Discussion of AC mains isolation transformers

[Cormorant]

I second Cornan's excellent recommendation for VH Audio star quad power cable.  I've been using it for years, both as a retail cord and as DIY cords.  The nice thing about making DIY cords is that the wire is not expensive, and the cords can be tuned with various IEC and plug ends, which can make a big difference to the sound.  No soldering is required to make these power cords.

 

These cords can work particularly well on DACs and amplifiers from my experience.

 

With some patience, there are sometimes very good deals on used Flavor 4 cords. 

 

 

 

[zilch0md]

Thanks Cornan.  Reading John's posts again (quoted above), I have no contention with his statement that the star-quad configuration does a great job of reducing vulnerability to externally applied EMI.  None of the article I quoted say otherwise.  

 

What's being debated here is the degree of concern one must have for blocking external sources of EMI (by using star-quad cables) for applications other than microphone cables and line level cables - where weak signals are far more vulnerable to external EMI than stronger signals, especially in long cable runs, as with microphone cables on a stage.

 

Both Canare and Blue Jeans discount the value of using star-quad cables for higher voltage (higher current?) applications, except when the goal is to limit magnetic emissions outward from the cables themselves (all of which is consistent with the quoted Wikipedia article.)

 

In the end, it's possible that Canare and Blue Jeans Cable and the contributors to that Wikipedia article are simply underestimating the noise-reduction benefits of using star-quad cables in applications other microphone and line-level cables and, as I mentioned previously, it probably can't hurt to use star-quad cables everywhere, even though the benefits are allegedly less valuable or, at least, less cause for concern, with some applications.

 

[Cornan]

3 hours ago, zilch0md said:

Thanks Cornan.  Reading John's posts again (quoted above), I have no contention with his statement that the star-quad configuration does a great job of reducing vulnerability to externally applied EMI.  None of the article I quoted say otherwise.  

 

What's being debated here is the degree of concern one must have for blocking external sources of EMI (by using star-quad cables) for applications other than microphone cables and line level cables - where weak signals are far more vulnerable to external EMI than stronger signals, especially in long cable runs, as with microphone cables on a stage.

 

Both Canare and Blue Jeans discount the value of using star-quad cables for higher voltage (higher current?) applications, except when the goal is to limit magnetic emissions outward from the cables themselves (all of which is consistent with the quoted Wikipedia article.)

 

In the end, it's possible that Canare and Blue Jeans Cable and the contributors to that Wikipedia article are simply underestimating the noise-reduction benefits of using star-quad cables in applications other microphone and line-level cables and, as I mentioned previously, it probably can't hurt to use star-quad cables everywhere, even though the benefits are allegedly less valuable or, at least, less cause for concern, with some applications.

 

 

It is probably correct to use another type of power cable on high power devices such as powerful amps, powerful active speakers, powerful subs and powerful integrated amps. These devices might need thick gauge wires that a starquad simply is not suitable for due to its construction. But I think we are talking about really high current devices here.

 

All I can say is that starquad is the best type of power cable that I have tried, but I do not have any quite that power hungry devices in any of my setups. My Brooklyn DAC have a dual starquad which consists of 8 14awg conductors plus ground return. It is massive. Still my much thinner ATL starquad power cable (single starquad with 4 14awg conductors plus ground return) sounds just as good to my ears with a non powerful device like Brooklyn.

 

As always it is best to try. Not sure you will like it just because I do, but there is actually a chance that you will! ?

 

BTW. I use only short 50cm power cables. Surely not effected by EMI that much. Still my starquad makes a big difference compared to my 1 meter Audioquest NRG-2. I cannot say exactly why. I only know that it does.

[One and a half]

2 hours ago, Cornan said:

 

It is probably correct to use another type of power cable on high power devices such as powerful amps, powerful active speakers, powerful subs and powerful integrated amps. These devices might need thick gauge wires that a starquad simply is not suitable for due to its construction. But I think we are talking about really high current devices here.

 

What's the voltage rating on the star quad?

[JohnSwenson]

9 hours ago, zilch0md said:

Thanks Cornan.  Reading John's posts again (quoted above), I have no contention with his statement that the star-quad configuration does a great job of reducing vulnerability to externally applied EMI.  None of the article I quoted say otherwise.  

 

What's being debated here is the degree of concern one must have for blocking external sources of EMI (by using star-quad cables) for applications other than microphone cables and line level cables - where weak signals are far more vulnerable to external EMI than stronger signals, especially in long cable runs, as with microphone cables on a stage.

