How do you know if amping is required?

[curtisngl]

Where is the line between amping slightly helping and making a significant difference? Do even IEMs benefit?

 

[PurpleAngel]

Where is the line between amping slightly helping and making a significant difference? Do even IEMs benefit?

Part of "amping" is delivering power to the headphones the right way, over just an "unamped" line-out jack that can output voltage.
It's preferred to have the impedance of the headphones to be 8 times (or more) the impedance of the jack they are plugged into.
IEM are usually very low impedance and most portable audio has a low output impedance, so they work well together.
Where as in a music studio, they could be using higher impedances amps and headphone with really high impedances, which works together.
 
Are you thinking of using an amplifier with your IEMs?

 

[curtisngl]

Part of "amping" is delivering power to the headphones the right way, over just an "unamped" line-out jack that can output voltage.
It's preferred to have the impedance of the headphones to be 8 times (or more) the impedance of the jack they are plugged into.
IEM are usually very low impedance and most portable audio has a low output impedance, so they work well together.
Where as in a music studio, they could be using higher impedances amps and headphone with really high impedances, which works together.

Are you thinking of using an amplifier with your IEMs?

No, my shure se215 work fine without amping, but I wanted to improve my knowledge, especially for future headphone purchases. 8x my phone's impedance is 26.16. Could you explain what that would mean for anything above and below that?

 

[manbear]

If your headphones have an impedance more than 8x the output of the amp, nothing much happens. If the headphones are below 8x though, it can change the way the headphones sound. Depending on the headphone, this could make no practical difference, or it could be really obvious. 

IMO, the main benefit of an external amp for headphones that are easy to drive like IEMs is that you plug the external amp into an external DAC. That external DAC may significantly improve the sound (you hear more details, the soundstage becomes bigger, the bass more controlled, etc.), even if the stock headphone jack has enough power by itself. 

I think a lot of people that use amps with IEMs just have the audiophile bug and like buying gear, too. Not that that invalidates anything. But IEMs "need" an amp much less than planar magnetic headphones for example. 

 

[curtisngl]

If your headphones have an impedance more than 8x the output of the amp, nothing much happens. If the headphones are below 8x though, it can change the way the headphones sound. Depending on the headphone, this could make no practical difference, or it could be really obvious. 


IMO, the main benefit of an external amp for headphones that are easy to drive like IEMs is that you plug the external amp into an external DAC. That external DAC may significantly improve the sound (you hear more details, the soundstage becomes bigger, the bass more controlled, etc.), even if the stock headphone jack has enough power by itself. 


I think a lot of people that use amps with IEMs just have the audiophile bug and like buying gear, too. Not that that invalidates anything. But IEMs "need" an amp much less than planar magnetic headphones for example. 

My IEMs impedance is 20 ohms and my headphones are 33 ohms. So you're saying my IEM's could use amping?

 

[manbear]

There is nothing magic about the 8x factor. I've seen people say 5x, 6x, 10x as well. If 8x your phone's impedance is 26.16, then your 20 ohm IEMs are about 6 times the impedance of your amp. That's probably good enough. I imagine you'd get some level of improvement by amping, but it doesn't sound like you "need" an amp. Do you want one?

 

[curtisngl]

There is nothing magic about the 8x factor. I've seen people say 5x, 6x, 10x as well. If 8x your phone's impedance is 26.16, then your 20 ohm IEMs are about 6 times the impedance of your amp. That's probably good enough. I imagine you'd get some level of improvement by amping, but it doesn't sound like you "need" an amp. Do you want one?

I guess that's the golden question isn't it? I don't really want one much. I mainly wanted to know more about amps since before I thought the higher the impedance of the headphone, the more amping it needs. Could an upgrade cable affect the impedance? My IEMs have an upgrades cable.

 

[manbear]

Most headphone amps deliver less power into higher impedances, For example, an amp might have 200 mw into 150 ohms, 100 mw into 300 ohms, and 50 mw into 600 ohms. So it's not quite that high impedance headphones need more juice, it's that amps need to be really beefy to have enough power into high impedances. 

Changing cables would certainly affect impedance at an academic level, but probably wouldn't make any different in practical terms unless something is really extreme about the cable.  

 

[rubinstein]

sensitivity or efficiency of headphone is very important factor, from which one can tell if the headphone needs amp or not!
 
http://www.head-fi.org/t/680240/would-a-fiio-e17-be-good-enough-for-a-he-4#post_9775764
http://www.head-fi.org/t/688743/had-a-beyer-dt990-2005-600-for-a-few-years-whats-next#post_9953057

 

[PurpleAngel]

No, my Shure se215 work fine without amping, but I wanted to improve my knowledge, especially for future headphone purchases. 8x my phone's impedance is 26.16. Could you explain what that would mean for anything above and below that?

