Headphones, earphones, in ear monitors, media players, get the lowdown on the tantalizing world of personal listening
A headphone amp is an amplifier specifically designed to power or drive your headphones. Your smartphone, for example so long as it has a headphone socket, has a headphone amplifier built-in. But here we're talking about a standalone headphone amp that'll derive max performance from your headphones, especially higher impedance designs. Higher impedance headphones – think 25 ohms and above – require more power, which is where the headphone amp comes in. If your headphones sound quiet, you likely need a headphone amp. A capable headphone amp can boost the audio performance of pretty much any headphones, but the more capable the cans, the more pronounced the results.
The wireless reference refers to the absence of wire between the headphones and the music device. However, with this convenience comes a compromise. Most wireless headphone designs use Bluetooth to enable wireless communication. However, even the latest Bluetooth audio codecs (codec is short for compression/decompression) don't have the required bandwidth to deliver hi-res audio fully intact. Sony's LDAC- currently the most capable of the available codecs tops out at 990kbps, well short of even CD quality.
Some wireless designs also offer a wired connection – connecting via a cable remains the way to max performance levels but if this is important to you, look for a design that has jack rather than a USB input as this will bypass the decoding of the headphone.
Noise cancellation headphones use active noise cancellation (ANC) technology to block out background sounds. Noise-cancelling designs rely on electronics, unlike noise isolating models, which depend on a physical structure to defeat ambient interference. Most modern noise cancelling headphones use a pair of microphones to compare noise levels inside and outside the enclosure which allows them to dynamically adjust the amount of noise cancelling they need to apply.
Bone conduction headphone technology has its origins in the hearing aid market. The tech doesn't rely on the eardrum but instead sends information by routing vibrations from the cheekbones directly to the cochlea. When it comes to audiophile performance, bone conduction technology has a way to go. Still, for those looking to remain audibly aware of their surroundings, such as cyclists and runners, bone conduction headphones leave the ear canals open to the outside world.
Closed-back headphones employ a sealed shell for the earcup. The result of this design is an immersive experience, one where minimal sound 'leaks' from the headphones. So, suitable for noisy environments such as public travel, you'll be better isolated from external noise. Thanks to the lack of sound spillage, your music listening will also be less of a bother to others nearby but can also suffer from sounding a little congested and closed in compared to an open design.
Open-back headphones allow air – so, sound – to pass through the earcups. Up against a closed-back design, you'll likely experience a more airy, natural listen. Also, detail levels with open-backs can be high, helping explain the design's popularity among music engineers. Your headphones will leak sound, though, and open-back cans are poor at blocking external sounds – so, good for home listening, great for mixing, but extremely irritating for other travellers on the London underground.
Also known as on-ear, the earcups of super-aural headphones rest directly on your ear. On-ear headphones tend to be lighter and smaller than over-ear designs. Consequently, they are better suited for those looking to 'travel light'. However, an on-ear design doesn't provide the same 'seal' around your ears; therefore, it doesn't block outside noise as well. The smaller design also often means smaller drivers than over-ears, so potentially less dynamic range. Check for comfort, too, as the pressing of the cups on your ears can prove uncomfortable for longer listening sessions.
Let's unpack this one, class – circum, meaning around, plus aural meaning related to the ear or hearing. So, the ear cups of circumaural headphones fit around your ear. Also known as over-ear, advantages of this design include its good levels of noise cancellation thanks to the seal formed around your ears. You also tend to get bigger, more capable drivers meaning potentially excellent sound quality. Comfort is also good, given that the ear cups don't rest directly on your ears. Over-ears can be bulky, though, so less well suited to on-the-go activities, and, under prolonged use, the headphone band can become uncomfortable.
Most headphones on sale use a dynamic driver; effectively a shrunken version of the type used in more conventional speakers. Some headphones though make use of planar magnetic drivers. This comprises a thin film that has a voice coil printed on it. This coil excites the whole film when a signal is passed through it. A planar magnetic driver is lighter than a dynamic driver and can respond faster but can lack the same level of low end extension.
Electrostatic headphones are musch rarer and work on a modified but similar principle. A thin film is excited by having an electrostatic force applied to it via an external field. This is even more responsive than a planar magnetic design but the field needs power that is usually supplied by a dedicated headphone amplifier and there are further limits both to the absolute volume level that can be achieved and the level of bass output.
In essence, balanced drive is a headphone amplifier design scheme that delivers 'balanced' equivalent and opposing (i.e., negative/positive) audio signals independently to each side of the headphone driver coils. This both increases the voltage available to the driver while lowering distortion and reducing crosstalk (the unwanted transmission of audio from one channel to another). To achieve this, balanced headphones will need to use either a 2.5mm or 4.4mm four pole jack or a single four pin XLR or twin three pin XLR sockets and have access to a balanced source to supply the signal.