Cheater Plugs to reduce ground loop hum

[gbrlex]

Does anyone have any experience using cheater plugs that convert a 3 prong plug into 2? It worked perfectly in reducing the hum, but I don't want to damage the amp. Rotel recommended against it - any thoughts?

[michael hurd]

You could also try a ground wire to each of your components, if they do not have a screw for this purpose, you can back out a screw on the rear of the chassis, and use fork terminals and a small piece of wire to connect them.

Connect all the source devices, preamp/receiver& amp together, and see if this helps.

[jbsl]

My components have the ground connection on the back but I have never been sure were to run the ground wire from to where? Not realy sure how to ground equipment. I thought that is what the ground on the 3 prong power cable was for.

So if you use cheater plugs on 2 amps should you run the ground wire from the amps to say your preamps ground connector?

Xman

[dragonfyr]

The best way to resolve this is to have all of your interconnects' shield soldered only at the end connected to the pre-amp - and to leave the shield floating (disconnected) at the other end. This will provide RF shielding while it prevents ground loops.

This also makes the cables 'directional', as you always want the connected end to go only to the preamp (so you will want to mark this end!).

All equipment grounds should be referenced to the preamp in what is referred to as a star ground - as in a starfish - thus minimizing the difference in emf potentials and creating various ground paths.

Do it correctly and forget the cheater plugs. They are used for safety!

[sfogg]

" It worked perfectly in reducing the hum, but I don't want to damage the amp. Rotel recommended against it - any thoughts?"

Disabling the ground on grounded equipment is a safety issue, that is why Rotel recommended against it.

Try working the problem backwards.

Disconnect *everything* from your pre-amp and just run the RCAs from it to the amps.

Do you still have hum?

If not plug in one component at a time (be sure each isn't connected to anything else) until the hum comes back. When it does you know where the ground loop is coming from. When you know that you can plan a course of action to get rid of it.

Shawn

[sfogg]

"The best way to resolve this is to have all of your interconnects' shield soldered only at the end connected to the pre-amp - and to leave the shield floating (disconnected) at the other end. This will provide RF shielding while it prevents ground loops."

There will still be the ground connection between both ends and therefor the potential for ground loops. There must be a ground connection between the two or it is an incomplete ciruit and no music will flow... or it will try to use a different ground path which usually *will* cause huge ground loop noise.

A drain/shield connected on the low impedance side (output) helps against induced RF noise in the cables, it won't help with ground loops.

"Do it correctly and forget the cheater plugs. They are used for safety! "

Agreed, removing ground lugs on grounded equipment is a safety hazard.

Shawn

[gbrlex]

Are there any drawings that show how to disconnect the shield on the interconnects? I'm using Straight Wire interconnects?

[NOSValves]

When using normal inter-connects (not modified like suggested above) your entire audio system is grounded as long as one component has a 3 wire. Simply lift all other components from ground leaving this single piece grounded and all your hum issues should be resolved. This is taking for granted that your house is grounded properly. While there is some small margin of safety in having gear grounded its very small. Look at how many big name audio and vidoe components come from the factory with absolutely no ground. CD players, AV amplifiers, DVD players, TV's ....... To me grounding your audio system to every other grounded component in your home is just another way for noise to enter your system.

Craig

[dragonfyr]

"The best way to resolve this is to have all of your interconnects' shield soldered only at the end connected to the pre-amp - and to leave the shield floating (disconnected) at the other end. This will provide RF shielding while it prevents ground loops."

There will still be the ground connection between both ends and therefor the potential for ground loops. There must be a ground connection between the two or it is an incomplete ciruit and no music will flow... or it will try to use a different ground path which usually *will* cause huge ground loop noise.

A drain/shield connected on the low impedance side (output) helps against induced RF noise in the cables, it won't help with ground loops.

Shawn

Nope!

The shield is used for RF 'shielding! Both ends of the shield do NOT have to be connected! You disconnect the end of the shield (the wire connected to the outer ring of the RCA plug) on the end away from the pre-amp. And as one end will be disconnected, there is no continuity, but the grounded shield will still act as an RF 'shield' for induced noise.

If 'no music flows', then I have a very vivid imagination!

And as this conductor is normally referenced to the chassis, it most certainly often plays a role in creating ground loops!

