If there is enough interest... but it would end up in another forum as a DIY project. Or email me and I'll give you a schematic. I had said I would do a piece for Linear Audio magazine but as time goes by, I just dont have the energy to do it (or interest). It was to include such things as I showed regarding how we (in USA) created ground loops and made equipment vulnerable to lightning.
THx-RNMarsh
If grounding is bad and with high impedance, no one filters or power conditioners could solve noise. Any kind of noise. This is simple energy problem, this energy need to be traced to ground or in heat, which is almost impossible in wide frequency spectrum.
So, all kind of spikes, leaking current, etc, need to be simply traced to ground(not only to some ground line). But if ground line have high impedance, possibility of ground loops,then, everything is problem, even the capacitance between power transistors and heatsink.
So, all kind of spikes, leaking current, etc, need to be simply traced to ground(not only to some ground line). But if ground line have high impedance, possibility of ground loops,then, everything is problem, even the capacitance between power transistors and heatsink.
Careful, that logic leads to a "universal magic ground" where all energy goes to die. Its doesn't really work that way. A good ground bond (really a flat 1" copper braid) will help with lightning strikes and will help your long wave antenna pickup VLF broadcasts from Australia but it won't help reduce powerline noise.The impedance of the conductor pairs at high frequencies is high enough that grounding 50' (15M) away will have little effect. Even surges get shared on the conductors through induction between them. Same with noise- it gets "shared" such that there is noise between any pair of conductors. A L-N and a N-G cap will work, BUT if the wall is not wired right you may be pulling a chassis to the same potential as the line. My beef with the standard caps between G and L/N is that an ungrounded chassis is now at 1/2 line potential. If it gets grounded through another chassis then that current is shared on an audio return. If the total R/Z on the audio return is 1 Ohm and your are dumping 1 mA you get 1mV of hum with your 100 mV of audio or 40 dB SNR. Usually its much better but not always.
The medical grade filters are low leakage current for safety reasons. With really good connections to human bodies for medical sensors leakage could have a serious consequence, not to mention reduction of SNR. They also are better suited to audio.
Power distribution is similar but NOT the same around the world. Some markets have a centertapped source and two lines with equal potential. The centertap may be grounded but in some places its not grounded. Some markets do not have the centertap and only a single line and ground/neutral. Power can be as low as 95 Volts or as high as 250V+. There are few universal solutions. Currently I'm working with 3 very different surge/filter circuits to meet the different market safety/performance requirements.
Switching supplies that work across this range are available but over about 100W get expensive compared to ones with voltage switches (These are details you learn making volume products). Transformer/rectifier supplies won't meet the power factor requirements in some markets and going forward most markets.
The medical grade filters are low leakage current for safety reasons. With really good connections to human bodies for medical sensors leakage could have a serious consequence, not to mention reduction of SNR. They also are better suited to audio.
Power distribution is similar but NOT the same around the world. Some markets have a centertapped source and two lines with equal potential. The centertap may be grounded but in some places its not grounded. Some markets do not have the centertap and only a single line and ground/neutral. Power can be as low as 95 Volts or as high as 250V+. There are few universal solutions. Currently I'm working with 3 very different surge/filter circuits to meet the different market safety/performance requirements.
Switching supplies that work across this range are available but over about 100W get expensive compared to ones with voltage switches (These are details you learn making volume products). Transformer/rectifier supplies won't meet the power factor requirements in some markets and going forward most markets.
Thanks for that Demian.
Years ago, an AES workshop on grounding and noise featured Ralph Morrison. He told some amusing stories of misled people and their attempts to make bad signals go away. One in particular involved a General who had them run a very long conductor and bury it in the physical earth, in hopes that it would be something into which they could dump all their unwanted and potentially security-sensitive currents.
Medical grade filters have their own pupurpose. Because of grounding patient, for therapy or measurements...
We can also look at NMR rooms, for purity of noise. But it is expensive overkill.
We are searcing for solution. Maybe real
And yes, earth is earth, power distributions are different, but grounding is matter of ground rods and grounding lines.
We can also look at NMR rooms, for purity of noise. But it is expensive overkill.
We are searcing for solution. Maybe real
And yes, earth is earth, power distributions are different, but grounding is matter of ground rods and grounding lines.
Last edited:
A rod stuck in the dirt has no relevance to a properly grounded audio system. Audiophiles who go adding ground rods to connect their gear to simply have know clue about what they're doing.
se
It's hopeless.
