Wednesday, May 4, 2016

Headphone Impedance

We often see speaker impedance charts from reviews, but rarely do we see them in headphones, so I thought it might be fun to do so for my two reference headphones.

One nice exception are reviews from InnerFideility which do include this information.  Why should we care about headphone impedance? The lower the impedance at a given frequency, the more current an amplifier must provide. Portable headphone amplifiers are especially limited in current drive. This causes the sound to track the impedance curve instead of the music. So, in general, a headphone with a higher impedance and low phase angle will be easier to drive to the same high quality sound. They will tend to sound more consistent across different headphone amplifiers.


To do this I used my trusted Dayton Audio Test System v. 2. Of course most use this for speaker testing, but what are headphones but speakers you can wear?

I have two completely different headphones I have been using as my standards. They're probably now considered quite old.  The headphones I turn to most often are the AKG K712.

The impedance plot was a solid 60 Ohms or more.


My other set of references are Shure E4c in ear monitors. I'm not even sure they used that term when I purchased them. They are definitely the most "discerning" or "demanding" of the two. While they have fantastic noise isolation, the bass doesn't open up except with the best headphone amps.  All others need not bother. This should not be a good thing! What buyers really should look for are headphones that play great with cheap amps. The minimum impedance here is a punishing (for portable amps) 24 Ohms.


The only portable player so far that I have heard play this very well is the Pono. I just wish the Pono had more features that would make it a no brainer.  The amplifier part of the player is just simply outstanding. I need to get either easier IEM's or bite the bullet and get a Pono. The other sub-$1k player that played these well was the UFO DSD DAC, until it died. 

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