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Amplifier with low and high impedance headphone

post #1 of 19
Thread Starter 

after reading difference between low and high impedance, i still didn't get clear of some things in my mind so i'll just ask anyway

when you use amplifier, say that can drive up to 600 ohm, with low impedance headphone will the difference is as big as the one with high impedance? or its just like reaching point a to b and high impedance like a truck that requires big engine and low impedance headphone like sports car, it can reach them easily but eventually the difference is the same?

post #2 of 19

sensitivity enters the equations too - high sensitivity headphones require less power to cause the same acoustic loudness in SPL than low sensitivity headphones

 

dynamic (magnet and coiled wire) headphones sensitivities ranges by factors over 10000 (yes ten thousand - no fat finger on the zero key) between sensitive IEM and some "pro studio monitor" headphones

 

so sensitivity is even more important in the discussion

 

to reach some reference SPL each model of headphone requires a certain amount of power, usually measured in milliwatts, you need the sensitivity spec for the particular headphone to determine this power level

 

and the particular model headphone's impedance determines the ratio of Volts and (milli)Amps the amplifier has to be able to supply

 

in audio the standard assumption is that amplifiers amplify, supply to the output a controlled Voltage - the headphone impedance then determines how much current will flow - the amp also has limits to the current it can supply and when the limit is reached the amplifier can no longer control the output Voltage

post #3 of 19
Quote:
Originally Posted by Viciel View Post

when you use amplifier, say that can drive up to 600 ohm,

A headphone amp usually can drive loads down to x ohms, for example 8 ohms, not up to. With equal sensitivity (dB SPL @ 1Vrms) a higher impedance headphone is easier to drive by the amp. (After all, the amp needs to supply less current.)

 

So, problematic are low impedance headphones with low sensitivity. The amp may not be happy with the low impedance => higher distortion. And the low sensitivity may result in too low volume, i.e. you turn the amp up to max but it still is not loud enough.

post #4 of 19
I am not sure if this is the right thread to ask this question.

Anyway. Let's say I have a pair of headphone with 8Ohms and 108dB SPL. Do you think DAP with output imedance at around 5 ohm can drive it well?
post #5 of 19
Quote:
Originally Posted by BillsonChang007 View Post

I am not sure if this is the right thread to ask this question.
Anyway. Let's say I have a pair of headphone with 8Ohms and 108dB SPL. Do you think DAP with output imedance at around 5 ohm can drive it well?

Not too sure if you are saying 8 Ohms or 80 Ohms.

8 Ohm headphones are virtually non existent and are best driven by a small speaker amp.

If you mean 80 Ohms, then your DAP will have no problem driving them.
post #6 of 19
Opps... My wrong biggrin.gif I'm talking about 8 Ohms.

Here's the link http://www.sony.co.uk/support/en/product/XBA-4/specifications
post #7 of 19

Well you'll get a bit higher distortion and more treble (or more correctly: less bass and mids). The XBA-4 has an impedance peak at over 3 kHz and at about 6.5 kHz where the boost will be the biggest.

post #8 of 19
Will the E11 help solve the distortion issue?
post #9 of 19
If I am correct, any amplifier with a low impedance would improve it, but if I am wrong' I am sure somebody can correct me


Sent from my Nexus 7 using Tapatalk 2
post #10 of 19
Thread Starter 
Quote:
Originally Posted by jcx View Post

sensitivity enters the equations too - high sensitivity headphones require less power to cause the same acoustic loudness in SPL than low sensitivity headphones

 

dynamic (magnet and coiled wire) headphones sensitivities ranges by factors over 10000 (yes ten thousand - no fat finger on the zero key) between sensitive IEM and some "pro studio monitor" headphones

 

so sensitivity is even more important in the discussion

 

to reach some reference SPL each model of headphone requires a certain amount of power, usually measured in milliwatts, you need the sensitivity spec for the particular headphone to determine this power level

 

and the particular model headphone's impedance determines the ratio of Volts and (milli)Amps the amplifier has to be able to supply

 

in audio the standard assumption is that amplifiers amplify, supply to the output a controlled Voltage - the headphone impedance then determines how much current will flow - the amp also has limits to the current it can supply and when the limit is reached the amplifier can no longer control the output Voltage

 

Quote:
Originally Posted by xnor View Post

A headphone amp usually can drive loads down to x ohms, for example 8 ohms, not up to. With equal sensitivity (dB SPL @ 1Vrms) a higher impedance headphone is easier to drive by the amp. (After all, the amp needs to supply less current.)