Friend of mine years ago insisted that a dedicated ground rod is the ideal solution. I told him that it wasn't.
He said I didn't know what I was talking about and suggested I talk to someone who did, like Henry Ott. So I got in touch with Henry and he agreed with me, saying that if anything, it could make things worse.
When I told my friend this, he threw Ott under the bus and said Ott didn't know what he was talking about, and suggested I talk to someone who REALLY knew this stuff and suggested Ralph Morrison. So I got in touch with Ralph. He agreed it's me as well. He threw Morrison under the bus and suggested a third guy whose name escapes me at the moment. So I got in touch with him and got the same answer that I got from Ott and Morrison.
My friend literally went to his grave believing that he was right and that myself and these three other guys who HE told me to talk to to get the straight dope were wrong.
Some people will get something into their head and there's simply no disabusing them of it no matter how erroneous it is.
Sad.
se
If it is low impedance rod, audiofile got the point in the middle of the dirt.
I can imagine him listening "Horse with no name"..
Measuring, measuring,,,and then listening.
Sent you a PM.
They don't allow email anymore via the forum these days.
Many thanks in advance,
Patrick
It's fun to watch them pounding copper into the ground though. We should advise that a good radial ground setup is best, so you have to dig up the lawn...
You are thinking too small. Tell them they need to flatten the house, dig a pit an then put a large mesh down there to give the house a 'ground plane', then rebuild on top.
The first source of AC power parasitic leakage in standard gear is EI transformer capacitive leakage to frame which is usually solidly (and electrically) mechanically mounted to chassis.
Indeed there is discussion regarding importance/effects of EI transformer primary winding connection polarity to minimise capacitive leakage to chassis.
So, as I see it EI transformer should be insulation mounted and the frame connected to AC supply neutral to keep transformer primary winding to frame capacitive leakage currents out of PE/system ground.
Toroidal power transformers are a different case.
In my present PB system, the active speakers are individually powered via 300VA 240V toroidal screened isolation transformers.
I have the screens connected to PE, but on second thoughts it might be better that they are connected to N....I have not tried the experiment but should.
The speakers are balanced line input, and the rest of the system is an Edirol balanced output USB DAC powered from a USB isolator/power injector board which is powered by a 12 car battery, music is USB fed from a netbook to the isolator board.
So in the case of my balanced line system, PE currents are of no real consequence, but in typical unbalanced systems any change in individual device N and/or PE currents and the ratios of those currents might manifest as an audible change.
Change in ratio of device N/PE currents and system N/PE currents would be justification for subjective changes in audio according to 'special' AC and audio interconnect cables....justification of prices of such 'special' cables is another subject and irrelevant in this discussion.
Dan.
Indeed there is discussion regarding importance/effects of EI transformer primary winding connection polarity to minimise capacitive leakage to chassis.
So, as I see it EI transformer should be insulation mounted and the frame connected to AC supply neutral to keep transformer primary winding to frame capacitive leakage currents out of PE/system ground.
Toroidal power transformers are a different case.
In my present PB system, the active speakers are individually powered via 300VA 240V toroidal screened isolation transformers.
I have the screens connected to PE, but on second thoughts it might be better that they are connected to N....I have not tried the experiment but should.
The speakers are balanced line input, and the rest of the system is an Edirol balanced output USB DAC powered from a USB isolator/power injector board which is powered by a 12 car battery, music is USB fed from a netbook to the isolator board.
So in the case of my balanced line system, PE currents are of no real consequence, but in typical unbalanced systems any change in individual device N and/or PE currents and the ratios of those currents might manifest as an audible change.
Change in ratio of device N/PE currents and system N/PE currents would be justification for subjective changes in audio according to 'special' AC and audio interconnect cables....justification of prices of such 'special' cables is another subject and irrelevant in this discussion.
Dan.
Hmmm, in my system, the speakers each have PE connection, but the source DAC is totally floating........except for the speaker bal line input stages which will provide to the DAC a relatively high impedance PE connection via the balanced signal wires.
So I should disconnect the screen at the DAC XLRs, or at the speakers XLRs do you reckon ?.
Second thoughts, the DAC outputs need some conductance to DAC local ground to ensure CM range of the speaker inputs is kept within limits....I will check.
This system is dead quiet and dead clean (and fun) as it is, but chasing improvements this easily is a no brainer, thanks.
Dan.
- Status
- Not open for further replies.