DC Blocker

[spkrdctr]

BDH, I think the power company might fix your [problem since you have PS Audio monitoring your line. That gives them data (proof) that you do have a problem. But,finding that pesky motor is the main issue. It might just be as simple as changing out the motor for a new one which should not do that to your power lines. I worked with 440 volt AC power supplies for 300 volt motors (DC) and the excess power from when the motor became a generator was fed back into the AC lines. It did not affect the AC lines in our building at all and our units slammed the lines with excess power quite often. It was all designed and made to take it with no problems. So, I think something is not right causing that spike and when you can figure it out, it will be a fairly easy fix. Good Luck. I hope Duke takes care of you as I have Duke here in Florida too.

 

[Brad225]

It is possible that it is what all of your neighbors homes put back into the power lines.

 

[BDH55]

BDH, I think the power company might fix your [problem since you have PS Audio monitoring your line. That gives them data (proof) that you do have a problem. But,finding that pesky motor is the main issue. It might just be as simple as changing out the motor for a new one which should not do that to your power lines. I worked with 440 volt AC power supplies for 300 volt motors (DC) and the excess power from when the motor became a generator was fed back into the AC lines. It did not affect the AC lines in our building at all and our units slammed the lines with excess power quite often. It was all designed and made to take it with no problems. So, I think something is not right causing that spike and when you can figure it out, it will be a fairly easy fix. Good Luck. I hope Duke takes care of you as I have Duke here in Florida too.

PS Audio support made it clear that these things are usually very difficult to run down because while it could be in our house, it just as easily could be in a neighbors house. Also, while they said that it could be a motor, they also said it could be a simple as a bad dimmer. I suppose I could go around swapping out our dimmers, I don't really want to be swapping out motors... especially if it turns out to be from something down the street.

Does anyone know what these DC spikes do to electronics over time? If Duke Energy either doesn't help, OR they can't find/fix the issue, I guess I can put a DC blocker on the feed to my P20 (the only piece of equipment that seems to be having a problem with these spikes, at least that I am 'aware of'). But what about all the other electronics in the house... do I need to put DC blockers on my mono blocks, my rear subs, and my projector (the only devices not served by my P20 in the main system)... or how about the upstairs system, or even our Macs? Also, since my limited data shows the spikes hitting (mostly) in the middle of the night when our systems are off, should I even care about these spikes (other than messing with my P20 that is)? If I make the move to tube equipment in the future, would tubes be more (or less susceptible to these spikes)?

All I really want to do is bring the best music possible to our home and I am starting to feel like I need to go back and get an engineering degree!

 

[Robert D]

Is it possible to have a DC blocker for the entire home, running on the main breaker box?

 

[Brad225]

Is it possible to have a DC blocker for the entire home, running on the main breaker box?

I would guess it is possible but it will be expensive. That is a lot of big costly capacitors.

The main thing with audio/video and DC is it is a problem for transformers. I'm not sure everything else in you home would benefit from it. I will ask my EE friend and see what he says.

 

[Stefan_DR3]

That’s right. Toroidal transformers don’t like DC and will vibrate at 60 Hz making an audible buzzing noise. They can also get magnetized long term reducing efficiency. Most tube amps use EI core transformers which are more tolerant of DC. Note that DC offset is not hard to find, and you can certainly get the power company or an electrician to fix.

But your problem of a spike in the night is not the same thing. It could be someone throwing a switch in a substation to manage load on the grid or whatever maintenance they do.

 

[spkrdctr]

Well,if you can power down your audio equipment at night, then your problem is solved. The cost is free. It probably will not hurt anything else as you stated almost everything is turned off at night.

 

[BDH55]

Is it possible to have a DC blocker for the entire home, running on the main breaker box?

Something like this would be my preferred approach but since PS Audio said that it could be coming from inside our home, my 'guess' (and that's all it is) would be a whole house approach might miss a spike that is generated inside our house. I hadn't even thought about what Brad225 said about it being expensive. It will be interesting to see what his EE friend says.

Well,if you can power down your audio equipment at night, then your problem is solved. The cost is free. It probably will not hurt anything else as you stated almost everything is turned off at night.

Unfortunately, I'm working with a limited data set right now. I haven't got any info from PS Audio for the past several nights. Also, while the bulk of the occurrences have been around 2 AM, they did report one at 8 PM which would be prime listening/watching time, so I really would prefer to fix the problem if possible.

 

[Tosh]

In our house, our printer turning on made my amp's transformer growl, so I made one of Rod Elliot's DC blockers. But that was just to stop an annoying noise, not related to any chance of damage. I attempted to check the peak "DC" voltage at the DC blocker a few times, and it was never more than 2V, but that was with a normal DVM.

