Amplifier with low and high impedance headphone

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

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.

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.

Opps... My wrong I'm talking about 8 Ohms.

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

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.

Will the E11 help solve the distortion issue?

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

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

 

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

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!

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