Andy W.'s hum and buzz blog post

[Guest " "]

Just got my hair cut...add my electric barber hair clipper to the 2 prong list.  Also add my 12 amp vacum to the 2 prong list.

 

Got my hair cut in the bathroom, I survived with out getting electro-cuted. 

 

Also noticed my wife's hair blower and curling iron (1400 watts+) are also 2 prong.

 

[michael hurd]

Cutting off a 3rd prong, using a "cheater plug" and other means are by far the lazy person's approach. All equipment that has 2 prongs are built different than 3 prong equipped devices. Ensuring that the chassis all have the same potential, you can run a ground wire between the components. This wire attaches to the chassis of gear, you might have even seen a small screw on the back of something with GND over it.... ever wonder what that is for?

Introducing the Behringer DCX 2496 into my system I had a slight ground loop hum.... how did I fix it? I unplugged it and plugged it into the same circuit as the amplifier.That fixed the problem. There are also isolation transformers that could be used inline between components to eliminate this. I have been relatively lucky and have only had to deal with this a few times. Each time, the fix was easy. I fixed a ground loop hum between a mixer and power amps with a simple 18 gauge wire that connects to the ground screw on all. ( they had a screw that was designated GND ) If they do not have a screw that is marked chassis ground, sometimes you can use any screw on the chassis.

You have been lucky and this is not easy, otherwise there would not be the discussions on this topic. bTW - when you ran a ground wire between the chassis you probably did not 'fix' the problem, but just reduced the hum quite a bit.

If the fix is easy, just give me the solution for the problem I posted, since the writer thought the only solution was 'the lazy person's approach'.

The solution to which problem? The chanedelier? Run new wire period, then it is hooked up as it is meant to be. As far as the cd player to preamp>? You can use an isolation tranformer to get rid of the hum. Have you tried connecting a wire from one chassis to the other>? Each and every situation is different, and unique, requiring different fixes. By the way, yes the wire from the mixer to the power amps COMPLETELY fixed the problem, zero hum. ( not just attenuated it )

[Cut-Throat]

Cutting off a 3rd prong, using a "cheater plug" and other means are by far the lazy person's approach. All equipment that has 2 prongs are built different than 3 prong equipped devices. Ensuring that the chassis all have the same potential, you can run a ground wire between the components. This wire attaches to the chassis of gear, you might have even seen a small screw on the back of something with GND over it.... ever wonder what that is for?

Introducing the Behringer DCX 2496 into my system I had a slight ground loop hum.... how did I fix it? I unplugged it and plugged it into the same circuit as the amplifier.That fixed the problem. There are also isolation transformers that could be used inline between components to eliminate this. I have been relatively lucky and have only had to deal with this a few times. Each time, the fix was easy. I fixed a ground loop hum between a mixer and power amps with a simple 18 gauge wire that connects to the ground screw on all. ( they had a screw that was designated GND ) If they do not have a screw that is marked chassis ground, sometimes you can use any screw on the chassis.

You have been lucky and this is not easy, otherwise there would not be the discussions on this topic. bTW - when you ran a ground wire between the chassis you probably did not 'fix' the problem, but just reduced the hum quite a bit.

If the fix is easy, just give me the solution for the problem I posted, since the writer thought the only solution was 'the lazy person's approach'.

The solution to which problem? The chanedelier? Run new wire period, then it is hooked up as it is meant to be. As far as the cd player to preamp>? You can use an isolation tranformer to get rid of the hum. Have you tried connecting a wire from one chassis to the other>? Each and every situation is different, and unique, requiring different fixes. By the way, yes the wire from the mixer to the power amps COMPLETELY fixed the problem, zero hum. ( not just attenuated it )

The problem is the picture I posted. Amp and Pre-amp - the writer of the article claims that the only solution is to lift the ground of a chassis. BTW - he mentions running a wire between chassis

Running new wire in an old house - Oh Yeah! simple, why didn't anyone think of that! - Maybe, because it's all embedded in plaster walls.

