Discussion of AC mains isolation transformers

[Speedskater]

On 8/5/2019 at 9:06 PM, One and a half said:

Capacitance meters are often inaccurate and expensive.

I never found that to be true.

In the R&D labs, I measured some 1% capacitors on different expensive meters. At home the values were the same on very inexpensive meters.

But trying to measure anything in an AC power system in the low pF ranges is a total waste of time.

 

[Ralf11]

I know some sell for $40 now - I bet they are not very accurate but have not tested them.

 

I also suspect the guy asking about his Topaz lacks a uA meter...  maybe there are some codes stamped somewhere that could help him.

 

Worst case, he'll have to hook it up and....   listen.

[cool_chris]

21 hours ago, Ralf11 said:

I know some sell for $40 now - I bet they are not very accurate but have not tested them.

 

I also suspect the guy asking about his Topaz lacks a uA meter...  maybe there are some codes stamped somewhere that could help him.

 

Worst case, he'll have to hook it up and....   listen.

 

I did listen.

it is impressive what it does.

I am just little confused with part if the „airly atmoshere „ dissapiring.

only some of it is gone.

do you see simmilar effect ?

 

[cool_chris]

So you get a lot of good things but there is a little price to pay for it ?

[Bdht]

1 hour ago, cool_chris said:

So you get a lot of good things but there is a little price to pay for it ?

Whats the rest of your equipment?  Also could just need additional time to acclimate to noise free sound.  I noticed no ill effects.

[cool_chris]

Thank you.

it was not used for last 10 years....

I will try to burn it in.

also Topaz is very cold for 1h but after that it gets very hot .

I use 5kw Topaz that is capable for probably 8A current for less than 1A current ( DAC only) so nit sure why this gets so hot.

is it normal ?

 

[Ralf11]

you mean there is less of an airy atmosphere?  i.e. less air around the instruments?

 

why not list your entire system and if you live in an apt. or stand alone house, etc.

 

also, the one hour until it gets hot is consistent, or just sometimes?

[One and a half]

For the audio system, I purchased a 1000VA Topaz and found that with ongoing demand in the future, that Topaz would need to be changed to a larger transformer. This indeed happened, the 1000VA was replaced with a 2000VA Topaz transformer some time ago.

 

For now, the 1000VA transformer is used for powering IT equipment, switches, router, sequencer and so on around the house, the load is very low, some 460mA at 120V.

During the summer, there would be frequent drop outs where the 120V failed and during the winter months there were no drop outs. Yesterday I measured the load and the case temperature of the Topaz. With the same 460mA, the case temperature was 49C for an ambient of 18C. 

In summer, typically 32C + (49-18), the case temperature can climb to 63C. The operating temperature is rated for 0-50C ambient, so it should be capable, but these are old transformers now and still absorbing common mode noise. I suspect that the transformer is getting too hot and the output voltage starts to drop. It would be better if there was a larger load, but not in the foreseeable future.

 

Goes to show that over-dimensioning a Topaz is not entirely a good thing. The Topaz was replaced with a standard toroid transformer of the same value, and its case temperature was a reasonable 30C. 

[sahmen]

I may have posted this query in the wrong forum, and have been directed to bring it here so bear with me. 

 

Embarrassing Noob question : Between the Etherregen and its own power supply unit (SMPS or LPS unit), what role (if any) might a Topaz Isolation Transformer have to play.  I am thinking of purchasing an apparently good 2.4kva Transformer to insert in my system in order to help in the business of reducing certain types of noise, and helping with surge suppression duties, but I do not have the expertise to evaluate how useful it might be, especially, in enhancing SQ, if I am also going to place the etherregen with its own power supply (or SMPS) inside the system, between my router and my Metrum Acoustic Ambre Streamer/Roon Bridge.

