yes, they work wonders when needed -- ifi, van alstine, audiolab, ps audio, they all make them
I'm using a Long dog audio one inline to my power conditioner. it makes a positive effect in my opinion in my system but it does limit my power cord to 12 gauge.
my issue is a fish tank with variable DC pumps and variable LED lights.
one day I'm going to try blocking the DC at source (other side of the room)
Then taking it out of the system, I get no hum on my transformers without but I find the tone sweeter with it.
@holmz I don't necessarily have a problem. Don't know if I have a problem or the equipment to test if I do. Was more a general question after viewing reviews of DC blocker products and the positive affect for minimal investment.
@tunehead - Avoid them unless you have an issue. One more piece of gear to break.
DC should almost never happen in a home, and usually it's caused by things like LED power supplies and dimmer switches. Usually best to deal with the source of the problem and only if that can't be dealt with due to WAF and budget or being a tenant then a DC blocker is in order.
A better idea IMHO is to monitor your AC voltage near your rack and see how much it varies. If you see too much a voltage regulator may be a good idea.
this is correct and consistent with my experience
reality is, dc in the powerline is a reality for most, in modern homes, with modern electronics, lighting and appliances...
My experience of using a few different DC blockers is they seem to choke the transient impact, bass and speed of the power amplifier.
If you have DC issues, like I did in my last apartment, they can make the sound cleaner and clearer, but with the above mentioned negatives. So they give and take away.
If you have no DC issues, like in my current house, they just become a net negative and your system is better without them.
I have noticed that in my area the DC on the line situations come and go, when they occur they persist for a few weeks. Whenever there's a holiday, that's when it starts and persists.... the cause is most likely overloading of the entire neighborhood, and it got much, much worse since the outbreak of the pandemic with most people staying at home / working from home / losing jobs & full time at home watching TV and hanging on all times to their electronic devices.
The most practical solution I found is to bleed the DC when it happens with a parallel inductor (Richard Grey - RGPC makes such device, for example). Then I get a major improvement in sound quality in all areas.
However, when there's no DC on the line, I keep the RGPC off.
This way I can avoid the negatives of a series DC blocker...
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.
I do not think that UV and heat affects aluminium, unless the global worming is higher that I believe it to be.
But then again, which does, or what do, harmonics have to do with DC blocking?
So far we have two things that are not known, or shown to exist on the OPs power that need to be fixed.
Thanks @jea48 - but I can read, so I was sort of expecting something added and not a rehash of the thread.
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.
I move slowly.
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.
@allears4u it is redemanded to use on source equipment such as DAC, Phone Pre, Streamers/servers. Not recommend for amplification. I bought a couple of these for my Daughters system as they live in a condo and worked quite nicely cleaned here system up, used on Analog and Digital sources.