Geek Out DC Spike damages Headphones?
May 1, 2015 at 10:28 PM Thread Starter Post #1 of 3

Aiyah

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Hello esteemed headfi'ers, I recently bought a Fostex TH-900, as my end all be all headphone. I also bought a Geek Out 450 as a portable dac. I've been keeping the headphone plugged in to the dac when I plug it in. I've just read that the pop I was hearing when plugging it in is a DC spike and can damage the headphones. If it were to have caused damage, what would the symptoms be?
 
Would it change the audio signature of the headphones permanently, or would it be catastrophic or nothing? Maybe I'm being paranoid but ever since I plugged it in and heard the pop the headphone has seemed a bit more veiled than I remember. Is this possible or am I being a worry wart?
 
I'm getting a Schiit Modi2/Magni2 stack to replace the geek out as I cannot fathom trusting an amp without a muting relay now. 
 
May 1, 2015 at 11:28 PM Post #2 of 3

kramer5150

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Why are you plugging the cans into the amp before its powered up?  You should do it the other way around.  Plug in the amp first.  With no music playing and the volume turned all the way down, plug in the cans.
 
I switched gain resistors in my PPA to lower the circuit gain.   I forget what it was but it was in the vicinity of 2-2.5.  I ran it for an afternoon and it sounded great.  Not realizing my mistake and that had forgotten to swap out the OPA637s for a lower gain-stablity OPAamp.
 
I step away to take a shower, feed the fish... and putter about for a little.  I left the amp & cans just sitting idle on my desk.  When I come back I hear this LOUD noise coming from my headphones,  that were just sitting idle on my desk.  Like static, like a distorted clipping square wave motor-boat sound.  The OP amps had gone into some kind of crazy "DC-like" oscillation.  I call it that merely because I don't have a scope to actually see what it is... but at any rate it sounded BAD and LOUD.
 
By the time I unplugged them and powered everything down... it was too late, I had smoked one of the coils in my HD580, and the left side was severely deficient.
 
Lesson learned!!... I am really careful about that kind of stuff now.
 
May 2, 2015 at 6:49 AM Post #3 of 3

Aiyah

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Well I will do the proper order now that I'm aware. I'm just trying to figure out the possibility of the headphone being damaged. I read somewhere that the discharge is around 2 volts
 

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