djnanite
I was playing a gig recently and noticed a lot of humm coming from my speakers when the AC power cord was plugged into my laptop. Unplugging the power cord eliminated the humm immediately, but reinserting it caused it to start again.
Apparently this is because the AC adapter for my laptop is grounded, and was causing a ground loop.
Questions:
* Why doesn't this happen in all environments? If I plug my laptop in at home I don't get this noise.
* The noise was coming from my pair of Pioneer CDJ400's. Weirdly, they were plugged in via USB (so should be digital, and shouldn't pick up any interference). My laptop's AC adapter was causing them to humm. How can this be possible?
* Apparently if I remove the earth pin from my AC adapter plug, this will eliminate the noise. What are the risks involved in doing this?
* My Pioneer CDJ400's use only 2 pin connections. Why don't they need to be earthed? Their power requirements are similar to my laptop.
* If eliminating the earth pin fixes the ground loop problem, why did my Pioneer CDJ400's have this humm when they use only 2 pins?
Although I could use a ground loop isolator, this is not an ideal when I am using 2 or more outputs.
Thanks for any help you can offer.
Apparently this is because the AC adapter for my laptop is grounded, and was causing a ground loop.
Questions:
* Why doesn't this happen in all environments? If I plug my laptop in at home I don't get this noise.
* The noise was coming from my pair of Pioneer CDJ400's. Weirdly, they were plugged in via USB (so should be digital, and shouldn't pick up any interference). My laptop's AC adapter was causing them to humm. How can this be possible?
* Apparently if I remove the earth pin from my AC adapter plug, this will eliminate the noise. What are the risks involved in doing this?
* My Pioneer CDJ400's use only 2 pin connections. Why don't they need to be earthed? Their power requirements are similar to my laptop.
* If eliminating the earth pin fixes the ground loop problem, why did my Pioneer CDJ400's have this humm when they use only 2 pins?
Although I could use a ground loop isolator, this is not an ideal when I am using 2 or more outputs.
Thanks for any help you can offer.
Inviato Thu 02 Aug 12 @ 3:38 pm
Support staff
djnanite wrote :
* Why doesn't this happen in all environments? If I plug my laptop in at home I don't get this noise.
Possibly due to other equipment plugged into the same mains ring (E.g: Fridge in bar, smoke machine/lights, etc.)
Also, are you checking with the same setup at home? Using your laptop's own built-in output is different to using the CDJ's (Could be an issue with the USB ground - See below.)
djnanite wrote :
* The noise was coming from my pair of Pioneer CDJ400's. Weirdly, they were plugged in via USB (so should be digital, and shouldn't pick up any interference). My laptop's AC adapter was causing them to humm. How can this be possible?
USB has a ground connection, so the interference is probably being transferred to the CDJ's via this and then coming out through their built-in audio outputs.
djnanite wrote :
* Apparently if I remove the earth pin from my AC adapter plug, this will eliminate the noise. What are the risks involved in doing this?
Potential electrocution or even death in the event of a fault. You must NEVER remove the ground pin. It's there for a very important reason.
You could try replacing your laptop's power supply with a compatible double-insulated power supply. This by default has no ground and does not need one. This will usually eliminate ground loop issues and/or noise/interference created by the electronics in the power supply.
djnanite wrote :
* My Pioneer CDJ400's use only 2 pin connections. Why don't they need to be earthed? Their power requirements are similar to my laptop.
Because they are designed to be double-insulated and don't need this.
djnanite wrote :
* If eliminating the earth pin fixes the ground loop problem, why did my Pioneer CDJ400's have this humm when they use only 2 pins?[/quotes]
It's probably coming through the USB ground - See above.
[quote=djnanite]Although I could use a ground loop isolator, this is not an ideal when I am using 2 or more outputs.
It's probably coming through the USB ground - See above.
[quote=djnanite]Although I could use a ground loop isolator, this is not an ideal when I am using 2 or more outputs.
This is the best and most safest option. Or as above, you could try to obtain a compatible double-insulated power supply for the laptop.