 

Both Canare and Blue Jeans discount the value of using star-quad cables for higher voltage (higher current?) applications, except when the goal is to limit magnetic emissions outward from the cables themselves (all of which is consistent with the quoted Wikipedia article.)

 

In the end, it's possible that Canare and Blue Jeans Cable and the contributors to that Wikipedia article are simply underestimating the noise-reduction benefits of using star-quad cables in applications other microphone and line-level cables and, as I mentioned previously, it probably can't hurt to use star-quad cables everywhere, even though the benefits are allegedly less valuable or, at least, less cause for concern, with some applications.

 

The reason for using star quad in the DC cables I talked about about in the other thread was not to decrease EMI pickup but to reduce inductance of the cable which significantly lowers voltage drop across the cable from the sharp current load changes brought about by digital devices.

 

The star quad geometry has about 1/3 the inductance of a twisted pair and 1/9 the inductance of "zip cord". There have been quite a few studies that seem to point to low inductance as a good thing for speaker cables, so star quad is a probably very good way to do speaker cables.

 

Interconnects are more iffy, star quad increases capacitance which can be a bad thing for some systems. But star quad interconnects CAN be very good, I'm currently using some DIY star quad ICs and they are fantastic.

 

John S.

[Cornan]

5 hours ago, One and a half said:

 

What's the voltage rating on the star quad?

 

Here is the exact starquad power cable that I use, except for my Brooklyn DAC where I use a dual starquad that is no longer in production:

 

http://www.atlhifi.com/shop/audio-cables/0-5-m-power-cable-silver-in-ptfe-rhodium-plated-schuko-iec-connectors/

 

US (gold plated) plug is available for an extra EUR5.- charge. Pretty sure he can get UK plugs as well if needed, but best to ask.

Worth to notice is that I only use these for my Gophert csp-3205II floating SMPSs so far (have two more Gopherts and starquads on order). On my active speakers and on my in-line AC mains DC Blocker trap filter I still use DH-Labs super sonic power plus. I intend to change them to starquads sooner or later.

 

Here is the voltage and max input from that link:

• Max Input: 3500W max.
• Specifications: 250V, 15A

[Forehaven]

I bought an Elgar Isol Transformer.  I love the audio benefits, but it sits only 5' from my listening position and puts out about a 5dB of typ. transformer noise.

Any posts/pics/ideas of how to quiet this baby down?

 

Thanks guys.

[mozes]

57 minutes ago, Forehaven said:

I bought an Elgar Isol Transformer.  I love the audio benefits, but it sits only 5' from my listening position and puts out about a 5dB of typ. transformer noise.

Any posts/pics/ideas of how to quiet this baby down?

 

Thanks guys.

I also used to have Elgar IT, it was humming all the time. Try to play with the cables to put it as far as possible from the seating position. I found no other easy fixes, others talk about special enclosures to minimize the noise but beware of the heat as it needs good ventilation.

[jamesg11]

Which Elgar IsoT?

Anyone had luck with a DC Blocker before the Elgar? (& I think I saw that @Cornan believed this would improve SQ regardless of hum reduction dbs?).

[Cornan]

52 minutes ago, jamesg11 said:

Which Elgar IsoT?

Anyone had luck with a DC Blocker before the Elgar? (& I think I saw that @Cornan believed this would improve SQ regardless of hum reduction dbs?).

 

If you live in the US do not bother with a DC blockers trap filter pre the IT. It seems that it is mostly effective in EU countries with Schuko type plugs. It still can make a difference in other countries, but are more or less a gamble you'll need to be prepared for.

DC blockers trap filters improves almost everywhere for me. Same thing with AC mains voltage regulators.

[jamesg11]

In Australia, 230-240V ...?

[sandyk]

8 minutes ago, jamesg11 said:

In Australia, 230-240V ...?

 

 Yes. It's now a nominal 230V AC, but the standard is + and - 10% which means it can still go as high as 253V.

[jamesg11]

3 hours ago, sandyk said:

 

 Yes. It's now a nominal 230V AC, but the standard is + and - 10% which means it can still go as high as 253V.

Yep, was trying to tease out Cornan's sense of the value of a dc blocker re SQ on an Elgar IT ... but of course you know more than a bit on this stuff, so thoughts ...?

[sandyk]

45 minutes ago, jamesg11 said:

Yep, was trying to tease out Cornan's sense of the value of a dc blocker re SQ on an Elgar IT ... but of course you know more than a bit on this stuff, so thoughts ...?

 

 

I have never felt the need for a DC blocker, or for that matter, an A.C. Isolation transformer. A buzz from a toroidal transformer could be due to a distorted A.C. mains supply, but normally it is just the way it is mounted.

