Laptop DJing

It's all about the equipment

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tornredcarpet
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#541 Post by tornredcarpet » Tue Jan 15, 2008 1:37 pm

So how do circumaural headphones fit with head-mounted displays ?

Mr Awesomer wrote:Even 12 inches felt to small to work with.
I'm definitely quoting you on that.
Jesse (Los Angeles, CA/Hampton Roads, VA)

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#542 Post by Surreal » Wed Jan 16, 2008 1:15 am

tornredcarpet wrote:So how do circumaural headphones fit with head-mounted displays ?
The engineer in me wants to build a helmet with a HUD and headphones...

(although such things probably exist; likely in the military)

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#543 Post by tornredcarpet » Tue Jan 22, 2008 5:01 pm

next in the future- instant DJ helmets that you plug into a USB port... or probably you hook up a USB/firewire drive to. hahaha
Jesse (Los Angeles, CA/Hampton Roads, VA)

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#544 Post by Surreal » Tue Jan 22, 2008 5:57 pm

So we start with a helmet, attach a display visor and headphones, stick a hard drive dock at the back... oh, and don't forget two beer holders on either side.

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#545 Post by Toon Town Dave » Wed Jan 23, 2008 12:37 pm

That sounds a little too Tim Allen.

Researchers are working on contact lens displays, add a some sort of hand gesture interface to control stuff and combine with wireless earphones and you'd have the ultimate high-tech DJ setup. We'll probably see this technology sooner than later.

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#546 Post by tornredcarpet » Sat Jan 26, 2008 3:43 am

featuring DJ Precog straight out of Minority Report? She knows what song you want next.
Jesse (Los Angeles, CA/Hampton Roads, VA)

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#547 Post by Surreal » Sat Jan 26, 2008 12:08 pm

I've seen some science articles for implanted "earphones" before. Some sort of experimental treatment for the deaf, where the devices are attached either to a damaged drum or near the ear-bones themselves.

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#548 Post by Surreal » Mon Feb 11, 2008 1:58 pm

For those with the mini turtle beach usb sound cards, do they disable the internal sound when you plug them in?

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#549 Post by tornredcarpet » Mon Feb 11, 2008 7:32 pm

Surreal wrote:For those with the mini turtle beach usb sound cards, do they disable the internal sound when you plug them in?
No but it likes to make itself the default device.
Jesse (Los Angeles, CA/Hampton Roads, VA)

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#550 Post by GemZombie » Tue Feb 12, 2008 9:09 am

Surreal wrote:For those with the mini turtle beach usb sound cards, do they disable the internal sound when you plug them in?
As with most people here, I would guess, I set my sound profile in windows to "no sounds". I hate all those internal clicks and bleeps anyway, but they specifically don't belong on a DJ laptop.

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#551 Post by Surreal » Mon Apr 21, 2008 4:48 pm

Repost since the boards reset: a link I cam across while looking up causes for laptop audio hum
http://ask.metafilter.com/20028/Laptop-Audio-Hum

I always get a hum when I connect my laptop to speakers. The intensity varies from place to place, though it doesn't seem to matter if the speakers are on the same outlet as the computer (although in the instances I've tried different outlets, they were on the same wall, so likely the same circuit).

Unplugging my laptop immediately cancels the noise. Removing the ground (a simple 3 prong to 2 prong converter will do) also significantly removes the noise, though you can still hear a little bit if I crank the dials up.

So I don't know if the hum is due to ground loops or maybe has something to do with "dirty AC" as mentioned in the thread I linked above. Any thoughts?

Also, has anyone had any experience with the direct injection boxes? (also mentioned in the link) http://www.radioshack.com/product/index ... Id=2062214

edit: fixed link

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#552 Post by Lawrence » Mon Apr 21, 2008 10:57 pm

Surreal wrote:Repost since the boards reset: a link I cam across while looking up causes for laptop audio hum
http://ask.metafilter.com/20028/Laptop-Audio-Hum

I always get a hum when I connect my laptop to speakers. The intensity varies from place to place, though it doesn't seem to matter if the speakers are on the same outlet as the computer (although in the instances I've tried different outlets, they were on the same wall, so likely the same circuit).

