Headphones date from the beginnings of the history of the telephone and the radio. The weak electrical signals of the early instruments were enough to operate only headphones audibly.
They are normally detachable, using a jack plug. Typical products to which they are attached include the walkman, mobile phone, CD player, Minidisc player, digital audio player (MP3 player), and personal computer. Headphones can also be used with full-size stereo components. Some headphone units are self-contained, incorporating a radio receiver. Other headphones are cordless, using radio (for example analogue FM, digital bluetooth, Wi-Fi) or infrared signals to communicate with a "base" unit.
Headphones may be used to prevent other people from hearing the sound either for privacy or to prevent disturbance, as in listening in a public library. They are also used to exclude external sounds, particularly in sound recording studios and in noisy environments. Another advantage of headphones over conventional speakers is that the listener experiences total stereo-separation with no mixing of the left and right channels, helping them pinpoint the 'location' of sounds with much greater accuracy. This is of special relevance to videogames that use 3D positional audio, allowing players to better judge the position of an offscreen sound (such as the footsteps of an opponent). A good example of this 3D positioning in action is the game Battlefield 2 for PC. Headphones are almost required in order to listen for enemies firing around you, or someone sneaking behind you for a quick knife kill.
Headphones generally use a 3.5 mm "mini pin" jack.
Types of headphones
In descending order of size:
These type of headphones have pads that go around the ears, usually very large and very comfortable. This is the type typically used in recording studios. Examples include: AKG K501, Audio-Technica ATH-A900, Beyerdynamic DT880, Sennheiser HD650, Bose Tri-Port Headphones, and Sony MDR-SA5000.
These type of headphones have pads that go on top of the ears. They were commonly bundled with personal stereos during the 1980s. Examples include: Grado SR-60, Koss Sportapro, Sennheiser PX-200.
Earbuds (American English) or Earphones (British English) are small headphones that are placed directly outside of the ear canal, but without fully enveloping it. Earbuds are generally inexpensive and are favored for their portability and convenience. However, due to their inability to provide isolation, they are not capable of delivering the precision and range of sound offered by many full-sized headphones and canalphones.
During the 1990s, they became the most common type bundled with personal stereos. For example, the distinctive white headphones included with the iPod are earbuds.
Professional canalphones (also known as "in-ear monitors") were originally developed for professional audio by Marty Garcia in the early 1980's and designed to be placed inside the ear canal, positioning them closer to the eardrum than other types of headphones. They have excellent isolation quality (up to 32 dBs) because they fit in much the same way as earplugs. Isolation from canalphones is generally superior to that provided by active noise cancellation mechanisms. Hearing aids are a type of canalphone.
Canalphones are traditionally used by live performers as an alternative way of monitoring their music as they allow the performer to protect themselves from the high amount of competitive stage noise present, while mantaining audio fidelity. Their use can eliminate the need for unsightly onstage monitor speakers and feedback problems, and to allow the audience an unobstructed view of the performers. Also, as canalphones can be molded in various colors and sizes, a flesh tone that completely fits inside the ear is commonly preferred by performers for its discreetness.
Despite their roots in live monitoring, canalphones manufacturers have branched out to cater to the audiophile market. Many manufacturers now offer universal fit tips in contrast to the custom ear molds that were the trademark of canalphones which, although offering higher quality, required a trip to a audiologist to make.
A common misconception with canalphones is the higher risk of hearing loss. However, as canalphones block out large amounts of noise, the listener can enjoy his music without being forced to turn it up to a higher level. This is especially true when canalphones are utilized "on the street". With proper discipline, canalphones actually help to prevent hearing loss if the volume is carefully maintained.
The main canalphone manufacturers and their more popular models are :
Dynamic drivers use magnetic material attached to a diaphragm that oscillates back and forth. This is the most common type of driver used in headphones.