[Cut-Throat]

I found this little article interesting and it in fact describes the actual ground loop that I have isolated in my Gear and they also agree that the cheater plug is the only solution, even though it is not recommended. Notice it says that home audio gear 3 prong plugs are almost unheard of. Yeah maybe if you buy your gear at Walmart! - "And the only solution would be to somehow disconnect the power line ground from one of the chassis'. This is not approved by electrical inspectors and fortunately doesn't need to be done in home stereo equipment."

Ground Loops

Figure 1. Ground loop involving line cords.

Both the preamp and power amp are equipped

with 3 wire line cords and 3 prong plugs. (Note: this is almost unheard

of in home audio equipment. This example is given for illustration

purposes only). The green wire in each line cord is connected to the

chassis of each unit. The ground prong of each plug connects to the

local power ground. The two chassis' are also connected together by the

shields of the audio cable. The audio cables are much longer than

indicated in the diagram.........................................

What can be done?

In the case of Figure 1.

You might try grounding the two chassis'

together with very heavy wire in an attempt to short out the induced

voltage. The added wire will just create another loop unless you place

it physically very close to the audio cable. Even if you do that all

you will succeed in doing will be to reduce the volume of the hum but

it will still be audible.

You might also try bringing the line cords

close together and close to the audio cable but most likely all you

will accomplish will be to increase the hum. You will place AC carrying

conductors into close proximity with the audio cables thus inducing

more hum than you are getting rid of.

The only sure way is to break the loop.

Cutting the shields on the audio cable rarely works with unbalanced

inputs. There will always be a potential difference between the two

chassis' even though they are grounded to the power line ground. The

reason is that the grounding wire gets a current induced in it because

it is in such close proximity to the current carrying conductors of the

line cord. If this were a real situation, the only solution would be to somehow disconnect the power line ground from one of the chassis'. This is not approved by electrical inspectors and fortunately doesn't need to be done in home stereo equipment.

Here is the problem again - In case you missed it!

[michael hurd]

Just because it is DIFFICULT to run new wire, should that stop you from doing it? Will it be expensive? Yes it most certainly will cost. In case you have not noticed, nothing in life is free, cheap or easy.

Regarding the picture, I read the article, and I suggested an isolation transformer.

http://www.epanorama.net/circuits/audio_isolator.html

From shure's page: read # 3 again and again.

Do's and Don'ts of Audio Transformers

Do use a transformer to match impedances.

Do use a transformer to increase or decrease signal level by up to 25 dB.

Do use a 1:1 transformer to isolate problem components in an audio chain.

Do not use a transformer to increase signal level by more than 25 dB.

[michael hurd]

http://www.jensen-transformers.com/iso_aud.html

http://www.jensen-transformers.com/datashts/dinli.pdf

[michael hurd]

I gave you the wrong link, this is the one that should have been pasted. This one inserts into the RCA line cords, no fuss no muss.

http://www.jensen-transformers.com/ci2rr.html

http://www.jensen-transformers.com/datashts/ci2rr.pdf

Is it expensive? It certainly is more expensive than using a cheater plug.

[michael hurd]

This is a noncommercial site
operated by Max Robinson and
dedicated to passing on and preserving
knowledge of vacuum tube circuits and techniques.

Keep the electrons flowing and the tubes glowing.

He talks about fear mongers telling him about the dangers of lifting safety grounds, but it does not seem like this fellow has done much trying to fix a problem which can be easily corrected. He would rather disconnect a "safety" ground. Oh well, all the power to him.

Just hope that one day he does not touch two components at once and have the electrons flowing through him.

[Cut-Throat]

$177 - Yikes!

I like my GFCI solution a lot better!

[NOSValves]

This is a noncommercial site

operated by Max Robinson and

dedicated to passing on and preserving

knowledge of vacuum tube circuits and techniques.

Keep the electrons flowing and the tubes glowing.

He talks about fear mongers telling him about the dangers of lifting safety grounds, but it does not seem like this fellow has done much trying to fix a problem which can be easily corrected. He would rather disconnect a "safety" ground. Oh well, all the power to him.

