I've had a pair of creative ep-630 earbuds since May 06. Recently, I went to an ear-nose-throat doctor and got all the wax taken out of my ear, and just started noticing that I'm getting a hiss in my x51v. By hiss, I don't mean the background noise from a low-bitrate mp3. To me that's inevitable and even acceptable. This hiss occurs whether or not I play music. There would be about 5 seconds of it every time a sound plays (for example, the "click" from opening the start menu). And if I'm playing an mp3, the hiss would be continuous. Also, the loudness of this hiss is independent of the volume level. Only when I mute sound completely does the hiss disappear.

I also know that my ep-630's are not defective, because my friend has the exact same pair, with the same hiss. I've also tried my pair on his hp-4700. Same problem. However, when I plug them into my harmon kardon speakers, which are plugged into my PC, the hiss becomes almost unnoticeable.

Note that I was only able to hear this hiss after I got a lot of wax taken out of my ear. Also, my father who may or may not have earwax, says he cannot hear any hiss at all. My ear-nose-throat doctor tells me that people of different ages are able to hear different frequencies, so that just MAY be a cause of why I can hear it and my dad can't. Strange, isn't it?

As some of you know, one of the users at this site has obnoxiously bumped every single hiss thread with "his" solution, that higher resistance earbuds mean little or no hiss. Since my ep-630 is 16 ohms, I decided to see if he's right. I tried my friend's Creative Aurvana's, which are 42 ohms. Not only was there hiss when plugged into my x51v, now there was volume dependent hiss when plugged into my PC speakers! However, I did notice that the hiss from my pocket pc with these higher resistance ones was slightly less than with my ep-630's

I tried one more pair of headphones, my friend's TDK CP100 ear clip headphones (http://www.tdk.com/consumer/headphones/earclip.html). For some reason, TDK also released a pair of clip earbuds with the exact same name. I tried the one in the link, which my friend bought for less than $10. Surprisingly, there was no hiss whatsoever when plugged into my x51v's.

Here's a summary of what just happened:

Headphone: Creative EP-630
style: noise blocking in-ear earbuds
Sensitivity: 106 dB
Range: 6 - 23000 Hz
Resistance: 16 ohm
Price: about $30
Result: hiss when plugged into pocket pc, barely noticeable hiss when plugged into pc speakers

Headphone: Creative Aurvana
style: noise blocking in-ear earbuds
Sensitivity: 115 dB
Range: 20 - 20000 Hz
Resistance: 42 ohm
Price: about $80
Result: slightly less, but still very noticeable hiss when plugged into pocket pc, hiss when plugged into pc speakers

Headphone: TDK CP100 (large round ear clips, not the ones found on google. See link above):
style: large round ear-clips
Sensitivity: 104 dB
Range: 20Hz-20kHz
Resistance: 32 ohm
Price: less than $10
Result: NO HISS ANYWHERE, EVER

My dad also had a couple of earphones at home which I tried with my pocket pc.

headphone: shure e2c
style: noise blocking in-ear earbuds
sensitivity: 105 dB
Range: N/A
Resistance: 16 ohm
Price: about $80-90
Result: hisses with pocket pc and PC

headphone: sony MDR-w20g
style: vertical over-head earbuds (google the mdr to see what I mean)
sensitivity: 106 dB
range: 10 hz - 23 khz
Resistance: 16 ohm
price: about $15
result: hisses with pocket pc and PC

Again .Note that when I say hiss, I don't mean it only hisses when I play music. I mean that there is 5 seconds of a hissing noise after every "sound" that is made by the device. That also happens to mean when music is playing there is a constant background hiss. Also, to eliminate the possibility that it's a defective device, I've used my x51v, my friend's ipaq 4700, and my dad's ipaq 6315 for each of these headphones.

Now for the interesting part: when I plug all these into my sister's cheap RCA lyra 256 MB flash player, there appears to be no hiss in the background. Although I really can't tell for sure unless I had a completely silent mp3 file, since flash mp3 players can't make such singular sounds like the pocket pc's "click". My mp3 songs sound a lot more crisp and pure than when I play them from a pocket pc.

Here's perhaps my most interesting discovery however. I also have a couple of other earbuds lying around; the crappy ones that were bundled with the audio players I've bought over the years. I also have a couple fake sony earbuds from street vendors in China, and a couple that I got for 1.79 from WalMart. Of course, audio quality is crappy. Surprise, all of them are completely hiss free.

So, If I were the type to be rash and jump to conclusions, here's what I would probably say:
- Pocket pc's are not designed for audio. When you plug a high-quality pair of earbuds into them, you will get hiss because these earbuds are sensitive to almost any signal.
- on the other hand, crappy and cheap phones like the tdk-cp100's and the buds bundled with mp3 players do not hiss, because they are simply not sensitive enough to pick up the hiss-causing interference
- flash players don't hiss (as far as I can tell; I would need a completely silent mp3 file to safely make this conclusion)
- some people can hear the hiss, other people can't. Whether this is due to earwax or age-related differences in perception of different frequencies, you can't deny the fact that there is hiss, whether you can hear it or not. For those of us that can, it's as loud as a fan blowing about 5 feet from your head.
- hiss is NOT caused by low resistance, no matter what a certain poster on this forum will scream otherwise

So right now I'm kind of faced with a dilemma; either:
1. listen to pocket pc with high quality phones that hiss
2. listen to pocket pc with low audio quality phones that don't hiss
3. buy a cheap flash player which I will have to carry around in addition to the pocket pc
4.

Discuss

Low impedance is part of the problem, but high sensitivity is also the culprit with regard to the hissing. Also hissing will be much more noticeable with any headphone that sits in your ear canal. My ER6i headphones also have hissing with X51v, they are high sensitivity, low impedance, canal-phones. There are a couple of things you can do to eliminate the hiss:

1. One thing you can do to eliminate the hissing is add in-line resistance to the headphones. Radioshack sells a small cheap inline volume control that can be put between your x51v and headphones. It will act to both increase the impedance and decrease the sensitivity, and will greatly reduce or eliminate the hissing. At this very moment I am using this with my x51v and ER6i and it eliminates the hiss completely. It means you must turn the volume up more on the x51v of course, which could drain the battery slightly faster. It will also change the sound (frequency response) of the headphones slightly. Shure also sells it's own inline volume control, but it costs more than the Radioshack one.

2. Buy a headphone amp. I know it can be expensive and reduce the portability somewhat, but it will result in the best sound quality. A headphone amp has a very high input impedance (typically over 10kohms), so it will be an easy load for the pda/mp3 player. You must make sure, of course, that the headphone amp itself does not hiss with sensitive headphones. Check www.head-fi.org for reviews and advice if you want.

Good response by slindeman.

I have low impedance, high sensitivity (Westone UM1) IEMs as well. I also posted in response to another 'audio hiss' thread in this forum, and suggested the Shure in-line attenuator to solve this problem. The hiss doesn't bother me enough to warrant me either getting an in-line attenuator, or building my own cmoy, so I've just "1. Listened to my Pocket PC with my high quality phones that hiss".

I would also like to refer you to www.head-fi.org
It's my Aximsite for headphones =P

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