This is also the reason many interconnects are labelled as directional! (it is not because of the supposed electron flow!) It simply indicates which end of the shield is lifted.

http://www.jdbsound.com/art/art510.html re: THE LAST BEST RIGHT WAY TO DO IT

[whell]

Grounding appliances makes great sense to Underwriters Laboratories, since for a fairly small investment, you get a safety-related benefit. There is little to no audible benefit of grounding audio components. Rather, it introduces the opportunity for noise to be audibly reproduced by your system, and compromise the listening experience. Lots of folks out there dig the sound of their old 60's & 70's Marantz tube and SS amps, and not one of them came from the factory with the 3 prong power cord.

[gbrlex]

I was wondering about that. None of my 3 adcom amps rated from 200wpc to 60wpc have a 3 prong plug. I thought they may have been grounded internally.

[sfogg]

"When using normal inter-connects (not modified like suggested above) your entire audio system is grounded as long as one component has a 3 wire. Simply lift all other components from ground leaving this single piece grounded and all your hum issues should be resolved."

That is not good advice.

What happens when one component has an internal failure? Instead of grounding out the plug that is built for current and blowing a fuse or a breaker the current is going to try to pass through the only ground it has available... the interconnect. Interconnect grounds are not built to carry any appreciable amount of current in them, it will burn up very quickly. Maybe starting a fire, maybe not. If the ground connection on the interconnect breaks before you you pop a circuit breaker (very likely) you now have one piece of equipment with 120v AC *LIVE* on its chassis. Touch that and touch something grounded and your days of modding amps could come to an abrupt end.

" Look at how many big name audio and vidoe components come from the factory with absolutely no ground."

And they are designed that way from the factory with a floating ground. See if their chassis are connected to ground in that equipment or not. Is it a metal chassis or not? The equipment that comes with a ground lug was designed to have the ground operation from the factory. Check if its chassis is grounded in that situation.

And I am refering to new current UL certified equipment. Not 35 year old equipment that was built before safety measures like this were put into place.

"This is taking for granted that your house is grounded properly."

If your house is properly grounded there is little need for any sorts of quawkery like this. Keeping all equipment on the same circuit or at least the same phase will do a lot to reduce ground loops. If the system still has ground loops noise isolate where the loop is coming from and deal with it. It is the proper way to fix it.

Shawn

[sfogg]

"Nope!

The shield is used for RF 'shielding! Both ends of the shield do NOT have to be connected!"

I understand that.

What I was pointing out was that on connections like this there are THREE connections in them.

One is the signal hot, one is ground, the other is the shield. The shield is only connected on one end to drain RF noise away.

However if you take a multi-meter to these connections you will find that the ground (the lug on the RCA) is most definitly still connected on both ends.

Therefor there is still a ground connection through the plug. Therefor it does *nothing* to eliminate ground loops.

Don't believe me... go get one of your store bought 'directional' cables and test it with a multi-meter.

If you try using a cable with no ground connection between it on a connection that doesn't have a ground loop problem you are going to be *CREATING* a huge one.

Ever unplugged a RCA cable 'hot.' Notice how it buzzed incredibly loudly while it was coming out and was the last connection between the two pieces of gear? That is because the ground connection 'breaks' first and just the hot is connected. Instant ground loop... lots of nasty buzzing.

Shawn

[NOSValves]

"When using normal inter-connects (not modified like suggested above) your entire audio system is grounded as long as one component has a 3 wire. Simply lift all other components from ground leaving this single piece grounded and all your hum issues should be resolved." That is not good advice. What happens when one component has an internal failure? Instead of grounding out the plug that is built for current and blowing a fuse or a breaker the current is going to try to pass through the only ground it has available... the interconnect. Interconnect grounds are not built to carry any appreciable amount of current in them, it will burn up very quickly. Maybe starting a fire, maybe not. If the ground connection on the interconnect breaks before you you pop a circuit breaker (very likely) you now have one piece of equipment with 120v AC *LIVE* on its chassis. Touch that and touch something grounded and your days of modding amps could come to an abrupt end. " Look at how many big name audio and vidoe components come from the factory with absolutely no ground." And they are designed that way from the factory with a floating ground. See if their chassis are connected to ground in that equipment or not. Is it a metal chassis or not? The equipment that comes with a ground lug was designed to have the ground operation from the factory. Check if its chassis is grounded in that situation. And I am refering to new current UL certified equipment. Not 35 year old equipment that was built before safety measures like this were put into place. "This is taking for granted that your house is grounded properly." If your house is properly grounded there is little need for any sorts of quawkery like this. Keeping all equipment on the same circuit or at least the same phase will do a lot to reduce ground loops. If the system still has ground loops noise isolate where the loop is coming from and deal with it. It is the proper way to fix it. Shawn