 

Using the most simple terms I can possibly muster, here is my current situation.  I have various types of power conditioners deployed in various parts of my general HT and AV networks around the house, which include :

 

1. A Belkin pure AV PF60 Ht Power Console 

2. Several Emotiva CMX-6 POWER DISTRIBUTION SYSTEMs WITH PRECISION COMMON MODE AC LINE FILTER

3. Several Emotiva CMX-2 PRECISION COMMON MODE AC LINE FILTERs WITH DC OFFSET ELIMINATORs

 

4. A Furman M-8X2 Merit Series 8 Outlet Power Conditioner and Surge Protector

 

 

The Topaz unit I am thinking of is a DIY unit listed with the following specs:

 

Topaz 91002-32
2.4kVa
0.0005pF 

 

-Hospital grade receptacles all wired in parrellel with equal length wire so all plugs have the same amount of wire between them and the transformer
-All wiring 10 awg milspec silver plated copper wiring with Teflon insulation
-Rhodium plated IEC inlet
-FHN55W Fuse holder

55lbs 8oz
12.25” long
8.75”wide
9” tall

 

My question is whether there is some advantage (s) to be gained, technically, and in SQ terms, if I replace all (or some fo) my current power strip line conditioners as listed in 1-4 above, with the Topaz.  I shall attempt the replace, especially, if there is some noise reduction/Sq advantages to be gained, but I do not have the expertise to make an informed evaluation in this case. I also have no way to test the unit in my system before buying because it is an a different region of the country, although I trust the Seller who also DIY'ed the unit, as far as its functionality goes. It is also relatively expensive, which is why I want to know about what advantages it might bring before taking the jump.

 

I am consulting the collective wisdom of this forum for advise, and any helpful hints would be appreciated. Thanks.

 

Now here are pictures of the unit :

 

   

[jas]

Regarding a 750va Topaz 91097-32 I just received on eBay, I checked voltage with a multi-meter and read 123-126v, and for continuity I heard the audible sound made when the meter reads continuity.  However, when I use a Sperry Outlet Circuit Analyzer, the light indicating Bad Ground lights up. I am trying to be diligent but don't know much about these things. Is the Bad Ground reading measured on a Topaz a worry, or is it indicating a floating neutral or floating ground situation as it should?  The Sperry unit was built to measure home circuits.

 

I have a few days to decide if this unit is a keeper or one that I should return, but since it is of the .0005 variety, I'd like to try to keep it.

 

Any guidance is appreciated.  Thanks,

 

[Speedskater]

Check the continuity of all possible combinations.

Input plug:

Hot, Neutral & Safety Ground

Output Receptacle:

Hot, Neutral & Safety Ground

 

I think that there are 15 combinations.

Sperry makes some smart testers and some dumb ones. What model number?

[jas]

I will check them all.  Sperry HGT6520. Amazon carries it.  Yellow, with a wider than usual body.  Thanks

 

[jas]

I checked hot, neutral and ground combinations for the input plug and output receptacle: 3 tests each making 9 total. The Sperry buzzed only on the hot to neutral connection for the plug and the same for both sides of the receptacle. But no continuity hot to ground or neutral to ground on the plug or receptacle.

 

I tested all combinations (6) between the plug and the receptacle.  I got continuity ground to ground but not for the other combinations.  I have no idea how this should test.

 

I ran it for 8 hours without a load and it got very warm to nearly hot to the touch, but not so hot that I could not keep my hand on it. 

 

Thanks for your help, much appreciated. 

[Speedskater]

If there is continuity from the plug Safety Ground to the receptacle SG, but no continuity from either SG to any H or N, that's a normal way that smaller Isolation Transformers are wired.

[jas]

That is what I found.  Thanks again, I would have sent it back without your guidance.  Much appreciated. 

[kvm]

Very useful info on this thread - many thanks to all the contributors. Am trying to revive an old thread - hopefully will get some guidance!

 

I am evaluating deploying an Isolation Transformer in my setup to primarily tackle any EMI/RFI noise on the lines. I currently have an Emerson 3KVA double-conversion online UPS on a dedicated circuit/phase feeding the entire components - both digital/ analog and amplifier. 

