Discussion of AC mains isolation transformers

[zilch0md]

On 9/12/2017 at 8:18 AM, zilch0md said:

 

Thanks for your advice!  I've successfully canceled the order for those star-quad RCA cables and have instead ventured into star-quad by placing an order for a GhentAudio star-quad DC power cable - which I'll use with my USB Regen.  I have a Blue Jeans Coaxial cable that rocks, by the way.  They make great stuff at great prices.  

 

Since receiving it three days ago, the reduced inductance of my Ghent Audio star-quad DC power cable has been lowering the voltage drop that would otherwise be suffered in supplying 7.0V DC to my USB Regen from my el cheapo LPS - making no audible improvements whatsoever as it is incapable of offering any significant reduction in EMI thanks to the voltage being so high (relative to voltages seen in microphone cables and line level interconnects, where star-quad cables can make a huge difference.)

 

So now, with the exceedingly well-made Ghent Audio DC cable making no audible improvements, I'm going to select and order some star-quad RCA interconnects, where the line level voltages are more susceptible to EMI - and as long as the interconnects are short, as mine will be, the star-quad disadvantage of increased capacitance shouldn't be a problem.

[Cornan]

41 minutes ago, zilch0md said:

 

Since receiving it three days ago, the reduced inductance of my Ghent Audio star-quad DC power cable has been lowering the voltage drop that would otherwise be suffered in supplying 7.0V DC to my USB Regen from my el cheapo LPS - making no audible improvements whatsoever as it is incapable of offering any significant reduction in EMI thanks to the voltage being so high (relative to voltages seen in microphone cables and line level interconnects, where star-quad cables can make a huge difference.)

 

So now, with the exceedingly well-made Ghent Audio DC cable making no audible improvements, I'm going to select and order some star-quad RCA interconnects, where the line level voltages are more susceptible to EMI - and as long as the interconnects are short, as mine will be, the star-quad disadvantage of increased capacitance shouldn't be a problem.

 

Sorry to hear that the Ghent Audio DC cables did´nt make an audible improvement in your setup Mike. Mine with JSSG surely did! Anyway if you want to order starquad RCA cables this post by John Swenson might interest you:

 

Good luck!

 

[zilch0md]

5 hours ago, Cornan said:

 

Sorry to hear that the Ghent Audio DC cables did´nt make an audible improvement in your setup Mike. Mine with JSSG surely did! Anyway if you want to order starquad RCA cables this post by John Swenson might interest you:

 

Good luck!

 

 

Thank you Cornan, but that particular JS post you've quoted, makes no mention of star-quad RCA interconnects, but he does offer a great explanation of the reduced inductance enjoyed when using star-quad DC cables - as I had mentioned, quoting him, actually, in my post this morning, lamenting that I can not hear any audible improvements when using the Ghent Audio star-quad DC power cable to supply 7.0V to a USB Regen.  

 

So, as I had said before, I'm disappointed that the star-quad DC cable's ability to reduce inductance yielded no audible improvements in my particular application, but I've not, at any time said, a star-quad cable cannot make audible improvements by reducing inductance.

 

What I have said, only parrots the following JS post, where he recently explained that star-quad DC power cables do not offer the same advantage  of immunity to EMI, that can be enjoyed with star-quad microphone and line-level interconnects (i.e. RCA interconnects) - where the voltages are much lower and, thus, more susceptible to EMI, with the only downside being, as I recently stated (again parroting JS), the possibility of increased capacitance, in longer cable lengths.)

 

 

Mike

[Cornan]

44 minutes ago, zilch0md said:

 

Thank you Cornan, but that particular JS post you've quoted, makes no mention of star-quad RCA interconnects, but he does offer a great explanation of the reduced inductance enjoyed when using star-quad DC cables - as I had mentioned, quoting him, actually, in my post this morning, lamenting that I can not hear any audible improvements when using the Ghent Audio star-quad DC power cable to supply 7.0V to a USB Regen.  