A thin, electrostatically charged diaphram (typically a coated mylar membrane), is suspended between two perforated metal plates (electrodes). The musical signal is passed through the plates and depending upon the signal, the membrane is drawn towards one of the plates forcing air through the perforations. This continuous movement of the membrane generates the soundwave. Examples of electrostatic headphones are the Stax SR-007 Omega II, and the Sennheiser HE90 "Orpheus".
Usually used only in canalphones such as sensaphonics.
Open headphones (sometimes marketed as "open air" headphones) have an open grille on the back of the driver, allowing the sound to vent freely. This usually makes open headphones sound better than closed ones of the same cost range. They also expose the user to more outside sound in cases where that is desirable. Examples of open headphones: AKG K-501, Grado RS-1, Sennheiser HD-650.
Closed headphones are just that, closed backing. Usually these are used where isolation is preferred over sound quality. Examples of closed headphones: AKG K271S, Audio Technica ATH-A900, Sennheiser HD 280 Pro, Sony CD3000.
A headband goes over the head. It is usually used with circumaural and supra-aural headphones, but is sometimes used with earbuds or canalphones.
Behind the neck
Behind the neck go behind the neck, and are usually used in portable supra-aural headphones. They do not disturb one's hair like an over-the-head headband does, and can be worn with hats, etc. This now-popular style was newly popularized recently by a particularly trendsetting pair by Sony.
A clip secures the earpiece with a clip that goes behind the outer ear. Usually used with earbuds, but also sometimes used with supra-aural headphones or canalphones.
Many earbuds and canalphones do not need or have anything to secure themselves inside the ear.
Using headphones at a sufficiently high volume level causes temporary or permanent hearing impairment or deafness. Other risks arise from the reduced awareness of external sounds - some jurisdictions regulate the use of headphones while driving vehicles. Also, most European countries have imposed high penalties since 2002 on drivers not using a headset while operating a mobile phone in a car, to ensure that drivers keep their hands on the vehicle's controls.
Some headphone amplifiers have an optional input capacitor. This article discusses the tradeoffs involved in choosing this capacitor's value, or for choosing to eliminate it entirely.
The comments in this article were made with the CMoy Pocket Amp, META42, MINT, PPA and PIMETA amplifier circuits in mind, as they are the only ones I have extensive personal experience with. In some other circuits, the input capacitor is absolutely required due to the design of the circuit, so it cannot be eliminated. You must understand your amplifier's design before you try to apply this article's information to it.
In circuits like those I mentioned above, the input capacitor is not required in the ideal situation. They receive an incoming AC signal (music), and they amplify it for the headphones. Very straightforward.
But in real life, music sources have some DC offset: the AC signal is shifted by some constant DC level. The amplfier multiplies the source's DC offset by the amp's gain, and adds some offset of its own. If this total offset is large enough, it can damage headphones, so a source that has an acceptably low DC offset can still become a problem when used with an amplifier.
DC offset is a problem because it can either strain the headphone driver by pushing it one direction continually, or by heating up the coil to the point where damage occurs.
A conservative limit is 20mV across the driver. If your amp has a gain of 10, then the source must have a DC offset of no more than 2mV, and that's assuming that the amp has no DC offset of its own.
How Do You Measure DC Offset?
Put your meter on the DC millivolts scale and measure from ground to each channel.
It's most useful to measure this at the output of the amp, while it is plugged into the source. If your amp uses mini jacks (1/8"), put a mini-to-mini cable in the jack and measure from the long "sleeve" part to the "tip" and "ring" parts out at the end of the plug. With 1/4" jacks, it's a bit tougher because 1/4" to 1/4" cables aren't very common. Instead, it's simplest to measure between the solder lugs on the inside of the amp. If you don't want to open the amp up and can't find a 1/4" patch cable, a 1/4" to dual RCA adapter will also work: just measure from the inside of each RCA jack to the outer shell.
You can also measure DC offset at the source. Remember to multiply this by the amp's gain when deciding if it's acceptable.
What is 'burn in'?