For further information, please see our FAQ pages:
http://www.virtualdj.com/wiki/Ground%20Loop.html
Inviato Fri 03 Aug 12 @ 3:21 am
cesarcastillo
djnanite wrote :
* The noise was coming from my pair of Pioneer CDJ400's. Weirdly, they were plugged in via USB (so should be digital, and shouldn't pick up any interference). My laptop's AC adapter was causing them to humm. How can this be possible?
Support staff wrote :
USB has a ground connection, so the interference is probably being transferred to the CDJ's via this and then coming out through their built-in audio outputs.
Try to remove the USB's if it still having the Humm? if then you must also try to unplugging the power adaptor and used only your laptop battery just to check if it is the power adaptor causing your laptop to have humm.
Support staff wrote :
[quote=Support staff]Possibly due to other equipment plugged into the same mains ring (E.g: Fridge in bar, smoke machine/lights, etc.)
djnanite wrote :
* Why doesn't this happen in all environments? If I plug my laptop in at home I don't get this noise.
[quote=Support staff]Possibly due to other equipment plugged into the same mains ring (E.g: Fridge in bar, smoke machine/lights, etc.)
If your connection at home does not have humm at all and clean meaning it is very clear that is the power line source of the place and the environment of the venue where you are currently located some might have near to the cell site or the radio station transmitter it is maybe contaminated with interference or the power line source earthing needs to be check. Try move your DJ's booth/table and repositioned it somewhere try to look some other place around the venue and try to locate another power line source for your equipment.
Inviato Fri 03 Aug 12 @ 10:29 am
djnanite
Support staff wrote :
Potential electrocution or even death in the event of a fault. You must NEVER remove the ground pin. It's there for a very important reason.
djnanite wrote :
* Apparently if I remove the earth pin from my AC adapter plug, this will eliminate the noise. What are the risks involved in doing this?
Potential electrocution or even death in the event of a fault. You must NEVER remove the ground pin. It's there for a very important reason.
But if I plug my 2-pin plug into a surge protected outlet, then electrocution/death shouldn't be an issue, right?!
Inviato Sat 04 Aug 12 @ 1:07 am
Martin FourS
Wrong! Surge protection means that the connected equipment is protected against high voltage spikes but it is no substitute for a ground connection.
Don't take any risks with this. It could go very well for several years, but it only has to go wrong once....
Don't take any risks with this. It could go very well for several years, but it only has to go wrong once....
Inviato Sat 04 Aug 12 @ 6:24 am
blckjck
The ground plane is passing from the laptop to the CDJ's. Your best bet would be to use 2 isolators.
http://www.radioshack.com/product/index.jsp?productId=2062214
Trying to bypass any grounding could cause damage to you or your equipment.
You could try an A/C voltage Isolator. I use one in my rack and it has cut out humm from one site that I have an issue with. Although it is another piece of equipment to carry, chances are your using a multioutlet pack anyway. My particular unit has 8 outlets.
http://www.radioshack.com/product/index.jsp?productId=2062214
Trying to bypass any grounding could cause damage to you or your equipment.
You could try an A/C voltage Isolator. I use one in my rack and it has cut out humm from one site that I have an issue with. Although it is another piece of equipment to carry, chances are your using a multioutlet pack anyway. My particular unit has 8 outlets.
Inviato Sun 19 Aug 12 @ 11:00 pm
djnanite
Thanks for the advice.
Those ground loop isolators are no good if I'm using XLR connectors - it'd mean I'd have to isolate each input instead. If I'm running a 4 deck setup, then I'd need 4 ground loop isolators. That seems excessive, plus it means fiddling around with lots more equipment, and is yet another link in the chain that could fail. I'd really like to solve the problem at the source.
Weeeelllll....you know, I've been looking into this. I'm pretty sure the only thing that is likely to get damaged is the AC adapter itself. Or at the very worst, the battery (both which are easily replaceable).
Also, I would only be bypassing the grounding on the occasions where I get the humm. All other times I'd be using the normal 3 pin setup.
Finally, everyone says how dangerous it is to bypass the grounding. That being the case, how do countries that only use 2 pins (like the US) manage to stay safe?
Unfortunately, I live in New Zealand which pretty much rules me out of 100% of the available products that can solve this problem at the source.
