Cheater Plugs to reduce ground loop hum

[dragonfyr]

Common bonding to the water line at the point of entry into a home is part of the Electrical Code.

...As simply using a copper grounding rod does not insure the same ground potential as that used by the other components and simply provides yet another path.

I think it's long overdue for this thread to die!

[Daddy Dee]

thank you Shawn.

[NOSValves]

Daddy,

I must advise you that driving the rod into the ground could possibly result in injury. I suggest you hire it done. But then be absolutely sure the person you hire is covered under workman's comp and relieves you of all legal obligation if he happens to hurt himself........ This is alarmists day 2005

Craig

[Erik Mandaville]

Dee:

Installing your own ground rod is relatively easy to do. I've mentioned to Shawn recently that I actually use two, daisy-chained, as it were, together by the same hardware and heavy ground wire Shawn suggested in his post. What can come into play with this, however, is the nature of the soil you are hitting the rod into. The Houston area has a consdirable amount of dense clay, which seems to work especially well for earth grounding. My parents have very hard, rocky soil layers in AZ, which takes jack hammers and tons of labor to deal with -- even for a simple ground rod. My dad installed his own isolated earth ground for radio equipment in their back yard, and he mentioned what a pain it was. You might want to wait after a good rain to do this (if you do), which would probably make the work go a little easier.

BTW: I have my equipment earth-grounded at two power amplifiers, with the rest floating by way of cheater plugs. IMO, Shawn is very correct with regard to the safety concern -- especially if one handles powered equipment with both hands while it is energized. When I test amps, I always make sure that the safety ground IS NOT defeated.

Also: Ground loops resulting from the shield connections on ICs are different from coaxial and twinaxial cable. The shields on my own coax ICs are bare copper 95% braids, which are more able to handle the current demands when relied upon for safety grounding between equipment. Still, it's neither as reliable nor as safe as connecting the ground lug on IEC jacks to the chassis (separate from the circuit and signal grounds) by way of a heavy wire (12AWG+) Twinaxial cables that are earth-grounded at one end only (for RFI/EMI immunity ONLY) rely on the ground return by much smaller wire -- often 22 AWG or narrower. Thus, they are not intended for use as a means of protecting one's self against electrocution should the chassis of a component suddenly become live by component failure or poorly installed wiring. One of the reasons, for example, that IMO good, neat wiring is important.

Since I just made a pair of cables for you that fit the above (twinaxial/single-sided-shield connection) description, please follow Shawn's advice for safe grounding with the older, two-prong outlets in your home. When I was using the Lowther horns, along with a modded Foreplay preamp and Moondogs, I connected the chassis to one another (or just the preamp to one amp, I think) by a 14AWG lead. This helped reduce some ground hum problems, but not RFI pollution. BTW, the Foreplay was sold with an inexpensive, two-prong, ungrounded plug. That was also one of the first things I changed on it, so that I could earth ground the chassis for safety.

Also: I'm not sure that ground loops within components themselves have been mentioned. This can be a maddening source of noise, buzz, hum, etc., but is something that must also be dealt with when designing equipment. Grounding seems to be a sort of 'black art' as it were in audio, and what works well as a ground scheme in one instance, might not be so effective in another. Some of the problems that the originator of this post may be experiencing may thus have to do with ground loops within one of the components themselves (though probably not).

Dee: If you install your own ground rod, confirm (or have confirmed for you by a professional electrical contractor) that you are hitting it into a safe area around your house. An electrician friend of mine told me a story about a guy who installed a ground rod righ into a high voltage underground supply. But you can do it yourself very easily. Wear safety goggles in case the sledge you use glances off the rod, possibly causing sparks.

I have always kept my system earth grounded at one point at least, and it has helped enormously with ground loop problems. However, I'm glad this post has come up, because it has made me re-think about my own safety practices with all of this. It is doubtless better to put up with a little bit of background noise when listening to music, than taking risks that might result in a sudden lack of hearing.......or heartbeat.

Erik

[Daddy Dee]

Thanks Erik. makes sense.

Good to see you posting.

Craig,

If I hire it done, I'll make sure the contractor is properly bonded!

[NOSValves]

Eric,

long time since we heard from you.

BTW: I have my equipment earth-grounded at two power amplifiers, with the rest floating by way of cheater plugs. IMO, Shawn is very correct with regard to the safety concern -- especially if one handles powered equipment with both hands while it is energized. When I test amps, I always make sure that the safety ground IS NOT defeated.

Hate to tell you this but your system is dangerous quit using it now.

Craig

[Erik Mandaville]

Kraig:

"Hate to tell you this but your system is dangerous quit using it now."

You are right. It is more dangerous than it needs to be in order to be considered a completely safe audio system, with redundant safety grounds.

