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Mains DC Filtering

Jim Audiomisc said:
I'm concerned by *any* home audio equipment which generates an audible buzz when you're listening to music. In general, the makers can't take for granted all customers will be headbangers.
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I don't share your concern. Obviously it's better if they don't and obviously if it's really obvious OK it can be an issue but a transformer making some audible mechanical hum just audible in a quiet room from say a couple of feet away... nah...
 
I got rid of my Naim PSU’s because Teddy’s sound better (my ears, my room e.t.c), however, I don’t miss the buzzing! Strangely, 555’s were the worst, Olive SC’s the ‘quietest’.
 
Arkless Electronics said:
I don't share your concern. Obviously it's better if they don't and obviously if it's really obvious OK it can be an issue but a transformer making some audible mechanical hum just audible in a quiet room from say a couple of feet away... nah...
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That's fair enough if it doesn't bother you. But when I can clearly hear a buzz when trying to listen to music it is a real distraction during the quieter passages. "Just audible" depends on the type of music you are listening to.

What I *don't* know is if this would be fixed by a "dc blocker" or not. I'm tempted to try one, but don't want to waste money on one if it makes no difference. I also noted that the model someone referenced is priced in Euros which could be a pest from my POV. However rather that try to dampen the transformer maybe it is time I check this approach out. If nothing else, it would be an interesting experiment.

Maybe you should make one to Rod Elliot's design and I give it a try. :)
 
sq225917 said:
Sjostrom audio, dct03.
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I'm with sq, this is a proven beast, will cope with more dc than many, there are group buys from time to time or you can pick up the PCB unpopulated or populated from Sjostrom. Build one, if it doesn't solve the issue, pop it in classifieds and watch it disappear in an instant. I had more interest in a spare kit I had than anything I have ever sold on ...
 
Jim Audiomisc said:
That's fair enough if it doesn't bother you. But when I can clearly hear a buzz when trying to listen to music it is a real distraction during the quieter passages. "Just audible" depends on the type of music you are listening to.

What I *don't* know is if this would be fixed by a "dc blocker" or not. I'm tempted to try one, but don't want to waste money on one if it makes no difference. I also noted that the model someone referenced is priced in Euros which could be a pest from my POV. However rather that try to dampen the transformer maybe it is time I check this approach out. If nothing else, it would be an interesting experiment.

Maybe you should make one to Rod Elliot's design and I give it a try. :)
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I don't use them myself and have no problems with transformers buzzing generally. I built one for someone a few years ago (to my own design of course:)) and apparently it worked a treat but I have no plans to make any more.

FWIW some Croft power amps and integrated amps appear (I've only seen photo's and haven't been able to examine one) to have one built in! I guess too many awkward customers complaining about buzzing toroidals...
 
Shame. I'd much prefer if possible to try one made by someone in the UK. Can anyone suggest a UK maker who does these and I can contact?
 
You can buy just a board from Sjostrom and make your own! Hey if there are enough people who are that bothered about "made in UK" I'll make them (not the Sjostrom ones. My own version of course). They would be heavier duty still and longer life than the Sjostrom ones and several times the price.
 
TBH I'm trying to avoid my making a DIY one. Partly because I find that harder than I used to, and am wary of making an error when mains is concerned. (I've also always been rubbish anyway wrt putting things into boxes rather than having boards about the place! Mechanical skillls = zero!)

Partly because if I find this works I'd be writing about it, and then of course others might want one.

However my curiosity is: Would this fix the problem? Need to find out by experiment as the buzz may be down to something else about the transformer.

In this case (pun alert!) the current level required will be small, as it would be for 1 or two ESLs, not an amp. But they get left on, unattended for hours every day.
 
I would make one for £500 of top quality and reliability, boxed and with a captive mains inlet lead and captive output lead with a good quality 4 way extension block. This would use 35A rectifiers and computer grade capacitors for very long life and reliability.
Not worth my while to make anything smaller and cheaper.
 
I get hum from my power if I plug in to the wall. If I plug it in to my Russ Andrews plug board with all the rest of my kit it is gone. Silent ------
 
misterdog said:
Properly designed kit cares not one jot.
https://en.wikipedia.org/wiki/Power_supply_rejection_ratio#

Though Traffo hum is annoying at even low levels. I use a balanced mains transformer and a big DC blocker.
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Yep. Which is why EVERYTHING said about the mains affecting sound quality is complete bollox. All my gear is powered by extension blocks from Asda, Lidl etc... no DC blocker or balanced mains transformer and never will be.
 
I use an Aldi extension block after the BMU, then whatever kettle lead comes to hand.
The BMU and Dc blocker does make a difference in my system, possibly the transformers in the Quad ESL's.
Though the same BMU at Si's made no discernible difference.

You should never say never.
 
misterdog said:
I use an Aldi extension block after the BMU, then whatever kettle lead comes to hand.
The BMU and Dc blocker does make a difference in my system, possibly the transformers in the Quad ESL's.
Though the same BMU at Si's made no discernible difference.

You should never say never.
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Oh yes you should! Things should be brought down to black or white when it's THAT clear cut, as is the case with mains. And no there's nothing you could say that would make me believe it made a difference in your system. If you produced 100 "witnesses" I would put it down to mass hysteria and nothing more!
 
Arkless Electronics said:
Yep. Which is why EVERYTHING said about the mains affecting sound quality is complete bollox. All my gear is powered by extension blocks from Asda, Lidl etc... no DC blocker or balanced mains transformer and never will be.
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My compliments on your excellent sense of humour. Your post above only means you have either perfectly clean power at your home / location or that you simply have not experienced the parasitic effects of less than optimal power supply. You cannot dismiss real-world problems in this domain recounted by real people with first-hand experience as being "bollox". That is an indefensible position to take.
 
Arkless Electronics said:
Oh yes you should! Things should be brought down to black or white when it's THAT clear cut, as is the case with mains. And no there's nothing you could say that would make me believe it made a difference in your system. If you produced 100 "witnesses" I would put it down to mass hysteria and nothing more!
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A little bit more of this nonsense and you could take over where Jim Jones left things in Guyana...
 
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