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Has Hifiman upgraded/downgraded the HE500 drivers?

post #1 of 43
Thread Starter 

Okay so I measured impedence on my HE500 drivers to see how close it is to spec.  The specs say it should be 38 ohms, however I am getting 52 ohms. This seems very close to the HE6 impedence of 50 ohms.  Has Hifiman change the latest revision of HE500's? Mine is way out of spec, bought it new last month.


Edited by flargosa - 2/3/12 at 9:53pm
post #2 of 43

Subscribed.  I was thinking about "upgrading" to the HE-500's after returning my HE-400's.  After looking inside the HE-400's I get a very queasy feeling about everything about this company.  I am, however, hoping that the HE-500's are better with respect to internal build quality and overall QC.  Your post gives me pause...

post #3 of 43

Have you actually asked Fang about it directly? 
 

Quote:
Originally Posted by flargosa View Post

Okay so I measured impedence on my HE500 drivers to see how close it is to spec.  The specs say it should be 38 ohms, however I am getting 52 ohms. This seems very close to the HE6 impedence of 50 ohms.  Has Hifiman change the latest revision of HE500's? Mine is way out of spec, bought it new last month.



 

post #4 of 43
Thread Starter 


Yes, I have.  Waiting for a response.  I know that another head-fier got a reading of 50 ohms as well, so I am not the only one with an out of spec HE500.  

Quote:
Originally Posted by detoxguy View Post

Have you actually asked Fang about it directly? 
 



 



 

post #5 of 43

Where are the measurements taken?

post #6 of 43
Thread Starter 

I took it at the headphone input plug, where you screw in the cable.  So there is no added impedence from the cable.  I have a pretty good Fluke multimeter, the measurements from my other headphones are within 2-3% of spec.  


Edited by flargosa - 2/4/12 at 7:46am
post #7 of 43

I wonder what exactly is changed about the driver, or maybe yours is simply an isolated incident of a one-off oddity?

post #8 of 43

The HE-500 Tyll measured a while ago is 47 ohms. Hifiman's published specs are very off at times. I don't know how they measure them. The HE-6 Tyll has is much harder to drive than 83.5 dB/mW, not as hard as 83.5 dB/V, so it's not just a matter of units.

post #9 of 43

At what frequency is the impedance spec?  You guys are just measuring the DC resistance.  The impedance of many headphones varies wildly with frequency.

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post #10 of 43

There were people here who claimed that the impedance of planar magnetic headphones don't vary with frequency. I'm not entirely sure if they actually measured it from 20Hz to 20kHz.

post #11 of 43
Thread Starter 

I'm not sure if this is the correct graph, but it shows the HE500  impedance to freq as flat.  I'm guessing it shouldn't matter what freq it is tested at.  

 

graphCompare.php?graphType=7&graphID[]=3241

post #12 of 43

I think we have a couple of plots of different Orthos, on one I think a bass bump may be barely visible, flat the rest of the way

 

a 1st principles argument also supports the flat electrical impedance

low electro-dynamic coupling efficiency of the Ortho design means that you are mostly looking at the membrane electrode foil electrical resistance with little added mass-spring motional impedance coupled to the electrical terminals

some voice coils show rising high frequency Z due to inductance of the coiled wire, Ortho's planar, meander electrode pattern is very low inductance too


Edited by jcx - 2/4/12 at 4:43pm
post #13 of 43

As far as I know, HE-500s have always measured at about 50 ohms impedance despite the official specs.

post #14 of 43

Do they sound bad? 

post #15 of 43

No, the HE500 that I have sound superb and at $699 a major bargain. biggrin.gif

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