[jjmai]

I am a newbie with regard to amps, so don't flame me.
I don't quite understand the purpose of amp if the source can already output a good audible range.
If I just change the volume and EQ on the source player, wouldn't that achieve the same purpose of an amp?
Why do I often hear people say certain headphones sound better when amped, wouldn't jacking up the volume help too? And how come not all headphones benefit equally from amp?

 

[MrGreen]

Nope.
Amping supplies extra voltage and current, whilst EQ simply increases the signal volume (which will eventually result in clipping).

What you get is better movement of the coil in your headphones, rather than the production of a louder signal (which results in more movement). An amp increases finesse as well acts as a volume control.

However, if you have a $300 headphone and add a $1000 amp you aren't going to get $1300 worth of sound quality, you're just going to be allowing the $300 headphone to reach its potential.

Regarding amping issues its pretty complex, but you might want to read up on ohms law (and I believe theres a few threads on it in the SS forum)

 

[kunalraiker]

Quote:

Originally Posted by MrGreen /img/forum/go_quote.gif Nope. Amping supplies extra voltage and current, whilst EQ simply increases the signal volume (which will eventually result in clipping). What you get is better movement of the coil in your headphones, rather than the production of a louder signal (which results in more movement). An amp increases finesse as well acts as a volume control. However, if you have a $300 headphone and add a $1000 amp you aren't going to get $1300 worth of sound quality, you're just going to be allowing the $300 headphone to reach its potential. Regarding amping issues its pretty complex, but you might want to read up on ohms law (and I believe theres a few threads on it in the SS forum)

I was checking this thread to see what interesting answers members may have, you have described it in the best and simplest possible way

 

[Oskari]

This could be useful reading material: http://www.head-fi.org/forums/f5/amp-465090/

 

[jjmai]

Thanks for the explanations.
I guess, in terms of a voltage amplitude of an analog waveform, it's not about how high the voltage is, but it's about how quickly and accurately the voltage can get there.

 

[Helmore]

Quote:

Originally Posted by jjmai /img/forum/go_quote.gif Thanks for the explanations. I guess, in terms of a voltage amplitude of an analog waveform, it's not about how high the voltage is, but it's about how quickly and accurately the voltage can get there.

Yes, it should be so quick enough to exactly follow the waveform it's being fed by a/the DAC. The main problem is the fact that the coil in a dynamic headphone is basically an inductor and you have to deal with its inductance. When you change the current through an inductor, it's inductance will induce an opposing electromagnetic force (opposing voltage) which wants to prevent that change in current. The faster current changes of course happen at the higher frequency, but it affects the entire sound signature.

This effect leads to phase shifts, the voltage and current across the voice coil are not rising and falling at the same time, but the voltage is following what the current does. Keep in mind, the voltage I'm talking about here is the total of both the voltage provided by the amp and the voltage which is 'created' by the voice coil. That latter voltage is in opposite 'direction' to the voltage provided by the amp. The higher the frequency the more pronounced this effect will be and it negatively affects sound quality.

These effects can also occur inside the amp and is part of why certain amps are better than others. There is more to this than just inductance, we haven't even talked about capacitance here, although that would be a much smaller part of the headphone itself (more pronounced in the amp itself) and the cable may provide more capacitance than the voice coil.

In short and in layman's terms, it comes down to how well the amp can tame the voice coil in doing exactly what the DAC tells the amp to do with the voice coil. Most amps can provide the voltage to make a headphone loud, but you usually end up with quite expensive amps if you need one with enough authority to really drive the headphone.