Just hope that one day he does not touch two components at once and have the electrons flowing through him.

Are we talking two components in a working audio/video system? If so absolutely no electrons are going to "flow through him" both devices are already common ground connected together via the ground/shield of the interconnects and other cable systems. No voltage potential difference could possibly be present. An auto system can be grounded VIA one single components 3 prong power cord and all other components will also be ground via the IC's. This is exactly what creates the ground loop problem in the first place (multiple paths to ground creating a loop). The isolation transformer would be a fine solution but really what amount of safety are you gaining. Besides the young Jedi (which I really don't believe) who else has ever received more then a little tingle shock from audio equipment?? I work on old vintage 2 prong equipped gear everyday and have never been shocked from a lack of 3 prong cord. This is basically a bunch of alarmist crap. Is gear safer with a 3 prong?.....yup. How much safer?..... not much.

Craig

[michael hurd]

The "right" solution always costs more.

For example, at a bodyshop I worked at, a vehicle that REQUIRES stripping ( cracked crazed paint ) that is over 15 mils thick, people ran to another body shop as it is cheaper for a complete repaint. We quoted to chemically strip and refinish the vehicle in RM-Diamont ( BASF line ) They decided to go with the shop that was about $ 1000 cheaper. Sure it is cheaper, but did they strip? Heck no, the shop in question simply sanded it down, threw some primer over top, sanded it again, and laid another finish coat.

Inside of 3 months, the vehicle owners showed up again at the doorstop of the bodyshop where I was employed and asked what happened. My boss ( GM and BASF approved refinish painter ) said that you didn't listen. "Live with it."

And these people were ANGRY at us why? Because they went elsewhere, and the problem was not fixed. The shop in question ( I will not name it ) stonewalled the customer saying that there was "environmental" conditions and that there was zero warranty, lying through the teeth, and happily counting the greenbacks from the job.

[michael hurd]

"This is basically a bunch of alarmist crap. Is gear safer with a 3 prong?.....yup. How much safer?..... not much."

Again, believe what you want. If you choose to defeat a safety device, you are playing engineer, electrican and maybe a mortician. 2 prong devices are designed and built differently than a 3 pronged device. A 3 pronged device REQUIRES that the 3rd ground be connected. It does not magically transform into a 2 pronged device when you chop off that pin, or use some other means of not hooking it up.

[joshnich]

I have to go with Mr Otsby on this. I can only imagine the amount of on the phone ground loop hum trouble shooting he has done. He know of what he speaks. I know that I had a ground loop issue with my Pcats and Mark suggested to use the lifters until he could install a ground loop lift in my preamp. I do not think that Mr Deneen would have steered me into dangerous territory. Craig and Marks' track record for surviving customers speaks for itself.

Josh

[NOSValves]

"This is basically a bunch of alarmist crap. Is gear safer with a 3 prong?.....yup. How much safer?..... not much."

Again, believe what you want. If you choose to defeat a safety device, you are playing engineer, electrican and maybe a mortician. 2 prong devices are designed and built differently than a 3 pronged device. A 3 pronged device REQUIRES that the 3rd ground be connected. It does not magically transform into a 2 pronged device when you chop off that pin, or use some other means of not hooking it up.

I don't have to believe what I want. I BELIEVE WHAT I KNOW......... I'm not advising anyone do to anything in this thread. Just simply stating that you guy's are making a mountain out of a mole hill.

Please search the newspapers, libraries, online and find reports of all these fatalities from people using 2 prong adaptors....... Please show me the proof to back up your claims of immense danger.... Again this is alarmist crap.

Craig

[michael hurd]

And why should I find this information? How about you find some information PROVING that nothing can happen when you are intentionally defeating a SAFETY device. How about going into a hospital.... you think that defeating a safety ground on a machine that regulates the flow of intravenous drugs is a good idea>?