Unplugging my laptop immediately cancels the noise. Removing the ground (a simple 3 prong to 2 prong converter will do) also significantly removes the noise, though you can still hear a little bit if I crank the dials up.

So I don't know if the hum is due to ground loops or maybe has something to do with "dirty AC" as mentioned in the thread I linked above. Any thoughts?
Because the hum occurs when on AC and stops when on battery, it is likely a ground loop. They are common in older, improperly-grounded electrical systems. You can get rid of it by eliminating the ground (not ideal), running on battery, getting an extension cord and using a different outlet, or using an isolation transformer. Click here for a much better discussion of the problem.
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#553 Post by SoundInMotionDJ » Tue Apr 22, 2008 6:06 am

Surreal wrote:I always get a hum when I connect my laptop to speakers. The intensity varies from place to place, though it doesn't seem to matter if the speakers are on the same outlet as the computer (although in the instances I've tried different outlets, they were on the same wall, so likely the same circuit).

Unplugging my laptop immediately cancels the noise. Removing the ground (a simple 3 prong to 2 prong converter will do) also significantly removes the noise,
That is a classic "ground loop." Lawrence covered the basics on this already.

I will add that laptop power supplies are notoriously noisy in an audio environment. The solution is to replace the power supply. That is probably not happening in this case, since pulling the battery made the noise go away.

You should consider replacing the battery.
Surreal wrote:though you can still hear a little bit if I crank the dials up.
That is classic "board noise." The mixer is simply not clean enough electrically to crank it up. Most mixers will provide some amount of pre-amplification. Most mixers in the price points that are common at clubs and mobile DJ setups are not capable of cleanly amplifying past the point of "unity" gain (or 0dB if the sliders are marked.) The solution is to not turn it up as much.

The real solution is to properly set the "gain structure" of the entire sound system...but that is beyond that scope this post. Search "gain structure" to find out more.
Surreal wrote:Also, has anyone had any experience with the direct injection boxes? (also mentioned in the link) http://www.radioshack.com/product/index ... Id=2062214
I have had experience with DI boxes. They can solve the problem, provided they are used correctly. The link that Lawrence provided is full of good information.

The link you provided does not seem to mention DI boxes for me....perhaps they were keeping track of your surfing history. However, the ground loop isolator that you did link to could also solve this problem.

--Stan Graves

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#554 Post by Surreal » Tue Apr 22, 2008 9:48 am

Whoops, I meant to write ground loop isolator but wound up writing DI since I was reading that elsewhere. I'm not even entirely certain what the DI box does, though from reading the wiki entry it seems kind of similar to the isolator.
SoundInMotionDJ wrote:I will add that laptop power supplies are notoriously noisy in an audio environment. The solution is to replace the power supply. That is probably not happening in this case, since pulling the battery made the noise go away.

You should consider replacing the battery.
But if the noise is coming from the power supply, what would replacing the battery do? (It's a new computer, if that makes any difference). I note that my old laptop isn't as noisy as my new one.

Lawrence wrote:You can get rid of it by eliminating the ground (not ideal), running on battery, getting an extension cord and using a different outlet, or using an isolation transformer
I've tried running to different outlets, but it doesn't seem to make a difference. Running on battery does work, but that's not an ideal solution as I only have a 2-3 hour battery life.

Is the isolation transformer the same as the ground loop isolator?

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#555 Post by Toon Town Dave » Tue Apr 22, 2008 10:41 am

Here's a great paper that explains things in technical detail (note, it will probably make sense only if you have a fundamental understanding of electricity and magnetism):

Suppression of Powerline Noise with Isolation Transformers

Ground loops are common-mode noise, an isolation transformer should do the trick. I believe the term "ground loop isolator" is used to describe the entire circuit used to isolate ground loops. Here's a schematic for a home-brew version.

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