Good chance of a new-fangled fridge being the source of DC, as they have all sorts of things going on in there.
How much DC offset is there?

 

[BDH55]

How much DC offset is there?

I have no idea. I do have a multimeter but would need someone to coach me to figure out DC offset. The other challenge is as far as I can tell (from my P20 locking up), this is also a rare problem...

 

[Brad225]

This is the schematic of the 10 amp DC blocker my friend built for my front end equipment.
Hopefully it means something to you all but it really doesn't to me.

 

[Rob83]

Maybe I’m just thinking to simple but wouldn’t a simple mains isolation transformer archive the same as well as eliminating any potential ground loops and other interference?

 

[spkrdctr]

It has been many years since I looked at this stuff, but it looks like he built a decent DC blocker with some high frequency/hash noise blocking too. But, I'm not sure. But it seems that it should work.

 

[Brad225]

spkrdctr,
I think he called them snubbers and it eliminates a high frequency dip that causes the distortion.

On a different subject he took my network switch and piggybacked glass capacitors on them to eliminate oscillation that happens with a gigabyte signal. It definitely made the sound a bit quieter at the speakers. Was it night and day, no but it was noticeable.

 

[jacek-k-wawa]

When I read this tread I am getting more and more concerned. And there are 3 main areas of my concerns:

1. all this deal with potential lethal voltages so whatever you do it is good to have at least understanding of how it works and what you do.
2. DC blocker - as name suggest - may help to eliminate DC from your mains. And this is nothing to do with spikes and other noises some of you suggest that DC blocker with help with. If there is a effect of attenuating such by your DC blocker it is not intentional and there are much more better devices to deal with (RF filters etc).
3. Using this circuit to measure DC in mains by DMM is not only dangerous but also does not makes any sense. Maximum voltage across in/out for this circuit will never be higher than few volts (forward voltage of 1 or 2 pairs of diodes) and does not indicate what is DC offset in your mains.

So be careful of what you do as this is dangerous and do not expect this circuit to do what is not intended to do.

 

[Brad225]

I would not suggest anyone that doesn't know exactly what they are doing attempt something like this. Agreed, electricity can be extremely dangerous.

If my friend was not an experienced knowledgeable EE I would not be putting these in my home.

They do work amazingly well though, I have no idea how.

 

[Stefan_DR3]

I mentioned that before DC offset is a very specific problem. Here’s a fun video from Paul @ PS Audio

 

[BDH55]

This is the schematic of the 10 amp DC blocker my friend built for my front end equipment.
Hopefully it means something to you all but it really doesn't to me.

Brad, thx for the schematic. Not anything that I would tackle though. However, like you, I've got a good EE friend I could rely on assuming Duke Energy doesn't step up to the plate...

BTW, gorgeous listening room and very impressive setup! Turns out that I will soon be joining you in the ARC camp...

I mentioned that before DC offset is a very specific problem. Here’s a fun video from Paul @ PS Audio

I watched Paul's video and it was helpful. For one thing, Paul states that they have a 'DC blocker' built into their Regenerators. That's interesting as the only equipment that is showing any adverse effect from these 'DC spikes' (as PS Audio tech support call them), is my PS Audio Power Plant 20 Regenerator. Also, PS Audio was who recommended that I might want to look at a DC blocker, and pointed me down that road, which now seems a little odd...

 

[spkrdctr]

I believe the video. You should as he stated, be getting a clean A/C wave out of the P20. Is the DC so high that it is messing up the internal working of the P20? It seems you need to talk to one of the engineers and find out what is happening. The P20 should be blocking all the DC so that you have a clean signal. Now, why is the P20 locking up? That seems to be a whole different question. I'm very tempted to say that it needs to be bench tested with a fairly high DC input to see if any of the circuit components are breaking down. Then it becomes a simple repair. As usual though, and you guys have heard it from me before, an intermittent problem is extremely hard to fix. I'm just saying that according to Paul's whiteboard design it "seems" that the DC should be easily blocked and therefor not cause any problems, but I'm not an engineer or designer of the P20.
So, I'm just thinking out loud............

 

[Stefan_DR3]

PS Audio called them DC spikes? I think we may be confusing current with voltage here. DC offset is actually a constant voltage as discussed in the video. Perhaps they mean literally Direct Current which is current that a component in your system may be drawing unexpectedly. Does the P20 log current waveforms?

Either way the power plant shouldn’t be locking up. I assume “lock up” means the control software is crashing and the P20 power has to be cycled to recover? It sounds like PS Audio have got a software bug and your sudden current draw is just triggering it. It could be a waveform they have never seen before.