 

So, problematic are low impedance headphones with low sensitivity. The amp may not be happy with the low impedance => higher distortion. And the low sensitivity may result in too low volume, i.e. you turn the amp up to max but it still is not loud enough.

so if we're talking about high impedance high sensitivity and low impedance high sensitivity or mix of it, if i understand correctly, its the signature of the sound that will be affected(such as bass treble, etc) not the actual improvement even if driven from the same amp?


Edited by Viciel - 11/11/12 at 1:07am
post #11 of 19
Quote:
Originally Posted by BillsonChang007 View Post

Will the E11 help solve the distortion issue?

Yeah with an output impedance of 0.5 ohms it should definitely improve the situation.

 

Quote:
Originally Posted by Viciel View Post

 

so if we're talking about high impedance high sensitivity and low impedance high sensitivity or mix of it, if i understand correctly, its the signature of the sound that will be affected(such as bass treble, etc) not the actual improvement even if driven from the same amp?

Higher impedance headphones often have not such a high sensitivity as low impedance headphones, so yeah in reality it's a mix.

 

The main reason for frequency response changes is the output impedance, so it should be low. Also, distortion will be lower with a nice amp regardless of load compared to some integrated amps. All of these points are improvements to sound quality.

 

But while the amp could be able to drive a 600 ohm load perfectly it could struggle with a 30 ohm load. So in that regard it could sound worse than the integrated amp in a portable player.


Edited by xnor - 11/11/12 at 2:44am
post #12 of 19
Quote:
Originally Posted by BillsonChang007 View Post

Opps... My wrong biggrin.gif I'm talking about 8 Ohms.
Here's the link http://www.sony.co.uk/support/en/product/XBA-4/specifications

Ooops!
My wrong!
I should have figured they were IEMs!
They are so sensitive they take very little power to drive!


A real short answer is:
- an amp with low output impedance would be nice.
- not much power required
- must not output much noise or hiss

The FiiO may be the amp!
post #13 of 19
Thread Starter 
Quote:
Originally Posted by xnor View Post

 

Higher impedance headphones often have not such a high sensitivity as low impedance headphones, so yeah in reality it's a mix.

 

The main reason for frequency response changes is the output impedance, so it should be low. Also, distortion will be lower with a nice amp regardless of load compared to some integrated amps. All of these points are improvements to sound quality.

 

But while the amp could be able to drive a 600 ohm load perfectly it could struggle with a 30 ohm load. So in that regard it could sound worse than the integrated amp in a portable player.

ahhh i understand now, but in theory say one amp that could drive perfectly low and high impedance headphone. will the sound signature from the amp present perfectly on both headphone? i'm just talking about the sound signature of the amp though. or its impossible because it really depends on lot of things? lets just say the sensitivity is the same

post #14 of 19

A perfect amp, aka "wire with gain", has a completely flat frequency response, at least in the range 20 Hz - 20 kHz. So it doesn't really have a sound signature. In other words it's the lack of a sound signature that makes the amp perfect.

The amp would also have ~0 ohm output impedance, low distortion, noise floor etc.

post #15 of 19
Quote:
Originally Posted by xnor View Post

A perfect amp, aka "wire with gain", has a completely flat frequency response, at least in the range 20 Hz - 20 kHz. So it doesn't really have a sound signature. In other words it's the lack of a sound signature that makes the amp perfect.
The amp would also have ~0 ohm output impedance, low distortion, noise floor etc.

In addition, it would be able to output enough current and enough voltage to drive any reasonable load.
Headphones don't actually require much current or voltage, but, despite that, finding an amp whoch can drive virtually any headphone can be a challange and normally will cost you a few $$$ more than, for example, a FiiO.

I'm trying not trying to dump on FiiO or cheap headphone amps in general.
I have a FiiO and an iBasso and and quite satisfied with both of them.
They will both drive all the phones I have to a decent volume, but then I don't own power hungry pigs like LCDs or listen at insane volumes.
Edited by Chris J - 11/11/12 at 10:04am
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