Computer generated sound cues


Active Member
Hello everybody,

I have a great TD at my school who insists on running sound cues from her laptop computer. She purchased a wonderful program from a gentleman from australia that is very editable and allows for some interesting overlaping effects.

My concern... whenever it comes time for a sound effect, she unmutes the computer's channel and there is a whinning sound coming through the speakers. It almost sounds like the spinning hard drive or fan motor is creating some form of harmonic that is being amplified.

Does anybody have any tricks to stop this whinning? I would like to use this program as it allows you to have crowds scream while simultaneously running a police siren... etc. I've tried lifting the ground and have tried muting all unused components on the computer to no avail.

well what it might be is that you have to get a quieter fan they arent that expensive but still cost money
most likely its due to and electrical problem in the laptop... because laptops are so tightly compacted the sound cards (and i say that loosly) are packed in next to other components that give off interferance that the sound card easily picks up.... this is why most high end sound cards to the A/D conversion outside of the computer so they do not pick up the interferance as readily... either switch to a desktop with a dedicated sound card (make sure the sound card is in the farthest PCI slot that it can be) or pick up something like this (though there are MANY other options out there...)
When you say you have lifted ground does this mean you have tried running the soundcard output through a DI box? If you haven't I would try it.

As has been already mentioned maybe an external soundcard would solve the problem. You could ask around school to see if anyone had a USB soundcard to trial.

You mention whining is it more like an electrical hum? Another thing I would try to help locate the exact cause of the problem is to connect the laptop up as normal. However disconnect the mains supply and see if the noise is still there on battery only. If the noise disappears then it is a power supply problem as opposed to being generated by the components inside the laptop eg electrical noise off Harddrive motor.

If it is the power supply you could try swapping supplies to see if it is only the one the TD has or do all power supplies of the same model cause the noise. You could try replacing the powersupply with a generic one to see if that is any better. If none of this works try an external soundcard.

It is not uncommon for Laptops in this situation to cause noise.

By the way are you able to tell us the name of the Sound Cue program as it sounds interesting to check out. A Website if possible would be helpful.
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My advice is on trying a DI, then a sound card. Whirlwind makes the "PCDI" made just for this purpose..
though any DI should do the job, the PCDI has RCA and 1/8th inch inputs on it and offers 2 XLR outputs for the left and right channels where as one would need 2 standard DIs to keep the stereo image.

If you are going to be spending money though my advice is on a sound card. There are several out there, personally I would advise a recording interface such as the Presonus Firebox/Firepod (one is 2 channels one is 8, 2 is all you would need since the outputs are what you are using not the inputs) though a standard sound card such as Creative Labs Sound Blaster Extigy.

Before making any purchases do any troubleshooting you can without spending money. If you had a DI around try using that first. If the buzz/hum/noise goes away then the problem is known and the solution is to use that DI or get another DI specifically for that. If that doesn't fix the problem try a different channel in the board with the DI (it is doubtful that it is noise in the board, but possible).

If it is an option eBay might offer these items cheaper, but remember before choosing eBay that it was in fact eBay.

Thats all I can think of at the moment...
I've had that happen before, it could just be a hum off of the battery which is what happened to me. I had to remove the battery and plug the laptop directly into a wall outlet.
hey compleatly off topic what is the software called?
Footer4321 said:
how far away from the board is the laptop in cable length?

About 2'.

Hughesie89 said:
hey compleatly off topic what is the software called?

I'll be honest. I am not really sure. My TD took a summer workshop two years ago with my one TD friend who had the program. He gave her the contact information and she downloaded a perusal version. I'll get the name from her. If I can't I'll call my contact at the theater where she took the workshop and get the name from him.

If memory serves, the program wasn't badly priced at all.
I think you can do that with quicktime, which is free. Just open each media file in quicktime in separate windows. I believe you can have multiple files playing at once up to your computer's capabilities.
The reason software like Protools use external sound interfaces(besides money) is so it picks up no noise from the computer.

Between fans and electrical itnerferance more gets "transfered" to 1's and 0's because it is picking up the sound that is "leaking" into the processor priot to it being changed.
For those that are unaware, the reason that external sound cards are being suggested is noise. Noise is the result of interference. Now with a digital signal, it has a certain tolerance for interference. With a digital signal, essentially you get a nice clear signal or you get nothing. Since the interference is not that great, the digital signal leaves the computer as it should. If you then convert this digital signal to analogue away from the interference, then you get a better quality sound. With an analogue signal, interference will affect the signal. In this case, it is a whining type sound.

The other factor that heavily contributes to the ability of computers to induce noise is that they are using an unbalanced signal. A balanced signal receives the interference equally on both the hot and cold, but since it is using the difference between the two to produce the signal, the interference cancels out.

Ultimately, the best solution would be to run a digital output from the computer into a digital input of the mixer and keep the signal digital up until it reaches the amplifier. Unless you have the equipment, this is not likely to be a feasible solution. The external sound card options offer a more viable solution.

With regards to the software, you could also edit the tracks such the the the siren and the crowd became one...
Sometimes its not the computer at all, just the program giving feedback. In our aud we have a computer thats based through the board for AV and such. Ive noticed that this happens with some programs and not with others. With photoshop premire, u can run av fine with nothing, same with just mediaplayer. But as soon as i try quicktime, theres that harmonic mentioned above. Play around with different programs. Also, turn down the internal volume of the computer and turn it up on the board. Let your good amps do the work, not the nasty ones in the computer. Turn up your computer speakers now and i guarentee that you hear a harmonic, take the speakers off and plug it into a board and youll get it to.

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