Discussion of AC mains isolation transformers

[Speedskater]

Note that NEC & UL rules don't permit running cords thru walls or floors.

The home theater folk get around the rule by using products the have wall mounted plugs and sockets. so they can use normal in-wall wires.

 

Also there is almost zero chance of hearing a difference in these different (good engineering practice) AC wiring layouts. Not likely to measure a different either.

[Daudio]

14 hours ago, joelha said:

I feel bad (mostly for myself) that I'm not going going to be able to give you better information than I am right now.

 

You will, as I drag it out of you, morsel, by morsel ! Do you know the TV detective shows where they tell the witnesses "you don't know what you know !".

 

14 hours ago, joelha said:

It appears that my front end is going into only panel. However, as that panel is squirreled away behind a shelving unit, it will be difficult (although not impossible to access). So, right now, I don't have a clear view of which switches power which specific outlets or how many amps go to each switch.

 

Do you mean the main circuit breaker box for you house ? I think it would be a code violation to prevent ready access to it. Even if it isn't, a very unwise thing to do 

 

14 hours ago, joelha said:

The power amp outlets are attached to the basement ceiling. Each is about 2 - 3 feet away from the backside of their respective power amps.

 

I drew up a little picture of your system wiring from your previews replies, and now we are getting to the things I'm most interested in to try and solve your problem, so stick with me here.

My picture shows your speakers as "12-13 feet apart", with the amps suspended "directly below". I have a feeling it might actually be a little different...

 

So you have 2 separate outlets in the basement ceiling, one for each amp. Where are they located in relationship to the room ? (x,y displacement from a corner would be nice). Also you mentioned that one amps AC path was longer in the past, so there was a wiring change in your memory - what ,who, why ?

 

Does you basement have a ceiling, or can you see the Romax AC wire runs up there ?  And just for context, are you in the USA, or ?

 

[joelha]

2 hours ago, Daudio said:

 

You will, as I drag it out of you, morsel, by morsel ! Do you know the TV detective shows where they tell the witnesses "you don't know what you know !".

 

 

Do you mean the main circuit breaker box for you house ? I think it would be a code violation to prevent ready access to it. Even if it isn't, a very unwise thing to do 

 

 

I drew up a little picture of your system wiring from your previews replies, and now we are getting to the things I'm most interested in to try and solve your problem, so stick with me here.

My picture shows your speakers as "12-13 feet apart", with the amps suspended "directly below". I have a feeling it might actually be a little different...

 

So you have 2 separate outlets in the basement ceiling, one for each amp. Where are they located in relationship to the room ? (x,y displacement from a corner would be nice). Also you mentioned that one amps AC path was longer in the past, so there was a wiring change in your memory - what ,who, why ?

 

Does you basement have a ceiling, or can you see the Romax AC wire runs up there ?  And just for context, are you in the USA, or ?

 

Daudio,

 

Let me try to answer the questions I can for now.

 

I'm not referring to the main circuit breaker.

 

Yes, you've described my speaker and power amp placement fairly well.

 

The outlet for one power amp, while only a few feet from a wall is probably more like 7 - 10 feet from a corner.

 

And the other power amp outlet is about 10 feet from a corner as well.

 

The AC path is longer from one power amp than from the other only because one power amp is further from my front-end equipment than the other.

 

My basement is unfinished but the home is automated. There is so much wiring running through the ceiling that it's very hard to figure what is going where.

 

Here again, I hope this helps.

 

All the best.

 

Joel

[Daudio]

42 minutes ago, joelha said:

I'm not referring to the main circuit breaker.

 

1) Then what ???

 

41 minutes ago, joelha said:

The outlet for one power amp, while only a few feet from a wall is probably more like 7 - 10 feet from a corner. And the other power amp outlet is about 10 feet from a corner as well.

 

2) I'm sorry but that is just too vague for me to get much out of.  Look, let's call the wall behind your speakers the 'Back Wall', and the wall to the right, with your upstairs audio gear next to it is the 'Side Wall'. Now if you could grab a tape measure, and maybe a helper, and measure the locations of the two amp outlets by distance from the back wall, AND distance from the side wall. I'd also like the same for the holes in the floor up to your gear rack (I assume that is close to the upper AC outlet).

 

You might be getting frustrated, but the point of this is to try and describe your layout, to see if we might be able to rearrange your AC cabling to solve the original problem (what was it again )

 

3) I'm still curious about why and how the one amp outlet got moved. Do you have a electrical 'guy' or company ?

 

[joelha]

On 6/16/2017 at 2:07 PM, Daudio said:

 

1) Then what ???

 

 

2) I'm sorry but that is just too vague for me to get much out of.  Look, let's call the wall behind your speakers the 'Back Wall', and the wall to the right, with your upstairs audio gear next to it is the 'Side Wall'. Now if you could grab a tape measure, and maybe a helper, and measure the locations of the two amp outlets by distance from the back wall, AND distance from the side wall. I'd also like the same for the holes in the floor up to your gear rack (I assume that is close to the upper AC outlet).

