Mains conditioner for poor people :)

[Gidorra]

I am looking at an Audiolab DC Block 6, which amongst other things, claims to eliminate DC creeping in, if that is a real thing. The Audiolab is ca 400 bucks/Euros.

I already have a power strip per the attached pic for 50 bucks, and that claims to clean RF interference. This actually works, as we have a dimable light switch which makes the muisc sound terrible when swichted on, but that power strip actually fixes that.

Is there something in the Auddiolab that I don't already have?

Cheers!

 

[DVDdoug]

which amongst other things, claims to eliminate DC creeping in, if that is a real thing.

It CAN be a "real thing". But do you have some kind of power-related problem?

Don't go looking for solutions and wasting money on problems that don't exist for you...

DC offset SOMETIMES causes mechanical vibration/hum in transformers. It doesn't get-through to the audio circuits. I have an amplifier that used to vibrate when the TV was turned on. At the time I didn't know about DC offset so I only knew it was some kind of power problem caused by the TV. I don't have that TV anymore and the problem is gone.

 

[EERecordist]

Hello, there have been many discussions of power / mains filters you can search. I use the Eaton Tripp Lite Isobar series. The "premium" was originally the normal every day one I have used for years, because we used them in labs. You can often find them used.

As an EE with a lot of knowledge of electric utilities, I do not see a way for DC to enter the mains unless there are a lot of bad earth grounds at the pole transformer and electrical panel.

 

[kyuu]

Just to pile on here: unless you have a specific problem, don't go looking for solutions. You don't need to block DC unless you have an issue with a DC offset causing a transformer to vibrate audibly.

 

[DVDdoug]

I do not see a way for DC to enter the mains unless there are a lot of bad earth grounds at the pole transformer and electrical panel

It's an offset or asymmetry where the positive is higher than the negative or vice-versa. I assume it's usually caused by something on the load side (as it was in my case).

 

[Speedskater]

Connections to Planet Earth have nothing to to with this problem.
Or any other day-to-day AC power quality problems, for that matter.
Save for some 'Lost Neutral' problems.

 

[Alan O]

That Tacima strip can stop some mains-borne interference, but it doesn't block DC. I have one, and even using it I still used to experience buzz from an amp transformer. I built a DC blocker (which I'd advise most people not to do, for safety reasons) of the same essential design of the Audiolab one, and I use that between the Tacima strip and the amp. It stops the transformer buzz - or rather, it buzzes for a fraction of a second (due to initial current inrush I guess) and then goes silent. It's easily demonstrable and repeatable.

However, I can't really say there's been any other improvement other than stopping the buzz. And I wouldn't spend money on blocking DC unless I had evidence I actually had a DC problem. But if you want to try it, Audiolab also make a single-outlet one that a fair bit cheaper than the 6-outlet one.

 

[Alan O]

It's an offset or asymmetry where the positive is higher than the negative or vice-versa. I assume it's usually caused by something on the load side (as it was in my case).

Yes, DC doesn't get through your local distribution transformer, but devices downstream from the transformer can create asymmetry. Things that do half-wave rectification, like hair dryers implementing half power by just using a diode, are a common example.

 

[Speedskater]

It takes power hungry devices to create any significant DC offset. In a residential area, there are very few (if any) of these devices that run 24 by 7. So the question is: does the transformer buzz come and go?

 

[Alan O]

It takes power hungry devices to create any significant DC offset. In a residential area, there are very few (if any) of these devices that run 24 by 7. So the question is: does the transformer buzz come and go?

It was almost always present for me during the day (and I didn't check at night). But I'm in a UK city with dense residential areas sharing small numbers of large transformers - and we don't have US style pole transformers. So I'd guess the potential number of DC sources downstream from the power company transformer is greater here.

 

[Roland68]

A DC mains filter is a very simple circuit consisting mainly of diodes/rectifiers and a few electrolytic capacitors. Even if you use high-quality components that aren't strictly necessary, the parts alone shouldn't cost more than €10-20.
There's no reason why a finished product should cost more than €50-100, perhaps up to €150 with a fancy enclosure and nice connectors, but that doesn't improve its functionality.

Those with the necessary skills can find plenty of circuit diagrams, DIY instructions, and kits. But please always be aware that mains voltage is dangerous, and you are responsible for any devices you build yourself.

 

[Janfi67]

People who are a little poorer could use this one instead.
A DC blocker, differential and common mode filter, rated for 8 amps for less than 15€