 

I see the recommended setup is: wall plug --> IT --> Online UPS --> components; have any of you used an IT in conjunction with a double conversion UPS in a dedicated circuit and still obtained SQ benefits? Or are these  predominantly useful in a shared circuit where other household appliances emit noise on the line? 

 

Secondly any views/ experiences on the noise filtering capabilities of an IT versus a more compact surge suppressor/ EMI filter from SurgeX etc.

 

I will NOT be able to import/source a Topaz but the best available locally is rated 0.001 pf with >100 db of common-mode noise rejection ratio. Would it be useful at all or turns out a more futile exercise - from SQ perspective?

 

Appreciate any inputs/ guidance,

 

regards

[lmitche]

3 hours ago, kvm said:

Very useful info on this thread - many thanks to all the contributors. Am trying to revive an old thread - hopefully will get some guidance!

 

I am evaluating deploying an Isolation Transformer in my setup to primarily tackle any EMI/RFI noise on the lines. I currently have an Emerson 3KVA double-conversion online UPS on a dedicated circuit/phase feeding the entire components - both digital/ analog and amplifier. 

 

I see the recommended setup is: wall plug --> IT --> Online UPS --> components; have any of you used an IT in conjunction with a double conversion UPS in a dedicated circuit and still obtained SQ benefits? Or are these  predominantly useful in a shared circuit where other household appliances emit noise on the line? 

 

Secondly any views/ experiences on the noise filtering capabilities of an IT versus a more compact surge suppressor/ EMI filter from SurgeX etc.

 

I will NOT be able to import/source a Topaz but the best available locally is rated 0.001 pf with >100 db of common-mode noise rejection ratio. Would it be useful at all or turns out a more futile exercise - from SQ perspective?

 

Appreciate any inputs/ guidance,

 

regards

Hi Kevin,

 

Looking at your setup diagram I would not say an active UPS is a good idea. Simple and passive works best here. On the AC side I have two layers of isolation transformers, one big balanced IT for the analog gear also feeding individual isolation transformers for each of 4 LPSes feeding a digital component.

[One and a half]

9 hours ago, kvm said:

Very useful info on this thread - many thanks to all the contributors. Am trying to revive an old thread - hopefully will get some guidance!

 

I am evaluating deploying an Isolation Transformer in my setup to primarily tackle any EMI/RFI noise on the lines. I currently have an Emerson 3KVA double-conversion online UPS on a dedicated circuit/phase feeding the entire components - both digital/ analog and amplifier. 

 

I see the recommended setup is: wall plug --> IT --> Online UPS --> components; have any of you used an IT in conjunction with a double conversion UPS in a dedicated circuit and still obtained SQ benefits? Or are these  predominantly useful in a shared circuit where other household appliances emit noise on the line? 

 

Secondly any views/ experiences on the noise filtering capabilities of an IT versus a more compact surge suppressor/ EMI filter from SurgeX etc.

 

I will NOT be able to import/source a Topaz but the best available locally is rated 0.001 pf with >100 db of common-mode noise rejection ratio. Would it be useful at all or turns out a more futile exercise - from SQ perspective?

 

Appreciate any inputs/ guidance,

 

regards

If you search for UPS|common mode|isolation transformer, it’s possible to use the UPS with an isolation transformer on its output. 
The isolation transformer provides for very good common mode rejection, depends which one works best, the very low pf should work well.

Very important to arrange the earths from the audio equipment so that all are connected individually to the transformer case. 
Now there are several cases either way to earth the secondary or not, my preference is for a balanced 120-0-120V since this method can reduce noise from the audio equipment to low levels. It’s also possible to earth on leg of the secondary to keep the neutral to earth voltage extremely low. 
In either case secondary needs additional protection, rcd, breakers and the like, there’s lots of information in this thread. 
240V is dangerous stuff, need to remind that there are mandatory rules that apply for its use. 