 

You might be getting frustrated, but the point of this is to try and describe your layout, to see if we might be able to rearrange your AC cabling to solve the original problem (what was it again )

 

3) I'm still curious about why and how the one amp outlet got moved. Do you have a electrical 'guy' or company ?

 

Daudio,

 

Sorry. I was off-line for last 24+ hours.

 

I appreciate your time and help so much. But for now, getting an electrician involved is going to be more than I'm up for.

 

I'm sure I'm losing out on some tremendous advice from you as a result.

 

I hope you'll understand and accept my sincere gratitude for trying to help a fellow audiophile.

Joel

[mikicasellas]

Hi everyone,

 

After following this thread and purchasing my TOPAZ ISOLATOR, i have been using it for a month and very happy with the results, but today i heard an electrical sound/noise, it is the same like when you are close of an electrical plant, like "DZZZZZ" that is coming from my TOPAZ UNIT and i am concerned because i don't know if that is already causing ANY issues or is it normal.

 

Is anyone experimenting these "sound" coming from their Topaz units, i know that in the beginning i did not heard any sound coming from it.

 

Any suggestions?

[Speed Racer]

The Topaz will buzz when there is DC offset in the AC mains. In other words, when it is doing its job. I would guess you have a dimmer switch or some other new device(s) being used that is causing this.

[mikicasellas]

1 hour ago, Speed Racer said:

The Topaz will buzz when there is DC offset in the AC mains. In other words, when it is doing its job. I would guess you have a dimmer switch or some other new device(s) being used that is causing this.

 

Just today in the morning that heard this sound and all my system was connected to it, but nothing was "ON" and the Room has a dedicated line from outside, yesterday a company that is installing me Solar Panels and the inverter could have been that they connected their stuff to my "dedicated line", that is the most i can think...

 

Thanks for the input!

[mourip]

2 hours ago, mikicasellas said:

Hi everyone,

 

After following this thread and purchasing my TOPAZ ISOLATOR, i have been using it for a month and very happy with the results, but today i heard an electrical sound/noise, it is the same like when you are close of an electrical plant, like "DZZZZZ" that is coming from my TOPAZ UNIT and i am concerned because i don't know if that is already causing ANY issues or is it normal.

 

Is anyone experimenting these "sound" coming from their Topaz units, i know that in the beginning i did not heard any sound coming from it.

 

Any suggestions?

 

I have a Topaz and a couple of other medical grade isolation transformers in my house for isolating my audio equipment. They all have a physical humm. I assume DC in my AC but the transformers help so much that I do not worry much. I cannot hear it from my listening position.

[mikicasellas]

I have almost zero experience with dedicated "High End" power isolators/conditioners AKA Torus, PS  and stuff like that cost between 1000 to 3000, Do you guys think that the TOPAZ are quite in the same level or even better the ones here:

 

https://www.musicdirect.com/power/torus-rm-15-power-conditioner

 

https://www.musicdirect.com/power/torus-tot-power-conditioner

 

https://www.musicdirect.com/power/torus-is-10-power-conditioner

[mikicasellas]

...Forgot this one:

 

https://www.musicdirect.com/power/ps-audio-p3-power-plant

[Speed Racer]

I am not a big fan of uber expensive power line conditioners. The 2.5kVa Topaz 91002-31 isolation transformer that I am using right now was inexpensive and works fabulously! I think I paid $150 including shipping for it.

 

Read this thread from the beginning....

[jamesg11]

On this dc matter - thoughts?

 

From here -

http://www.stereo.net.au/forums/topic/123729-isolation-transformer-anyone-tried-the-tortech-or-any-other-one/#comment-1865035

 

"Ok, so in the end I got Anthony Holton to make me a DC blocker; I figured he designed the amp so might as well keep with the same design philosophy. 

What he designed and made is a bit of a step up in the DC blocker world, with current and voltmeters included, and a measured 100000uf (!!!) capacitance (he said that actually it's 400000uf but the circuit layout realises it at 100k?).

It measures 430mm wide (not incl rack mounts) and 230mm deep, so essentially a full width component. 

Does it work? Well now my amp is almost deathly silent; in a quiet room at night I used to hear it hum from 3m away without music playing, now I have to put my ear within 10cm of it. During the day I struggle to hear any hum at all. 

In terms if sq, impact of all frequencies is even sharper, and the imaging is off the charts; it was great before, but now its come a long way forward as well as backwards and is incredibly precise. For example, listening to Lost Cause by Beck, the picked guitar notes seem to sparkle, dance, and pop in 3D space; truly freaky, trippy stuff! 

Money very, very well spent ($600), and an upgrade I'd highly recommend if you suspect any DC contamination!"

[Speedskater]

Solar panels are a known source of noise & interference. Jim Brown a pro-audio EMI/RFI expert writes:

 

Solar Power Systems can be very strong noise sources as a result of poor design, poor installation,
or both. The best charge current regulators are DC-DC converters, and most are noisy. DC – AC
inverters that provide 120VAC are also often noise sources.  Both charge and discharge circuits
carry large pulsed currents with strong harmonics; those harmonics will radiate if the current flows
through large area magnetic loops. A large system with all wiring in steel conduit has the best
chance of being quiet, provided that the conduit is continuous and bonded to all equipment enclosures at both ends.