I tried doing a Google search for A/C voltage Isolators and all I got were a load of circuit diagrams and/or physics papers.
Can you provide a link to a specific product that I can use as a reference?
Thanks!
blckjck wrote :
The ground plane is passing from the laptop to the CDJ's. Your best bet would be to use 2 isolators.
http://www.radioshack.com/product/index.jsp?productId=2062214
http://www.radioshack.com/product/index.jsp?productId=2062214
Those ground loop isolators are no good if I'm using XLR connectors - it'd mean I'd have to isolate each input instead. If I'm running a 4 deck setup, then I'd need 4 ground loop isolators. That seems excessive, plus it means fiddling around with lots more equipment, and is yet another link in the chain that could fail. I'd really like to solve the problem at the source.
blckjck wrote :
Trying to bypass any grounding could cause damage to you or your equipment.
Weeeelllll....you know, I've been looking into this. I'm pretty sure the only thing that is likely to get damaged is the AC adapter itself. Or at the very worst, the battery (both which are easily replaceable).
Also, I would only be bypassing the grounding on the occasions where I get the humm. All other times I'd be using the normal 3 pin setup.
Finally, everyone says how dangerous it is to bypass the grounding. That being the case, how do countries that only use 2 pins (like the US) manage to stay safe?
blckjck wrote :
You could try an A/C voltage Isolator. I use one in my rack and it has cut out humm from one site that I have an issue with. Although it is another piece of equipment to carry, chances are your using a multioutlet pack anyway. My particular unit has 8 outlets.
Unfortunately, I live in New Zealand which pretty much rules me out of 100% of the available products that can solve this problem at the source.
I tried doing a Google search for A/C voltage Isolators and all I got were a load of circuit diagrams and/or physics papers.
Can you provide a link to a specific product that I can use as a reference?
Thanks!
Inviato Mon 20 Aug 12 @ 3:51 pm
Support staff
You can purchase XLR ground loop isolators, although these are more expensive than RCA phono ones. Search Google, eBay, etc. and you should find them.
NEVER remove the ground connection from your laptop's power supply or any other equipment. It's there for a very important reason. Removing it could result in serious injury or even death in the event of an electrical fault. Although the chances of this happening are quite small, it's not worth risking your life for the sake of removing a hum from your audio.
Equipment designed for use in countries that don't normally have ground on their mains sockets would normally be double insulated.
You might be able to replace your laptop power supply with an 3rd party compatible power supply that's double insulated and has no need for a ground connection.
Please see http://www.virtualdj.com/wiki/Ground%20Loop.html
NEVER remove the ground connection from your laptop's power supply or any other equipment. It's there for a very important reason. Removing it could result in serious injury or even death in the event of an electrical fault. Although the chances of this happening are quite small, it's not worth risking your life for the sake of removing a hum from your audio.
Equipment designed for use in countries that don't normally have ground on their mains sockets would normally be double insulated.
You might be able to replace your laptop power supply with an 3rd party compatible power supply that's double insulated and has no need for a ground connection.
Please see http://www.virtualdj.com/wiki/Ground%20Loop.html
Inviato Mon 20 Aug 12 @ 4:57 pm
djnanite
Support staff wrote :
You might be able to replace your laptop power supply with an 3rd party compatible power supply that's double insulated and has no need for a ground connection.
That would be ideal.
Forgive my ignorance, but how would I go about searching for one of these? If I search for "double insulated power supply" on Google, the results I get aren't helpful.
Should I be looking for generic AC adapters specific to my model of laptop? Or would any universal AC adapter with the correct input/output, correct laptop connector, and 2-pin connector be suitable?
Can you give me an example of some products (doesn't matter if they're not suitable for my laptop) that I can use as a starting point?
Thanks!
Inviato Mon 20 Aug 12 @ 5:02 pm
djnanite
Ooops! Double post.
Sorry.
Sorry.
Inviato Mon 20 Aug 12 @ 5:10 pm
blckjck
djnanite wrote :
Those ground loop isolators are no good if I'm using XLR connectors - it'd mean I'd have to isolate each input instead. If I'm running a 4 deck setup, then I'd need 4 ground loop isolators. That seems excessive, plus it means fiddling around with lots more equipment, and is yet another link in the chain that could fail. I'd really like to solve the problem at the source.