 

So, as I had said before, I'm disappointed that the star-quad DC cable's ability to reduce inductance yielded no audible improvements in my particular application, but I've not, at any time said, a star-quad cable cannot make audible improvements by reducing inductance.

 

What I have said, only parrots the following JS post, where he recently explained that star-quad DC power cables do not offer the same advantage  of immunity to EMI, that can be enjoyed with star-quad microphone and line-level interconnects (i.e. RCA interconnects) - where the voltages are much lower and, thus, more susceptible to EMI, with the only downside being, as I recently stated (again parroting JS), the possibility of increased capacitance, in longer cable lengths.)

 

 

Mike

 

Well, that link is about starquad RCA cables. Did you read this?

 

For a single ended cable (RCA plugs on each end), star quad carries the signals, one pair to the pin, one pair to the ring. Shield around bundle is not connected in any way to the star quad or RCA plugs. A separate wire connects one end of the shield to the other.

 

I have been experimenting with interconnects done this way, Canare microphone cable did not sound so great, BUT Belden 1804A sounds fantastic! This is very thin, very flexible shielded starquad with silver plated copper strands with polypropylene insulation and a braided shield. I used the new Eichman harmony RCA plugs with this ($39 for 4 at VH Audio). For the shield wire I loosely wrapped silicone rubber insulated 24AWG super flexible wire (on Amazon from GNTECHGO) (about three turns per foot). 

 

These connectors are a dream to use and they even have an insert for using thin cable. The shell has plenty of room to cover the shield to wire connection. Highly recommended.

 

The cable takes quite a while to burn in, I would give it a week of constant playing before assessing sonic qualities. It sounds fantastic, is super flexible and inexpensive to make.

 

I got my cable from Markertek in the US, there is a place in the UK that also sells by the foot, I'm not sure about other areas.

 

John S.

 

 

[oneguy]

On 9/26/2017 at 6:20 PM, One and a half said:

Ah ok, all is good, 127V, 5.8% on the 120V... OK.

 

60Hz transformers can run on 50Hz, they get a little warmer. 50Hz Transformers on 60Hz are over fluxed, also get a bit warmer.

Confirmed it’s 50Hz in my building. 

[One and a half]

44 minutes ago, oneguy said:

Confirmed it’s 50Hz in my building. 

Get a bit warm then.

[Speedskater]

Note that depending on where you live a 240V circuit may:

a] have two Hot lines, each 120V away from Neutral, Safety Ground/Protective Earth.

b] have one Hot line and one Neutral line.

 

In situation [a] any switches or circuit breakers need to control both lines and be linked.

In situation any switches or circuit breakers need to control only the Hot line. (no switches or breakers on the Neutral)

 

[Speedskater]

On 9/28/2017 at 10:05 AM, zilch0md said:

Since receiving it three days ago, the reduced inductance of my Ghent Audio star-quad DC power cable has been lowering the voltage drop that would otherwise be suffered in supplying 7.0V DC to my USB Regen from my el cheapo LPS

The reduced inductance only impacts very high frequency noise and interference.

The DC voltage drop is only influenced by the end-to-end resistance. Same goes for low frequency AC.

[zilch0md]

6 hours ago, Speedskater said:

The reduced inductance only impacts very high frequency noise and interference.

The DC voltage drop is only influenced by the end-to-end resistance. Same goes for low frequency AC.

 

Thanks Speedskater,

 

I was paraphrasing what JS had written, here:

 

 

[Speedskater]

I should add that the reason we want a low inductance cable on a DC cable is so that bad high frequency noise generated at the other end of the cable sees a low impedance at the source end.

[JohnSwenson]

5 hours ago, Speedskater said:

I should add that the reason we want a low inductance cable on a DC cable is so that bad high frequency noise generated at the other end of the cable sees a low impedance at the source end.

