Discussion of AC mains isolation transformers

[JohnSwenson]

Once full digital part has been isolated, why not isolate only the dac with AC isolation instead of DAC + (preamp) + amp ? The transformer will be chapper and smaller.

HF are not critical for amp as they are for the DAC (except mabe for D class amp) and "leakages" the way J.S. describe them would be blocked.

 

 

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Tplink optical bridge/etalon streamer/audiogd nfb29/linn klout/athom sirrocco + athom rafale v38 hypex

 

Please read the post I linked earlier in this thread, the isolation transformer is NOT to provide leakage current isolation, it is a means to provide surge suppression and AC mains noise suppression from the outside world into the audio system.

 

This is important because I am recommending getting rid of the traditional "power conditioner" multi-outlet boxes with lots of filtering, in order to achieve very low AC mains impedance between boxes. Without the filtering when using a plain power strip (just wire) you need something else to provide surge suppression and outside world noise suppression. These extremely low capacitance isolation transformers do that in a very simple, elegant solution.

 

John S.

[JohnSwenson]

Can someone who uses a smaller to medium size Topaz comment on how much heat these units generate?

 

When sitting idle (with equipment also sitting idle but powered on) and when playing music?

 

Thanks.

 

I have the 1KVA Topaz, at full playing LOUD for hours at a time, it gets a little warm, only a few degrees above ambient.

 

My system is pretty low power, I have very efficient speakers and a 60W amp, the entire digital front end is taking about 10W. So I'm not pulling very much out of the Topaz.

 

Remember these are big heavy transformers, it takes a LONG time to reach thermal equilibrium (MANY hours).

 

John S.

[fob69]

Please read the post I linked earlier in this thread, the isolation transformer is NOT to provide leakage current isolation, it is a means to provide surge suppression and AC mains noise suppression from the outside world into the audio system.

 

This is important because I am recommending getting rid of the traditional "power conditioner" multi-outlet boxes with lots of filtering, in order to achieve very low AC mains impedance between boxes. Without the filtering when using a plain power strip (just wire) you need something else to provide surge suppression and outside world noise suppression. These extremely low capacitance isolation transformers do that in a very simple, elegant solution.

 

John S.

 

I had undestrood but don't the isolator transfo block the leakages you describe too by breaking the way to the amp psu ?

 

B.

 

 

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Tplink optical bridge/etalon streamer/audiogd nfb29/linn klout/athom sirrocco + athom rafale v38 hypex

[fob69]

(If on the dac only)

 

 

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Tplink optical bridge/etalon streamer/audiogd nfb29/linn klout/athom sirrocco + athom rafale v38 hypex

[sandyk]

a very interesting thing that i remarked about to a friend is that when the noise was inaudible, these measures subjectively resulted in the sorts of classic changes we've all described in these pages - better soundstage and imaging, more detailed intonation in vocals and instrumental playing, a greater sense of ease in listening.

 

So i know for a fact these things work to reduce noise, and my subjective impression is that even when noise was not audible they were beneficial in my system.

 

spot on !!!

[JohnSwenson]

I'm sure this is a very small sample size but I will ask anyway:

* has anyone who uses a Topaz/Eaton quality iso transformer ever used it with or replaced an Uberbuss (my power conditioner for my front end).

 

Also,a more general question, is the attack plan to first size and use a Topaz for the front end or for the amps (assuming one cannot find or afford to size for both)?

 

Hi Ted,

I'll cover the general question first, specifically where do you need the isolation transformer? It is there to provide external world noise suppression and surge suppression to a simple power strip with no filtering or surge suppression. THAT strip is used to provide extremely low AC mains impedance to help decrease the sonic degradation from leakage currents.

 

IF everything is plugged into the same simple strip you can only have one device to provide surge and noise suppression. The only way you can have more than one outside world suppressor is if you have two or more power strips, and that blows away the advantage from having the single simple power strip, you now have a higher impedance between groups of devices.

 

Remember the single strip is to decrease the degradation due to existing leakage loops, if you don't have any leakage loops you don't need the single strip stuff. So if you have a digital source powered by an LPS-1 and the DAC is also powered by a LPS-1 (either separately or VBUS from say a microRendu) and you are going directly into a power amp, then you can't have a leakage loop through the poweramp since the only thing connected to it has all ITS leakage loops blocked.

 

As to your specific existing power conditioner, IF it has nothing between outlets, just wire, then you can use it as is. IF it has anything other than wire between outlets (all three connections, a common ground is not sufficient), then you could use the existing conditioner as an outside world filter and plug a separate simple power strip into one of the existing outlets. This keeps the low impedance and gives outside world filtering. Something like the Topaz is actually a much better filter than what you have, but yours is much better than many others, so it is certainly all right to use it, you don't HAVE to switch to the isolation transformer approach.

