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DC blocker tryout

ppataki

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I have a 1500VA toroidal isolation transformer - my whole audio-video system is connected to it.
Pretty often I hear a quite loud buzz coming from the isolation transformer which might be caused by some DC component that is fed from my solar panels' inverter unit.
After discussing with my brother-in-law who is a trained electrician I have decided to try a DC blocker - mainly just for fun to see/hear if it would do anything with the buzz from the isolation transformer

I have ordered this unit - once it arrives I will share my experience here

I am not expecting any audible changes at all - but I would be happy already if the buzz was gone (yeah I know I could just remove the isolation transformer.... :D)
 
It is possible the noise is because the inverter is not producing a 0-average voltage output (which appears as a DC offset), but it cold also be noise bleeding through and/or saturating the transformer. It would be interesting to see the noise spectrum of the AC feeding the isolation transformer. You may need noise filtering beyond (in addition to, or instead of), the DC blocking circuit.
 
The typical problem with some US solar panels is RFI.
Yah, that is my thought, though there are some inverters that produce average output offsets as well. A DC blocker is easy enough to try; RFI filtering is also easy but may be harder to find a powerline filter that really works, and may not solve the problem if it is coupled over the air.
 
So the solar inverters are not producing a decent, low distortion, low noise, symmetric sine wave and they are spewing RFI. That doesn't surprise me.

Looks like a real opportunity for PS Audio to produce a solar inverter that takes the DC from the array and feeds it into half of one of their power-plants. It could bypass the AC primary side altogether. I reckon Paul McG would be all over my idea. Coupled with battery storage and you've got an audiophile solar system.
 
So the solar inverters are not producing a decent, low distortion, low noise, symmetric sine wave and they are spewing RFI. That doesn't surprise me.
Yeah, I bet it doesn't!

Looks like a real opportunity for PS Audio to produce a solar inverter that takes the DC from the array and feeds it into half of one of their power-plants. It could bypass the AC primary side altogether. I reckon Paul McG would be all over my idea. Coupled with battery storage and you've got an audiophile solar system.
You've a streak of evil in you I greatly admire.
 
In the U.S., Emotiva sells a low cost CMX2. I took some measurements

 
Part of the solar panel problem is that some installers don't follow good engineering practices. People may not associate interference caused problems with near-by solar panels.
 
So the solar inverters are not producing a decent, low distortion, low noise, symmetric sine wave and they are spewing RFI. That doesn't surprise me.

Looks like a real opportunity for PS Audio to produce a solar inverter that takes the DC from the array and feeds it into half of one of their power-plants. It could bypass the AC primary side altogether. I reckon Paul McG would be all over my idea. Coupled with battery storage and you've got an audiophile solar system.
Am I the only one thinking they should rename to BS Audio?
 
There is one thing that surprises me in many discussions about purifying AC power that is never spoken of - that is a dedicated AC circuit for audio equipment that has no ground wire connection to the AC panel but a dedicated ground wire connected to earth ground via a water-main connection or a dedicated ground rod planted in the soil nearby the equipment - even better. I have an AC "conditioner" and a dedicated ground and AC power input and would prefer an isolation transformer if i could justify the cost of a decent unit. This relatively simple dedicated ground and AC power direct from the fuse in the panel eliminates noise from other devices on the same AC circuit and all ground noise from the household. I guess people are pointed to buy another gadget as there's no money to be made by electronic suppliers by what I have suggested. People may say that the house ground is satisfactory but I have seen that ground noise/disturbance is a loose goose until it actually gets to the house ground rod. Anybody think I am crazy in my thinking? Comments please..
 
There is one thing that surprises me in many discussions about purifying AC power that is never spoken of - that is a dedicated AC circuit for audio equipment that has no ground wire connection to the AC panel but a dedicated ground wire connected to earth ground via a water-main connection or a dedicated ground rod planted in the soil nearby the equipment - even better. I have an AC "conditioner" and a dedicated ground and AC power input and would prefer an isolation transformer if i could justify the cost of a decent unit. This relatively simple dedicated ground and AC power direct from the fuse in the panel eliminates noise from other devices on the same AC circuit and all ground noise from the household. I guess people are pointed to buy another gadget as there's no money to be made by electronic suppliers by what I have suggested. People may say that the house ground is satisfactory but I have seen that ground noise/disturbance is a loose goose until it actually gets to the house ground rod. Anybody think I am crazy in my thinking? Comments please..
An independent (isolated) safety ground is illegal (against code) here (CO) and most places. The safety ground must return to the service panel and ultimately incoming power lines to avoid voltage differences among line (wall) neutral and safety ground connections. An isolated ground can allow significant voltage difference between wall power neutral and the new ground connection, creating a safety hazard. It is also hard to create an independent ground that is better than that provided; you can find directions on the 'net, and it usually involves an array of ground rods with heavy bus bars tying them together.