Thanks for your advice,

Erik

[NOSValves]

Erick,

You spelt my name wrong []

[Erik Mandaville]

Ooops! you're right about that too! Sorry! But......isn't 'spelt' a grain of some sort?

[dragonfyr]

But......isn't 'spelt' a grain of some sort?

I was thinking a type of fish![]

[sfogg]

Hi Erik,

"rely on the ground return by much smaller wire -- often 22 AWG or

narrower. Thus, they are not intended for use as a means of

protecting one's self against electrocution should the chassis of a

component suddenly become live by component failure or poorly installed

wiring. "

Exactly, and many may not even be 22 ga, I have seen them with 28 ga.

or smaller yet. That won't be able to handle 15amp at all and will melt

long before a circuit breaker trips. In that case the equipment could

easily be sitting there with the chassis hot. It isn't a pipe dream...

it happens.

If every interconnect in the system was 16 gauge or better and every

box could handle 15 amps through its signal ground connections

(probably not) and every box has chassis connected to signal ground

(that can handle current) then one could probably float the safety

ground and still be covered by one grounded box. But that is a lot of

ifs in my book.

"This can be a maddening source of noise, buzz, hum, etc., but is

something that must also be dealt with when designing equipment."

All the more reason why RCA connections should be abandoned for XLR

connections between equipment. XLR connection are extremely resistant

to ground loops (signal negative is carried different from chassis

ground) and also have noise rejection for induced RF noise and such.

"It is doubtless better to put up with a little bit of background noise

when listening to music, than taking risks that might result in a

sudden lack of hearing.......or heartbeat."

You shouldn't have to do either. Ground loops can be beat without

compromising safety. It takes work though to tear a system back to just

a single component and work forward from there connecting one

additional component at a time to wait for the ground loop noise to

spring back up. Once it does one has found out between which two

components the ground loop is coming from. When one has determined

which two components the ground loop is between it becomes much easier

to fix the problem without just arbitrarily removing the safety ground

from all the equipment.

Just simple steps will help to avoid ground loops in the first place.

Use the same circuit for all the equipment. If that isn't possible use

two circuits that are on the same phase of the wiring. That will help

reduce noise and ground problems.

Plug in all of the three prong equipment into one long power bar and

plug that into a grounded outlet. That will star ground all of the

equipment right there to one point. If you don't have a grounded outlet

(or it has a bad ground in it) use a cheater plug and connect its

ground lug to a good ground point in the house. If there are no other

ground points in the system (cable, sat., external antenna,

ethernet...etc...etc) there should be no ground loops.

What also gets some people is other types of noise may be mis-diagnosed

as ground loops. Buzzes from noisy dimmers being on the same circuit

for example.

Shawn

[Erik Mandaville]

Shawn:

"Plug in all of the three prong equipment into one long power bar and plug that into a grounded outlet."

This is essentially a ground buss, on which the components of the system ride, and which are hence earth grounded at the one outlet -- very similar to what is effective grounding inside a component, itself. For example, I had a slight but frustrating buzz I isolated to the Moth amp I built last year, and worked for hours, scratching holes in my head trying to find the source. With three levels of wiring inside that amp -- much different from any SET amp I've made -- I had accidentally ground the input/driver stage twice, at different points in the chassis (or rather one on the ground node for the input/driver stage, the other at the power supply ground. The noise was not bad, and I could only hear it with my ear inside the midrange horns (I have removable ears, that I can place inside equipment to ferret-out noise problems). For me, that was not acceptable, and the removal of the extra signal ground at the power supply B- side cured it completely. with regulated DC on the 2A3 filaments instead of the usual AC plus hum-null pot, the Moth is truly very near the Teac as far as residual noise. (wait, I should qualify this: it's very nearly as quiet in terms of circuit-related/ground noise, but does suffer from some mechanical hum from the power transformer.) I found a company that will build a nice toroidal transformer to my specs, which includes an electrostatic shield between the primary and secondary windings. The other thing I can do is 'float' the current transformer from the chassis using rubber grommets to help dampen the vibration.

With a total of four monoblock and two stereo tube amps in the system, plus source equipment and Lexicon processor, I'm happy with how things are going. But it's taken some work to get it to that point because of the very topic of this thread.

I do appreciate the reminder of adequate safety grounding, as well as some effective ways of carrying that out.

Erik

[Erik Mandaville]

...And do check those pesky dimmer switches! They can generate horrible noise through house wiring. I've had the same problem with small cooling fans, like the one I use in my workroom to blow solder fumes away from my face, that use variable or slide potentiometers like a dimmer switch. That fan was a source of noise at some other time (there's been many such occasions) that I just hadn't considered.

Erik

[jpm]

I'm confused (happens often). On the patchcord (or whatever you call it) from my cd player to the preamp, does the direction arrow go to the preamp or to the cd player.