With Headphones (or IEMs) that are 33-Ohms, it would be recommend to use a headphone amplifier that has an output impedance of around 4.125-Ohms or less. (33 / 8 = 4.125)
But nothing is perfect, I use my 40-Ohm headphones with an amplifier that has an output impedance of 10-Ohms, that is only 4X and it sounds fine.
I have some 600-Ohm headphones that I use with an amplifier that has an output impedance of less then 1-Ohm, sound great, the headphone have over 600 times the impedance of the amplifier they are plugged into.
 
Your phone has an output impedance 26.16-Ohms, not the best for driving headphone/IEMs, but nothing is perfect.
Companies save on costs by putting the cheapest hardware they can to save a few cents.
 
I believe Apple portable audio devices have an output impedance of around 5-Ohms or less.
I guess that's is one of the reasons Apple products cost more then their non-Apple counterparts.

 

[curtisngl]

With Headphones (or IEMs) that are 33-Ohms, it would be recommend to use a headphone amplifier that has an output impedance of around 4.125-Ohms or less. (33 / 8 = 4.125)
But nothing is perfect, I use my 40-Ohm headphones with an amplifier that has an output impedance of 10-Ohms, that is only 4X and it sounds fine.
I have some 600-Ohm headphones that I use with an amplifier that has an output impedance of less then 1-Ohm, sound great, the headphone have over 600 times the impedance of the amplifier they are plugged into.

Your phone has an output impedance 26.16-Ohms, not the best for driving headphone/IEMs, but nothing is perfect.
Companies save on costs by putting the cheapest hardware they can to save a few cents.

I believe Apple portable audio devices have an output impedance of around 5-Ohms or less.
I guess that's is one of the reasons Apple products cost more then their non-Apple counterparts.

The in impendence or my phone times 8 is 26.16. I'm using an iphone 5 which has an output around 3.25 I'm guessing because I don't remember the exact number

 

[curtisngl]

sensitivity or efficiency of headphone is very important factor, from which one can tell if the headphone needs amp or not!

http://www.head-fi.org/t/680240/would-a-fiio-e17-be-good-enough-for-a-he-4#post_9775764
http://www.head-fi.org/t/688743/had-a-beyer-dt990-2005-600-for-a-few-years-whats-next#post_9953057

And this is where the whole amping thing gets confusing for me haha

 

[rubinstein]

I am not still clear about correlating all these parameters!

 

[tomb]

Where is the line between amping slightly helping and making a significant difference? Do even IEMs benefit?

Yes, IEMs benefit.  Something like the Etymotic ER-4S, for instance, needs an amp.  The old Altec Lansing IM716 (an Etymotic OEM) could not perform well without an amp, period.  Grados are known for not needing an amp, yet almost every one but the bottom-of-the-line SR60's perform better with an amp.
 
All this talk about impedances is too confusing.  It really doesn't matter when it comes to whether you should use an amp or not.  Besides, very few amps publish their output impedances. You have to find someone who's reviewed one and then went even further to measure it, before you can determine the output impedance.  There seems to be a huge emphasis on amplifier output impedance lately.  Maybe it's good for education, but it's not a panacea.  In fact, higher damping factors (the ratio between headphone impedance and amplifier output impedance) don't necessarily translate into better sound with all headphones.
 
The impedance of the amplifier determines how much power it will provide to a load at a given impedance.  A high impedance headphone will need more voltage swing than current impulse, whereas a low impedance headphone will need more current impulse rather than voltage swing.  Portable devices are limited by batteries, for instance, which means their voltage swing is limited.  That's why you may see many recommendations for low-impedance headphones to be used with portable devices.  On the other hand, high impedance phones need a high voltage swing but little current.  Portables can't provide that because of their battery limits.
 
That's almost a digression, though, at this point.  What's easier to consider is POWER of an amp and EFFICIENCY of the headphone.  Power is the end result desired, period.  If you don't have enough, the impedances in question matter little.  When it comes to power for instance, just to hear a 3dB difference - usually the threshold of where a human can hear a difference in sound volume - you need 2X power.  For a 6dB difference, you need 4X power, but the real relationship is exponential.  If you need a 12dB peak, the power requirement is 15.8X power over 0dB, and so on.  (Even the worst compressed music usually has at least a 20dB range on a peak level meter.)  Pretty soon, if you consider fleeting transients and momentary peaks, you find out that power needs increase drastically very quickly.
 
The main point is, every device that powers a headphone contains an amplifier.  The real question: is it sufficient?  If you think you're listening to a headphone without an amp - you're not.  So are you missing something, confident that whatever amp is contained in whatever device you are using is sufficient to capture every detail, every transient, every musical peak without clipping into distortion that you typically never notice because you've heard nothing better?
 
That's the question you have to ask yourself.

 

[rubinstein]

tomb, thanks