If your using XLR, you could try using ground lift adapters or make your own cables that lift (disconnect) the ground on the XLR only.
http://en.wikipedia.org/wiki/Ground_lift
djnanite wrote :
Finally, everyone says how dangerous it is to bypass the grounding. That being the case, how do countries that only use 2 pins (like the US) manage to stay safe?
As a licensed electrician, I would loose my license if I started installing ungrounded recepticales. We've been using grounded "3-prong" outlets for a while here.
djnanite wrote :
Can you provide a link to a specific product that I can use as a reference?
I am not recommending this vender, I have no knowledge of them it was just the first result in a google search. Furman makes good power conditioners however, and I would recommend them.
http://www.3ups.co.nz/power_conditioners.html
Inviato Mon 20 Aug 12 @ 5:25 pm
djnanite
blckjck wrote :
As a licensed electrician, I would loose my license if I started installing ungrounded recepticales. We've been using grounded "3-prong" outlets for a while here.
As a licensed electrician, I would loose my license if I started installing ungrounded recepticales. We've been using grounded "3-prong" outlets for a while here.
As a licensed electrician, would you mind answering a (hopefully) simple question?
I've been looking into getting a double insulated Universal AC Adapter that uses just a 2-pin connector. This should eliminate the problem at the source.
The output of the adapter is 90W. Different adapters make this Wattage up with varying Current and Voltage combinations.
Does it matter which current/voltage combination I use? Do I have to ensure the current/voltage combination is identical to my current laptop? Is there a degree of tolerance? Or is the wattage output the only real factor in an AC adapter?
Thanks!
Inviato Mon 20 Aug 12 @ 5:28 pm
blckjck
[quote=djnaniteAs a licensed electrician, would you mind answering a (hopefully) simple question?
I've been looking into getting a double insulated Universal AC Adapter that uses just a 2-pin connector. This should eliminate the problem at the source.
The output of the adapter is 90W. Different adapters make this Wattage up with varying Current and Voltage combinations.
Does it matter which current/voltage combination I use? Do I have to ensure the current/voltage combination is identical to my current laptop? Is there a degree of tolerance? Or is the wattage output the only real factor in an AC adapter?
Thanks! [/quote]
A licensed electrician does not an electrical engineer make. However, you are in luck, I have studied the latter as well.
You need to pay attention to voltage and wattage/amperage. You do not want to under/over volt your laptop. That said, there are "universal" supplies that adjust their output to the demand/load. The wattage/amperage should not be lower then what you currently have. More wattage/amperage on the power supply rating is okay. The listing is showing the maximum that the power supply can give. It will not force a constant 90w for example, into your laptop.
Hope this helps.
I've been looking into getting a double insulated Universal AC Adapter that uses just a 2-pin connector. This should eliminate the problem at the source.
The output of the adapter is 90W. Different adapters make this Wattage up with varying Current and Voltage combinations.
Does it matter which current/voltage combination I use? Do I have to ensure the current/voltage combination is identical to my current laptop? Is there a degree of tolerance? Or is the wattage output the only real factor in an AC adapter?
Thanks! [/quote]
A licensed electrician does not an electrical engineer make. However, you are in luck, I have studied the latter as well.
You need to pay attention to voltage and wattage/amperage. You do not want to under/over volt your laptop. That said, there are "universal" supplies that adjust their output to the demand/load. The wattage/amperage should not be lower then what you currently have. More wattage/amperage on the power supply rating is okay. The listing is showing the maximum that the power supply can give. It will not force a constant 90w for example, into your laptop.
Hope this helps.
Inviato Mon 20 Aug 12 @ 6:05 pm
djnanite
blckjck wrote :
Hope this helps.
That's very helpful.
Thanks!
