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Fixes for electronic noise interference on laptops (60 cycle hum)
Submitted by Enim27 on Wed, 01/18/2006 - 20:00.
I ran into a problem when using my laptop with Dragon Naturally Speaking of a buzzing sound coming in through the microphone in line, which was identified as a 60 cycle Hz AC hum.
These were the many tricks and resources that were suggested by the group. All of them might not work but at least one most likely will.
What worked for me: I bought a test/jumper lead cable (for those of you who don't know about electronics, like me, it looks like a tiny, tiny, tiny jumper cable like you would use for your car with clips at each end about the size of your thumb) and grounded the laptop by clipping one end on to one of the screws at the back of the laptop (chassis?) and the other on to the screw, which I had to loosen, that holds the plate onto the wall socket. And it worked great, no more background sound, and my recognition accuracy shot way up. Just like on battery power. Only cost me five bucks! I did this with the help of a laptop technician, so if you don't know much about electricity like me, be sure to talk to someone knowledgeable first.
Things that worked for other people which I did not have success with were using a 2-prong adapter, a much better AC adapter/filter, a hum elimator such as by Musician's Friend or Ebtec, or a ground loop isolator. These last two I did not actually try.
Using a ground loop isolator doesn't seem to be an option because I can't figure out where I would plug things in.
What still remains confusing is that there is not one source to the problem and the sources actually seem kind of contradictory -- the problem could be because the laptop is not grounded, or because the laptop IS grounded, or the hum that you're hearing is not an AC buzz at all but DC hash.
For future reference, if anyone else runs into this, here are a couple of web sites where musicians talk about this problem a lot and have suggestions:
http://www.packetradio.com/humsolving.htm (I called and talk to this guy, he's quite a character.)
http://www.djchat.com/boards/archive/index.php/t-1... (musicians)
http://ask.metafilter.com/mefi/20028 (more musicians)
About grounding, you might want to doublecheck with your manufacturer that that is an okay thing to do. I have a Toshiba Satellite A10, and Toshiba said it was no problem to ground it.
Jasmine
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Excellent post Jasmine!
Excellent post Jasmine! I'll upgrade you to the FAQ area for posterity.
I'd like to see more posts like this one!
Can somebody tell me more
Can somebody tell me more about this test/jumper lead cable solution, prefarably with a picture? When you mention the screw that holds the plate on to the laptop, I am confused. Can you point to a test/jumper lead cable ?
Before I explain further,
Before I explain further, please note that I don't have a background in doing this. I tried this solution and it worked for me with no problems, but I was at my wit's end. I did this under the instruction of my friend who fixes my computer routinely. But I cannot tell you if there is any risk or harm involved. So you should proceed cautiously.
here are a couple of pictures of the clips and cables to give you an idea:
http://img.thomasnet.com/pad/387322/00387322_19545...
http://www.lashen.com/vendors/testum/images/TP40.g...
if you go to radio shack and ask for the above, they will have it. They are also called alligator clips, I believe.
Try to get them as long as you can find, longer than 4 feet if possible. I was not successful in finding a long cable and that means you end up needing to work pretty close to a wall socket. I'm going to try to make a longer cable using copper wire, but let me know if you find something longer.
1) So to clip on to the back of the laptop -- (meaning where all your various cables go -- printer cable, USB ports, etc.) -- there are several metal surfaces on the back -- miniature metal knobs, etc. any of which can be cliped on to with one end of your "jumper cable".
This is a picture I found of the back of a laptop:
http://support.axiolearning.org/images/kyc/laptop/...
ANY of those metal exposures back there can be cliped on to. Basically any metal surface on the laptop will do the trick.
2) cliping onto the wall socket --
Look at this picture --
http://www.clipartguide.com/_small/0060-0503-3017-...
You see the screw between the two sockets -- loosen that screw with a screwdriver just a few turns -- then clip the other end of your cable onto that screw and then tighten the screw back up.
It makes my microphone work beautifully, otherwise sound quality becomes nonfunctional.