[Erik Mandaville]

I'm confused often too, JPM -- this grounding thing can be a pain in the fanny. I don't know what cables you're using but the arrow may indicate the shield connection in a two-conductor-plus shield cable. Try it both ways and see what works best in your system. Wire is wire, and IMO is not 'directional' per se' in terms of propagating a signal. It can make a difference in terms of whether the sheild connected end is at the high or low impedance side, but you can experiment to see what works best in terms of any associated background noise. By high or low impedance side, I'm referring to the source (preamp) output impedance and load (amplifier) input impedance.

Good luck!

Erik

[NOSValves]

Hi Erik,

Exactly, and many may not even be 22 ga, I have seen them with 28 ga. or smaller yet. That won't be able to handle 15amp at all and will melt long before a circuit breaker trips. In that case the equipment could easily be sitting there with the chassis hot. It isn't a pipe dream... it happens.

Shawn

So there are 17000+ members here on the Klipsch forum all with Audio and Video equipment. I wonder if anyone has ever had this happen? I bet a good number of them have ungrounded equipment as I do. All of my equipment whether 3 wire grounded or not I can measure from the outer chassis case or a screw on the outer case when the case is plastic to the hot side of the AC plug and get 117 VAC which means they are all earth grounded together. To accomplish what you suggest almost everyone on this forum would have to get out a soldering iron and modify at least some of there gear (mostly sources and video equipment). While you say THIS CAN happen I say it's VERY VERY unlikely to EVER happen. Kind of like getting struck by lightening.

Craig

[Erik Mandaville]

Craig:

You are probably right that chances of something happening are not very great. That said, I still don't go out for a walk in the middle of a lightning storm.

Erik

[NOSValves]

Erik,

Well yea I wouldn't either. But with the current mind set of some here I think it would be best to hide my head under the covers and never get out of bed. Who knows what might happen today.

Craig

[sfogg]

" I wonder if anyone has ever had this happen?"

That is why safety grounds are now on a lot of equipment compared to fifty years ago.

As far as having components fail and ground out the hot... yup.. it has

happened to me on a big SS amp that had failures in its PS. But it was

safety grounded and the damage ended with the amp.

I'm sure you of all people wouldn't claim that amps/components last

forever and failures never happen. If they did there were be no need

for restorations....

"All of my equipment whether 3 wire grounded or not I can measure from

the outer chassis case or a screw on the outer case when the case is

plastic to the hot side of the AC plug and get 117 VAC which means they

are all earth grounded together."

Which means nothing. Go put 15 amps through them and see how well it

diverts that much current to ground. Also see if that current flow

through the equipment does any additional damage to the interconnect

systems..

"To accomplish what you suggest almost everyone on this forum would

have to get out a soldering iron and modify at least some of there gear

(mostly sources and video equipment)."

BS. I am *certain* I have a dramatically more complex interconnected system then you do. I don't have ground loops.

Just because you can't figure out how to get rid of ground loops (or

avoid them in the first place) without resorting to hacks doesn't mean

that holds for everyone.

" I say it's VERY VERY unlikely to EVER happen. Kind of like getting struck by lightening."

Lightening struck about 25 feet away from me when I lived in OK and

started a small fire in the yard it hit. I was riding by in a car and

saw it happen.

In a different house/state lightning struck the cable feed or somewhere

nearby (which was underground) into the house and blew up the cable box

and the VCR (which was plugged into the cable box) when I was literally

walking over to change the channel. The other equipment connected to

the VCR was fine.

Years later in the same place we had another lightning strike somewhere

nearby again and burnt up one of the hot feeds from the electric

company (again underground in conduit) to the house. Half the circuits

in the house worked until that got replaced.

So don't talk to me about lightening.

And speaking of which a safety ground can also help to limit collateral

damage for things like lightening strikes to. And without a safety

ground the vast majority of surge suppressors out there can't do

anything. The way most of those units is literally by shorting a surge

to ground. Without a ground they can't short the surge out... so it

passes right through the surge suppressor and onto your equipment.

There are a few suppressors that don't work the same way. They act more

like a low pass filter on the AC line. Surges by their very nature are

transients (high high frequency spikes)... if you in effect put a low

pass crossover in the AC it rolls off the transient. This also works

well for removing noise on the AC. They also try to store the energy in

big capacitors and then slowly drain it out into the neutral line.

Everyday I work around a couple of power systems with enough capacity

to run a house with 100amp service off battery power for around 12-14

hours or longer if the load is lower. You screw around near those

systems and you die. The AC outlet you plug your equipment into can

kill you just as quick.

Shawn

[sunnysal]

Lightning hit me in 1985, since then I only like horn speakers....