Specs of earphones - meaning?

Hey everyone!

I am searching through websites comparing earphones but I don't get some of the terminologies used. Below are some:

What does impedance mean? The more or the less better?

What does sensitivity mean? The more or the less better?

What does frequency response mean? The more or the less better?

What does driver unit mean? The more or the less better?

Also, different types of plugs and cord type? Which ones are good and which ones are bad?

Any help much appreciated!

Originally Posted by iversonjack

Hey everyone!

I am searching through websites comparing earphones but I don't get some of the terminologies used. Below are some:

What does impedance mean? The more or the less better?

What does sensitivity mean? The more or the less better?

What does frequency response mean? The more or the less better?

What does driver unit mean? The more or the less better?

Also, different types of plugs and cord type? Which ones are good and which ones are bad?

Any help much appreciated!

Impedance is measured in ohms. Not the same thing as resistance. A resistance becomes an impedance when you add an inductor to the circuit. And a speaker is an inductor that has a coil. It also means that the impedance varies with the frequency. It's not always for example 32ohm.
The impedance should match the source but in the case of an MP3 player that is not as important as with a home stereo equipment. But the higher impedance is, the lower sound volume will be.

The sensitivity is how many dB (decibel) you'll get with 1 watt or milliwatt. The higher the more volume at the same volumesetting. It also brings at the bad sides from a noisy sound source. A 9-11dB change is what the ear believes as doubled in sound volume. And to get a 3dB change you need to put twice the effect to the speaker. 2-3dB is also the smallest change a normal ear can hear.

The Frequency response (FR) is a measurement in how the speaker reacts on a certain input. Often measured in dB and Hz.

Driver unit is the "speaker" If you have two driver units then you can in a way compare it to a two way speaker system. One speaker for the bass and one for the mid and highs. If you have three in each plug then you'll have one unit for each band.

There are many different plugs on the market. What sounds good is up to you.

I recommend sites like www.head-fi.org or http://www.headphone.com if you are interrested in more info. Or if you ask me too of course

Cheers!

Pretty useful information, thanks to you both :D

I am just building on what Peter @ JAYS already stated.

What does impedance mean? The more or the less better?

Quick Take: Doesn't matter to the user.
Full Take: Theoretically the higher impedance, the less electrical noise. However this isn't the same as noise such as white noise or hiss but electrical noise can add to white noise or hiss. Almost all Headphone/Earphones have the same impedance rating. If you half you impedense you technically get double the power (minus losses) but the amplifiers in mp3 players don't like doing that and nor do I suggest it.

What does sensitivity mean? The more or the less better?

Quick Take: More sensitive is better.
Full Take: If your earphones/headphones are more sensitive they are more efficient as using the power supplied by your amplifier.

What does frequency response mean? The more or the less better?

Quick Take: More is better but depends on you music source.
Full Take: Most people hear from 30hz to 18000hz depending on the person. Some can here above 20000hz and others not past 16000hz. All songs from CDs are 20Hz to 22000hz. Mp3's/Other formats when they compress the song a lower bitrate determines the highest freq's including. 1 128bit MP3 cuts off the songs freq at I believe 16Khz (16000hz) so they throw away all data above that freq making the file smaller. People can't hear below 30hz because its Sub Harmonic frequency's. At that freq you can feel bass (Sub whoofer) but you can't hear it. Chances are your headphones will easily play the 20hz - 22khz no problem. Its the question of will you music have it?

What does driver unit mean? The more or the less better?

Quick Take: More Drivers are better.
Full Take: A driver is the name for speaker. A speakers uses alternative current to create a magnetic field. There is a cone in the centre with a coil (known as the voice coil) that pushes and pulls the speaker depending on the direction of the current. This creates sound. More drivers are better because they usually dedicate one driver to higher freq's and another to lower freq's so they don't have to work so hard. In earphones you usually don't see this until some nice highend ones. ~$200 USD. Headphones you can find starting around $100.

Also, different types of plugs and cord type? Which ones are good and which ones are bad?

Quick Take: The bigger the better usually but you don't need to worry about it.
Full Take: There is basically only 1/4 inch jack for mp3 players. Some phones that play mp3's may use 1/8inch. Its easier to send more power with less resistance (losses) with a bigger conducter. However with the small amount of power that mp3 players have, the losses between the two would be negligable.


I hope this helps. I am in Electrical Engineering if your wondering how I know this. Also I love audio equipment. Hope this helps!!

Freq response is not the whole picture, though. It is good to look at the freq response curve, as well. Just because a speaker/headphone has a freq fall in its bandwidth, does not mean it does it well. Check headphone.com , the have freq and impedance curves that will give you an idea just how much a headphone/speaker will color/distort over its entire bandwidth.

Quick Take: More Drivers are better.
Full Take: A driver is the name for speaker. A speakers uses alternative current to create a magnetic field. There is a cone in the centre with a coil (known as the voice coil) that pushes and pulls the speaker depending on the direction of the current. This creates sound.