When speaking of headphones, 'burn in' is the term used for the settling oft he design parameters of the diaphragms into their intended state. The physical process is that the diaphragms loosen up through use and eventually reach a point that could be considered final. A similar situation is breaking in a new pair of shoes.
Why do people choose to burn in a new pair of headphones shortly after getting them?
Fresh out of the box, a pair of headphones may not sound as good as a well used pair, as the designers have intended. Often, people want their headphones to sound the way that they are intended as soon as possible. Most people don't want to wait for weeks or months of regular use, so the choice is to expedite burn in by getting the process over with in the first week of ownership. Others choose to listen to their headphones as they change over the burn in period.
How do I burn in my new pair of headphones?
You can simply play music through them continuously. Some prefer using pure tones, sine wave sweeps, pink noise, or AM/FM static for burn in. Some recommend using bass heavy music. The method of burning in a headphone does not change depending on model or manufacturer.
Which burn in method is most efficient?
There is no scientific evidence proving that one is better than the other. Choose the method that you prefer.
What do I do with my headphones while they are burning in?
You can set them on a table, put them in a sock drawer, put them under some pillows, or put them on your head. It's up to you.
Do I have to burn in my new pair before I listen to them?
No. You can listen to your new pair of headphones straight from the box. Whether or not to burn in your headphones is your choice. As you listen, you may hear gradual changes in the sound through use. Some people choose to listen periodically during the process, while some hold out until the process is complete. While still others listen for the burn in throughout the entire process listening from day one and enjoying the evolution in sound.
How much does burn in effect the sound of the headphones?
Some say burn in has a drastic effect, some say there is little effect, and some say that there is no effect. The amount of change resulting from burn in will be different for each model of headphones.
How long should I burn in my new pair?
Many recommend approximately 100 hours for most headphones. Some recommend as many as 200 hours or more. Different headphones may take longer than others for a so-called 'complete' burn in, and there is no exact or set length of time for burn in. It is best to use your ears to listen for changes to decide when you should stop the burn in process.
When is burn in complete? Can I burn in too much?
The idea behind initial burn in is to reach the point at which audible changes stop occurring and you are left with drivers than have settled into the sound that they will have forever after, the sound that it was designed to have. After that point, regular use of the driver won't cause significant change in the sound, until perhaps years and years later when thousands upon thousands of hours have passed and the life of the driver is at its end. However, some say that burn in is never complete. The argument is that regular, long-term use constantly wears on the drivers and that wear always has an affect on the sound. Still, it is safe to say that, after a driver has reached its designed parameters through burn in, regular use won't cause significant audible changes.
Is there a wrong way to burn in my headphones?
You risk damaging your headphones at any time by using extremely high volumes. Some recommend setting the volume to a comfortable listening level during burn in, while others recommend a volume slightly higher than your normal listening level. If you hear distortion, pops, or cracks due to high volume, you are likely doing damage to the drivers. Also, using very low volumes will not be very effective in burning in your headphones.
Is burn in actually real?
The idea of burn in has always been controversial. Some people say that there is evidence that proves it while others say that there is evidence to disprove it. Some consider the phenomenon to be purely psychological conditioning while others insist upon physical changes to the drivers, and some agree upon a combination of the two. You are free to be a believer, and you are free to be a skeptic. Whether or not you believe in it and the position you take on the subject is a choice that you should make for yourself.
Is there anything else that I should know?
Burn in has been discussed at length over the years of Head-Fi. Any question you have concerning burn in has likely been asked numerous times, and by using the search function and reading through previous threads, you will almost surely find answers and opinions. This FAQ has been created to limit the number of redundant threads posted by newcomers or especially curious existing members of the Head-Fi community asking the same questions that have been asked in the past. The subject of burn in is not especially complicated or involved, nor is it something to have great concern about, nor is it an exact science. Opinions, methods, and results vary from person to person, headphone to headphone, system to system.
Sorry, no time to write my own articles hope these helps.
This post has been edited by AlamakLor: Nov 18 2005, 07:10 AM