 

I think it is a really good idea to make a diagram of all the audio equipment, power and signal connections, include any digital connections etc. From this you can trace connections and see where you have leakage loops through power supplies and come up with an approach to minimize the affects due to these. Make sure you include paths through power strips, power conditioners etc, they are part of the loops.

 

John S.

[JohnSwenson]

(If on the dac only)

 

 

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Tplink optical bridge/etalon streamer/audiogd nfb29/linn klout/athom sirrocco + athom rafale v38 hypex

 

Aha, you are talking about using the low capacitance transformer on just one component as a means of blocking leakage current through that specific component.

 

I don't know how well that would work. I have not tried that specific configuration. That depends on how well the transformer blocks leakage currents. If the component of leakage current that causes a problem is high frequency then it will probably work well. If the lower frequency components are important then the transformer will not be effective since it is designed to pass line frequency and close in harmonics. (usually stated that it passes up through 400Hz and starts suppressing above that)

 

That configuration might have some usefulness in some circumstances but in my looking at leakage current waveforms I see that most of the time the line frequency and close in components make up by far the largest component of the leakage current. But if it is just high frequency components that affect SQ it might work.

 

It would be an interesting test to compare a low capacitance transformer and an LPS-1 to the same component in the same system and see what the difference in SQ is.

 

John S.

[genjamon]

Aha, you are talking about using the low capacitance transformer on just one component as a means of blocking leakage current through that specific component.

 

I don't know how well that would work. I have not tried that specific configuration. That depends on how well the transformer blocks leakage currents. If the component of leakage current that causes a problem is high frequency then it will probably work well. If the lower frequency components are important then the transformer will not be effective since it is designed to pass line frequency and close in harmonics. (usually stated that it passes up through 400Hz and starts suppressing above that)

 

That configuration might have some usefulness in some circumstances but in my looking at leakage current waveforms I see that most of the time the line frequency and close in components make up by far the largest component of the leakage current. But if it is just high frequency components that affect SQ it might work.

 

It would be an interesting test to compare a low capacitance transformer and an LPS-1 to the same component in the same system and see what the difference in SQ is.

 

John S.

 

Thanks, John. I'm also curious - wouldn't this also create a larger possibility of more traditional ground loops in the system as well? Due to the different components connected through interconnects being on slightly different ground potentials?

[One and a half]

Thanks, John. I'm also curious - wouldn't this also create a larger possibility of more traditional ground loops in the system as well? Due to the different components connected through interconnects being on slightly different ground potentials?

 

Not necessarily. By sourcing all the AC at one point is one step to providing equipotentials.

There will always be a ground loop with RCA connections however. The ISO transformer will keep the certain house AC crud out but the audio components are their own worst enemy.

[ericuco]

John - you keep mentioning a "simple single strip".

 

In my case, I would need to have a "simple single strip" plugged into the isolation transformer but I need to have at least one and possibly two additional "simple strips" plugged into the first "simple strip" in order to reach all my equipment. Obviously I could get longer power cords as well.

 

So my question is having multiple secondary strips coming off the main strip accomplish the same results?

 

 

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[asdf1000]

Hi Ted,

I'll cover the general question first, specifically where do you need the isolation transformer? It is there to provide external world noise suppression and surge suppression to a simple power strip with no filtering or surge suppression. THAT strip is used to provide extremely low AC mains impedance to help decrease the sonic degradation from leakage currents.

 

IF everything is plugged into the same simple strip you can only have one device to provide surge and noise suppression. The only way you can have more than one outside world suppressor is if you have two or more power strips, and that blows away the advantage from having the single simple power strip, you now have a higher impedance between groups of devices.

 

Remember the single strip is to decrease the degradation due to existing leakage loops, if you don't have any leakage loops you don't need the single strip stuff. So if you have a digital source powered by an LPS-1 and the DAC is also powered by a LPS-1 (either separately or VBUS from say a microRendu) and you are going directly into a power amp, then you can't have a leakage loop through the poweramp since the only thing connected to it has all ITS leakage loops blocked.

 

As to your specific existing power conditioner, IF it has nothing between outlets, just wire, then you can use it as is. IF it has anything other than wire between outlets (all three connections, a common ground is not sufficient), then you could use the existing conditioner as an outside world filter and plug a separate simple power strip into one of the existing outlets. This keeps the low impedance and gives outside world filtering. Something like the Topaz is actually a much better filter than what you have, but yours is much better than many others, so it is certainly all right to use it, you don't HAVE to switch to the isolation transformer approach.

