PA equipment help

hutdon

This doesn't have anything to do with Parallax products but this is the sandbox and between any 3.1416 of you guys all knowledge is known.... My problem is week after next I will be part of a small group who will be teaching a class on concrete mix design. We do this at a out of the way camp with a large assemble hall where we give the presentations before breaking into workshops. For several years we have used PowerPoint with an LCD projector for the presentation part while also using a number of videos connected to 4 TV's located around the hall. (We have 80-100 people in attendance) Last year we found it was quite a bit better to feed the video from the VCR into the LCD projector and display it on the big screen. That worked fine. The problem was audio. When we tried to feed the audio from either the VCR or the laptop's sound card into the PA system, either the volume had to be turned down too low or there was irritating distortion. This year we won't be using a VCR, we have all the videos on DVD, but we need to hook the output of the sound card into the PA and run the volume at an acceptable level without distortion. Is there some 'magic' impendance matcher or preamp or what is needed? Thanks - Don

Tricky Nekro

Well when I connected my PC to my 650Watt amplifier it seemed to have no such problem... Check the grounding and the cable... Should they be the source of the noise try replacing the cable and check the connections... Remember that usually audio has L - R but also a third and most precious, most of the times, copper colored which is the grounding.... This must fit somewhere...
If it isn't for this check if te outputs are simple (RCA level) and not a amplifier output...


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Zoot

Depending on the PA amp you may need an impedance matcher or a "direct box" -- if the PA has XLR or 1/4" inputs this will certainly be the case. If you need a box, I would try a music shop and see if they will rent or sell you one cheap.

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kelvin james

The problem you are having is that the input to the PA is being driven too high. Typically, you would use a low level input, which would be the line-out from the pc sound card. Using the audio-out ( speaker / headphone ), which is an amplified high level signal, you will get plenty of distortion happening. If your sound card does not have a line-out, you could try the headphone jack connection at the front of the laptop, and keep the volume there to the bare minimum. A good short shielded cable with good connectors helps a lot also.

kelvin

Robert Kubichek

Of course he could use an antenuating patch cable made for such a use...
Just output enough to get a good low distortion signal...

Bob