If you live in an  Industrial area , or in a big block of apartments with lifts etc.you may need to use such measures though.

TBH, Due to our use of the much higher 230V AC at 50 HZ, I don't believe that in Australia we have anywhere near the amount of problems in this area that our U.S. cousins do.

Alex

 

[Cornan]

1 hour ago, jamesg11 said:

Yep, was trying to tease out Cornan's sense of the value of a dc blocker re SQ on an Elgar IT ... but of course you know more than a bit on this stuff, so thoughts ...?

 

AC mains DC blocker trap filter works for me where ever I put them. They do not effect the sound signature. Just clean up the sound. However, I live in an appartment in a bigger city in Sweden. Difficult to know if it will improve as much if you live in a house in Australia. It needs to be tested first hand. I can only say that a DC blocker trap filter can have almost the same impact as a isolation transformer on the right spot.

[jamesg11]

Cornan, appreciated! Will definitely look into setting up a dc blocker.

[Cornan]

15 minutes ago, jamesg11 said:

Cornan, appreciated! Will definitely look into setting up a dc blocker.

 

My pleasure!  Please do report back if/when you´ve tried it. It is always interesting (for other and me) to know.

[John769]

13 hours ago, Cornan said:

 

If you live in the US do not bother with a DC blockers trap filter pre the IT. It seems that it is mostly effective in EU countries with Schuko type plugs.

 Hi .  Why is it more effective with Schuko plugs?

[Cornan]

5 minutes ago, John769 said:

 Hi .  Why is it more effective with Schuko plugs?

 

That´s still a mystery and ofcource not a firm rule without exeption. So far however I know that Alex C have mensioned that DC blockers seems more efficient in EU countries than in the US. The ac mains DC blocker have also not been consistant in some other countries. Hard to say why, but that is why I do not want to give a firm recommendation to everyone. It is all about if it is needed in your country and how much DC offset/DC interfearences you have in your ac mains.

[John769]

Maybe it's a 230v thing rather than specifically Schuko...

[Cornan]

28 minutes ago, John769 said:

Maybe it's a 230v thing rather than specifically Schuko...

 

Yeah, maybe!

In the end a AC mains DC blocker trap filter will be a trial and error path. You might win, but you might end up with no improvement! 

I guess the fact that I live in an appartment in a fairly old building is a clue as well. Another guess is that if a isolation transformer did´nt improve things a DC blocker will not either, but if a isolation transformer did improve things there is a good chance a DC blocker will improve things further.

[octaviars]

This article is intresting if you like to read about DC on the AC line and what may cause it. Notice that he writes that this is mostly a problem with larger toroidaltransformers above 300VA smaller ones have so high resistans in the primarywinding that DC will not affect them.

 

http://sound.whsites.net/articles/xfmr-dc.htm

 

I talked to a guy that designs audio equipment and he have done some testing with DC on the AC line with different transformers and he also could see that the DC problem is mainly with larger toroidal transformers.

[Forehaven]

Thanks for the help guys.  I bought a 1kV Elgar, model HIT .001R

 

Sounds like I'm kind of screwed with the noise.  Unfort. I live in a 1905 built home, with old....circa 60's?...wiring.  Plus, I live on a street surrounded by lg multi residential bldg's.  

 

Are there actually IT's that are silent??

[Cornan]

12 minutes ago, octaviars said:

This article is intresting if you like to read about DC on the AC line and what may cause it. Notice that he writes that this is mostly a problem with larger toroidaltransformers above 300VA smaller ones have so high resistans in the primarywinding that DC will not affect them.

 

http://sound.whsites.net/articles/xfmr-dc.htm

 

I talked to a guy that designs audio equipment and he have done some testing with DC on the AC line with different transformers and he also could see that the DC problem is mainly with larger toroidal transformers.

 

That´s interesting to know! My Peaktech 2240 is 500VA and have a torodial transformer.  However, I have a DC blocker trap filter pre my router where it makes a quite a big difference for the better as well. There is no toroidal transformer in that spot AFAIK, so I guess there is more to it than just toroidal transformers. LED-lights (popular these days) for example?

[Cornan]

9 minutes ago, Forehaven said:

Are there actually IT's that are silent??

 

Yes for sure. My Peaktech 2240 is as good as silent. I can only hear it wisper (=very quiet hum) if my ear is roughly 10-15cm from the case. However, there is several reasons for a IT to hum. DC offset is just one of many various reasons. Usually it could be a "loose" bolt (or rather a bolt that is not tightened enough) inside the case that will make the transformer hum.