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Author Topic: Leaving headphones plugged in.  (Read 4749 times)

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Offline TonyMc

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Leaving headphones plugged in.
« on: September 22, 2011, 05:17:01 AM »
Is it a bad habit to leave your phones plugged in all the time? I usually kick on the crack and let it warm up a bit then plug them in, and unplug them before shutting it down.
Just wondering what everyone else's habits are.

Offline Wanderer

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Re: Leaving headphones plugged in.
« Reply #1 on: September 22, 2011, 05:33:13 AM »
I use a headphone modified Quickie and I am concerned a turn on pulse could damage the drivers.

I unplug after use and plug in after turn on. 
Kevin R-M

Offline Doc B.

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Re: Leaving headphones plugged in.
« Reply #2 on: September 22, 2011, 06:01:55 AM »
Since the Crack is an OTL amp there can be DC across the output for a bit as it starts up. That's why that resistor is across the output. It's a good idea to unplug your more delicate and expensive headphones before you turn the Crack on.

All the other amps have transformer outputs and thus won't have a DC offset across the output at startup but they could in theory thump when turned on.

The modded Quickie uses DHTs that heat up pretty much instantly and thus it might make a little noise, but since the headphone version is a DIY mod and not something we sell I don't have enough data to offer whether there is a turn on transient or not.

The stock S.E.X. kit uses indirectly heated tubes that take several seconds to warm up so there shouldn't be a thump unless maybe if you switched off a running amp and immediately switched it back on. If the kit has the C4S in it there might be a bit more chance of a thump as the tubes begin to conduct.

The Smack has a soft start and indirectly heated tubes. We were hot plugging power cords on our prototype yesterday, which doesn't even allow the soft start time to reset even so we had no problems whatsoever with thumps. And yes, once again that crazy accidental power cord kit of ours sounded better than some other aftermarket power cords.

All that said, better safe than sorry. If you are concerned, unplug your headphones before you turn on the amp.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Laudanum

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Re: Leaving headphones plugged in.
« Reply #3 on: September 23, 2011, 04:04:53 AM »
Just wanted to point out that the DC on the Crack output a few seconds after turn on seems to be higher if film output caps are installed.  Speedball may have something to do with higher DC as well but Im not sure so the techies would have to chime in on that.  But I measured a little over 20 volts DC, as I can recall, after replacing the stock electrolytic output caps with film caps.  Another member measured 14 vdc I believe.  The peak occurs a few seconds later with Speedball installed and it seems to be shorter lived as well.  After several seconds of turn-on DC climbs to it's peak and falls all within probably less than a second.  I dont know if this really matters as the DC voltage is lower if there is a load connected (headphones).  But just thought I would mention it since the subject was brought up.  I have always turned Crack on first then plugged in my phones.
Desmond G.

Offline xcortes

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Re: Leaving headphones plugged in.
« Reply #4 on: September 23, 2011, 04:42:19 AM »
The modded Quickie does thump at turn on and off.
Xavier Cortes