 

I think it is a really good idea to make a diagram of all the audio equipment, power and signal connections, include any digital connections etc. From this you can trace connections and see where you have leakage loops through power supplies and come up with an approach to minimize the affects due to these. Make sure you include paths through power strips, power conditioners etc, they are part of the loops.

 

John S.

 

Hi John, if I had 3 power outlets fitted to the iso transformer, and had double adapters in each, giving a total of 6 outlets, would that be the same as having a single strip with 6 outlets - in terms of impedance between devices.

 

Seems hard in Australia to find a well built power strip with no filtering, circuit breaker etc etc

[One and a half]

Hi John, if I had 3 power outlets fitted to the iso transformer, and had double adapters in each, giving a total of 6 outlets, would that be the same as having a single strip with 6 outlets - in terms of impedance between devices.

 

Seems hard in Australia to find a well built power strip with no filtering, circuit breaker etc etc

 

The chain should look like this:

Iso transformer output -> portable rcd 30mA -> standard 6+ standard plug board with no suppression devices.

Have the power amp and pre amp close to the cable end and the sources can follow whatever you wish.

 

Try to find boards that are 4x 2 instead of 6 x 1.

[sandyk]

John - you keep mentioning a "simple single strip".

 

In my case, I would need to have a "simple single strip" plugged into the isolation transformer but I need to have at least one and possibly two additional "simple strips" plugged into the first "simple strip" in order to reach all my equipment. Obviously I could get longer power cords as well.

 

So my question is having multiple secondary strips coming off the main strip accomplish the same results?

 

 

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If it was me I would have the distribution boards side by side if possible , and cut the lead length of the AC input cables of the additional strips as short as possible, with each additional strip plugged into the outlet closest to the incoming mains cable of the previous additional strip. Just be careful when shortening the AC cables and fitting new plugs to them.

[asdf1000]

The chain should look like this:

Iso transformer output -> portable rcd 30mA -> standard 6+ standard plug board with no suppression devices.

Have the power amp and pre amp close to the cable end and the sources can follow whatever you wish.

 

Try to find boards that are 4x 2 instead of 6 x 1.

 

This is the hard part to find here in Aus: standard 6+ standard plug board with no suppression devices

 

John S mentioned, no filtering, no switch, no circuit breaker.

 

So I have the option to fit 3 outlets on the iso transformer output. I can then add a double adapter to each (which only has wiring, no filters) giving a total of 6 outlets. Will that achieve the same impedance between devices as a single strip with 6 outlets?

 

And what would be the role of the portable RCD after the iso transformer? Especially if I had a 10A switch/fuse at the iso trans input?

[esmit]

Does the RCD help sound quality in a way? Is it needed even if you have an RCD where the power enters your house?

 

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[One and a half]

This is the hard part to find here in Aus: standard 6+ standard plug board with no suppression devices

 

John S mentioned, no filtering, no switch, no circuit breaker.

 

So I have the option to fit 3 outlets on the iso transformer output. I can then add a double adapter to each (which only has wiring, no filters) giving a total of 6 outlets. Will that achieve the same impedance between devices as a single strip with 6 outlets?

 

And what would be the role of the portable RCD after the iso transformer? Especially if I had a 10A switch/fuse at the iso trans input?

 

Even Bunnings?

[asdf1000]

Even Bunnings?

 

Yeah, they all have surge protection, or a circuit breaker, or both. If you know if any without switch/surge protection/circuit breaker, let me know because I've looked everywhere. Possibly only Elsafe can make a power distribution board, but that would have to be a custom make.

 

What's the advantage of having an RCD between an iso transformer and your gear, compared with the RCD in the home's meter box (which @esmit is also asking above I think)

[One and a half]

Does the RCD help sound quality in a way? Is it needed even if you have an RCD where the power enters your house?

 

Sent from my D6633 using Computer Audiophile mobile app

 

I will find a previous post explaining why rcd is necessary on the output of an iso transformer and link it in this thread.

[asdf1000]

Even Bunnings?

 

Also regarding impedance between devices, can anyone help me with this: I have the option to fit 3 outlets on the iso transformer output. I can then add a double adapter to each (which only has wiring, no filters) giving a total of 6 outlets. Will that achieve the same low impedance between devices, as a single strip with 6 outlets would?

[fob69]

Aha, you are talking about using the low capacitance transformer on just one component as a means of blocking leakage current through that specific component.

