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Anyways...
Reading the Box
On the back of the box on for a pair of headphones you would usually see information like:
- Frequency response
- Transducer principal/type
- Open or closed
- Stereo vs surround
- Impedance
- Weight
- Cable length
- Jack type
Frequency Response
The frequency response of a pair of headphone is the frequency range a pair of headphones can output. The human ear can detect frequencies from 10-20,000hz. Just about all headphones you can get cover this range. But does this mean that all headphones sound good because they can respond to all the sounds a human ear can hear? No it doesn't! Even though all headphones can output all the sounds a ear can hear, they output different frequencies at different volumes or decibels (dB).
So if this is the case, how can you tell how a pair of headphones sound?
The answer is simple, you use frequency response charts.
Frequency response charts show what amplitude (or how loud, note this is measured in dBr) a pair of headphones will output a certain frequency.
In this example, you see the Shure SRH440 compared with the Monster Beats by Dr. Dre Studio. These two headphones are like heaven and hell, the Beats Studios are extremely bass heavy or "dark" headphones while the Shure SRH440's are the exact opposite, having an extremely "bright" sound with softer bass.
I suggest going to a single source for frequency response charts, the best source I have found would be Headroom.com
Transducer principal
The transducer principal tells you the method the of sound production and whether the headphone is open or closed.
TYPES OF SPEAKER/HEADPHONES
Dynamic
These two words, dynamic and electrostatic tells you how the headphones make sound. Dynamic headphones use a metal coil(mainly copper) that create an electromagnetic field which interacts with the diaphragm and in turn, moves it. This technology is used in most speakers and headphones use because of the price, it is also the most convenient solution because it does not require any special amp or power source like an electrostatic speaker or headphone.
Electrostatic
These types of headphones and speakers are rare because of their price and their demand for a special amp to power them, but they offer the least distortion among commercial sound reproduction techniques. These drivers work by placing a thin diaphragm that holds an electric charge that is placed between two electrodes. When an electric charge is applied to the electrodes, they create a magnetic field that can be used to control the movement of the electrically charged diaphragm. This technique currently creates the least distortion in the sound of the headphone/speaker but is also the most expensive and you cannot forget that even if you get a headphone using this technology, you must remember you need to get a special amp to power it.
Balanced Armature
The balanced armature technique is the most common technique you will ever see in earbuds (dynamic is type used but this technique is rarer then balance armatures) the other or in-ear headphones. This technique works by using an arm-like mechanism that is attached to the diaphragm, this "arm" is then attached to a coil of wires that control magnets. In its neutral state, the arm puts no force on the diaphragm so the setup is "balanced." When the magnetic field of the magnets is changed by the current coming from coil, the force on the arm is no longer balanced. This in-balance causes the "arm" to tilt which causes the diaphragm to move, producing sound.
Balance armatures are considered more "unreliable" then dynamic drivers which is why most high end balance armature IEM's use multiple balance armature drivers to make up for this so you have one driver specializing in a certain part of the sound range. But when doing this, the headphone maker must ensure that the sounds of the drivers blend together well.
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| A representation of how multiple balance armature drivers add to the sound (FR charts of the Sony XBA series) |
Planer Magnetic
This is another uncommon driver technology, planer magnetic drivers use a thin film-like diaphragm imbedded with a conductive insert fitted behind (or in front) of a setup with rows of magnets setup so they can form a "boundary" around the metal inserts (if ")(" is a magnet and "|" is an insert under the magnet, it would look something like this: {)( | )( | )( | )(}). The magnets create a strong magnetic field so the housings are usually very ridged and strong, but what happens is: when a current is put through the insert, it interacts and disrupts the magnetic field created by the magnets which cause the insert and in turn the driver to move.
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| Planer Magnetic Driver in a pair of HifiMan HE-6 |
Open VS Closed
This part of the tech specs shows you whether or not there is a part of the headphone that is open to let air in to the diaphragms. For this, there is no optimal choice, but personal opinion and needs as both open and closed headphones have their own advantages and disadvantages.
Open
Open headphones have a hole somewhere on them to allow air through the back to the diaphragms. This allows the sound to seem like it is coming from outside the headphones rather then inside a boxed room. This type of design is used on many in-ear headphones as the disadvantages are not as noticeable as they are on over-ear headphones. The open design usually benefits acoustic sounds where a degree of "airiness" usually exists but also tend to soften bass.
Advantages
- There is almost no chance for the sound to bounce off the back and create an echo
- Best for acoustic reproduction
- The sound feels like its coming from an outside source
- Open headphones are not the best in noise isolation and can sometimes have no isolation at all
- lower bass tone can have less impact and seem aired out
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| Sennheiser HD 800 |
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| Sennheiser HD 600 |
Closed headphones are completely sealed, any headphones with active noise cancellation and really effective noise isolation are closed-back headphones. They are the best for noisy environments. Soundstage still exists but it sounds like you're in a "closed room"
Advantages
- Can have extremely good noise cancelation
- Bass generally has more impact due and sounds more like a pulsing sub woofer
- The sound may seem like it is coming from inside a room or a closed off source
- There is a chance for reflected sound at high volumes
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| Audio-Technica ATH-A700 |
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| Shure SRH 440 |
***Noise Cancellation VS Noise Isolation***
Noise Cancelling headphones block out outside noise and use microphones to record outside noise of a certain noise level and play it back within the headphone while noise isolation just blocks out outside noise to a certain degree (amount of noise blocked is measured in dB and is listed in the dB section of isolation).