Inviato Mon 20 Aug 12 @ 6:07 pm
Jessmile
Universal Laptop Power Adapters
Complying with most mains power supplies worldwide, a universal power adapter or power supply is able to accept an input voltage ranging from 100 - 240 V with a frequency range of 50 - 60Hz. A truly universal product. However, the term universal also applies to the array of laptops it can supply power to. Laptops are built to various specifications and the power consumption varies accordingly. Physical attributes also differ between laptops and are not limited to the power socket. Manufacturers of universal laptop power adapters supply various connecting tips allowing the adapter to be connected to various laptops. These connecting tips help the power adapter detect the correct voltage to supply the laptop.
Universal power adapters are also available for cars and airplanes. Supplied with different types of plugs to fit a car cigarette lighter socket or the in-seat adapter on most airplanes, such power adapters truly allow the user to be mobile over great distances. The universal ac adapter can power 98% of laptop computers.
Complying with most mains power supplies worldwide, a universal power adapter or power supply is able to accept an input voltage ranging from 100 - 240 V with a frequency range of 50 - 60Hz. A truly universal product. However, the term universal also applies to the array of laptops it can supply power to. Laptops are built to various specifications and the power consumption varies accordingly. Physical attributes also differ between laptops and are not limited to the power socket. Manufacturers of universal laptop power adapters supply various connecting tips allowing the adapter to be connected to various laptops. These connecting tips help the power adapter detect the correct voltage to supply the laptop.
Universal power adapters are also available for cars and airplanes. Supplied with different types of plugs to fit a car cigarette lighter socket or the in-seat adapter on most airplanes, such power adapters truly allow the user to be mobile over great distances. The universal ac adapter can power 98% of laptop computers.
Inviato Sun 25 Nov 12 @ 7:56 am
Killbah
This little thing made my day...
Inviato Wed 28 Nov 12 @ 1:31 pm
berjonha
There are people who have several laptops in their homes complete with individual chargers for each. Sometimes the long cords and built-in adapters can become troublesome and difficult to handle. In this regard, many people have begun raising questions as to possible solutions to this predicament.
The wonderful thing about the present time is that it is in the mode for globalization and multi-purpose gadgets. The universal laptop charger and the universal AC adapter are latest innovations, much like universal chargers which can be used for cell phones of different brands and universal remotes which can operate different TVs and set top universal ac adapter at [Link removed]
[Moderated: Advertising and links to commercial sites are not permitted on the VirtualDJ forums. Please read the forum rules. Users who wish to purchase a universal laptop power adaptor can search Google to find suitable suppliers at the best priice.]
The wonderful thing about the present time is that it is in the mode for globalization and multi-purpose gadgets. The universal laptop charger and the universal AC adapter are latest innovations, much like universal chargers which can be used for cell phones of different brands and universal remotes which can operate different TVs and set top universal ac adapter at [Link removed]
[Moderated: Advertising and links to commercial sites are not permitted on the VirtualDJ forums. Please read the forum rules. Users who wish to purchase a universal laptop power adaptor can search Google to find suitable suppliers at the best priice.]
Inviato Mon 17 Dec 12 @ 11:32 pm
Dazmax
If you are using XLR connectors these are balanced line. This means that they can be used with the Screen/Ground connected at one end only.
All you need to do is disconnect the screen wire on one end of each XLR cable. This connection is always Pin 1 on a ballanced XLR connector.
This is called screen telescoping and is normal practice for avoiding Ground loops in pro audio equipment. Make sure that you insulate the disconnected wire to avoid short circuits occuring inside the XLR.
The above is good practice with any inter connected system using balanced line equipment. If you find that the Hum goes away when the Laptop is running on Battery power then (As has been said) a Double Insulated power suppy for your Laptop might be the only solution
Good luck
Daz
All you need to do is disconnect the screen wire on one end of each XLR cable. This connection is always Pin 1 on a ballanced XLR connector.
This is called screen telescoping and is normal practice for avoiding Ground loops in pro audio equipment. Make sure that you insulate the disconnected wire to avoid short circuits occuring inside the XLR.
The above is good practice with any inter connected system using balanced line equipment. If you find that the Hum goes away when the Laptop is running on Battery power then (As has been said) a Double Insulated power suppy for your Laptop might be the only solution
Good luck
Daz
Inviato Mon 24 Dec 12 @ 6:26 am