Hope that helps, let me know if you have more questions.
Jasmine
Thanks a million. I will try
Thanks a million. I will try as you so beautifully explained. I am really grateful for your help.
While researching, I also found this, but have not yet tried it
'GROUND LOOP ISOLATOR - Designed to connect between two pieces of audio equipment that have a ground loop problem.'
I will report back once I get a soultion.
Builder
sure, no problem. And yes,I
sure, no problem. And yes,I am interested in what you find as a solution.
I second the method. I use a
I second the method. I use a 3 prong PC power cable (American). At the wall plug I keep the grounding connector (center round) and break off the two blades (hot and cold). Then I cut the other end of the cable, to get to the ground wire. Make sure to test the cable with a battery and bulb. At the cut end of the cable I made a small loop and I use a screw to attach it to the laptop's paralel port (or serial). Then I plug the cable in a grounded power outlet (only ground will make contact). This effectively reduces electronic noise (60 Hz hum). The procedure worked fine on 2 thinkpads and 2 Panasonic laptops.
To really see what is going on, use the a Spectrum Analiser (like the one made by Paul Kellett, freeware):
http://www.web-ee.com/Downloads/Sound%20Cards/soun...
This utility will nicely show the actual spike at 60 Hz, as well as other spikes within the audio frequency (I got one at about 500Hz from the network connection). It will also show the quality of your sound card, and the effectiveness of grounding.
I use VR for data input (Dragon Dictate), sometimes in ungrounded places. There, I use a speaker wire (any other wire will work) and connect the water pipe to the back of the laptop. When using the water pipe avoid working during tunderstorms.
There are lots of reasons for getting the hum. The hum is the AC base frequency. Overseas (Europe, China, etc.) it is at 50 Hz. In the US is 60 hz. Usually it is due to bad shielding. Unfortunately, it affects the USB pods too. The hum gets in the pod (e.g. Andrea) through the power, regardless of the USB noise filtering design. If you chose to work on battery make sure your body does not work as an antenna, and remove the power cable from the vicinity of the laptop. I have seen the hum sneaking in when the power cable was close to the mike cable or my body.
Severus
I found that just putting my
I found that just putting my hand firmly on the vga outlet of the laptop reduces the hum significantly. I am still waiting for connectors for the ground loop isolator that I bought to see if this will be effective. Some people have suggested cutting off the grounding (centre) connector at the wall plug may work but I havrn't tried this
builder wrote: I found that
I found that just putting my hand firmly on the vga outlet of the laptop reduces the hum significantly. I am still waiting for connectors for the ground loop isolator that I bought to see if this will be effective. Some people have suggested cutting off the grounding (centre) connector at the wall plug may work but I havrn't tried this
First, the reason that the 60 Hz hum decreases when you put your hand on the VGA output connector on your laptop is because you are effectively grounding it. The human body is a good ground source.
Second, be very careful when playing with plugs and outlets. If you're not careful you can not only damage your laptop, but a 115 V short to ground is the single biggest killer in terms of electrical shock accidents. You are more likely to survive a strike by lightning than you are to survive a 115 V 15 amp shock from the electrical wiring in your home. The suggestion for cutting off the grounding connector at the wall plug is a very very bad idea. It is extremely dangerous if you don't know what you're doing at worst, and potentially a very good motherboard destroyer at best.
I've been following the posts in this section and most of them, including your reference to the "ground loop isolator", which is a good idea and generally safe. However, having been both an electrician and electronics technician in the Navy, I can't stress enough that there is a need for caution. Don't gamble either with your computer or your life. You will be very unhappy if you accidentally create a 115 V short to ground. I guarantee it.
Chuck Runquist
Former DNS SDK & Senior Technical Solutions PM for DNS
"We are all victims of mythology in one way or another. We are the inheritors, and many times the propagators, of a desire to believe what we want to believe, regardless of whether or not it is true." -- J.V. Stewart
Thanks for your warnings.
