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HM 801 headphone out L R channel imbalance issue

post #1 of 7
10/1/11 at 2:32am
Thread Starter 
Received hm801 with standard v2.0 amp and game amp yesterday. I've been using my LCD2s with it for the past few hours, once gained up the channel imbalance is almost undetectable but at low gain only the right channel plays. I just plugged my GR07s into the headphone out and discovered the same effect. this points to a problem with the headphone out. I've tried both amp modules with the same effect. I have tested the line out and channels are evenly balanced, I have also updated firmware to latest. I'm looking for any option other than to send it back as i just got it. Ideas appreciated!
Edited by temporaryname - 10/1/11 at 5:17am
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post #2 of 7
10/2/11 at 4:46pm
Thread Starter 

Bump

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post #3 of 7
10/16/11 at 6:34am
Thread Starter 

Tested a friends HM-801 and got the same result - channel imbalance at low volumes. Can't use IEM's with the Hifiman HM-801 due to their high sensitivity. Seeing as two different units (spaced apart by 5 months) have the same characteristic, leads me to believe that there are more HIfiman HM-801's out there with this defect.

Mailed Fang and he said that it will be fixed if sent back... which I take as an admission of guilt that this is a defect.

 

Anyone else have the same observations?

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post #4 of 7
10/16/11 at 7:28am

It is not about the headphone-out nor is it a defect.. It is a common issue with analog potentiometer (the volume pot). Most of them becomes imbalance on the lowest few degree, that's why more and more portable amp are switching to digital volume control these days.

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post #5 of 7
10/17/11 at 12:56am
Thread Starter 
Quote:
Originally Posted by ClieOS View Post

It is not about the headphone-out nor is it a defect.. It is a common issue with analog potentiometer (the volume pot). Most of them becomes imbalance on the lowest few degree, that's why more and more portable amp are switching to digital volume control these days.



Thank you ClieOS!! It's incredibly satisfying to receive an answer and learn something useful.

It is curious, however, that Fang would offer to fix something that would be deemed a characteristic of his chosen analog potentiometer. Does it mean that he can fix it or does he assume the situation is worse than I made it seem? ....hmmm.

 

Again, thank you ClieOS!

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post #6 of 7
10/17/11 at 1:54am

Well, the two (general) ways to fix imbalance caused by pot are 1) replace the old pot with a new pot that has higher precision and lesser imbalance or 2) lower the overall gain so you need to turn the pot higher (and thus the lowest few degree becomes lesser a problem). The first way is usually preferred as it is more of a long term fix without making the device less suitable for high impedance / low sensitivity headphone, but it really depends on how one is planning to use his player. I remember some of the latest HM801 comes with 2 power amp module - one on high gain and one on low gain so user can choose which gain is most suitable for his/her need.

 

As for why people still use analog pot when there is digital volume control around - 1) some regards most digital volume control being not as transparent sounding as analog pot, since extra circuit needs to be implemented which can affect the sound quality. 2) as extra circuit is needed, cost goes up as well as extra space / PCB is needed.

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post #7 of 7
10/18/11 at 12:05am
Quote:
Originally Posted by temporaryname View Post

Received hm801 with standard v2.0 amp and game amp yesterday. I've been using my LCD2s with it for the past few hours, once gained up the channel imbalance is almost undetectable but at low gain only the right channel plays. I just plugged my GR07s into the headphone out and discovered the same effect. this points to a problem with the headphone out. I've tried both amp modules with the same effect. I have tested the line out and channels are evenly balanced, I have also updated firmware to latest. I'm looking for any option other than to send it back as i just got it. Ideas appreciated!


Any sonic differences between the standard and GAME amp?

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