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| Bose Quiet Comfort 15 |
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| Audio-Technica ARH-ANC7b |
Stereo VS Surround
The difference between surround and stereo can seriously affect your listening experience. A pair of surround sound headphones is meant to immerse you into an environment so you can feel and hear sounds like you are actually in the environment. This technology is best for watching a movie or a pair of gaming headphones where location is important. While stereo headphones just display a left and right sound that is separated by an artist so the music can be best experienced by the listener. Stereo headphones are the best for just listening to music.
Impedance
Headphone-wise
Impedance is an important part of picking the right headphones for you. The impedance of a headphone is the factor that affects the volume that is outputted by your headphone when you plug it into a device such as an iPod. Impedance tells you the power requirements of a pair of headphones. Impedance works like this: the higher the impedance, the more voltage required to power the headphones. But once impedance goes below 20ohms then the headphone you are getting requires more current. Generally, most motherboards can handle up to 64ohms of impedance, if the volume was turned up to about three quarters volume on an iPod/iPhone.
Now for those who want to understand a little more about impedance, here's a little physics lesson. Now first off, the main goal of headphones/speakers or any audio output device is to output an electric signal in the form of sound (or rather sound pressure measured in dB SPL for every mW of power provided). Given this, a headphone's performance is completely based on how well it can perform off of (x)mW incoming from the source.
To see how high impedance affects headphones, you must first look at the inside of a headphone, more specifically the drivers where the audio is produced. Using dynamic drivers as an example: Dynamic drivers usually rely on a voice coil (usually made of copper) that moves the diaphragm, and the impedance of a dynamic headphone depends thickness of this cable. At this point, a few things need to be known:
- The thinner the wire the more resistance it has and therefore, the higher the impedance
- The thicker the wire the more weight it has
- A heavier diaphragm takes more to move
Source-wise
The amp's output impedance should be as low as possible to avoid distortion and voltage drops with lower impedance headphones (32 ohms and below). Basically amp output impedance can a headphones by:
- changing their frequency response
- changing their bass performance
- struggling to power the headphone (this occurs mainly when you pair a low impedance headphone with a high output impedance amp, this occurs as voltage lost when a load is connected)
Weight
The weight of the headphones affect how portable headphones are, they don't affect the sound of the headphone what so ever.
Cable Length
The cable length affects the portability of the headphones, cables are generally 1-1.5m in length while some professional headphones have cables around 3.5m in length.
Jack Type
The jack or connector of the headphone can come in tree standard sizes, the 2.5mm, the 3.5mm and the 6.3mm jack. Majority of headphones and portable devices use the 3.5mm jack. Most over-ear headphones also come with a 3.5mm to 6.3mm adapter to enable you to use them with hifi/stereo systems. Some professional headphones have a 6.3mm jack and come with a 3.5mm adapter. You see the 2.5mm jack on some phones and there are rarely any commercial headphones that use this termination so using headphones with a 2.5mm device usually requires an adapter.These connectors are called TRS (Tip Ring Sleeve) connectors, as far as headphones go, this is the only type of connector that you will see besides USB. The rings/bands on the connector shows the amount of channels the jack has for information to be transfered. In the picture below, the jack 3.5mm jack with only one ring only has a channel for monotone information while, the 3.5mm jack with two rings has two channels for a stereo signal (one for the left ear and one for the right year).
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| Types of headphone jacks (from left to right): 2.5mm mono, 3.5mm mono, 3.5mm stereo, 6.3mm stereo |
Nice Definitions to Know:
Soundstage
Soundstage is basically the word used to describe the distance or dynamics of the sound. Soundstage is basically when you hear the guitarist sounds like he is 1m away and the drummer is 3m away, it is the distance of the sound.
Distortion
Distortion refers to the difference in sound reproduced vs the original sound signal/frequency that was recorded. This is usually measured as Total Harmonic Distortion. Distortion is usually created by the extra outputted energy by the headphones which create overtones or harmonics which end up distorting the sound.
What's left?
So is there anything else to be aware of while picking your headphones?
YES
You have to be aware of the brand of headphone that you are getting. Each brand has its pros and cons, some are better at making certain types of headphones, etc.
For my opinions on audio brands click this link:
The Brands
Achieving the best sound
So how can you get the best sound out of your new headphones other equipment may be needed and some requirements may need to be met.
Information on this may be found on my Audio 101
Resources
- Here is a link to an interesting interactive chart that shows the frequency range of a number of instruments: Click here
