Impedence question in headphones..

[sionghchan]

Hi all,

Another technical question from a headphone noob. I do notice that most manufacturers actually produces the same headphones but with different impedence...e.g. the Beyers DT770 has a 80 ohm version and another 250 ohm version (I'm not 100% sure but I think those are the two different impedence versions).

Just curious, why the different impedence? What's the advantage of higher or lower impedence?

Logically speaking, lower impedence and higher efficiency headphones should be what we are all looking for right? Since we can then drive them out of almost any kinds of players... Please correct me if I'm wrong..

Thanks!

 

[sionghchan]

bump...help anybody?

 

[Jazper]

in short, lower impendance is easier to drive, but there are tradeoffs making phones lower impendance in certain designs.

The 250 ohm version probably sounds different because the drivers are slightly different. I suppose beyer wanted to give users the option of using either.

 

[DaHoboFest]

I would think that it would be like this:

low impedence version for the average user

then if you are able to power it with a nice amp, then it will sound nicer than the lower impedence version amped.

 

[Claus1100xx]

but why is a high impedance phone better sounding

 

[Jazper]

Quote:

Originally Posted by Claus1100xx but why is a high impedance phone better sounding

I think you misread it - high impendance does not mean better sounding.. just means different sounding.

 

[Claus1100xx]

Quote:

Originally Posted by Jazper I think you misread it - high impendance does not mean better sounding.. just means different sounding.

sorry - long day at work. but so what is the advantage of a high impedance driver? just that it needs amped sound which drives it better?

 

[DaHoboFest]

I'm not saying thats how it is. That's what would make logical sense for having 2 different versions.

 

[Jazper]

Quote:

Originally Posted by Claus1100xx sorry - long day at work. but so what is the advantage of a high impedance driver? just that it needs amped sound which drives it better?

there is no advantage to high impendance, only a drawback (harder to drive) - though I suppose the sound produced could be an advantage if you prefer the higher impendance 'phone

 

[ephemere]

It's a tradeoff.

A higher impedance requires more voltage but proportionally less current to achieve the same power. This means that a higher-impedence headphone will be easier to drive without distortion (less likely to demand too much current from your source, pushing it into non-linear behavior), but will tend to require that you turn the volume knob up higher (because the volume knob is controlling voltage, not current).

So, it's not so cut and dry. A high impedance headphone can offer real advantages, just like with speakers.

 

[sionghchan]

Hi all,

Thanks for all your replies so far. It has been very educational. I think so far, ephemere's reply makes the most sense ... I suppose that is the main difference. Now, my question is, do the different impedence version of the same headphones really do have different drivers? I'll be surprised if they do because if they do, then it realy is almost a different headphones entirely...do they even sound remotely the same?

I'm truly intrigued by this topic then..

Thank you all for your replies so far..

 

[Jazper]

Quote:

Originally Posted by sionghchan Hi all, Thanks for all your replies so far. It has been very educational. I think so far, ephemere's reply makes the most sense ... I suppose that is the main difference. Now, my question is, do the different impedence version of the same headphones really do have different drivers? I'll be surprised if they do because if they do, then it realy is almost a different headphones entirely...do they even sound remotely the same? I'm truly intrigued by this topic then.. Thank you all for your replies so far..

well I think the answer is : they use the same materials, but have different coils in the drivers, so while almost identical, they're not.

 

[gsferrari]

Every driver coil has an inductance, capacitance and resistance. Impedance is a combination of these factors.

CRITICAL POINT: A high impedance is a low load. A low impedance is a high load. Therefore a 300 ohm headphone isnt a big load...whereas a 32 ohm headphone is. Weird isnt it

You'll get used to it...

DAMPING FACTOR : In Audio it is more important to have control over the driver than to deliver maximum power. See the link at the end of this post. The link will show you the equations.

Lower impedance -> 32 ohms for example

Higher impedance -> 300 ohms for example

Tubes are traditionally high voltage low current devices. Transistors are low voltage high current devices. This is just a gross generalization. But in practice high impedance headphones work better out of a low output impedance amplifier and low impedance headphones work better with amps that have *lower* impedance.

If the output is loaded, then the available voltage from the source drops, and that in turn means that more amplification is needed to obtain the final voltage needed. That is why tube amps (high output impedance) need transformers to step up the impedance of the low impedance drivers...so that the amp's output impedance becomes lower relative to the apparent driver impedance.

ASL amps like the MG head had both OTL (output transformer less) and T (transformer coupled) outputs. You would use OTL with high impedance headphones and T with low impedance headphones. The amps still sucked with low impedance headphones.

Do a google for Impedance Matching and you will learn a little more.

http://en.wikipedia.org/wiki/Impedance_bridging

 

[sionghchan]

Thanks gsferrari! Great reply..