Sorry to burst your "bubble" so to speak, Speakers/drivers only use DC or Direct Current, always have. You are correct in that the speaker cone is "pushed" out by the magnetic field, that creates the sound wave, which reproduces the electronic signal into sound waves. Yes, the speaker does "pull" back, but this is due to the tension on the cone.

Why do you think that ALL amplifier speaker outputs and speaker inputs are polarized? It's because of the DC current! As the voltage produced varies with the signal amplitude, the amount that the speaker cone is being "pushed" out will vary, ie, sound output in volume and frequency. Now one can reverse the DC connections, causing the speaker to "pull in" rather than "push out", but that will fry a voice coil fairly quick as there is not much room for the voice coil to move backwards within the speaker. Plus it causes a lot of distortion. That's why speaker and amplifier manufacturers are so emphatic about the "POLARITY" of hooking up the speakers correctly.

In addition, Alexander Graham Bell invented the telephone which uses a voice coil and DC voltage, quite a few years before Nikola Tesla invented AC or alternating current!

No offense, but you're electrical engineer? Right.....

Originally Posted by Fluffywings

Quick Take: More Drivers are better.

Not really, at least not for speakers. There are enough negative effects, so that it doesn't make a lot of sense. They can be fought, but usually more than 2 drivers are troublesome, they don't work well together.

Originally Posted by Peter @ JAYS

Impedance is measured in ohms. Not the same thing as resistance. A resistance becomes an impedance when you add an inductor to the circuit. And a speaker is an inductor that has a coil. It also means that the impedance varies with the frequency. It's not always for example 32ohm.
The impedance should match the source but in the case of an MP3 player that is not as important as with a home stereo equipment. But the higher impedance is, the lower sound volume will be.

The sensitivity is how many dB (decibel) you'll get with 1 watt or milliwatt. The higher the more volume at the same volumesetting. It also brings at the bad sides from a noisy sound source. A 9-11dB change is what the ear believes as doubled in sound volume. And to get a 3dB change you need to put twice the effect to the speaker. 2-3dB is also the smallest change a normal ear can hear.

Sorry to cut your post and correct me if I'm wrong.

I studied something regarding sound pressure level (SPL) in my Polytechnic in SG. According to what I'd learnt, the summation of SPL is using a Log function (A mathematical function) equation. And with that, what you said, the increase in 3dBA is roughly around twice of the SPL. But unfortunately, I don't think the earphones work the same basis for the sensitivity.

Taking 100 dBA as a guide:

What you said is -> 100 x 2 = 103
OR -> 103 / 2 = 100

BUT what it actually means is -> 100 + 100 = 103
OR -> 103 - 100 = 100

What I'm saying is, if there is two sound sources of the same SPL of 100dBA, they sum up to be 103dBA in total. But the effect is not twice of what we hear. If you were to imagine two sound sources of 100dBA, say a TV and a radio, when both heard at the same time, you don't hear it as twice as much as you hear it individually.

Hence, the sensitivity of a pair of earphones is based on a single source of sound. A different pair of earphones with higher or lower SPL/mW of 3 do not give you twice the sound volume. Else, if you know the actual equation, a 116dBA/mW earphone will sound more than 300 times louder than a 90dBA/mW earphone which will be ridiculous.

Anyway, for reference, the equation of calculating SPL is as follows:

SPL(total) = 10log[10^(source1/10) + 10^(source2/100 + .....]

Sample:
SPL(total) = 10log[10^(100/10) + 10^(98/10)]
SPL(total) = 10log[1e10 + 1e9.8]
SPL(total) = 10log[16.31e9]
SPL(total) = 102.1dBA

Originally Posted by nibiru2008

Sorry to burst your "bubble" so to speak, Speakers/drivers only use DC or Direct Current, always have. You are correct in that the speaker cone is "pushed" out by the magnetic field, that creates the sound wave, which reproduces the electronic signal into sound waves. Yes, the speaker does "pull" back, but this is due to the tension on the cone.

Why do you think that ALL amplifier speaker outputs and speaker inputs are polarized? It's because of the DC current! As the voltage produced varies with the signal amplitude, the amount that the speaker cone is being "pushed" out will vary, ie, sound output in volume and frequency. Now one can reverse the DC connections, causing the speaker to "pull in" rather than "push out", but that will fry a voice coil fairly quick as there is not much room for the voice coil to move backwards within the speaker. Plus it causes a lot of distortion. That's why speaker and amplifier manufacturers are so emphatic about the "POLARITY" of hooking up the speakers correctly.

In addition, Alexander Graham Bell invented the telephone which uses a voice coil and DC voltage, quite a few years before Nikola Tesla invented AC or alternating current!

No offense, but you're electrical engineer? Right.....

How does this work? Have you ever burned out a set of headphones by accidentally putting DC through them? If you hook up any audio source to an osilloscope, you will see waves correct? The waves are AC current. If it were DC current, you would only see the top half of the wave, or the bottom half.