Yes but I think the following way of thinking about it makes more sense to a lot of people:

 

many digital devices have very rapid current load fluctuations as different parts of the circuit turn on and off. These rapid changes in current create voltage across the inductance of the cable, the higher the inductance, the greater the voltage for a given load current change. Thus the lower the inductance of the cable, the lower the noise generated across the cable due to rapidly changing current loads.

 

John S.

[YashN]

2 hours ago, JohnSwenson said:

Yes but I think the following way of thinking about it makes more sense to a lot of people:

 

many digital devices have very rapid current load fluctuations as different parts of the circuit turn on and off. These rapid changes in current create voltage across the inductance of the cable, the higher the inductance, the greater the voltage for a given load current change. Thus the lower the inductance of the cable, the lower the noise generated across the cable due to rapidly changing current loads.

 

Very neat!

 

How's life in the new house, John?

[Ralf11]

has anyone tried these leakage current reduction / isolation transformer setups on systems where the computer or server is galvanically isolated from the DAC?  if so, what were the results?

 

e.g. using optical isolation ( @jabbr) or WiFi ??

[Speed Racer]

4 minutes ago, Ralf11 said:

has anyone tried these leakage current reduction / isolation transformer setups on systems where the computer or server is galvanically isolated from the DAC?  if so, what were the results?

 

e.g. using optical isolation ( @jabbr) or WiFi ??

 

Of course! My setup uses a Topaz 2.5kVa ISO transformer wired for balanced power. The only digital device plugged into the Topaz is my DAC which is galvanically isolated from the computer feeding it using an Eitr.

 

What do you want to know?

[Ralf11]

Can you describe the subjective improvement in SQ, before vs. after Topazification?

 

Also, have you done any blind tests, by moving the AC feed, etc.?

[Speed Racer]

2 hours ago, Ralf11 said:

Can you describe the subjective improvement in SQ, before vs. after Topazification?

 

Also, have you done any blind tests, by moving the AC feed, etc.?

 

The biggest differences I noticed were a more black background and better instrument and voice separation. What I mean by the later is that the locations on the soundstage are more distinct. The blacker background means there is more clarity as the whole sound is less muddled.

 

I didn't do A/B blind testing. It takes too long to power everything down and power everything back up. Too much time would pass for it to be meaningful.

[Dominique-Tanguy]

Hi all,

 

i am close to order a Topaz from the USA (91001-11) for the input, it is mentionned 120/240 volts.

 

we normally have 230 volts in Germany, but I measure 215 volts in my house. I am currently using a Isolation transformer from which I get 227 volts at the output when I plug it in the 215 volts from the wall. Can I expect the same thing from the Topaz?

 

cheers,

 

Dominique

[zilch0md]

47 minutes ago, Dominique-Tanguy said:

Hi all,

 

i am close to order a Topaz from the USA (91001-11) for the input, it is mentionned 120/240 volts.

 

we normally have 230 volts in Germany, but I measure 215 volts in my house. I am currently using a Isolation transformer from which I get 227 volts at the output when I plug it in the 215 volts from the wall. Can I expect the same thing from the Topaz?

 

cheers,

 

Dominique

 

YMMV, but my 120V, 500VA Topaz 19095-32 increases the voltage about 3% at the Secondary, relative to the input at the Primary, when driving my headphone system, which is putting a very light load on the 500VA Topaz. I've heard of isolation transformers that maintain a true 1:1 ratio, whether unloaded or fully loaded, but I can't imagine how that's possible without including some kind of voltage regulator circuit at the secondary (which would create some noise of its own), in combination with windings that provide the minimum input voltage required by the regulator.  

 

In my admittedly limited experience, and paying attention to what others have said, most so-called 1:1 isolation transformer will give you a higher voltage at the output, especially when not loaded to its rated capacity - which, in your case, would be desirable, given that you're not getting a full 240V from the mains.

 

I have the opposite problem:  I'm using a voltage regulator at the mains to reduce ~127V down to 110V, before my transformers increase the voltage back to where I want it (~120V).

