Amps at low volumes.
Mar 18, 2006 at 5:57 PM Thread Starter Post #1 of 5

gsk3

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Everyone says that amped headphones are much better, even for decent but not amazing cans. Is it just a volume thing? I don't like listening to music loud. At a given volume level, would the amped cans be noticably better?
If so, why? Is it just that good cans are harder to drive (impedance matching), or is there something else going on?

Thanks,
Ari
 
Mar 18, 2006 at 10:32 PM Post #3 of 5

TheSloth

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Amplification has little to do with volume level. A good example will be plugging a pair of 300ohm HD-580's into an iPod - to my ears, this combination can get pretty darn loud if you max the iPod's volume setting, however the quality is seriously lacking.

The exact same thing applies at all volume levels. It doesn't really take a great deal of output power in mW to get even the most insensitive headphone to play 'loudly'. The difference between a great headphone amplifier and a portable line out for example is firstly the transparency of the electronics to the music signal - a great amplifier should neither add nor subtract anything of the original signal in the gain stage; and secondly how accurately it can control the movement of the headphone driver. It may not take a lot of power to make the driver diaphragm move a lot of air, hence make a lot of sound, but it does take a lot of very well controlled power to control those movements and make sure they are accurate to the signal, i.e. that the diaphram does not move 1 nanometer too far, and moves at exactly the right speed, etc., even at low volumes. Think of it as if you were having to move something back and forth with your own arms/body. Assuming you are strong enough to move it with some degree of ease, it's not difficult to pull it backwards and push it forwards rapidly. But it's extremely difficult when pulling or pushing it to make sure it stops at an exact defined point with no margin for error, and moves at an exact speed with no margin for error - it will usually overshoot by a greater or smaller degree.

Now exactly how a dedicated headphone amplifier acheives this improved quality is very long winded, and depends on so many different design factors that I can't explain it simply here. But I hope the above explanation helps a little.
 
Mar 18, 2006 at 10:33 PM Post #4 of 5

rickcr42

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quality over quantity for some cans,essential drive requirements for others.

Using portable systems as an illustration :

obviously the headphones/buds that come pre-packaged with portable players would not benefit one bit from being amped requiring neither the power increase or increased detail which not only would not be a help but can even be detrimental in that it imposes anye shortcomings on the listener.no escape

Then there is the full size headphone used for portable duty case.that is where a headphone from either being inneficient or due to impedance mismatches needs an interface that will allow the front end source to drive the mismatched cans and that normally mean high imdeance input/gain stage to increase voltage levels to a usable state/low impedance output headphone driver.
Fail to have the proper device between the source and headphone sand you can expect not just reduced volume levels but what volume level you do get will mostly be totally lacking in dynamics,will be bass shy,have zero low level information retreival and more often than not will clip the output section on peak music events.

Esential gear for the 200 ohms up headphones

Upgrade those "generic prepackaged" cans to mid level high efficiency headphones that can be driven easily by a portable and it gets a bit more cloudy.Far less of an "absolute" unlike the previous example.
Since these can be readily driven straight from the portable source with not just enough overall VOLUME but in fact more than enough it comes down to the little things.Better bass impact,more dynamic with busy music where instead of a single wall of sound you get actual note separation and with the good amps can follow the single instrument even when surrounded by many others.
This type of headphone does not need voltage gain for volume but output DRIVE capability so really more impedance converter than it is amplifier.


In the end an amp allows matching need to device and whether it is voltage gain or current gain all about making a signal meant to drive a 10K and up load now able to drive a much lower impedance load without LOSING information !

Not about what an amp increases (volume) as much as limiting what is lost
tongue.gif
 
Mar 19, 2006 at 2:03 AM Post #5 of 5

gsk3

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So as I understand those two wonderfully detailed posts (thank you by the way!), there are sort of two effects going on:
1. For high-impedance headphones, the amp is acting as an impedance matcher. From the little I know of impedance matching, I assume this reduces the "reflections" that occur at the interface of the two when they are mismatched?
2. For all cans, the amp is doing something complicated which helps more precisely regulate the movement of the speaker diaphragms.

Bottom line is that no, it's not just about volume.

Is that about the size of it?

Ari
 

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