[kvm]

21 hours ago, lmitche said:

Hi Kevin,

 

Looking at your setup diagram I would not say an active UPS is a good idea. Simple and passive works best here. On the AC side I have two layers of isolation transformers, one big balanced IT for the analog gear also feeding individual isolation transformers for each of 4 LPSes feeding a digital component.

 

Hi @lmitche, thanks for the reply. Even my Audio Note dealer is somehow against an active UPS but I am more comfortable keeping it in the chain to address any sudden power outages :)

Do you by any chance have these ITs on a dedicated circuit and still found SQ improvement with them? That would help me decide. Also are any of your individual ITs with ~0.001pF/ 100dB CMNRR and found to be beneficial or I should rather forget/save money and continue enjoying music! :)

 

BTW, my moniker is kvm and not Kevin :)

 

15 hours ago, One and a half said:

If you search for UPS|common mode|isolation transformer, it’s possible to use the UPS with an isolation transformer on its output. 
The isolation transformer provides for very good common mode rejection, depends which one works best, the very low pf should work well.

Very important to arrange the earths from the audio equipment so that all are connected individually to the transformer case. 
Now there are several cases either way to earth the secondary or not, my preference is for a balanced 120-0-120V since this method can reduce noise from the audio equipment to low levels. It’s also possible to earth on leg of the secondary to keep the neutral to earth voltage extremely low. 
In either case secondary needs additional protection, rcd, breakers and the like, there’s lots of information in this thread. 
240V is dangerous stuff, need to remind that there are mandatory rules that apply for its use. 

 

Thanks @One and a halffor the reply. Somehow my UPS manual mentioned not to connect any transformer at its output so was puzzled. I would have ideally liked to connect this IT at the UPS output to take care of any perceived 'noise' generated by the UPS itself. Will research more and try to talk to my UPS dealer as well.

 

Got your view on the importance of earthing. All my equipment is connected to proper earthed terminals thru my UPS which is also properly earthed. Even I expect the IT earth to be connected from primary-secondary. I will also ensure to install circuit breakers on the IT secondary before it feeds either the UPS (in the former case) or the components (in the latter case, if I can get to connect it to the UPS output!)

 

 

[One and a half]

SQ improvements with EMC filtering

 

Digital music playback was good, but the involvement during listening would drift, is it me or is there some noise causing the problem. Both? With discussions on conducted noise with SMPS, there are quite a few of them close by the electrical input to the Topaz transformer. Although the majority of SMPS in computers are on a off line UPS with its own isolation transformer, there's no guarantee that common mode stays away from the Topaz, although it can knock quite a bit on the head.

 

So why not try an EMC filter to block out the noise for the pesky ultrasonic and RF frequencies. Schurter (via Mouser) produce a two stage filter, which filter from 100kHz to around 400MHz with varying degrees of attenuation. Although 30MHz is all that's needed for conducted noise, the extra bandwidth is some comfort. I chose the 10A model. The way these type of filters work, is different to a classic RLC filter where energy is absorbed. This filter reflects noise back to the source, so in essence it's a like to mirrors back to back (with a variable attenuation on either side for conducted noise. See the graphs below.

 

The filter is connected: Topaz output X1-X4 to L and N respectively (before via ELCB/RCBO/GFCI). The centre point at X2, X3 is connected to E (Line side) on the Filter. 

The audio load is connected to L' and N', the other E is connected to the the earth/ground of the audio system.

Physically the filter is about 20cm away from the Topaz. The audio equipment is some 25m cabling distance away.

 

Here's the circuit of the filter and the attenuation envelope. I didn't order the overvoltage VDR, since the Topaz already takes out spikes. Since the Topaz is a balanced output, the voltages across the two Cy caps are the same, so the caps work effectively like they are supposed to. When the N connection is close to the E, only 1 of the Cy caps are effective, since the voltage across the Cy is very low.

 

 

So what does it sound like? Not a night and day, but a pleasing amount of focus. It was a joy to listen at really loud levels for a change.