 

I don't want to be the bearer of discouraging news, but the Topaz 91001-11 that you've ordered does not have the low 0.0005 pF inter-winding capacitance of Topaz/SquareD/MGE/Daitron models ending in -31 or -32, as shown in this PDF:

 

http://www.pacificparts.com/vends/mge/images/t1.pdf

 

The 91001-11 is rated at 0.005 pF as shown in this photo:

 

 

 

 

See:   https://www.head-fi.org/threads/topaz-low-capacitance-isolation-transformers-for-affordably-clean-power.857448/

 

[Dominique-Tanguy]

Thank you for alerting me! I have not ordered yet but I was close to do it!

 

Dominique

[zilch0md]

Oh wow!  I feel so relieved to hear that!  I felt bad, sharing that information with the thought that it had already been shipped. 

 

Thank YOU for letting me know.  :-)

[jamesg11]

/& the Elgar 0.0005pfd, say 2.5kVa, are around.

[Ralf11]

Some Ruminations & Investigations on Sizing These Units:

 

 

[mourip]

I bought a Topaz 91001-31 iso transformer a bit over a year ago. I wired it up to do straight isolation, not balanced.  It made a very nice difference in my system. Much darker background allowing more fine details to emerge.

 

Today I was finishing building a good quality 8-gang power strip. I tested it with one of those simple AC socket testers that let you know about reversed wiring and ground faults. When I was done I decided to test the Topaz and it's associated hardwired 4 socket power strip. To my chagrin it told me that I had hot and neutral reversed. No problem I thought. I will just opened up my AC plug and the 4 plug box. I must have crossed my wires.

 

I opened up everything and it all looked good so I decided that it must have been the two output connections on my Topaz. I reversed them and now my tester is showing a "ground fault". I searched and searched and found no loose wires and that I had ground continuity from my AC inlet plug all the way through to the outlet box.

 

I finally gave up and left the hot and neutral rewired and put the Topaz back into service. I did test the AC tester on other wall plugs and it showed them to be correct. The plug that my Topaz plugs into also tests OK.

 

Any thoughts?

 

BTW. Here is the power distribution box I built. The box is from eBay and those are reasonably priced Leviton hospital grade receptacles. The box is really well made and costs about $50 and allows you to use your own power cord and choose your own duplex sockets.

[mourip]

19 hours ago, mourip said:

I bought a Topaz 91001-31 iso transformer a bit over a year ago. I wired it up to do straight isolation, not balanced.  It made a very nice difference in my system. Much darker background allowing more fine details to emerge.

 

Today I was finishing building a good quality 8-gang power strip. I tested it with one of those simple AC socket testers that let you know about reversed wiring and ground faults. When I was done I decided to test the Topaz and it's associated hardwired 4 socket power strip. To my chagrin it told me that I had hot and neutral reversed. No problem I thought. I will just opened up my AC plug and the 4 plug box. I must have crossed my wires.

 

I opened up everything and it all looked good so I decided that it must have been the two output connections on my Topaz. I reversed them and now my tester is showing a "ground fault". I searched and searched and found no loose wires and that I had ground continuity from my AC inlet plug all the way through to the outlet box.

 

I finally gave up and left the hot and neutral rewired and put the Topaz back into service. I did test the AC tester on other wall plugs and it showed them to be correct. The plug that my Topaz plugs into also tests OK.

 

Any thoughts?

 

 

 

Well it took a lot of time and head scratching but I believe that I have my answer. Perhaps it will help someone else.

 

As far as I can tell these little AC receptacle testers with the three lights on top and the error codes on the side are faked out by seeing a transformer up stream. I finally dragged out a stock toroidal encapsulated isolation transformer that I bought before my Topaz and tried it. It is hard wired from the factory and I get the same errors. The tester was useful for verifying the wiring of my two power distribution boxes but not once they were plugged into my IT.

[jamesg11]

Go figure ... wonder what the ‘upstream’ logic involved with that is?