StarDestroyer.Net BBS

Well, yesterday I connected my old SB16 soundcard to a 200 watts power amplifier I ripped out from my old Kenwood rack system. No preamps and the likes, I just directly connect the "line out" (stereo mini, not RCA) from my soundcard into the line in (RCA; I used an interconnect converter) jack on the amplifier.

Then I guess I was just being an idiot by turning off the computer **before** the amplifier**.

Well, but that's what I did. I powered off the computer while the amplifier is still on, then I heard a loud "DUB!" sound from my speakers.

When I turned on my computer again, the soundcard just disappeared from the Winblows control panel. No sound device, no joystick port, nada. Just out of curiousity (desperation?), I tried to detect a new hardware. Nope, it was like I never have a sound device at all.

So I guess my sound device had been completely damaged by the feedback current from the power amplifier. Is that correct? Was my soundcard completely damaged?

And next time I connect a soundcard to a powered amp, what should I do to prevent such things to happen again? I guess the safest way is to turn off the amplifier first **before** I turn off my computer, but in case I forget again, is there any "safety relay mod" or such to prevent such damage? Or probably I should connect the soundcard into a preamp before connecting it into a power amp?

I'm no expert, but that doesn't sound like a likely cause to me. Power shouldn't flow FROM the input of the amplifier TO the output of the sound card, and certainly not in sufficient quantity to fry a sound card.

Destructionator XIII wrote:I still use a SB16 (ISA ports yay!) in my normal use computer (though I just bought a new machine, very nice but not my normal useage one yet), and every time I turn it [the computer] off, I get a pop and some static out of the speakers. I think that is just normal.

Yup, but we're talking about 200 watts power amp here.

Destructionator XIII wrote:As for why it disappeared, I dunno. Do you have another old system into which you can plug the sound card to test it? If not, did you try removing the card, booting up (to reset the drivers), then putting it back in (after it's turned off!) to see if it works again?

Unfortunately no. Actually it's easier to find another soundcard than another ISA mobo. I guess I'm gonna put another soundcard there.

Destructionator XIII wrote:I'm no expert, but that doesn't sound like a likely cause to me. Power shouldn't flow FROM the input of the amplifier TO the output of the sound card, and certainly not in sufficient quantity to fry a sound card.

I know. It sounds like counter-intuitive, but a friend of mine told me about the danger of turning-off your computer (or any head unit not designed to connect to the power amp; like a walkman) before your power amps.

No idea, frankly. My sound card is connected to a preamplifier so I've never had any problems.

phongn wrote:No idea, frankly. My sound card is connected to a preamplifier so I've never had any problems.

Thanks. I guess it would be safer that way. So I guess you don't get that loud exploding sound when you're turning off the computer before the amps, do you?