balanced armature driver works, why IEMs stack several behind a crossover, how armatures make bass in a sealed ear, and what a hybrid IEM adds." url: "https://theaudiostuff.com/glossary/balanced-armature/" type: "article" author: "Jakub Charkiewicz" published: "2026-09-25T00:00:00.000Z" modified: "2026-09-29T00:00:00.000Z" --- > Markdown rendering of https://theaudiostuff.com/glossary/balanced-armature/ > Canonical URL to cite: https://theaudiostuff.com/glossary/balanced-armature/ > Generated from the published page. Text and links only; see the HTML for layout. Breadcrumb: [Home](https://theaudiostuff.com/) > [Glossary](https://theaudiostuff.com/glossary/) > Balanced Armature # Balanced armature drivers: how they work and why IEMs stack them {#term-title} A balanced armature is a miniature driver in which the music signal magnetizes a small metal reed balanced between two magnets. The reed rocks, and a pin passes the motion to a stiff diaphragm sealed inside a tiny case. Armatures are small and very efficient but usually strongest in one part of the band, so IEMs often stack several behind a crossover or pair them with a dynamic driver in a hybrid. - By [Jakub Charkiewicz](https://theaudiostuff.com/authors/jakub-charkiewicz/) - Published Sep 25, 2026 - Updated Sep 29, 2026 - 5 min read ## Glossary definition {#term-define-title} - **Balanced Armature**: A miniature driver used in IEMs where a metal armature pivots between magnets, allowing multiple drivers to be stacked in a very small shell. ## Inside a balanced armature {#inside-a-balanced-armature} The motor is built around the armature, a thin strip of magnetically soft metal. Part of it passes through a small coil, and its free end sits in a narrow gap between two permanent magnets, held exactly midway, where the pull from each side cancels. That balance gives the driver its name. When the music signal flows through the coil, it magnetizes the armature, which is drawn toward one magnet and pushed away from the other. The tip rocks by a tiny amount, and a drive pin carries that motion to a light, stiff [diaphragm](https://theaudiostuff.com/glossary/#diaphragm). The whole assembly sits in a sealed metal case a few millimeters long, with one port for the sound. Miniature armature drivers were developed for hearing aids, which need a receiver small enough to hide in the ear and frugal enough to run from a button cell. Both traits carried over. An armature is very efficient, since its motor drives only a tiny moving part, and it's self-contained, so it can sit anywhere in a shell and be piped to the nozzle through a tube. ## Why in-ears carry several of them {#why-in-ears-carry-several-of-them} A single armature can cover most of the audible band, and some in-ears use just one. Each unit's output is shaped by its own resonances and by the tube it plays through, though, so it tends to be strongest in one region. Makers build variants for each job, larger units for the [bass](https://theaudiostuff.com/glossary/#bass), others for the [midrange](https://theaudiostuff.com/glossary/#midrange) and small ones for the treble, and give each its share of the band. The division is part electrical and part acoustic. A passive network of small capacitors and resistors splits the signal between the drivers. The plumbing then shapes each output: the length and width of each driver's tube, and any damper in it (a mesh or fiber plug that acts as an acoustic resistor). The tubes end in the nozzle's sound bores, and the outputs combine in your ear canal. The [Kiwi Ears Orchestra Lite](https://theaudiostuff.com/reviews/kiwi-ears-orchestra-lite/) shows the layout at $249: eight armatures on a 3-way [crossover](https://theaudiostuff.com/glossary/crossover/), with two ultra tweeters, four midrange units and two for the bass. Its review notes what that count costs in the fit, a nozzle made extra thick by the crossover and the number of drivers inside. ## How an armature makes bass in a sealed ear {#how-an-armature-makes-bass-in-a-sealed-ear} In open [air](https://theaudiostuff.com/glossary/#air) an armature can barely make bass, because its diaphragm is tiny and hardly moves. An [IEM](https://theaudiostuff.com/glossary/iem/) changes the job. Sealed in the ear canal, the driver only has to change the pressure in a closed space of a cubic centimeter or two, and in a space that small the pressure follows the diaphragm's movement closely, so the output can stay level deep into the bass. The condition is the seal. An armature is sealed in its own case and needs