AC Filtration

[Pure_Brew]

Joe, that looks much better indeed. Could it be possible though that this ugly waveform could be induced in some other way? For example, if I touch the prob to my finger, I get a somewhat similar looking wave pattern, lower amplitude. Could the wall wort tranformer from radio shack do this? I do get that clean looking wave on the 1v output on the scope itself though still.

In any case I could send and email with some pics to the power company.

 

[Gepetto]

Hi Joe
Mine was also though a wall transformer so I think what you measured is an accurate representation of how ugly your line voltage is. What I cannot tell you is whether this is a result of the quality of power you are getting from the grid or from poor wiring inside the building you are in.

The power company may end up pointing at your landlord.

 

[Pure_Brew]

Well that's just it, will the problem get fixed? I feel doubtful. So I seek alternate options too. What kind of power product could I possibly use to deal with these issues?

 

[Gepetto]

Hi Joe
If you find that your landlord path is not productive and you are sure that it is the high frequency spike on the AC line that is producing the noise, we should be able to craft a line filter for your audio gear to at least subdue it.

What do you have for equipment that you would like to filter and approximate power levels of each?

 

[Pure_Brew]

Source components (cd player, TT, tapedeck) and preamp will probably be 20-30w each. I would think with a preamp and 2 sources running, for taping would be nearly 100w right there. (approximately 0.2-0.3 amps drawn as I see on the belkin power center)
The Jolida 50-60wpc Tube amp draws 1.3-1.5 amps. 180w
So if I'm calculating this properly, 280w.
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If I use different amplification...

With the pioneer SX-1280, idle is right around 0.6amps = 72w
Power consumption is listed as 430w(UL) 1100w max

If I ever use the PS Audio again. That might be more of an issue. Manufacturer recommended at the time a dedicated 20a breaker for it. 200wpc 8ohms/400wpc 4ohm/1000wpc 1ohm.
................................................................................
My usage is much lower then that, as it is rare for me to reach a speakers reference efficiency in db. The pioneer's meters barely move when I use it.

I will likely stick with the Jolida Tube amp, 3 source/preamp combo.
Worse case might be monoblock tube amps, equivalent or less wpc.

I'm certain that the spike is from the neighbors florescent light in his kitchen. The bad AC might be the cause of his, and my panel buzzing. So I'll get an email out to CMP, but I'll probably talk to the landlord on monday.

If your designing something, it sounds like and expensive venture?

Thank You

 

[Gepetto]

Hi Joe
You mention Belkin Power Center. Is it the PF60 model? It represents that it has advanced power filtering in it if that is the model you have. Where the scope shots you took with the wal wart plugged into the Belkin or straight into your wall outlet? If the latter, how does it look when plugged into the Belkin?

I have no idea what is inside the Belkin power center.

 

[Pure_Brew]

I do use the PF60 but there is no change to the waveform or spike that I can see under test.

In fact, the spike is what makes the Belkin buzz too.

 

[Gepetto]

Hi Joe
Have you ever looked inside that to see what Belkin considers a filter?

A real line filter should consist of common mode choke followed by a set of Y caps followed by another set of toroidal chokes followed by a differential cap. This is kind of jacks or better for a good line filter. Generally, the bigger the better.

 

[Pure_Brew]

I looked online for some pics. Different outlets have filtration that varies, depending on device types. I haven't personally cracked it open, or tried all of the outlets on it. Maybe tomorrow morning ill check it. The trouble shows up on the outlet for amps and on another accessory outlet, on the Belkin. No doubt they are all the same vs this noise.

 

[rtp_burnsville]

Hi,

Can I ask a silly question? In reality what does having a super clean AC source buy you? You convert the AC to DC for most everything other than tube heaters. So long as you end up with clean DC isn't that the goal? Sure keeping big things out and have a stable voltage is important just don't follow the logic on doing much more than that.

Robert

 

[Gepetto]

The artifacts on the AC in this case are producing audible noise in the primary side magnetic components...

 

[Pure_Brew]

Hi,

Can I ask a silly question? In reality what does having a super clean AC source buy you? You convert the AC to DC for most everything other than tube heaters. So long as you end up with clean DC isn't that the goal? Sure keeping big things out and have a stable voltage is important just don't follow the logic on doing much more than that.

Robert

Personally for me this is mostly about the buzzing transformer noise that is especially annoying during listening sessions that are often a low level.

But otherwise I've never noticed any differences in performance with or without these filters. Might be more important on laboratory side, but even as Joe said earlier, real trouble should be eliminated at the source rather then filtered out, if possible

 

[Pure_Brew]

Joe,
On another note, along the trials with this issue a few years ago, I picked up a PS Audio Humbuster. What it did do is keep Toroidial transformers quiet. It actually worked. Unfortunately, most of the amps I use are EI types, which it does not seem to work on. Have you ever looked at one of those? It's interesting I think.
I
Also, thinking further, that spike actually does cause the SX-1280 to emit some fairly loud buzzing though the speakers when this happens. It's very old and that may just be happening as due to age/old caps. I'm going to ask my landlord to replace that light/ballast over there tomorrow. That would hopefully get rid of the worst of it.

 

[laatsch55]

A very interesting thread fellers, very interesting. A variable speed drive on a hi horsepower submersible pump creates so many harmonics that are injected back into the power grid that it actually cancels some power out. Spo, the power company has been making us install filters at the inlet side of the drives.What makes the return AC so bad is the trip two miles below ground and back, with a lot of known disturbances that only happen in this environment. Drove the power company crazy for awhile. The profile fit the scenario that some one was stealing electricity, but they couldn't find where it was going. BTW, those filters have to be custom designed and built for each installation at 10K apiece.

 

[Pure_Brew]

Well Damn!

 

[Pure_Brew]

Spoke with the landlord. He's happy to change out the light. As far as the bad AC, he had a bunch of work done and put new panels in the apartments. His concern is the pole that feeds our building has a transformer that the power company always seems to be working on. True.

 

[Pure_Brew]

After further conversation with the neighbor, it turns out that its not the light I thought, but it's the overhead lights in the kitchen which are on a rheostat. So that should be an easy fix. Too bad the Belkin can't deal with it.

 

[speakerman1]

Wonder if it is a solid state Rheo? Or an old kind?

 

[Pure_Brew]

I haven't actually looked at it but a regular switch could just go in there I hope.

 

[Gepetto]

It is an old school thyristor based dimmer, you can tell by the quadrature signature on the waveform that Joe captured. A rheostat would not be practical nor would it produce that spike. Probably a more modern dimmer would fix it too.