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Old 9th February 2012, 05:46 PM   #2061
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It certainly shouldn't be anything approaching deafening. What headphones are you using?
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Old 9th February 2012, 05:47 PM   #2062
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Thanks for the response....

I am using a couple of different pairs of Magnum v4's and also a pair of monster turbine coppers at the moment with it.

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Old 9th February 2012, 06:05 PM   #2063
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Hmm, the Grado drivers aren't THAT sensitive. If it is indeed deafening or even really loud that would suggest a problem.
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Old 9th February 2012, 07:08 PM   #2064
billyk is offline billyk  United States
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The O2 has a very mild thump, hardly noticable, at least the two I built. I would sugest that something is wrong. My first one had a loud on-off but that was due to a faulty positive vreg. Once that was fixed, as I said, very quiet.
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Old 9th February 2012, 07:12 PM   #2065
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Location: Midwest USA
Originally Posted by dgcrane View Post
I just received a built o2 from a member who put it together for me. When the o2 is being turned off, there is a deafening pop through my headphones..... The member said this is normal, but I would like to confirn that information please. Does this happen to everyone ?

Darren C
The clicks and pops at power on and off aren't that loud even with my Shure SE530s which are very sensitive so it should hardly be "deafening" with the less sensitive Coppers or Magnums.

It sounds like there's something wrong with it to me.
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Old 9th February 2012, 07:30 PM   #2066
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Yeah I assumed there was a problem and have asked to return the item already.

Thanks for the input.

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Old 9th February 2012, 11:50 PM   #2067
Tawz is offline Tawz  Canada
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I currently have my O2 sitting next to me, and I am very much enjoying it. That aside, I am having issues that prevent me from running my O2 off of battery power.

The amplifier runs fine from the wallwart, nothing gets hot, no audible clipping or distortion, etc.. I do get between 13.0 to 11.6 volts on pin 8 and the inverse on pin 4 of u3 and u4. The surplus voltage does not seem to be a problem, and it is the only voltage issue I have when running from the wallwart.

Running the amp from batteries, however, nets me 9.1 Volts on both output channels (measured from p2).

The batteries are Tenergy 200mAh batteries as specified in the BOM. I have checked the board as best I can for bridges, and so far I have found none.

Is this an issue stemming from damage to u5 and u6, or do I have a bigger problem?
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Old 10th February 2012, 08:19 AM   #2068
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When building my O2, I accidentally singed C15 while correcting a mistake. One corner is now no longer a corner and more of a melted mess.

Do capacitors have a state between "fully working" and "fully broken", and what would the impact of a damaged/broken C15 be?

The various tests measured OK on the multimeter and the amplifier appears to function perfectly, but I'd rather be sure some non-obvious problem isn't going to blow things up.

A picture:
Click the image to open in full size.
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Old 10th February 2012, 08:54 AM   #2069
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U5 and U6 should not affect battery power at all, and since you can run from a wallwart it would appear that the regulated part of the power supply is functioning correctly. Full battery voltage on the outputs is definitely a problem though. I can't think of anything specific... I'd pull the chips U1, U3,U4 and attack it again with an ohmmeter and a magnifier.
Your C15 is fine. It doesn't appear that you compromised the capacitor innards in any way. It's just a cosmetic defect.
The answers to your questions are: yes; and shorted - a nonfunctioning O2, open - a noisier power supply. It's a bypass cap for the power supply.
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

Last edited by sofaspud; 10th February 2012 at 08:57 AM.
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Old 10th February 2012, 09:06 AM   #2070
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Good news! Thanks for the analysis and information.
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