no vent behind it, so an all-armature shell can be closed completely. The [Kiwi Ears Belle, Cadenza II and Orchestra II](https://theaudiostuff.com/reviews/kiwi-ears-belle-cadenza-orchestra/) review credits the ten-armature Orchestra II's non-vented resin shells with better isolation. A leak at the ear tip lets the bass escape, and an armature has little movement in reserve to make it up. If an armature IEM sounds thin, check the fit before you judge the driver. Beyond that, the amount of bass is a tuning decision. The [Orchestra Lite](https://theaudiostuff.com/reviews/kiwi-ears-orchestra-lite/)'s bass rolls off in the [sub-bass](https://theaudiostuff.com/glossary/sub-bass/), while the Orchestra II's review hears clear low bass once a proper dongle drives it. ## What is a hybrid IEM? {#what-is-a-hybrid-iem} A hybrid puts more than one driver type in one shell. The usual pairing is a [dynamic driver](https://theaudiostuff.com/glossary/dynamic-driver/) for the bass with armatures above it, so each works where it's strongest. The [Simgot EM6L](https://theaudiostuff.com/reviews/simgot-em6l/) does this at $109, with one dynamic and four [balanced armatures](https://theaudiostuff.com/glossary/#balanced-armature) on a hybrid 3-way crossover, tuned toward the Harman 2019 in-ear target. Its review finds the sub-bass and treble mostly on target and some extra mid-bass energy that can muffle vocals. Hybrid only means mixed types, and the partner isn't always an armature. The [KBEAR KB02](https://theaudiostuff.com/reviews/kbear-kb02/) pairs a 10 mm [beryllium](https://theaudiostuff.com/glossary/#beryllium)-plated [dynamic driver](https://theaudiostuff.com/glossary/dynamic-driver/) with a bone conduction driver that KBEAR tuned for the lowest frequencies. The hard part of any hybrid is the handover. Where two drivers share a band their outputs have to add up smoothly, and a poor match leaves a step in the response or a dip where they overlap. ## Output impedance and multi-armature sets {#output-impedance-and-multi-armature-sets} An armature's coil is strongly inductive, so its [impedance](https://theaudiostuff.com/glossary/impedance/) rises with frequency, and a crossover adds peaks and dips of its own. The impedance of a multi-armature IEM can swing a long way across the band. The Orchestra II's review gives its impedance as a range, 15 to 30 ohms, where most spec sheets print one number. That swing meets the source's [output impedance](https://theaudiostuff.com/glossary/impedance/#output-impedance-and-the-one-eighth-rule). The two form a voltage divider that takes more signal away where the IEM's impedance is low, so an uneven curve turns into an uneven response, and the same IEM can sound different on two sources with different output impedances. The fix is the rule of eighths applied to the lowest point of the curve instead of the nominal figure. With the source's output impedance under one-eighth of the IEM's minimum, the response moves by no more than about 1 dB anywhere in the band, however far the curve swings. For most multi-armature sets that means an ohm or two at most. The [impedance explainer](https://theaudiostuff.com/glossary/impedance/) covers the voltage divider in full. ## What a driver count tells you {#what-a-driver-count-tells-you} On its own, very little about the sound. Several armatures sharing a band can give more [headroom](https://theaudiostuff.com/glossary/gain/#headroom-and-why-gain-adds-none) there, but every extra crossover region is another place where two outputs have to sum in phase. More drivers also mean more tubes, more dampers and more assembly work, all of which has to be matched from one shell to the next. The Orchestra II's review praises its ten armatures for staying coherent, with no audible overlap between them and no obvious dips, which is what a high count has to achieve to be worth having. What reaches you is the [frequency response](https://theaudiostuff.com/glossary/frequency-response/) at your eardrum, set by the tuning, the integration and your fit. The [best IEMs guide](https://theaudiostuff.com/guides/best-iems/) ranks in-ears by score, whatever the shell holds, and the [IEM explainer](https://theaudiostuff.com/glossary/iem/) covers fit and ear tips. ## Reviewed gear that shows this {#term-products-title} 5 reviews in the catalogue. Each score is set against its own category's reference. - [![Kiwi Ears Belle earpieces on wood, one filigree-engraved faceplate up, joined by a twisted silver cable](https://theaudiostuff.com/images/thumb/kiwi-ears-belle-earpieces-160.avif) Kiwi