STAX OmegaII has arrived!! O2 users help!
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PATB

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I am not 100%, but the always ON bias must be getting the 580V bias voltage from the same power supply. In that case, if you have transformer hum, you are going to need more mechanical damping or clean up the power to your amp.

Do you use an AC conditioner? Try plugging directly to the wall or another outlet in the house.
 
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post-1466960
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barilie

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Quote:

Originally Posted by PATB
In that case, if you have transformer hum, you are going to need more mechanical damping or clean up the power to your amp.


How will I do that, I'm very new in this matters...

Quote:

Originally Posted by PATB
Do you use an AC conditioner? Try plugging directly to the wall or another outlet in the house.


What is a AC conditioner? Do I need one? Now I plugged directly to the wall. If the power is not clean, how could the buzz be away for some time? In the meantime the hum is there whithout interruption. Nothing (pressure....) helps anymore. I tried different plug-connections, but no difference.
 
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post-1467038
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PATB

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If you need mechanical damping, you may need to send the amp to Justin.

Some power supplies make a noise when used with some conditioners. Since you don't have one, that gets rid of that probability. I don't think you need a power conditioner unless your power is very dirty. I just use a hospital grade power strip for my system.

Time to send an e-mail to Justin. He has great customer service.
 
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post-1468036
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spritzer

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It is probably hum from either the main transformer or the small transformer on the bias supply. The always-on bias supply is a completely seperate unit with its own transformer. It can be seen here in close up (rather large picture). My unit also hums a bit but it doesn't bother me and it does no harm.
 
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post-1468299
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KenB

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Have you ruled out internal grounding problems? I had that condition with my STAX SR-313 amp, initially, although the hum was only noticeable when the volume knob was turned up above 6 (or 1:00 O'Clock on the dial). I solved it temporarily by running a wire from the external ground connector (back panel) to a cabinet screw. Subsequently, I received instructions from the manufacturer to simply carefully unscrew and remove the cabinet top and then reattach. That action must have accomplished a regrounding of the chassis because the hum immediately disappeared and has not recurred.

KenB
 
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barilie

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Quote:

Originally Posted by spritzer
My unit also hums a bit but it doesn't bother me and it does no harm.


I expressed myself in a wrong way: I can hear a clear hum or buzz IN the headphone!! When I said "the buzz comes from the KGBH", I wanted to make a difference between amp and digital source.

This is a part from my email to Justin from Headamp:
Quote:

First there was a little buzz with the amp off. I thought then: the always on bias supply is working!
By switching on the unit, the buzz even increase. When I reconnected the jack the buzz stops, then I thought I plugged the jack too deep in the socket but after a while it came back.
Then with a little pressure on the back of the unit it stops again. But
finally there was was no remedy anymore to stop the buzz.


 
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post-1470167
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pspivak

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I hate to sound stupid (stoopid?) but have you isolated your problem to the amp? Be sure to check your cables. Be sure you are not too close to hum generating things like light bulbs and refrigerators and air conditioners.

Enjoy the o-2's
 
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barilie

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Quote:

Originally Posted by pspivak
Be sure to check your cables.


I will check!
Quote:

Originally Posted by pspivak
Be sure you are not too close to hum generating things like light bulbs and refrigerators and air conditioners.


I did try three different plug-connections (in the same room) and there was no difference. I'll try in friend's house. But after my holidays in Scotland!
 
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post-1470758
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gajira

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I'm using a DIY KGSS.(PCB is Headamp's)I heard a hum from my O2 and
SR-003 too.When I touched a GND of cable,the hum went away.
So I guessed that the cause of hum problem is unstable GND of KGSS.
I connected wall's GND with KGSS's GND.
As a result,the hum has disappeared.
 
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post-1470920
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barilie

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Quote:

Originally Posted by gajira
I'm using a DIY KGSS.(PCB is Headamp's)When I touched a GND of cable,the hum went away.
So I guessed that the cause of hum problem is unstable GND of KGSS.



Sorry, but I don't know what "DIY", "PCB" and "GND" means.
 
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post-1470936
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KenB

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Quote:

Originally Posted by barilie
Sorry, but I don't know what "DIY", "PCB" and "GND" means.


As I wrote to you earlier, it now sounds more and more like an internal chassis grounding problem which I experienced on my brand new STAX SR-313. The fact that the hum stopped when you pressed on the unit suggests that possibility. Something may have come a bit loose in the way the chassis/cabinet is grounded inside the unit.

On the backplane of the amp do you see an external Ground (i.e. GND) connector? Using fingers on two hands, try holding the GND connector and touch another metal part on the cabinet housing. Does the hum stop? If so, unscrew and remove the cabinet from the main chassis (carefully) and, then, simply put it back together again. If that doesn't work, take a short wire and connect one end to GND and the other to any metal cabinet screw. That should only be considered a temporary workaround until you can get Justin to fix the problem permanently.

KenB
 
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post-1471027
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agile_one

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Quote:

Originally Posted by barilie
Sorry, but I don't know what "DIY", "PCB" and "GND" means.


DIY=Do It Yourself
PCB=Printed Circuit Board
GND=Ground
 
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post-1471156
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spritzer

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Well if the buzzing is in the headphone it could be a damaged transducer or something stuck to it that is creating a short.
 
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post-1489391
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barilie

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I now see a bit more clear in this problem! I opened the amp and saw that the wire from the +580V connector wasn't tight. So I screwed down that wire and then the hum didn't stop anymore. Quote:

Originally Posted by KenB
Using fingers on two hands, try holding the GND connector and touch another metal part on the cabinet housing. Does the hum stop?


No, but it stopped when I hold the +580V connector (on the bias supply board) with my electrical screwdriver (you know, with a light in it...) and simultaneously touched the cabinet housing. Quote:

Originally Posted by KenB
If so, unscrew and remove the cabinet from the main chassis (carefully) and, then, simply put it back together again.


In this case, should this work also?
How can I solv this problem?
 
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