DC blocker tryout

[solderdude]

I have concluded from input from others, it is not a safe idea.. Would independent grounding the stereo units chassis ground lugs only would have the same effect?

I will try to make it simple.

Ground-lift = a switch inside a device that connects/disconnects audio ground (also known as common) from/to the chassis. That chassis remains connected to safety ground (class-I devices) but the internal audio ground (common) thus may either be 'floating' or connected to the chassis. That floating audio ground then could well still be connected to safety ground via a connected device but at least there is no ground loop.
Ground-lift thus is NOT disconnecting the safety ground.

The chassis is a often a metal enclosure. It is often connected to audio ground (also known as common) this is done for screening (hum) reasons.
Whether or not that chassis is connected to a safety ground lug (3-pin mains plug/socket) depends on the power supply, filtering and whether or not the device is class-1 (3-pin and must be connected to safety ground or class-2 a.k.a. double insulated (2-pin, the usual figure-8 or IEC socket without the ground pin) in which case safety grounding is not needed.
The same is true for class-III devices which have an external low voltage power supply (up to 48VDC)

All other 'trickery' with safety ground is not safe... including using capacitors and diodes.

 

[Pluto]

View attachment 398716

"It's the volts that jolts, but the mils that kills"

 

[DWPress]

Looking at the table provided by DonH reminds me of a friends dad when I was a kid. He had his own bar in the basement that was wood surface but had hundreds of nail heads flush with the surface and wired to a car battery. He'd keep the bar top nice and wet and delighted in sliding a glass down to a willing recipient at which time he'd hit a momentary switch and give a shock to whoever grabbed the glass. Must have been around the 70mA zone because sometimes you'd be painfully stuck to the glass unable to let go. Funny, scary in retrospect...

To my knowledge nobody ever got seriously hurt aside from one occasion a visitor decided to reply to the prank with a fist.

 

[randym]

I respectfully thank everybody for your input, wisdom and experience. Nice to know that there's seasoned audiophiles on board here.

 

[restorer-john]

Brought to mind this video

I imagine that guy goes home, pours a drink, sits down to listen to his Hi-Fi, relaxes into his recliner and there's hum in his system. Argh!!

 

[Old_School_Brad]

Don't you have RCD's in the states? It's common in EU to have TT systems. Impedance should be low. RCD will detect stray current and trip.

 

[restorer-john]

RCD will detect stray current and trip.

RCD/Core Balance Relays/ELCBs are great, but not foolproof. They don't detect stray current at all. They trip when there is a difference between supply and return currents with the assumption being made the difference is going through something/somebody. I'm sure they've saved plenty of lives, but they've also been responsible for a whole lot of perfectly good electrical appliances being thrown out too.

An RCD won't save you if you drop a hairdryer in the bathtub while you're in it, especially with bathtubs being plastic/fibreglass/stone and the pipes being poly these days. It won't save you if you touch active and neutral and are wearing shoes or standing on carpet. An RCD wont save you if you put your fingers into a live lamp fitting, unless you are in bare feet and standing on the grass, wet cement or something close enough to ground. Basically, they save idiots, not sensible people.

And they nuisance trip a lot. Have several heating element appliances in your house all on at once and you can easily trip an RCD even though there's nothing wrong with any of the devices.

 

[voodooless]

Most RCDs do not trip reliably on DC currents anyway. You'll need a type-B (at least that's what it's called in Europe) RCD, to have it detect stray DC currents. These devices are significantly more expensive (2x to 4x) and are rarely used. Where I live, either you have a Type-B RCD in front of your Solar inverter, or the Solar inverter needs to be certified to be able to run without one (so, essentially be able to detect DC issues by itself and act accordingly).

 

[Old_School_Brad]

RCD/Core Balance Relays/ELCBs are great, but not foolproof. They don't detect stray current at all. They trip when there is a difference between supply and return currents with the assumption being made the difference is going through something/somebody. I'm sure they've saved plenty of lives, but they've also been responsible for a whole lot of perfectly good electrical appliances being thrown out too.

An RCD won't save you if you drop a hairdryer in the bathtub while you're in it, especially with bathtubs being plastic/fibreglass/stone and the pipes being poly these days. It won't save you if you touch active and neutral and are wearing shoes or standing on carpet. An RCD wont save you if you put your fingers into a live lamp fitting, unless you are in bare feet and standing on the grass, wet cement or something close enough to ground. Basically, they save idiots, not sensible people.

And they nuisance trip a lot. Have several heating element appliances in your house all on at once and you can easily trip an RCD even though there's nothing wrong with any of the devices.

By "stray current", I mean any current that isn’t flowing from live to neutral and must be going somewhere else - typically to ground. Unless you're accidentally making yourself part of the circuit between live and neutral, your body provides a path to ground for current that should have gone through the panel, the RCD will trip, and it's quite effective at doing so.

Of course, there are exceptions, like the scenario of a non-conductive bathtub and pipes and the classic hairdryer drop situation.

 

[Speedskater]

Power line noise & leakage currents have little interest in Planet Earth. They want to get back to their source. Which is the main breaker panel Neutral and then to that big power company transformer down the street.

Currents will take all available paths back to their source, inversely proportionally to each path's impedance, so a small amout of current may flow thru Planet Earth. But Planet Earth is never the destination.

Note that a path's impedance may be different at power line frequencies, than at noise & interference frequencies.

 

[ppataki]

I finally got my DC filter last week

I hooked it up with my isolation transformer and so far I have not heard any buzz from it
So it seems that it does what it is supposed to do
Needless to say, audio-wise there is no change whatsoever (I did not expect that anyway)