I have a Gibson Epiphone PR-5E VS... It plays just fine through my amp but when we tried to hook it up Wednesday through our sound system, nothing came out. It doesn't work through any sound system. Does anyone know why this might be happening?
It's a low-level / high impedance signal, whatever sound systems you're using aren't matching up with it and you're getting nothing or little sound. Don't waste your time with trying to make it work. Mic your amp like all the pros do. Some folks us Line 6 or other direct type boxes and those work fine, but if you like the sound of your amp just fine, mic it and be done with it. Nothing else has the dynamics and touch sensitivity of a real amp. What amp do you have?
Make sure you use a good mic that is made for amps. Sure 57 is probably one of the most common low-cost mics for this purpose. You can experiment around with different placements for the mic, which will give slightly different sounds going back to the sound board, but generally the mic is placed one to two inches from the speaker cone and slightly off center.
If you are going the mic route, do give a though to sound levels. Depending on the context of the music you are making, "that sound" might be too loud.
You can get that round that by putting the amp and mic in a soundproof box. I've heard that this approach is actually the way some guitarists actually get their sound even when posing in front of a wall of amps! Personally, I find that my Bass Pod (I'm mainly a bassist but play guitar once or twice a month) works just fine and gives me all the tone I need without overpowering anyone else.
does your amp have a line out ? you may need some type of pre - amp before going direct into the sound board . if your amp has a line out you can use your amp for this. if it has a head phone jack this could work as well but you won't hear anything from the amp itself.