Hooking a laptop up to a PA system

[Passacaglia]

Does anyone have any expertise with something like this? We're hoping to hook up our laptop (a Dell something-or-other) to someone's PA system. We don't know anything about the PA system right now, but we're hoping to go on Sunday to check it out. Does anyone know what kind of cords we would probably need, or have any advice for us?

Thanks!

[chinaski]

All youll need is some patch cable and a 1/4 inch to 1/8 inch adapter. That is if the PA only has 1/4" inputs, which I imagine it would only have 1/4 and maybe a mic (XLR) input. Plug the 1/4 patch cable into the input of the PA, connect the 1/8 adapter to the other end of the patch cable and then plug the 1/8 adapter into your audio out on the sound card of the laptop.

[Icy]

Chinaski explained it perfectly, just one note, always start with the volumes at minimum on both the PA and Notebook and raise them slowly, else you can damage your ears and the speakers badly as at first you don't know how sensible will the PA be to the notebook output. If the system distorts the sound is because the notebook output is too powerfull, it's better to lower the notebook volume and raise it in the PA system.

[Passacaglia]

Thanks -- now what do you mean by patch cable?

[dbd1963]

I do it every day when I'm practicing -- it's easy, but there are some things to know on top of the good advice chinaski gave you.

1) set the volume out on the laptop to somewhere in the midde. Too loud and you'll get distortion, too low and you'll get extra noise.

2) the output of your laptop is already going to be noisy, btw, so unless you just have to use the laptop, transfering to another device could be benificial

3a) ideally you want to plug into one of the channels, not through an aux in (with a caveat, in 3b), so you can tweak the volume and EQ (every PA has different features, so without knowing which you'll be using I can't be sure this matters, but it usually does). You'll recognize a channel-in because it has the 1/4" jack as well as the XLR (mic connector) jack. The aux-in may be RCA plugs or 1/4" jacks, but will have right/left channels. That's because the usual device used here is a tape or CD player to use between sets of live music, and these devices output a stereo signal.

3b) your computer's headphone out is a stereo jack too, but unless you use a cable splitter and plug the two ends into different channels, you will only get one side of the stereo file. To compensate for this, I mix my files to mono. If I don't do that, I only get one side of the stereo mix. Often that doesn't matter, but in music files, for instance, it does matter. You'll lose a lot of the parts in some music files. If what you are trying to amplify is music, then maybe you would be better off using a 1/8"stereo-to-RCA splitter. I don't even know if one of these is available, but it would be at Radio Shack if it is. If it isn't available, then use a 1/4"stereo-to-RCA and an 1/8" adapter. If you go this route, I don't think you get to use any EQ, but perhaps that's not so important.

4) the channel you choose will likely have a button you can press to raise the level, used to compensate between the values of a microphone or a line device. Set it to line.

5) the channel has a row of knobs. There will be
a- EQ knobs, two or three, high (mid, if it's there) and low
b- effects
c- monitor
d- main

Depending on how the PA is set up, the important knob is the main. This will raise and lower the volume of what is plugged into that channel (relative to how the overall main volume is set). Turn effects down to zero (unless you wanted to use effects, that is), if the monitor section of the PA isn't being used, set that to zero too. The EQ knobs should have a middle position where the knob will stop, if you turn it lightly. If it doesn't, there will be a mark on the dial that shows the neutral setting. That's where you want to start. If you think you need some EQ, though, twist away to find the sweet spot.

If you are using microphones too, you may get feedback if you have to make it vey loud, on account of the ever-present high-pitched whine the computer will want to make. Try lowering the high EQ if this is a problem, but you could also experiment with mic placement. Try to keep it from pointing right at one of the speakers if you can.

[chinaski]

Thanks -- now what do you mean by patch cable?


Thats what its called - patch cable. If you ever see a guitar hooked up to a amp, its connected to the amp with 1/4 inch patch cable. Im sure it has another name, but ive only heard it called patch cable. :o

[BrianD]

If what you are trying to amplify is music, then maybe you would be better off using a 1/8"stereo-to-RCA splitter. I don't even know if one of these is available, but it would be at Radio Shack if it is.

These are available at Radio Shack. I've used these often to connect a laptop to a stereo receiver or to a TV. It provides a nice, cheap home theater PC.

[Passacaglia]

Thanks, there's a lot of good advice in here! Perhaps I should have asked this before, but...would it be easier to use an iPod instead of a laptop? Hopefully, I'll get to have a look at the PA system on Sunday, and if I can't figure it out then, maybe I can figure out what I need to do to figure it out. If that makes any sense.

[dbd1963]

I would bet that the iPod would have less noise, since it's dedicated to reproducing sound. The laptop is a jack of all trades in that respect -- not so great at doing any one thing.

If it's music that you are getting off the iPod, then you may want to get the 1/8"-RCA (male ends) so you can insert into the aux. Well, only if the aux on that PA uses RCAs. If you want to see what it looks like, go to Radio Shack dot com and look for "6-Ft. Attenuating Dubbing Cord, 1/8" Phone Plug to RCA Plug".

If you want to keep it on the channel side of the PA, and it is a stereo source, you can also get a handy little "inline 1/8" Stereo Plug to 1/8" Mono Plug Adapter ", which will sum your stereo signals into a mono signal on the fly. You'll still need a 1/8" to 1/4" mono cable to complete that connection.