Power Handling Capacity and Amp Output - Page 2

 

Really? I can hardly feel mine.. 

Yes. Except that Ohm's Law tells us we can't arbitrarily have a lot of current or voltage. So impedance dictates the relationship of current/voltage, and sensitivity tells us how much power we need for a given SPL; now we have power = current/voltage, and Ohm's Law tells us how that's gonna play out. If the amp can deliver it, you're good to go. Simple as that.

These days, most amps can deliver for most headphones.

Not at all. Impedance has nothing to do with power input or distortion (at least in the manner you're describing). Power limit is dictated by the motor (thermal and mechanical limits), distortion is a result of that limit as well (mechanical limits and excursion). Impedance has no bearing on that (however motor design will influence impedance - but there is no hard and fast rule about "high impedance is better" or "low impedance is better" - it's just a result of how a driver is designed).

Rated power input specs is what'll tell you where the top-end is. If the cans in question have been measured by Tyll, he will measure them at 90 dB and 100 dB for THD, to give you an idea of power handling (if THD goes way up from 90->100, they don't handle "loud" well, if it goes down, they do).

NOT necessarily. It depend on amps. This was just a thought example. The higher impedance, the fewer mW. The lower impedance the more mW until some limit where the amp can't deliver the required current, and the amount of mW without distortion starts to drop. 

Because of this, (seen in an article) the O2 amp for example is not capable of driving the HE-500 (very current demanding, 38 ohms) 100% satisfactorily. Can't find the article, though :(

 

Want to add, that im not sure about this phenomenon impairing the sound quality of headphones

Impedance does not dictate power. It dictates the relationship between current and voltage relative to frequency - it's more or less arbitrary in the context of what you're discussing. Sensitivity will dictate power requirements.

The relationship between current and voltage (eg. impedance) dictates how many mW the amp can put out. And when it has to deliver a lot of current, it might distort before the upper voltage limit is reached.

How much power an amplifier can put out is not only dependent on ohms law...

Dual mono speaker Hifiman setup :P

 

 

 

 

 

HE-400 and 500. No distortion and even a bit of bass slam. The sound is a bit too hollow, though, which I don't think I can fix with EQ

If you go for 2/3 of the power of the amplifier I would suspect an instant hearing damage. But your amp should be able to drive your headphones to 100mW. I just don't know if it is without distortion. 

Edited by davidsh - 1/20/13 at 1:13pm

Seriously, I don't really know about all this amp talk. I just know that the fiio e17, for example, is able to drive the HE-500 loud enough, seemingly without any distortion and such. But on the other hand, I still don't find it to drive the HE-500 to sound its best, even though the sound seems technically fine, it just misses some musicality.

Ehm. One question. I have an mp3(cowon) and on my earbuds it sounds good but my full-size 32 ohm headphones sounds just bad and quiet(not problem in headphones they sound excellent on notebook). How much power do i need to drive 50mm 35 ohm headphones? Is player with output power 50 mW enough? Or should i get portable amp? Thanks very much.

What's their stated sensitivity? Even better if some place like InnerFidelity has measured it to confirm.

No, over-driving an amp will cause it to clip. This can fry your drivers.

 

KP