I keep my ep121 hooked up to pc speakers a lot of the time; when the computer is playing music or has any other sound-related job to do, this works fine, but left idle, the speakers hum. I would guess that this happens because the computer cuts power to the audio jack when it's not doing anything, and so the speakers hum just as though they were hooked up to a loose, powered chord. (It's the same sound you hear if you plug a cable into an amp without a guitar on the other end of it.) It ought to be possible to simply tell the computer to always run power to the audio jack when it's plugged in, but I can't figure out how this is done. Any thoughts out there? Best regards.
Well, certainly. I turn them off and on and off again. This isn't a crisis, just an annoyance giving rise to interest in a technical question.
<<...It ought to be possible to simply tell the computer to always run power to the audio jack when it's plugged in...>> sm: It may not be that simple. The hum that you are hearing may be due to EM noise produced by your tablet. All digital devices produce "digital noise" in the RF frequency range. The envelope of this noise, fed into analog devices like an amplifier (for example) can produce noise artifacts in the audible range. If this is what is happening to you, simply powering the audio jack may not fix the problem. There are things that can be done about this (notch filters), but they may involve some significant compromises. As a long-time audiophile, I can tell you that chasing down noise and hum in an audio system can be frustrating and (seemingly) illogical at times. Just pull the audio plug out when you are not using the speakers...
