Are ground loops only possible when components have mains ground?

[polmuaddib]

When I look vintage amps, preamps etc. they almost always have non detachable cable which only has two wires. No ground. And they have RCA inputs and outputs.
And there weren't many cases of ground loops back then, right? Things were simpler up until the nineties, i think.
Is it the introduction of the PC to audio chain with their switching PS that made a mess and introduced various ground loop issues?

Since my system is very susceptible to ground loops, I am slowly replacing everything that has RCA with XLR components (whether they are differential topology or just cmmr transformer based).
But I might go the other way, I am thinking.... Finding components that are single ended, but are without mains ground. I know it is not safe to just lift the ground when there is no double insulation sign.
Is it so hard to engineer an amp or preamp or whatnot with double insulation symbol and without the need to ground it? Are there any advantages of components that need to be grounded?
Sorry if i made some mistakes with terminology. Hope you get my point.
Thanks

 

[somebodyelse]

There's fairly comprehensive coverage of the issue at Jensen Transformers - AN007 has most of it in one place. You'll see that 'ground loop' is a slightly misleading shorthand for a fundamental problem with single ended interconnects whereby stray current that isn't meant to be part of the signal gets mixed into it, and that it can occur even with double insulated equipment via mechanisms such as capacitive coupling in transformer windings. The nature of common presentation has changed over the years from harmonics of mains frequencies giving hum or buzz to include odd modulation of noise from things like changes in computing load. The long standing solution is a properly implemented balanced interconnect, as widely used in the pro audio market where having things 'just work' trumps the small cost saving of using single ended. HiFi remains stuck with single ended for some mixture of cost, usually being good enough, and de facto standard.

 

[Speedskater]

There's fairly comprehensive coverage of the issue at Jensen Transformers - AN007 has most of it in one place.

Yes, Bill Whitlock now retired from Jensen Transformers is the go-to expert on all things about interconnects.

 

[polmuaddib]

Thanks. Then it is settled. Slowly replace all single ended equipment with balanced.

 

[mononoaware]

I also would like to share that I have been always using "Balanced (XLR)" connections, and recently ran into "noise" issues (ground loop/power supply noise) for the first time by using RCA connections.

So one could assume that Balanced connections (XLR etc) are the superior connection method (the future) and RCA is simply old technology.

 

[Speedskater]

Thanks. Then it is settled. Slowly replace all single ended equipment with balanced.

Actually in the distant past much XLR balanced pro audio equipment was susceptible to ground loops. In 1994/95 Neil Muncy (RIP) wrote a paper about 'The XLR Pin 1 Problem'. But it took a decade for the Audio Engineering Society to issue standard AES48 about the problem. Only then did all the pro equipment manufactures get onboard. There is still audiophile XLR equipment being manufactured with the problem.

 

[escksu]

When I look vintage amps, preamps etc. they almost always have non detachable cable which only has two wires. No ground. And they have RCA inputs and outputs.
And there weren't many cases of ground loops back then, right? Things were simpler up until the nineties, i think.
Is it the introduction of the PC to audio chain with their switching PS that made a mess and introduced various ground loop issues?

Since my system is very susceptible to ground loops, I am slowly replacing everything that has RCA with XLR components (whether they are differential topology or just cmmr transformer based).
But I might go the other way, I am thinking.... Finding components that are single ended, but are without mains ground. I know it is not safe to just lift the ground when there is no double insulation sign.
Is it so hard to engineer an amp or preamp or whatnot with double insulation symbol and without the need to ground it? Are there any advantages of components that need to be grounded?
Sorry if i made some mistakes with terminology. Hope you get my point.
Thanks

AFAIK, the purpose of grounding is mainly for safety reason. IT provides a path for the current to flow in even of surge/short circuit. IMHO, its not a good trade-off to remove grounding.

You can google around for ways to prevent ground loops. There are also commercial and DIY solutions.

 

[polmuaddib]

AFAIK, the purpose of grounding is mainly for safety reason. IT provides a path for the current to flow in even of surge/short circuit. IMHO, its not a good trade-off to remove grounding.

You can google around for ways to prevent ground loops. There are also commercial and DIY solutions.

I know it is not safe to remove grounding. I was talking about devices that have double insulation symbol (class II devices) which don't require grunding. They have non removable cable that only has live and neutral wire. No ground.
My question was whether those, class II, devices are less susceptible to ground loops even though they have mostly single end connections.
I got the answer that they are not imune to GL.

 

[Audiofire]

I know it is not safe to remove grounding. I was talking about devices that have double insulation symbol (class II devices) which don't require grunding. They have non removable cable that only has live and neutral wire. No ground.

The funny thing is that old vintage equipment was not made for a ground connection, so hum can be introduced if one adds a grounded power cable. Leaving the ground wire floating (non-connected) is a solution in that case.

The neutral wire is connected to the ground wire at the circuit breaker from what I understand. The problem is more something like "capacitive coupling" that was mentioned above.

Using a surge protector is a way to prevent a short circuit, which could be a capacitor inside the device that has stopped working due to voltage spikes and ripple current over time. That is important on vintage equipment, which was not designed for safety ground and can even have an outdated capacitor called a death cap that can short circuit the live and neutral wire (that can make the whole chassis charged with high voltage from the live wire!).