Thanks for your warnings. You might have saved my life there! The ground loop isolator did not work. I had to buy an RCA-F to 3.5mm jack to connect it to the laptop; then an RCA-M to Mini-jack-F to connect to the mike. The effect was horrible noise. I used the 'Skytronics high quality ground loop isolator'.
What I did that made a little difference was to attach the ground connector of an adaptor (taking off the life and neutral connectors) to a long thick wire and plugging it(only the center ground connector pls!) to a separate power point. The other end of the wire was then attached to either; 1.screwed to one of the vga port screws OR 2. inserting the wire into the female end of a minijack-F to male audio connector, and plugging the connector to the speaker port of the laptop. Of course, you can't then hear the speakers but you can use the mike. The hum reduced significantly to make voice recognition possible. Prior to that , the hum was so loud it was impossible to hear my dictation at all. The best solution I have found is to use a bluetooth microphone. With this , there is no hum at all.
For a very cheap bluetooth solution, buy the old sony bluetooth HBH-300 and a broadcom bluetooth version 2 dongle if your laptop has no bluetooth. My generic laptop bluetooth adapter seems to work well. There are of course more expensive bluetooth solutions, but I think it is unlikely their excessive price is justified over the old HBH-300 headset which is quite good with noise-cancelling.
Does anyone know how to improve the shielding in the laptop to prevent this hum? If there is a way, i am willing to open my laptop up to do it
supo
Builder, > There are of
Builder,
> There are of course more expensive bluetooth solutions, but I think it
> is unlikely their excessive price is justified over the old HBH-300
> headset which is quite good with noise-cancelling.
eMicrophones incorporated extensively tested the Sony/Erickson HBH-300. It worked OK in absolute quiet. We've even the most modest noise levels, a keyboard that had loud clicks, the microphone was a poor performer.
--
Martin Markoe, eMicrophones, Inc.
The best microphones for Speech Recognition
See us at: http://www.eMicrophones.com/index.asp
Read, "Key Steps to High Speech Recognition Accuracy" at:
http://www.emicrophones.com/docDetails.asp?Documen...
Problem solved
Problem solved !
eMicrophones incorporated extensively tested the Sony/Erickson HBH-300. It worked OK in absolute quiet. We've even the most modest noise levels, a keyboard that had loud clicks, the microphone was a poor performer.
I found it (HBH-300) ok with noise-cancelling to some extent. I can dictate ok with the TV at low volume(I can hear it clearly) and people talking at low volume 3 meters away from me. I also have an andrea anc 700 which I found to be a little bit more accurate with better noise -cancelling.
As to the problem with the hum, I got in touch with dell, and pressured them. I was sent a new AC charger which seems to have eliminated the hum. I can now dictate without any hum at all affecting my recognition. The new charger is heavier and I think must be better-shielded. Dell probably is aware of the problem and may only send the charger to people who complain.
builder wrote: As to the
As to the problem with the hum, I got in touch with dell, and pressured them. I was sent a new AC charger which seems to have eliminated the hum. I can now dictate without any hum at all affecting my recognition. The new charger is heavier and I think must be better-shielded. Dell probably is aware of the problem and may only send the charger to people who complain.
That's useful information, especially for anyone in similar circumstances. Both the fact that you PRESSURED the seller and that they seemed to have a solution at hand.
Bruce
I have a HP laptop
I have a HP laptop (approx.four years old) that has a very light mains adaptor, and an Acer laptop (approx.1 year and 8 months old) with a very heavy adapter, and neither of them have caused any problems with hums or electoral interference.
However have noted adapters for other peripherals, such as printers, which do buzz or hum, and they are heavy ones.
Quentin
crivon1 wrote: I have a HP
I have a HP laptop (approx.four years old) that has a very light mains adaptor, and an Acer laptop (approx.1 year and 8 months old) with a very heavy adapter, and neither of them have caused any problems with hums or electoral interference.
However have noted adapters for other peripherals, such as printers, which do buzz or hum, and they are heavy ones.
Quentin
I am not suggesting that the fact its heavy makes it not to cause a hum, I am only saying that to make people know its different.
Builder