DC blockers - what's your experience

holmz Said:

I do not think that UV and heat affects aluminium,

In response to this statement of mine;

"Also new hook up terminations. Aluminum wire terminations start to corrode and loosen over time when exposed to the outdoors environment. Sun’s rays, heat, cold, rain, wind. All will break down a tight, clean, low impedance termination."

TERMINATIONS... Repeat. TERMINATIONS...

@holmz Said:

And there is no “clean connection” with aluminium, as the stuff naturally gets a layer of alumina on it in a hurry.

When the outdoors 120/240V aluminum connections are first made-up at the utility power transformer and the utility overhead lateral triplex to the electrical service weatherhead service conductors the connections are clean and tight. With the passage of time, possibly many decades of service the terminations are subject to the Sun’ UV rays, rain intrusion, snow intrusion, heat, freezing moisture in the termination, and wind. High wind can whip the heck out of the wiring terminations.

As for the sun’s UV rays it will break down the insulating, waterproofing, material(s) that was originally installed over the terminations with the passing of possibly decades of time. It also will cause the deterioration of exposed THWN insulation covering the bare conductor. I've seen it first hand.

 

@holmz Said:

But then again, which does, or what do, harmonics have to do with DC blocking?

My post was in response to this post:

sns

2,947 posts

02-03-2023 at 08:50am

I had major problem with transformer hum that lasted for years, this along with over voltage issue(124-126v). Never could get rid of transformer hum, bucking transformer for the over voltage. Suddenly one day I come home no more transformer hum, voltage down to 119-121v, this has remained for years now. Seems electrical grid was finally repaired.

Best regards,

Jim

Thanks @jea48 - but I can read, so I was sort of expecting something added and not a rehash of the thread.

Which parts did I get wrong? Or which parts don’t conform to your understanding?

On the SNS part, it seems like the power grid was fixed and the voltage lowered, and all that @sns did to fix it was to come home suddenly. We don’t know if the power company had a DC offset, nor harmonics, we just know that he said that the voltage went down the same day that the hum went on walkabout.
Nor do we know that if he can home less suddenly, that the system wouldn’t still be humming.😋
(I sort of doubt that the suddenness was causal to fixing the problem.)

I move slowly.

@tunehead ,

Here is a thread that may help you better understand DC on the mains.

DC Offset Blocker/Killer - where to buy in the USA

more useful info on the subject for those who care to learn

Just bought the Audiolab DC blocker. I have two dedicated AC outlets feeding my system. Since I expected there to be possibly some DC seeping through and the EMF filtering, it was worth a try at $150. First off it created what sounded like a cleaner sound throughout. Crisp revealing but what little 'hum' that was residual in my system was also much clearer. At first I reasoned the enhanced clarity was worth the trade off but then I noticed something else troubling. The entire presentation had lost something. After giving the unit a week to break in (although it was a demo unit and hence should have had some miles on it) I pulled it out and listened again. Without overtly realizing it, the presentation had lost the warmth, organic, musical, 3-D quality to it. WOW, my system's magic was back. I'm a bit unsure what actual effect the Blocker had. Seemingly clearer but flat OR pinched I might say. And that extra 'hum' was gone receding into the faint background as I am OCD about the smallest trace of system sound of any kind. Unit has been returned for full credit. Lesson learned. Same result with "power conditioner" by Furman.