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Hiss with Hippo Pro One (single Balance Armature) / general impedance question

post #1 of 7
Thread Starter 

Hello everybody,



Recently, my SoundMagic E10 Headphones died. Having read many great thinks about Jaben i decided to buy a new pair there, feeling adventurous i picked the Hippo Pro One (single Balance Armature). Beside sounding great in my opinion, the first thing i noticed was a permanent hiss when no music is playing (i have a cowon iaudio 9). I tried other sources and in some the hiss was barely audible, in some other much worse. So i started reading up on the issue and found out that this is common (?) on most IEM with low impedance.


Nevertheless my first question is: Is there any way the hiss comes from a somewhat defective IEM and not from the source?

Beside this, I would like to know in which relation input- and output impedance on source and IEM would have to be to not produce any hiss.

My last question would be if there is anything I can do against the hiss in combination with the iaudio without spending a lot of money on extra-equipment?



Thanks in advance!

post #2 of 7

There are three solutions:


1.)  Replace the low impedance IEM with one that has higher impedance ( > Ohms ) preferably over 25 Ohms

2.)  The DAC in many portable devices are quite poor at times making noise easily audible.  To fix this you need to bypass the internal DAC in the device by by using a true LOD and external DAC

3.)  Increase the impedance of the headphone.  If the output impedance of a device is too high and the impedance of the load ( headphone ) is too low there will be an impedance mismatch.  This causes the signal from the device to the load to change possibly significantly adding unwanted noise.


Read more here:



The in-line attenuator is probably your best bet.

post #3 of 7
Thread Starter 
Thank you for your answer.

Buying new IEM is no option as i can't return the Hippo's (and i actually don't wan't to).
What is bothering me is that the output impedance of the iaudio9 is about 1.5 ohms and the one of the load 16 ohms - so there should be no mismatch in my understanding (according to http://www.head-fi.org/a/headphone-impedance the load should be at least 8 times as big as the one of the source). Am i right that this means that an in-line attenuator would have no effect?
So the source-dac produces the hiss somehow?
Again, is it possible that the IEM are defective and therefore responsible for the hiss by it self? Sorry, i am quite new to this.

kind regards.
post #4 of 7

I doubt the IEM is defective.  It is most likely hiss from a poorly designed DAC that is being amplified.  It comes down to signal to noise ratios of your gear. .  Better designed give higher signal to noise ratios and thus filter out the noise.


Try listening to a friend's iPod.  Most Apple products sound really good for the cost and are designed with audio in mind.  If the hiss still persists then it may be related to the IEM.  If the hiss is gone then the source is the cause and a better soundcard will be in order.


Also Check:


Any EQ settings you may have turned on

The jack plug is fully seated in the jack ( sometimes they interfere with the case of a phone for example )

Try several different tracks because the track you are listening to could simply be noisy

post #5 of 7
Thread Starter 
I tried an Ipod and also the Fiio X3 - the hiss was audible with both of them and really annoying on quiet tracks. I think ill have to go for other IEM after all frown.gif. Nevertheless thank you for your help.
post #6 of 7
I didn't have any noticeable hiss when using the Hippo ProOne with an ipod classic 7G with rockbox
post #7 of 7
Thread Starter 
That's somewhat strange. I guess with or without Rockbox should not make a difference hiss-wise? Do you have a FiiO X3 or a Cowon iaudio 9 so that you could check on these?

kind regards
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