Shawn,

I see its time for your meds again. I bet you read all this in a book !! By the time the inter-connect melts down the entire piece of gear would be junk. EVER HEAR OF A FUSE ??????

Maybe maybe maybe.

Alarmist bull........ I think you should go to work a Sony, Philips, Curtis Mathis Ect I bet you could start a trend and get them all to install grounded 3 wire cords. I mean there is a small amount a safety in grounded components but your making it out to be WAY more then it really is.

Craig

[dragonfyr]

"Nope! The shield is used for RF 'shielding! Both ends of the shield do NOT have to be connected!" I understand that. What I was pointing out was that on connections like this there are THREE connections in them. One is the signal hot, one is ground, the other is the shield. The shield is only connected on one end to drain RF noise away. ...Shawn

I don't need to buy premade interconnects to test them. I make my own with Mogami Neglex 2534.

I misunderstood your meaning to say that the shield was required for 'music to play'. So we were essentially saying the same thing in slightly different ways as I was simply trying to say it as simply as possible to help the gentleman who was not necessarily intimate with all the vagaries of interconnects...And I doubt he cares about the theory behind the various positions[]

[NOSValves]

Just checked my complete home theater, TV the works every component is indeed grounded chassis to chassis. How ......... through the interconnects. Ground any one component with a 3 wire and there all grounded to earth ground. By the way not a single one of these compoents comes originally with a 3 wire and almost everyone has a UL listing.

Craig

[Speedball]

My house was built in the 50's and there is not a grounded receptacle in sight. Guess Rotel would not want me to use one of their amps.

[robster]

The Panamax 5100 line conditioner,reduced my ground loop hum to almost zero.A used on on A-Gon for $175 seller said he would take $150. wwww.2baudio.com has them for $230. I have to stick my fat shubee head into the speaker to even hear it now. The cheater plugs helped before I got the Panamax,also for me plugging my preamp into a different power strip than the amps helped. When I had my second system in the den with TV/dvd etc. The TV cable gave me a gawd awful ground loop problem! when I had a amp/preamp combo I sold it and now I just have one main system. So some TV cables can be real bad for ground loop problems,my Time Warner TV cable shares the same ground at the house meter. Tech folks at Klipsch can give you great easy to understand info about ground loop hum and ways to fix it. When I used cheater plugs I was getting a louder slight pop in my speakers when I power up than when I wasn't using cheater plugs,which kind of scared me. Right now my rooftop antenna ground is fighting with my TV coax ground and that is probably where I ground loop hum is from.

Cheers,

Robert

[dragonfyr]

...regarding your issues with the antenna, cable, etc. ground loop problems. Make cable come out and be sure that the systems are "common bonded" per code at the entrance point of the cold water pipe, and ground your antenna there as well. This will resolve the difference in potential between the 3 systems.

[robster]

Tech folks at Klipsch were extremely helpful !!!!!to me when I had ground loop problems from HE_L when I was using a Cayin TA-30 and TAD 150 preamp together with TV/DVD. I definitely was getting ground loop hum from the Time Warner TV cable which is also our Road Runner computer cable. I almost bought a magic box from Klipsch,but those were on backorder for EVER! So I used 2-channel master antenna baluns connected back to back connected to the TV cable and one cheater plug on the preamp only,the amp I didn't use a cheater plug so the amp and preamp shared ground through the IC's . I still had a very slight ground loop hum.

IT DROVE ME CRAZY<I read every ground loop hum post on Audio Asylum,AudioKaharma and the KLipsch forum,when I called the KLipsch tech's it could have saved me hours of reading. I still haven't fully recovered from the nightmares of ground loop hum.

Just my 2-cents.