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BitHead turn-on thump

post #1 of 8
12/19/09 at 8:11pm
Thread Starter 
Hi there,

So I got myself a nice Total Bithead amp for Christmas. I must say I'm very impressed with the size of the thing (I expected it to be somewhat larger) and the sound of it, particularly when used as a DAC/amp combo.

Still, I'm a bit concerned about the click/pop produced by the amp when turning it on or off. Have you had any cases of damage to IEM's caused by it? I use q-Jays and ER-6i with the amp.

cheers!
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post #2 of 8
12/19/09 at 8:20pm
It gets on my nerves but doesn't seem to cause any harm. I just make sure the volume is turned all the way down before turing it on. It's better then the alternative, which is plugging the phones in after you turn it on. That doesn't sound too friendly either...
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post #3 of 8
12/19/09 at 9:03pm
Thread Starter 
Quote:
Originally Posted by Joelby View Post
<snip>
It's better then the alternative, which is plugging the phones in after you turn
it on. That doesn't sound too friendly either...
Oh, I've tried that too (though it's not recommended in the manual) and I can tell you it sounds even worse in the 'phones than the turn-on pop.

cheers!
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post #4 of 8
12/20/09 at 12:53am
Hi:

I own a Desktop Ultra and it also thumps on power-up. This effect concerned me also, and I contacted Mr. Mike Olsen at Headroom. He assured me the thump is quite normal and will not damage the phones.

I seem to remember documentation at Headroom's site explaining that their amps are class A devices, and though miniature versions of full-sized speaker amps, they remain relatively powerful. I recall the page explaining that, as one wouldn't intentionally short an amp by crossing ground and positive wires, one shouldn't also connect a pair of cans to a Headroom amp without taking certain precautions.

My amp bears a sticker warning users to un/plug headphones only after switching off the amp and/or completely lowering the volume. This prevents the ground and left/right positive sections of the headphone jack from inadvertently cross-connecting under full power, thereby preventing a blown rig.

Protection circuitry exists which prevent this sort of damage and also usually dampen or eliminate such thumps. Though at first glance desirable, such devices perceptibly degrade sound quality. Headroom avoids using them, thereby relying on their customers' caution when connecting phones.

Since the site remodel, I haven't been able to locate the safety information on this subject. I doubt Headroom's changed its circuitry; I'd wager they simply haven't posted the information, for whatever reason.

Perhaps a Headroom associate could point us in the right direction.
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post #5 of 8
12/20/09 at 8:11am
Yeah. Two things not to worry about.

That thump on powerup, as well as a delay in the power LED going out on powering down.

I've noticed this with all the HR Amps I've owned.
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post #6 of 8
12/20/09 at 8:31am
Just like to extend this to just about all amps.
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post #7 of 8
12/20/09 at 2:08pm
Quote:
Originally Posted by aimlink View Post
That thump on powerup, as well as a delay in the power LED going out on powering down.
Yup. DC coupling = thump. Lots and lots of power supply capacitance = long time for it to turn off due to energy storage.
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post #8 of 8
12/20/09 at 3:16pm
at first I had always pluggin the phones before I turned on the amp, but this thump noise, and some advise from others has made me to start plugin the headphones after I turn on the amp. I find this little psss noise much less worring than the thump noise.
anyway, probably both plugin methods are harmless.
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