Point of high resistance/impedance headphones and amp

[marioo1182]

So I am a current Electrical and Electronics Engineering student.

My questions is... Why would you want to have high resistant/impedance headphones?

 

They only reason that I can think of is that they offer more "precision" and therefore better sound.

 

If we start off with the obvious we all know that V=IR

So I=V/R

This is why you need an amp to drive higher impedance headphones, otherwise it would be to quiet. 

 

So if it is less expensive to buy lower impedance then what is the point? No amp required, decent sound for everyday listening, e.t.c.

Hopefully I don't sound too stupid but I've never understood why

[Enderman]

Well I don't know the answer, and I am not an engineer, but by my logical reasoning, small amounts of EMI can cause noticeable noise to be produced from the headphones that gets heard as static. If the headphones are 200 ohms instead of 20, those small amounts of electricity aka EMI will not cause a noticeable degradation in sound quality because of the high resistance. The small EMI would not be enough to make noise come from a 200ohm driver, therefore the signal coming from the amp would remain undistorted. This is just my logic though, I might be wrong.

[Lays]

There is a lot more to the equation than just impedance, plenty of high impedance devices still get loud on onboard / mobile devices.

Sensitivity is miles more important IMO.

 

I have heard a few people saying that higher impedance headphones have better driver control, not sure if that's true or not.

Also, higher impedance devices can be used with a wider array of amplifiers with different output impedance without sacrificing damping of the driver. ( IE: tube amps etc)

I believe nwavguy recommends a minimum damping factor of 8. (headphones impedance / output impedance of amp = damping factor)

[DigitalHermit]

Summoning @Dark_wizzie...

[mr moose]

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

 

Essentially, yes, Higher impedance's over come damping issues in high impedance amplifiers.

[BoredErica]

Here's what Nwavguy said:

High-End Headphones Favor High Impedance - There can be some significant advantages to higher impedance headphones. A higher impedance allows for more turns of wire to be used in the voice coil of the driver. This can result in a better “motor system” with fewer compromises resulting in better overall sound. Higher impedance headphones also require less current to drive and that typically reduces distortion in multiple ways. It makes them more immune to output impedance differences between sources and also less sensitive to long cables and sharing a common wire in 3 wire cables and 3 wire connectors (i.e. headphone plugs and jacks). The amplifiers driving headphone nearly always produce lower distortion into higher impedances.

And in the comments he said this:

More turns of wire on the same diameter voice coil generally means more magnetic force. But more turns also generally means higher impedance. It's the higher magnetic force that provides better sound quality. That's just one reason why higher impedance headphones, like the DT880-600, can sound better. Flat wire lets you pack more wire into the same amount of space (round wire leaves air gaps between the turns in the coil). So it can increase the magnetic force for a coil of a given size. The coil could also be smaller for the same force. Making it smaller in diameter could save some weight from the former but you're mostly leaving out air. Lower impedance does generally increase efficiency but it really depends on the driving source. The K701 is a relatively difficult to drive headphone as it needs relatively high amounts of current AND voltage. It's not especially sensitive or efficient. In general, flat wire allows for either a more powerful, or more compact, voice coil. So it does have some objective advantages. But the voice coil design is just one relatively small portion of headphone design. The magnetic system, diaphragm, suspension, damping and enclosure are all critical as well.

Somewhat related, we know that a harder to drive headphone is less versatile, but often the targeted market won't mind and can pony up the cash for an aftermarket amp. Or, we can go the other extreme with balanced armature IEMs with very low impedances. Those are very fun to drive as well. 

 

Also don't forget, it doesn't have to make sense. There are audiophiles buying magic cables. Some people WANT problems to fix. The large majority of headphones are not too difficult to drive, but that doesn't stop some people from losing sleep over their already overkill amp. A "high end" headphone that is too cheap or too easy to drive is almost a disappointment.

[creatip123]

There are a lot of articles and explanation on the web as to why they produce high impedance headphones. 

 

A lot of points, some are even arguable, but one thing that makes sense to me, is yes, the damping factor. 

 

Every amps have output impedance, some are small, others are not so small. In general, the smaller the better. This output impedance can cause speaker drivers (including headphone's) to have longer time to stop moving from the moving state. Let's say an ideal timespan for a single drum kick is 0.5 second. The drivers should move in 0.5 second to reproduce the drum kick sound, and then stop moving. High output impedance of an amp (relative to headphone impedance used) could cause prolonged timespan, from the intended 0.5 second to, say, 1 second, which some people dub it as 'muddy'.

 

So let's say we wanna get that ideal damping factor of 1:8. For a 32 ohms headphone, the ideal output impedance of the amp used would be max 4 ohms. Plugged to a high output impedance amps, it will become muddy, or maybe even hiss/noise floor. With a high impedance, for example, 300 ohms, the output impedance of the amp used could go up to max 37.5 ohms.

 

In a flash, keeping the damping factor of 1:8 in mind, lower impedance headphones work best only when plugged to a low output impedance amps, like a dedicated headphone amps, mobile device amps, etc. Higher impedance headphones can be plugged to a wider variety of output impedance amps, from mobile device amps, to bigger desktop amps (with high output impedance)

 

Well, that's how I understand it, anyway.