 

 

 

I don't know how well that would work. I have not tried that specific configuration. That depends on how well the transformer blocks leakage currents. If the component of leakage current that causes a problem is high frequency then it will probably work well. If the lower frequency components are important then the transformer will not be effective since it is designed to pass line frequency and close in harmonics. (usually stated that it passes up through 400Hz and starts suppressing above that)

 

 

 

That configuration might have some usefulness in some circumstances but in my looking at leakage current waveforms I see that most of the time the line frequency and close in components make up by far the largest component of the leakage current. But if it is just high frequency components that affect SQ it might work.

 

 

 

It would be an interesting test to compare a low capacitance transformer and an LPS-1 to the same component in the same system and see what the difference in SQ is.

 

 

 

John S.

 

I think an isolation transformer if if it has an electrostatic shield will block comon mode noise (included "leakage") that comes over transfo, througth the electrostatic shield (very efficient) and will block non comon mode noise an other way with its inductance (that migth be much less efficient). AC power goes from primary to secondary throught magnetic field for which electrostatic shield is transparent.

 

My dac has embeded class A preamp so i can't put it on battery or other decoupling power supply.

 

I had schaffners filters but since i optmised my digital chain with battery decoupling and network isolation, i have much less harchness in SQ and i realize i probably liked before the schaffner for their low pass action on audio spectrum and digital harchness more that their ability to filter ac noise. They probably do it well, but they colored the sound too and affect the dynamics.

I just removed them.

 

For my experience, isolation transfo colored the sound too. Mine opens the sound stage and i am quite sure it is due to hf noise filtering. But it has too a strong impact on sound with a low meduim lack. The effect i have is about the same that if i switch neutral and phase on my dac AC input (without the transfo). I ask myself if the fact to loose phase and neutral with the transfo wouldn't provide the same kind of effect.

 

DAC noise isolation, (and network noise isolation on ethernet side) are still for me to issues badly adressed.

 

B.

 

 

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Tplink optical bridge/etalon streamer/audiogd nfb29/linn klout/athom sirrocco + athom rafale v38 hypex

[One and a half]

As promised, here is the reason to install an RCD/GFCI.

[asdf1000]

As promised, here is the reason to install an RCD/GFCI.

Thanks for that. Might just stick with a single outlet on my iso trans and add one of these: Clipsal - 951 - Twin Switch Socket Outlet, 250V, 10A, 2 Gang, Circuit Identification, Safety Shutter, White Electric

 

And then add one of these to the RCD's outlet: https://www.racklink.com.au/products/5190dd8de387edcd65b49245

 

with the option of no circuit breaker, no switch and just a short 1m lead.

 

Thoughts?

[Jud]

John - you keep mentioning a "simple single strip".

 

In my case, I would need to have a "simple single strip" plugged into the isolation transformer but I need to have at least one and possibly two additional "simple strips" plugged into the first "simple strip" in order to reach all my equipment. Obviously I could get longer power cords as well.

 

So my question is having multiple secondary strips coming off the main strip accomplish the same results?

 

 

Sent from my iPad using Computer Audiophile

 

This may help:

 

GE 6-Outlet Grounded Adapter-Spaced Tap-50759 - The Home Depot

 

https://smile.amazon.com/gp/product/B0027JPKIE/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

Audio Catalog

[One and a half]

Also regarding impedance between devices, can anyone help me with this: I have the option to fit 3 outlets on the iso transformer output. I can then add a double adapter to each (which only has wiring, no filters) giving a total of 6 outlets. Will that achieve the same low impedance between devices, as a single strip with 6 outlets would?

 

Forget double adapters, their connections are too sloppy. There's nothing on the Australian market that does what we need to do.

 

You mentioned an electrician that is re-working the Elgar when it arrives? I thought to use standard 4 Way Outlets and a mounting block.

Put two of these back to back, and wire via shielded power cable to the RCD. A fire resistant timber perhaps would jazz it up. The joining wires can be short, there are only three, so impedance is not an issue.

 

Available here

 

Available here

 

This is what I made before standardising on Oyaide and Furutech Euro standard plugs and sockets, there's nothing much for AU style even from Furutech only one or two models, that's it. Euro gear is rated for 230V and it stops anyone else using a vacuum cleaner out of the system. Choices.

 

Never use NEMA 120V plugs and sockets on 230V systems. You don't pressurise a tyre rated maximum at 30psi and you put in 60psi?

 

[sandyk]

And then add one of these to the RCD's outlet: https://www.racklink.com.au/products...87edcd65b49245

 

with the option of no circuit breaker, no switch and just a short 1m lead.

 

Thoughts?

 

You do realise that this is meant to normally be the rear panel of a 1 Unit rack case such as the attached from Altronics ?

H5031 1U Black Aluminium Front Panel 19" Rack Case - Altronics