How many armatures do I need in my headphones?
Despite their small size, headphones can consist of one or more armatures and filter parts. Different headphone styles can feature significantly different technology. In a broad sense, the more components, the more expensive they are. But, are there really significant differences?
Before we answer the question, here are some pertinent terms:
Armature: The part of an electromagnetic device—in this case, a loudspeaker—that moves or vibrates; it is analogous to a driver.
In-ear monitor (IEM or IE): This is a professional-level headphone customized to fit your ear canals. Performers use these to minimize stage volumes, so they can hear the monitor mix clearly at lower volumes, thus saving their hearing. Clearer sound also helps to keep the performer on pitch and to maintain good timing.
Personal monitors (PM): Earphones with armatures used for personal audio playback.
Earbuds: Headphones with internal moving coil transducers.
Here’s how the use of armatures vary at different price points:
Entry Level: Entry level PM's use a simple balanced armature. The challenge the engineer has primarily rests in the design of the armature, particularly the damper and nozzle design. It’s difficult to achieve full range, since the transducer will work well in the low frequency (LF) or the high frequency (HF), but not generally in both (wideband). Typically, bass, vocals or drums suffer the most with this design, sounding slightly harsh, or not having audible output in a given range. In other words, the vocal sounds throaty or scratchy, depending on the model.
There is also limited sound pressure level (SPL) with the balanced armature, due to its design. Even with these potential disadvantages, it sounds better than traditional moving coil designs; since the mass of the diaphragm is smaller, the HF is much more accurate than with a standard earbud. The Klipsch Custom 1 has been optimized to give the best balance of LF and HF. This design uses a KG332 armature.
Mid Level: These PM's use either smaller premium single armatures or dual armatures with minimal—or no—EQ. Each product has its limitations and advantages.
For Klipsch's Image series PM’s, a premium armature is used; in this case, our proprietary KG926 driver. The KG926 is ultra-compact. Less weight generally results in greater comfort, because there is less force on the ear canal. This model has a proprietary "special sauce"—a unique technology which delivers very full range with delicate highs and smooth, deep bass. The sound is very accurate, due to its lightweight diaphragm. Vocals are silky smooth and drums have a nice snap to them.
Because of its size, a good air seal is required to prevent loss of bass. The micro-small chassis with its thin, aluminum extruded body places the armature closer to the eardrum than any other manufacturer’s headphones, creating a more accurate sound by reducing the volume of air modulated in the ear canal. Precision machining is required to make this model and the design is remarkably intricate, due to its size. The patent-pending Contour Ear Gel also ensures a better seal, since the oval shape—and different sizes—can achieve a fit that’s compatible with the user’s ears.
Other mid-level designs, such as our Custom 2, use dual armatures. For our Custom 2 design, we partnered with Sonion and have applied for an armature patent. The KG534 driver is really two drivers: two motors, two armatures and two diaphragms in tandem (back to back). The benefit of this design is that the diaphragms pump air in opposing directions, so vibration modes are minimized. This design would be similar to having dual air bellows with a single nozzle on a fireplace tool. With dual diaphragms, the SPL increases by 3dB and distortion decreases because they aren’t working as hard as a single unit.
Part of our applied patent revolves around the low-pass acoustic filter that is built into one of the two armatures. This gives us greater control over EQ, since we can have two pistons—one optimized for bass and one optimized for full range. This baby rocks! Musicians will love this product because it is affordable, yet very efficient. Vocals will stand out in the mix with an IEM application.
High Level: Most top-line PM's use two or three armatures and a passive crossover. Our Custom 3 goes much further. Not only does it have two different types of drivers and a second order passive crossover for both armatures, it also has a patent-pending low-pass acoustic filter.
The Custom 3 utilizes a Klipsch premium KG723 armature for the HF tweeter. This allows vocals to be ultra-silky and very low in distortion. The LF is implemented with a KG732 armature for the woofer. The Custom 3 also has two acoustic low pass filters: the armature has an internal LP filter plus the patent-pending LP filter on the outside, which is optimized for a very low crossover point without sacrificing sensitivity in the lower region of the response.
The passive crossover has more components than any other comparable headphone. With the two acoustic filters and second-order crossover, the LF has a 24dB per octave slope rolled off at 1kHz. Why so low? Most other headphones cross-over above the vocal region, but we wanted to eliminate intermodulation distortion (IMD), so we have removed the kick drum and bass tones from the tweeter, so the diaphragm can concentrate on reproducing highs without movement from the LF signal. This also allows us to take advantage of the shape of the crossover for additional EQ in the midrange. With Custom-3, the vocals are so natural that high frequencies won't fatigue your ears the way most designs can.
For those who appreciate good clean bass, Klipsch headphones deliver. These headphones are flat below the musical bandwidth, offering virtually no limitation to the bass.
So, how many armatures do you need in your headphones? Because you know your budget, your music source and your personal preferences, you’ll have to be the judge—but, when it comes strictly to sound quality, the number of armatures really does make a big difference in IEM headphones.