Post by Tim Meddick
Everyone seems to assume the speakers are powered (inbuilt amplification)
ones, when many are not. I don't think there's ANY risk in unplugging
unpowered speakers and a small (tiny) chance of damage with powered ones.
However, there's USB speakers around now, which should be certified as
'Hot Swap' and actually meant to be unpluggable while the PC is still on.
Sound cards, as a general rule, have 32 ohm drive on at least one port
(Lineout). In some cases, the 32 ohm drive option is under software
control, and more than one port can have that enabled. When 32 ohm
drive is enabled, the intention is to provide enough signal to
drive headphones. For example, you should be able to plug
a set of headphones into the Lineout jack on the sound card.
If you used unamplified speakers, that kind of output drive solution
only puts out about 1 volt RMS of signal. The total power level transferred
to a speaker, would not be enough for comfortable listening. So unamplified
speakers aren't likely to be the object of this question.
I suppose they exist, but I'm not immediately aware of a computer
sound card that comes with a nice amp strapped to it. There have
been 2W to 5W amps placed in some older computers, but nothing
recent comes to mind.
The other ports on a sound card, can be as weak as 600 ohm output,
and for those, they're only intended to be connected to the 10K ohm
input of an amplified device. That could include your conventional
stereo system, or an amplified computer speaker product. If 32 ohm
headphones, connect to a 600 ohm output, there is virtually no
signal level to work with.
This has caused problems for at least one neat device. Zalman
makes a 5.1 set of headphones, with a number of speakers inside.
The product is expecting a sound card to have 32 ohm drive, on
three output jacks on the sound card at the same time. Users
are annoyed to find, that two jacks on their sound card,
are too weak to make the product work properly.
The same rules would apply to your passive speaker scenario. Pulling
the plug could make the speaker pop. But since the 32 ohm sound card
has virtually no power output to speak of (it is not a 70 volt PA),
there would be little danger to a passive speaker. If the operation
of plugging in the plug, caused the output to be shorted, that could
be a cause for concern. But I don't think that normally happens
with audio jacks.
I do have one computer here, where plugging in any plugs while the
computer is operating, is a bit dangerous. The PCI connector on that
card, makes poor contact with the slot on the motherboard, and
if you're wiggling the plug-jack area, it can actually upset the
PCI bus. So that would be a reason for not tugging too strenuously
on a plugin sound card. Yes, the screw is as tight as I can make
it, but the poor design ($7.00 cheap sound card) means it just
doesn't fit properly in the computer. I have two cards of that
type, and they both fit poorly. Only one fits so bad, that
it disconnects from the PCI bus. The OS doesn't like to see
hardware disappear like that.
As far as the jack and plug are concerned, the interface is
"hot-plug" compatible. It is just the surrounding issues, like
making something pop, which may not be good. It would definitely
be safer than plugging in a PS/2 connector while the computer