Ears Belle, Cadenza II, Orchestra II Recommended $30 to $350 Score 8.1 out of 10](https://theaudiostuff.com/reviews/kiwi-ears-belle-cadenza-orchestra/) - [![Two blue Kiwi Ears Orchestra Lite earpieces in an open black box with a silver starburst logo](https://theaudiostuff.com/images/thumb/kiwi-ears-orchestra-lite-transparent-shells-160.avif) Kiwi Ears Orchestra Lite Recommended $249 Score 8.0 out of 10](https://theaudiostuff.com/reviews/kiwi-ears-orchestra-lite/) - [![Kiwi Ears Atheia closed-back headphones on a stand, with the retail box behind them](https://theaudiostuff.com/images/thumb/kiwi-ears-atheia-on-stand-160.avif) Kiwi Ears Atheia Recommended $349 Score 7.9 out of 10](https://theaudiostuff.com/reviews/kiwi-ears-atheia/) - [![Two glossy black Simgot EM6L shells with white silicone tips, three spare tips loose on a wooden table](https://theaudiostuff.com/images/thumb/simgot-em6l-shells-eartips-160.avif) Simgot EM6L Recommended $109 Score 7.6 out of 10](https://theaudiostuff.com/reviews/simgot-em6l/) - [![KBEAR KB02 on a wooden table, wrapped in its black braided cable with a gold 3.5mm plug](https://theaudiostuff.com/images/thumb/kbear-kb02-braided-cable-160.avif) KBEAR KB02 Mixed $39 Score 6.9 out of 10](https://theaudiostuff.com/reviews/kbear-kb02/) ## What our reviews say about balanced armatures {#term-said-title} 3 reviews raise it in their pros and cons: 3 lines credit it and 0 fault it. each quoted as its review states it. - Strength: Orchestra II's 10 balanced armatures stay coherent and linear - [Kiwi Ears Belle, Cadenza II, Orchestra II](https://theaudiostuff.com/reviews/kiwi-ears-belle-cadenza-orchestra/), 8.1/10 - Strength: 8 balanced armature drivers with 3-way crossover - [Kiwi Ears Orchestra Lite](https://theaudiostuff.com/reviews/kiwi-ears-orchestra-lite/), 8.0/10 - Strength: 1 dynamic + 4 BA drivers with hybrid 3-way crossover - [Simgot EM6L](https://theaudiostuff.com/reviews/simgot-em6l/), 7.6/10 ## Put it to use {#term-use-title} - [Buying guide Best IEMs This list ranks the best in-ear monitors for audiophile music listening at every price, from a $30 wired pair with a microphone to a $499 true wireless set. 7 ranked picks, led by the HIFIMAN RE2000 PRO Silver](https://theaudiostuff.com/guides/best-iems/) ## Sources and further reading {#term-sources-title} - [Jensen (2014): Nonlinear distortion mechanisms and efficiency of balanced-armature loudspeakers](https://orbit.dtu.dk/en/publications/nonlinear-distortion-mechanisms-and-efficiency-of-balanced-armatu/) Thesis Technical University of Denmark Doctoral research on how balanced armatures work through the magnetic domain, and why they are inherently nonlinear. - [Bække (2024): Vibroacoustic characterization and modeling of the balanced armature receiver in hearing aids](https://orbit.dtu.dk/en/publications/vibroacoustic-characterization-amp-modeling-of-the-balanced-armat/) Thesis Technical University of Denmark Doctoral research describing balanced armatures as power-efficient miniature loudspeakers, the only receiver technology used in hearing aids. ## Keep reading {#term-more-title} - ### [IEM](https://theaudiostuff.com/glossary/iem/) In-Ear Monitor, a headphone whose shell seals inside the ear canal instead of covering the ear. - ### [Crossover](https://theaudiostuff.com/glossary/crossover/) A network of filters that divides the audio signal into frequency bands before each reaches its appropriate driver, passive (in the speaker) or active (before the amp). - ### [Dynamic Driver](https://theaudiostuff.com/glossary/dynamic-driver/) The most common transducer type, using a voice coil in a magnetic gap to push a cone or dome diaphragm, the same principle as a traditional loudspeaker. - [The full audio glossary](https://theaudiostuff.com/glossary/) - [How we test](https://theaudiostuff.com/about/how-we-test/) Written by ## [Jakub Charkiewicz](https://theaudiostuff.com/authors/jakub-charkiewicz/) {#term-author-title} Founder & lead reviewer Writing for The Audio Stuff since May 2023 [Everything by Jakub](https://theaudiostuff.com/authors/jakub-charkiewicz/) [@TheAudioStuff](https://www.youtube.com/@TheAudioStuff) [LinkedIn](https://www.linkedin.com/in/jakub-charkiewicz) [Report a correction](mailto:contact@theaudiostuff.com?subject=Correction%3A%20Balanced%20Armature%20explainer&body=Page%3A%20https%3A%2F%2Ftheaudiostuff.com%2Fglossary%2Fbalanced-armature%2F%0A%0AWhat%20looks%20wrong%2C%20and%20where%20you%20read%20the%20right%20figure%20(if%20you%20have%20a%20source)%3A%0A%0A)