Your laptop probably doesn't have a line in. The last laptop I saw that had a line input on it was made almost 10 years ago. The input on a laptop is a mic input, not a line input. So anything you plug into it that's line level (like the output of your mixer) is gonna freak it out.

I use a USB sound card (an Edirol UA-30) for this sorta stuff. It's old and still works okay and everything. It has line inputs and outputs. And digital audio connections, too. Which you wouldn't need for this.

I think you can get a cheap USB cable that breaks out into a line level in and out for maybe $50? I forget. It's been so long since I looked into anything like that.

The humming is noise from drive activity. Ideally you want a laptop audio interface, basically a stereo direct box of sorts with the 1/8" connection in. Rapco has the LTI-100, and Whirlwind has a PCDI that has better options/better construction, but no 'mono' switch. Other manufacturers offer similar products...

If you're dealing with noise from the computer (my theory is that it's related to the dimmed fluorescent lighting for the video maybe as much as the hard drive spinning) all you have to do is unplug the laptop from the wall and run it on its batteries. The noise is leaked back onto your AC power and it gets into your other audio devices. It's not transmitted through the laptop's inputs and outputs. Unplugging the computer is what has always worked for me. And running the screen on full brightness, not at all dimmed.

Also, make sure you turn off power management on the laptop. They have a tendency to go into standby if you let them sit for a while without you touching the keyboard or mouse. That's really bad when you're recording.

Don't forget to plug the laptop back in when you aren't tracking. Unplug and replug. It takes a while to establish the right habits. It's easy to forget. Don't forget.

Yo Scott you were right! I hooked it all up running the laptop on its batteries and everything was running smoothly! There is still one problem though, I have only 1 and half hours of battery time so I cant really run it on its batteries! Is there something I can do to stop the power leaking? What if I plug it into a different socket or am I just babbling here? I dont know too much about connections or electrics, I just know how to get nice signals and mix them right! I guess I should have gone to college! Ha!!

Thanks for all your help so far though, it`s been great guys!!

I don't think moving it to another outlet is likely to solve the problem, but you can certainly try it. What's happening, as far as I know, is that the computer's internal noise is leaking backwards out through the power supply and into your actual electrical system, like for your whole house or apartment or studio or whatever. I would think your best bet, aside from a new battery, or a regimen of plugging in your power supply anytime you're not tracking and then unplugging it for tracking, would be to see if you can track down a UPS, an "uninterruptable power supply".

They're the battery backup boxes that folks use with computers... if your power goes out, the box has a battery in it that keeps supplying power to your computer long enough for you to safely power it down or whatnot.

The way I understand it, these boxes have some heavy filtering on the incoming power, and as such I would think it would serve to filter it in reverse as well. I don't know what ever happened to mine, I think maybe it got lost over the course of the last few moves, so I can't test it out and tell you if it solves the problem or not.

In order of cheapness:

1: Plug and unplug
2: Smallest UPS (I don't even know if the company APC is still the one to get)
3: New/second battery for laptop

Those are the only solutions I can suggest. We always just do the plug/unplug one. Sometimes that means stepping away for a half hour because we've run the battery to near death and need to get a little more juice in it. But usually the amount of time we spend setting up mics and tweaking the sound, the battery has enough time to recharge a bit in between tracking different instruments. If you're tracking all instruments at once, then obviously you have enough battery to make it through quite a few songs.

Ok! I`ll try out a few different options and decide which one suits best! I`ll prob just plug and unplug but as far as I remember, I can have the laptop plugged in and run the line out to a power amp and into monitors without any signal interference so does this mean its not getting into everything?

Anyway, I am just tryin to use this method as a temporary way of saving up for a firewire equipped Mackie and better monitors so I`m sure I can make it work till then!

You have been a great help Scott and every1 else that replied! Thanks very much!!

For the record and those interested, I had a problem with AC buzz, and when I used the classic ground lift adapter on the AC cable/transformer, it completely dissappeared. I always record plugged into AC.

Those goofy magnets that couple around power and VGA/HD15 cables are supposed to help reject some kind of interference as well, although I believe that's more for video signal interference...help me here?

rayj, if a ground lift adaptor solves this problem, I owe you a chicken sandwich or something. I don't know why I never thought to try it...

Those magnets you're talking about are supposed to block stray RF, right? I've heard them refered to as an "RF choke". I've never noticed any effect from them, in any context. I haven't messed around with them much as a result.

But hey, if the ground lift does the trick, holy cow, that's a lot of plugging and unplugging that you just saved me! A chicken sandwich worth, for sure!

Where do I get a ground lift adaptor guys? Which one do you use? Should they be available in good electrical shops?

They are available in bad electrical shops...

Seriously, I'm pretty sure you can get them anywhere you might pick up a power strip.


The problem with ground lifts is, well, you are lifting a ground. You shouldn't really have to do that. Except when you have to.

They are illegal in Canada...