 

But on the other hand he also writes:

 

.  Solar power systems should always be wired with twisted pair. Genesun, a relatively new company makes a line of MPPT (the most efficient type) solar charger regulators for small systems that is quiet enough for nearly all installations

 

There has been a trend in recent years to solar panels with self-contained regulators and inverters;
properly built and installed, these can greatly reduce the loop area and thus the noise. Because the
power leaves the panel as 120VAC (or even 240V), wiring from the panel is usually in conduit. And
because the output of the panel is at the higher line voltage, the current is much less than if it were
at battery voltage. RF trash produced is directly related to current, so all of these factors can combine
 to result in less radiated noise if the units are well designed.

 

 

 

[jamesg11]

My follow up question is -

 

do we need a dc blocker in circumstances of high dc if we have one of the Topaz etc low capacitance power isolators?

 

Trying to to get a handle on the fact that many are using various types of iso transformers, dc blockers, power conditioners etc to tackle the perceived 'dc problem'.

[Speed Racer]

No, the DC won't pass through the Topaz isolation transformer. Unless, of course, the Topaz is making a lot of noise because of the excessive DC. The DC blockers use big honking capacitors which don't pass DC either. But, make sure the DC blocker has as high an AMP rating as the Topaz.

[jamesg11]

4 hours ago, Speed Racer said:

No, the DC won't pass through the Topaz isolation transformer. Unless, of course, the Topaz is making a lot of noise because of the excessive DC. The DC blockers use big honking capacitors which don't pass DC either. But, make sure the DC blocker has as high an AMP rating as the Topaz.

So, can you explain the logic of this no dc passing thru the Topaz type iso tran (with very low capacitance) compared to these dc blockers (with very high capacitance)?

 

BTW, mine is what I would describe as mildly humming.

 

[Speed Racer]

DC blockers and transformers do not pass DC offset, but they block it in different ways. DC blockers typically use big capacitors that don't pass DC offset. I don't know the physics behind it nor do I really care to know. AC transformers don't pass DC offset either. Again, I don't know the physics behind it nor do I really care to know.

 

I am sure you can find out all you want about this using Google.

[Superdad]

On 6/26/2017 at 10:22 PM, jamesg11 said:

So, can you explain the logic of this no dc passing thru the Topaz type iso tran...

 

Transformers don't pass direct current.  For a transformer to work, the current in one coil has to make current flow in the other coil and in the circuit it's connected to. A DC current in one coil will make a magnetic field on the other coil, but a magnetic field by itself won't drive any electrons around.

[jamesg11]

Thanks Alex, starting to get a sense of this ... so no dc & nothing above about 400Hz getting thru - but, that magnetic field might be a cause of iso tran hum?

[Middy]

I don't know if the Topaz can be tightened up as it is made of plates bolted together these can also rattle.

My understanding was on side becomes more saturated because oF the DC offset causing the hum. I wish I new more. Others have said there shouldn't be DC in the mains but my DC blocker did reduce my Airlink toroidal Iso balanced a bit to very quiet. 

I don't know iF a little conformal coating on the outside would help. A transformer rewinders /reconditioning firm might be a place for advice??

Let us know how you get along..

 

Good luck

 

Dave

[Speedskater]

It's probably not a true DC current. It's a DC offset in the AC waveform. Many audio editing programs can test for this in a music file. The different harmonic distortions on the power line can sum together to make an asymmetrical waveform.

[JohnSwenson]

On 6/26/2017 at 11:00 PM, Speed Racer said:

DC blockers and transformers do not pass DC offset, but they block it in different ways. DC blockers typically use big capacitors that don't pass DC offset. I don't know the physics behind it nor do I really care to know. AC transformers don't pass DC offset either. Again, I don't know the physics behind it nor do I really care to know.

 

I am sure you can find out all you want about this using Google.

The common circuit for the "DC blocker" is a diode bridge made out of high voltage diodes. The bridge conducts during most of the AC waveform except for the the volt or so around 0V. Some high value low voltage electrolytic caps are placed across the bridge such that they only see the voltage +- the diode drop (a volt or two). These caps pass the portion of the waveform around zero and block the DC near zero. Since the frequency is very low (50/60Hz) and the current is high it needs very high value caps.

 

The problem is that you now have low voltage electrolytic caps in a 120V AC circuit, if anything goes wrong which causes full voltage on the caps they become bombs. They explode. This is nothing to take lightly. Back in my young and foolish days I had this happen (not a DC blocker, but another circuit) this is not something you want happening anywhere near you. The only thing that saved my hand was that I was using a a heavy steel box to house the circuit. 

 

The common implementation of this circuit violates all kinds of electrical codes.

 

Personally I would never put one of these in my house.

 

John S.

 

[Jud]

Thanks John - helping people be safer is one of the best things we can do.

[Speed Racer]

I am glad I have a Topaz isolation transformer and no DC blocker!!