The only time I have run a secondary ground was to provide a low-impedance path from a radio (HAM) tower to help prevent lightning incursion into the house in the event of a strike. The ground was just for the tower. The rods to meet code had to extend at least 18' into the ground IIRC.
 
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An independent (isolated) safety ground is illegal (against code) here (CO) and most places. The safety ground must return to the service panel and ultimately incoming power lines to avoid voltage differences among line (wall) neutral and safety ground connections. An isolated ground can allow significant voltage difference between wall power neutral and the new ground connection, creating a safety hazard. It is also hard to create and independent ground that is better than that provided; you can find directions on the 'net, and it usually involves an array of ground rods with heavy bus bars tying them together.

The only time I have run a secondary ground was to provide a low-impedance path from a radio (HAM) tower to help prevent lightning incursion into the house in the event of a strike. The ground was just for the tower.

You can imagine what would happen with a floating/lifted neutral in that situation @randym suggested.

There were a few people seriously injured several years back in government housing in our state due to a faulty/floating neutral and contact with copper water pipes.

There's two things I have extreme respect for: multiple earthed neutral systems and chainsaws.
 
An independent (isolated) safety ground is illegal (against code) here (CO) and most places. The safety ground must return to the service panel and ultimately incoming power lines to avoid voltage differences among line (wall) neutral and safety ground connections. An isolated ground can allow significant voltage difference between wall power neutral and the new ground connection, creating a safety hazard. It is also hard to create an independent ground that is better than that provided; you can find directions on the 'net, and it usually involves an array of ground rods with heavy bus bars tying them together.

The only time I have run a secondary ground was to provide a low-impedance path from a radio (HAM) tower to help prevent lightning incursion into the house in the event of a strike. The ground was just for the tower. The rods to meet code had to extend at least 18' into the ground IIRC.
You are absolutely correct and am aware of that fact. Thank you for pointing out that it is against code as I was unaware but it does make sense for safety. Your electrical panel will constantly have imbalances and diligent electricians try to balance loads as much as possible. Imbalances in current from one phase to the other is directed via the neutral bus in the panel to the ground bus with a heavy copper cable to the ground rod or watermain connection in some cases. - the ground rod being close to the panel in almost all cases. Imbalances via the neutral will always take the shortest path to ground. If the stereo equipment is located considerably further away as it would in most cases, the neutral to the stereo unit should not experience any of this current, and the small few amps required by the equipment ... ie; perhaps about 5 amps collectively,, this imbalance is negligible in so far as the panel is concerned. None the less, what you saying - that the neutral to your stereo unit might act as the house ground if there was a fault in the house grounding and could potentially start a fire or seriously damage your equipment is true and thus the code restriction. The chances are slim but I personally have seen something similar actually happen. Thank you for your input. I suspect the only way to alleviate this possibility is to put a small amperage inline fuse on the stereo circuit ground wire. Thankyou for your input.
 
I suspect the only way to alleviate this possibility is to put a small amperage inline fuse on the stereo circuit ground wire.
Safety ground (it isn't audio nor RF ground) should never have a fuse in it. when the fuse would break, when something goes wrong, metal parts on the device in question (when it is grounded) could have mains on it. Safety ground must always be connected.
 
You can imagine what would happen with a floating/lifted neutral in that situation @randym suggested.

There were a few people seriously injured several years back in government housing in our state due to a faulty/floating neutral and contact with copper water pipes.

There's two things I have extreme respect for: multiple earthed neutral systems and chainsaws.


Brought to mind this video, and the quote at the 2:26 mark:

 
Safety ground (it isn't audio nor RF ground) should never have a fuse in it. when the fuse would break, when something goes wrong, metal parts on the device in question (when it is grounded) could have mains on it. Safety ground must always be connected.
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?
 