Lift in height, better separation and location of instruments, especially high hat. vocals were clearly in focus and sibilant material i s still like that but less cringeworthy. I'd say bass is tighter and the boom on certain recordings is gone (Sade, Bullet Proof Soul). The filter is AUD30, so the cost is minimal, and the results are very good 'bang for buck'.  I thought the inclusion of the caps could cause some ringing, or that harsh effect, but listened to most of the afternoon, and didn't hear or notice that.

 

I bought three of these and installed another one on the 230V/120V 1kVA transformer that supplies the house with 120V and has routers, wireless stations and various IT equipment, all capable of producing hash and rubbish. So this will retard noise coming back to the Topaz, bit of extra prevention.

typ_FPBB_RAIL-1316580.pdf

[Speedskater]

14 hours ago, One and a half said:

This filter reflects noise back to the source, so in essence it's a like to mirrors back to back (with a variable attenuation on either side for conducted noise.

What does that mean? I couldn't find that on the mfg's web page. Seems like a description of a long transmission line (which doesn't apply here).

[jsawyer09]

After a recent move, I discovered (forgotten) I had a couple of Topaz Ultra-Isolator Noise Suppressors (91095-31 and a smaller VA unit, 1/811T35S5R). After reading up on this with some interest, I was wondering if there would be any benefit of plugging my Google Home router and EtherRegen/LPS combo into the 500VA version with the 0.0005 pF? 

[jas]

I assume you mean by benefit you mean SQ.  If so, I use two Ultra Isolator Noise Suppressor Topaz units one for most of the front end equipment (preamp, and DAC and uR--Topaz 91001-31 .75kVA, .0005pF) and another at the source (Topaz 91097-32 .75kVA, .0005pF) for the iMac as source, an eR, and a phone company router and modem. I found that they made a nice difference in SQ and clarity and do act, per John Swenson, as surge and noise protectors. I also use a B&K Precision 1604a Iso that plugs into the Topaz 91001 at the back end.  (Both are on dedicated lines on dedicated circuits from the box, one of them with 10 gauge and the other with 12 gauge wire.

 

Overkill? Maybe, but I was using them before buying the Topaz units so tried them out together for more of the goodness and liked the sound.

Others on here will know better, but it would seem that your Topaz could easily handle the router and eR, but I would still check it out.

 

Also, it would not surprise me if I were to add another sort of Iso unit or line conditioner that SQ would be improved. 

Hope this is of some help to you.

[jsawyer09]

Thank you @jas. That's great to hear. Yes, I was looking more for a SQ benefit. I figured I had them so why not see if anyone uses them in this capacity. I thought about using it on sources in my dedicated listening room, but thought putting it before these on the network might work at least as well. I've had a PowerVar ABC1200-11 for some time, so thought about using that as well, but I'm not real keen on utilizing the power conditioning aspect of that unit. I suppose I could place the PowerVar IT before the Topaz to see how it sounds. 

I also have dedicated 20a lines. My WiFi router and switch resides two floors below my music room in a utility closet in the basement, so far away from the hifi system.

Thanks for your input! It is really appreciated and informative.   

[One and a half]

On 2/16/2021 at 4:10 AM, Speedskater said:

What does that mean? I couldn't find that on the mfg's web page. Seems like a description of a long transmission line (which doesn't apply here).

Sorry for the late answer, really. Forgot about the thread for a while.

To answer the question, Schaffner mention this technique. 

 

Interference can be reflected towards its source by incorporating an
LC network in the noise path. This prevents interference energy from
leaving a suppressed device and entering the power supply line. An
efficient inductor-capacitor combination to protect against line conducted interference consists of the following:
I Series inductances in the interference paths
I Cx capacitors between phase and neutral
I Cy capacitors between phases and earth

 

That's part of the premise of EMC filters they make, plus a pile of other common mode and differential mode suppression methods. The quote is from page 44 of the pdf with this post.

Schaffner_Brochure_Basics_in_EMC_and_power_quality.pdf