Impedance? Sensitivity? What spec matters?
Aug 19, 2004 at 8:30 PM Thread Starter Post #1 of 38
slydacious

slydacious

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Can someone point me to a FAQ that addresses how headphone impedance and sensitivity factor in the ability for a given source to drive them appropriately?
 
Aug 19, 2004 at 10:19 PM Post #2 of 38
Impedence is the actual resistance the headphone adds to the circuit.
Sensitivity is just a measurement of how loud the headphones are at a specific output,(1 milliwatt I think) and really shouldn't affect your amplifier purchase, except maybe in choosing a gain setting.
 
Aug 19, 2004 at 10:24 PM Post #3 of 38
i **think** impedance is important....wont it determine whether u need an amp to get the best sound of your phones. like portable headphones are usually low impedance, because they're running off the portable audio device. but if you get some quality phone sfor home use, the impedance can be quite high but since ur home u have the ability to more easily add an amp to the device, and thus bring out the best sound possible out of the phones
 
Aug 19, 2004 at 10:36 PM Post #4 of 38
check out this link http://www.rane.com/note100.html
In fact, you can't really tell whether a headphone is hard to drive only by looking at the impedance and sensitivity ratings (maybe only half the truth).
For example: Sony CD3000 (which is not easy to drive, especially if you want some bass): Impedance 32ohm, sensitivity 104db. There a lot of other headphones that have simlilar specs but that are easier to drive.
However, if you want easy to drive headphones, you will have to look at something with an impedance below 100ohms while having a sensitivity, such as the hd25 which has a very high sensitivity.
Nonetheless, being to able to drive headphones doesn't necessarily mean drawing out the headphones' potential. For example: My receiver was definately able to drive me Senn HD 580 but it sounded awful whereas by using a dedicated headphone amp, everything just opened. (Well, I still didn't like them but that's a different story)

Edit:
here are some links regarding impedance (happy reading
smily_headphones1.gif
):
http://www5.head-fi.org/forums/showt...threadid=53279
http://www5.head-fi.org/forums/showt...threadid=57314
 
Aug 19, 2004 at 10:36 PM Post #5 of 38
High impedance phones usually do better with an amp as opposed to low-impedance. (there are exceptions). Many amps are tailored specifically to high or low-z phones, meaning better performance and synergy. The impedance of you phones do matter greatly when buying an amp.
(at least I think so)
 
Jun 25, 2011 at 11:51 AM Post #9 of 38
From what I understand the sensitivity and the impedance is the same? Doesn't the xxdB/mW mean that you need a specific amount of power to get the headphone to a certain level? Much like the impedance?
 
Jun 25, 2011 at 12:13 PM Post #10 of 38
No, sensitivity and impedance is not the same.
 
a headphone with a sensitivity of 96 dB / mW and 600 ohms (DT880 / 600) is easier to drive than a headphone with 94 dB / mW and 25 ohm impedance (AKG K701).
 
Jun 25, 2011 at 12:28 PM Post #11 of 38
I am confused right now but 96db/mW means 96dBm? This means a certain Level to the quantity of 1 mW? So, when I calculate I will get a power of 3.9 MW ??
 
 
 
Jun 25, 2011 at 2:23 PM Post #13 of 38
A large concern with portable players with many higher-end headphones is that they are constrained by battery power, size (and cost), so the max output voltage is limited.  With headphones with low sensitivity (requires more power for a given volume level) and high impedance (requires more voltage for a given power level), they may not be loud enough with such a source.
 
Other sources may have issues with poor distortion, particularly with headphones with low impedance and especially if you're playing them at higher volumes (requiring more power and thus more current).  It's harder to drive low impedance loads more accurately because they require more current.  Well, it's more complicated than that, but that's a starting point.
 
Another factor to consider is the damping factor, which relates to the headphone impedance and source impedance.  Also, it's important to note that many headphones--and especially some IEMs like balanced armature varieties--have impedance that changes quite a lot over frequency.  This can have a big impact as well, particularly if the source has significant output impedance.
 
Jun 25, 2011 at 2:36 PM Post #14 of 38
they both are important but depends. to most, sensitivity is the most important. impedance is as important but vary with frequency. headphones are like little speakers. they dip and spike at certain frequency range. output impedance can affect the speaker or headphone how it performs at certain frequency ranges. usually lower impedance needs more current(cause lower the resistance more current is drawn naturally) while higher the impedance little bit more voltage swing is needed to achieve the same amount of current pass through. voltage and current works together. it's like a water hose. the thicker the hose(more voltage) the more water can flow(current). higher the impedance usually means better in theory cause you can push more voltage and more voltage can affect how the coil push and pulls but in most cases nominal impedance specs of speakers or headphones mean very little to nothing in most cases cause it can vary by many things.
 
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