@BDWoody "electricity, heights and women"

perfect
 
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?
It should make floating ground products synchronize their ground (since there is sometimes some residual inaudible AC mains noise that is measureable and eliminated when the ground lugs are connected).

Using something like a Panamax/Nice power center that has a ground lug on the UL listed surge protector is also a convenient strategy.
 
It should make floating ground products synchronize their ground (since there is sometimes some residual inaudible AC mains noise that is measureable and eliminated when the ground lugs are connected).

Using something like a Panamax/Nice power center that has a ground lug on the UL listed surge protector is also a convenient strategy.
Nice idea - thank you. That's probably the safest option. Last year I have a nightmarish problem with grounding on my boat, that after long investigation I realized I had a similar issue with "multiple grounding" where the AC and DC (negative) grounds are connected inside the boat as a safety for both lightning strikes and AC devices, but in doing so my boat became a convenient ground (closer than the panel ground) for the whole dock and huge electrolysis followed. I have now realized the complexity of this issue takes a brain surgeon IQ to truly understand how things can potentially happen to ground systems that is way beyond my level of understanding and to be left alone. Thus, I understand the comments about heights, chainsaws and loose women. Somethings that you just don't mess with. Thanks for the wise and funny comments - cheers
 
You are absolutely correct and am aware of that fact. Thank you for pointing out that it is against code as I was unaware but it does make sense for safety.
You are welcome. I have lost friends and neighbors through bad safety grounds so am somewhat sensitive to it being corrupted.

Your electrical panel will constantly have imbalances and diligent electricians try to balance loads as much as possible. Imbalances in current from one phase to the other is directed via the neutral bus in the panel to the ground bus with a heavy copper cable to the ground rod or watermain connection in some cases. - the ground rod being close to the panel in almost all cases. Imbalances via the neutral will always take the shortest path to ground.
Technically current will normally take the lowest impedance path, which is not always the shortest path. It depends upon wire size and such, and for ground rods depends upon how conductive the soil and path to the power-line (service) ground. It can get tricky. Water pipe connections always used to be a "go to" solution but that is by no means guaranteed, and often enough these days there is plastic piping so even that does not work.

If the stereo equipment is located considerably further away as it would in most cases, the neutral to the stereo unit should not experience any of this current, and the small few amps required by the equipment ... ie; perhaps about 5 amps collectively,, this imbalance is negligible in so far as the panel is concerned. None the less, what you saying - that the neutral to your stereo unit might act as the house ground if there was a fault in the house grounding and could potentially start a fire or seriously damage your equipment is true and thus the code restriction. The chances are slim but I personally have seen something similar actually happen. Thank you for your input.
The problem arises when something goes wrong and the neutral isolation fails so the stereo (or any other) component chassis can rise to full mains voltage. That's what the safety ground is there to prevent. Double-isolation should prevent that from ever happening, but plenty of us can attest to a failure that led to voltage where it should not be. While voltage is often discussed, as it is easily measured and can indicate a problem, current flow is generally what kills. Static shock happens with a few kV but at such low current that we are not usually harmed (unless we jump and bump into something). However, the current level that can cause pain or death is small, see the old table below (I think is still valid).

1728843712865.png


I suspect the only way to alleviate this possibility is to put a small amperage inline fuse on the stereo circuit ground wire.
Also illegal (against code), since the safety ground is the "last resort" to prevent shock, and should never be fused.

Ground loops can be insidious but are usually very solvable with some effort to locate and fix the cause. It was popular for a while to implement a "star ground" by bringing the safety ground to a big connector (something like a small battery post or a terminal strip with several screws or lugs for wires) and running a ground wire from every component chassis to that ground point. These days the loop is often from something like the cable line (which usually has a separate ground) or subwoofers (or other amplifiers) plugged into an outlet away from the main system. There are commercial ground isolators for the signal path or wall power to break such loops.

Thank you for your input.
NP. One other thing to note, since I have read now and then of audiophiles implementing isolated ground systems in the interest of reducing "noise", is that if the ground system fails and causes a fire, insurance will normally deny the claim if it was installed in a manner that violates local codes. It is usually up to the homeowner to have any such work inspected to ensure compliance, and get it in writing!
 
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