[Chu]

EDIT : I wish I could edit the title, it should obviously be "headphones," not "sources"

I've seen a lot of complaints about while there being a huge number of headphone amps geared to high impedance headphones, there are very few geared towards low impedance headphones, Grado's in particular.

My question is, what makes one amp good at driving a low impedance headphone, and another good at driving a high impedance headphone?

 

[vcoheda]

you can edit the title. double click near it.

 

[jcx]

V = I * R

P = I * V

you need power (usual reference level = 1 mW) to drive the headphone, how much power a headphone draws from a source which puts out a certain V amplitude depends on that V and the current drawn by the headphone's R from the source

amps all have limited output V due to limited supply V

amps all have limited output current ability due to device limits

High Z (~= R for headphones) cans require high V to push the same power into the cans due to the low current they draw at each V

Low Z cans require much more current at at lower V to draw the same reference power from the amp

the situation is further complicated by the sensitivity (dBspl/mW), headphones vary in the amount of power needed to produce the same spl - by over 3 orders of magnitude

a couple of examples:

http://www.head-fi.org/forums/showpo...1&postcount=13

http://www.head-fi.org/forums/showpo...88&postcount=6


the supply V of the amp and the output device capabilities and how they're applied in the amp output can make an amp more suitable for one class of headphone over another