Mains DC Filtering

[chartz]

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!

True and entirely agreed on.
But the buzzing noise of big toroidals just annoys me. That said, properly made - or not dropped! - transformers don't buzz at all.
So I opted for a DC blocker to reduce that noise for ONE amp. Cheaper than replacing the toroidal, isn't it?

As far as leads and power blocks are concerned, Lidl and € 2 kettle leads it is. Let's be rational about this.

 

[Mike Reed]

As far as leads and power blocks are concerned, Lidl and € 2 kettle leads it is. Let's be rational about this.

Aldi rationality in the world won't lead to better sound.

 

[Jim Audiomisc]

True and entirely agreed on.
But the buzzing noise of big toroidals just annoys me. That said, properly made - or not dropped! - transformers don't buzz at all.
So I opted for a DC blocker to reduce that noise for ONE amp. Cheaper than replacing the toroidal, isn't it?

As far as leads and power blocks are concerned, Lidl and € 2 kettle leads it is. Let's be rational about this.

If I can get a suitable blocker I can probably also do something like hang a mic near the offending transformer and measure the audible buzz with/without the blocker in circuit.

 

[chartz]

Hi Jim,
I sometimes get a funny pulsating kind of buzz, quite strong and certainly audible several metres away.
I was wondering about my electric radiant panel heaters. The buzz seems to disappear almost completely when I unplug them from mains.
I also get a funny whistle from my ESL57’s when they are plugged.

 

[Jim Audiomisc]

I can't really say much about what you report as I can't tell what the cause may be. I assume the heater panels are just resistors. Or are they some kind of 'heat lamp'?

 

[Sue Pertwee-Tyr]

I’ve just swapped out a Hegel 390 (very buzzy trafo) for an Accuphase E480 (totally silent) so not all of it is down to the mains quality.

 

[IVELIN]

I’ve just swapped out a Hegel 390 (very buzzy trafo) for an Accuphase E480 (totally silent) so not all of it is down to the mains quality.

Just saw the innards of the two amps...I think the e480 has the trafo in resin (and who knows what else is differently thought of)

 

[Sue Pertwee-Tyr]

Just saw the innards of the two amps...I think the e480 has the trafo in resin (and who knows what else is differently thought of)

Fair point, but I’ve also had Albarry monoblocs (2 trafos, both silent, and not encapsulated). And I think the Accuphase trafo is just in a container, not necessarily encapsulated.

 

[IVELIN]

Fair point, but I’ve also had Albarry monoblocs (2 trafos, both silent, and not encapsulated). And I think the Accuphase trafo is just in a container, not necessarily encapsulated.

It's possible, I couldn't find an image of the e480 trafo alone.
I had a rotel ra02 which had toroidal transformer and was dead silent. Since I have/had different amps with toroidal trafos and all make/made some mechanical noise. On the other hand other amps I had with EI trafos were just fine. Maybe I need to reconsider the benefits of toroidals.

 

[davidsrsb]

If I can get a suitable blocker I can probably also do something like hang a mic near the offending transformer and measure the audible buzz with/without the blocker in circuit.

You need to have a repeatable mains supply for this to work. Mains voltage and harmonics seems to be highly variable.

If I was still in the UK I would consider marketing an expensive mains quality monitor for nervous audiophiles.

 

[NDL]

I had a Hegel H390 connected to an Audioquest Niagra 1200 which was silent, I upgraded to the H590 and was disappointed to find it had transformer hum (mainly because Id expected the Niagra to have dc filtering) , I've upgraded to a Puritan PSM156 and its now silent and sound is also improved. Not cheap but its a quality piece of kit

 

[Jim Audiomisc]

You need to have a repeatable mains supply for this to work. Mains voltage and harmonics seems to be highly variable.

If I was still in the UK I would consider marketing an expensive mains quality monitor for nervous audiophiles.

Given a suitable DC blocker I could probably fix the mic near the base of the ESL and start monitoring the output with a measurement program I've already written. Then repeatedly switch between the ESL being powered direct and via the blocker.

The problem is getting a suitable device. Ideally one I can try-before-buy and rated appropriately for just 1 or 2 ESLs. i.e. much lower current than required for amplifier, so should be cheaper and smaller.

 

[Jim Audiomisc]

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.

Alas, that has a null intersect with what I'm looking for. :-/

In my case I'd:

1) Want to try out before any purchase as my initial question is to find out if it actually makes any difference for my ESLs.

2) The current drawn by 1 or 2 ESLs will be piddle compared to something like a power amp. So the design could use much less capable components, and thus be smaller and cheaper.

The kits are interesting. But TBH my main (pun!) problems is that I can easily build components onto a board. But I've always been rubbish at putting things into decent cases, etc. And for this I'd doubt what I did would therefore be safe as it involved mains voltages.

However if I can get a blocker I can then use a mic to measure any change in the spectrum of the buzz when I switch between raw mains and via the blocker. Seems worth doing if I can...

 

[IVELIN]

I had a Hegel H390 connected to an Audioquest Niagra 1200 which was silent, I upgraded to the H590 and was disappointed to find it had transformer hum (mainly because Id expected the Niagra to have dc filtering) , I've upgraded to a Puritan PSM156 and its now silent and sound is also improved. Not cheap but its a quality piece of kit

This is good news but I feel that it's a little bit unnecessary; if one can spend big money on a DC/mains filter one might as well spend the money on an amp that has no transformer hum and sounds even better than "X" amp.

 

[chartz]

I can't really say much about what you report as I can't tell what the cause may be. I assume the heater panels are just resistors. Or are they some kind of 'heat lamp'?

Yes they are resistors with triac electronic regulation and sensing.

 

[NDL]

This is good news but I feel that it's a little bit unnecessary; if one can spend big money on a DC/mains filter one might as well spend the money on an amp that has no transformer hum and sounds even better than "X" amp.

It wasn't solely for the amp but fair point, just mainly for anyone possibly considering going the Niagara 1200 route. I agree its total overkill if you need a single DC filter

 

[Darth Vader]

Yes they are resistors with triac electronic regulation and sensing.

Triacs are prone to generating noise and RFI if careful attention to circuit design is lacking in this area. You need a snubber somewhere in the circuitry. What type and where depends on the triac controller circuit.

Or an alternative none triac method of controlling the heaters such as in the old days.......

Cheers,

DV

 

[Coda II]

Alas, that has a null intersect with what I'm looking for. :-/

In my case I'd:

1) Want to try out before any purchase as my initial question is to find out if it actually makes any difference for my ESLs.

2) The current drawn by 1 or 2 ESLs will be piddle compared to something like a power amp. So the design could use much less capable components, and thus be smaller and cheaper.

The kits are interesting. But TBH my main (pun!) problems is that I can easily build components onto a board. But I've always been rubbish at putting things into decent cases, etc. And for this I'd doubt what I did would therefore be safe as it involved mains voltages.

However if I can get a blocker I can then use a mic to measure any change in the spectrum of the buzz when I switch between raw mains and via the blocker. Seems worth doing if I can...

I have a pair of the ATL units not being used which you are welcome to try if you are happy to cover postage. They have IEC connections in and out and the UK price paid a couple of years ago was £164.

 

[Haruspex]

You could always have a look at the Russ Andrews site, he seems to have quite a bit of mains filtering solutions, if the mains is the problem.

 

[davidsrsb]

Triac control of a high current load would fail modern CE regulations for mains harmonics
https://www.emcstandards.co.uk/a-practical-guide-for-en-61000-3-2-limits-for-h