[michael hurd]

http://www.csao.org/uploadfiles/magazine/vol11no1/shock.htm

Less current required than a 100 watt bulb in a home can kill. Craig, are your products UL tested and certified? Will UL condone removing a safety ground to fix a problem that can be cured with an isolation transformer?

http://www.ndsu.nodak.edu/ndsu/police_safety/safety/training/PDF/CLSCourse3.pdf

Read pages 16 and 17, DEATH resulting from using a "cheater plug".

http://www.straightdope.com/mailbag/mguitarelectrocute.html

http://www.dvorak.org/blog/?p=3195

A pretty shocking story here.... actually several!

http://pogue.blogs.nytimes.com/2006/10/06/shocking-hp-laptops-2/

"

27.

October 9th,
2006
3:07 am

I have had this problem, too, but only outside the US when Im using a two-pronged adapter on my PB G4, which has an aluminum body. I dont experience the problem when I use an iBook, which has a plastic body. At hotels that have a US-style, grounded receptacle, as well as the 2-pronged, ungrounded receptacle, I can eliminate the problem, wich leads me to believe that the lack of a ground is the source of the problem. The higher voltage may be a factor, too.

Posted by Robert Jacob "

http://bremc.com/coopnews/CN&VMayJune04.pdf

http://www.gamespot.com/news/6163774.html

[NOSValves]

What the heck does construction deaths have to do with home audio??? The link even stated most of these construction related fatalities were dealing with over head power lines. Again more alarmist propoganda..........

No my products are not UL tested and certified very few tube audio is UL tested and certified........ You know what the fact that they are not UL certified has nothing to do with 3 prong power cords (although my amps come with 3 prong power cords) and plenty of products are UL certified without 3 prong power cords. You keep spouting how this magical modern two prong gear "is design specially to be 2 prong safe" Sorry dude the 2 prong stuff is not much different then 3 prong designed gear either one could "possibly" fatally shock you. About a million to one chance give or take 1% between the 2 types either way unless your digging around inside.

So please find these mass reports of people being shocked to death while using home audio equipment....... Why should you research and find these? Because your making the claim that this type stuff exists not me. I really hate searching for something that does not exist

Craig

[NOSValves]

http://www.ndsu.nodak.edu/ndsu/police_safety/safety/training/PDF/CLSCourse3.pdf

And this guy has an audio system in this lab??? The fluorescent shop lights can be very dangerous those ballasts carry a wallop.

http://www.straightdope.com/mailbag/mguitarelectrocute.html

again were talking home audio here are we not??

http://www.dvorak.org/blog/?p=3195

again not a home audio system.

http://pogue.blogs.nytimes.com/2006/10/06/shocking-hp-laptops-2/

again not a home audio system

http://bremc.com/coopnews/CN&VMayJune04.pdf

http://www.gamespot.com/news/6163774.html

Last time I handled a Nintendo it had a 2 prong plug..............

I see your having a real rough time finding all these fatalities with home audio gear.

[michael hurd]

Oh now home audio specific deaths? The two people that died touching a live mic don't fall into that category? Or how about the Lab teacher who's death was traced back to the improper use of a "cheater plug"?

So which is it>? Defeating a SAFETY grounding pin ( that UL says needs to be there, on a 3-prong device ) is no better than removing a guard on a circular saw. They are a preventative measure to reduce the possibility of injury and death.

[michael hurd]

Craig, it seems that no one is right when in an argument with you. I will leave this issue to rest.

How do I know about defeating safety grounds? When I was living with my ex-ex girlfriend, she had an upstairs apartment in an older home.

Seems that they only used 2 prong wires as well, but changed the outlets to more modern appearing 3 pronged ones. Well one day I sprayed the tv screen down with windex, and proceded to wipe it ( I had my left hand on my Phillips power amp chassis ) and touched the television with the right ( leaning over ) ZAAAAAAAAP..... The protection light turned on in the amp and it momentarily shut off.

I put an outlet tester into the wall socket one day ( had borrowed one ).... low and behold, there was no connection to the ground. ( safety pin ) Since there were 3 prong devices plugged in, there was no connection at all. The ground was defeated, in a similar way to using a 3 prong device with no ground connection. I was the "connection".