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Discussion of AC mains isolation transformers (started w/posts moved from "LPS-1 troubleshooting" thread)

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oneguy   
2 hours ago, Ralf11 said:

I attempted to create a Summary of this length thread.  Much of it direct quotes of John Swenson.

 

Interwinding capacitance being low is the key spec, ~~ 0.0001pF

 

Rule of thumb : (Sum all Watts, VA of audio equipment) / 0.6 = VA of isolation transformer

 

 

Plug everything into a Tripp Lite PS series power strip (which has no filtering in it)

 

Lowest interwinding capacitances:

Topaz 91002-32 - 0.0005 pF   1 kVA

 

Topaz 91001-32 - 30 amp

 

To reduce audible hum: The final solution is a larger box over a smaller box with air holes on the top of each with sheets of fiberfill (my wife is a quilter, she has lots of this stuff!) between boxes. On the top where the air needs to go up the sheets are diagonal so air can still go up, but there is not a straight channel for sound. It works very well at reducing the level of the hum and still leaves a fair amount of air flow so the transformer just barely gets warm.

 

Leakage Currents

 

Most leakage current consists primarily of line frequency with some harmonics.

 

 the loop that forms through one PS to its DC output through a device (usually the negative, but it can be the positive) through an interconnect,(again usually the ground or shield) (digital or audio) to another device, through ITS power supply and back through the AC line to the first power supply.   This is a low impedance loop in normally connected systems, usually less than an ohm through everything.

 

Leakage Loops are not the same as what most people call "ground loops". The traditional ground loop is caused by differences in the voltage of the safety ground wire (the third pin in the AC plug). Frequently these are caused by the AC in the hot/neutral wires causing induction into the ground wire that is traveling along with them (in the three wire "romex").

 

Leakage loops are completely different. They are caused by leakage of the AC line (hot/neutral) through capacitances in the power supply to the DC output of the PS. They have nothing to do with the ground wire.  Ground loops usually cause audible hum, but leakage loops do not typically result in any audible hum or buzz noise.  Leakage loops can decrease SQ.  Effects: noise floor, details and clarity in the timbre of voices and instruments, soundstage.  

 

 

Leakage loops go through AC line, power supply of box, through interconnects to another box, through ITs PS to the AC line and back to the original box. You may have MANY such loops in a complex system.

 

Make a schematic drawing of your system, include all the boxes and both their AC power connections and signal interconnects between boxes. Make a bunch of copies of this and trace out possible leakage loops.

 

Next, assess which loops are going to be most detrimental to sound quality. Loops going through the actual audio equipment are the most likely, so a loop through a DAC, preamp, poweramp etc are the most critical ones to look at. It's important to asses the amplitude of the loops, this is broken up into two primary issues, power supply type and impedance of the connections. Switching supplies (SMPS) usually have significantly [greater] leakage issues than linear supplies. Thus a loop going through two SMPS is going to have the highest amplitude, a loop going through two linears is going to be low amplitude and a loop with one SMPS and one linear is going to medium amplitude.

 

A very common situation is a computer with a USB connection to a DAC. This can be a very bad loop because the computer frequently uses a switching supply, AND is frequently on a different outlet or power strip from the DAC. Thus you have high amplitude from the SMPS and high impedance on the AC side of the loop. You can help this in several ways: put a linear supply in the computer, put the computer PS on the same strip as the DAC, or break the loop with an isolating device such as an intona or the upcoming ISO REGEN on the USB connection.

 

Devices like the LPS-1 and the Intona actually BLOCK leakage loops, the LPS-1 through the device it is powering, and the Intona through the USB line. This is particularly important because the SMPS in most computers is usually the source of the worst leakage loop in the system, which goes through the computer to DAC and back through the line. The leakage loop through the DAC is particularly bad because the noise from the leakage loop can modulate the clock in the DAC.

 

Devices like DACs, preamps, power amps etc that have their own AC power supplies, WILL have leakage loops

 

 

An Isolation Transformer does NOT block leakage currents. 

It prevents high frequency noise from outside your audio system from getting into your audio system, AND provides surge suppression without requiring MOVs which can degrade sound quality.

 

Once the leakage currents are eliminated or reduced via an Intona, LPS-1, etc. an isolation Transformer with a simple (Tripp-Lite) power strip attached is a simple, elegant way to decrease the effect of leakage loops through other devices.

Excellent summary!

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mourip   
7 hours ago, jamesg11 said:

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

 

Dunoh! I am very curious also...

 

It is a guess on my part based upon repeatable results but with not enough understanding to be certain. I was hoping someone with more EE knowledge would shed some light on it. All I can say is that using the meter with a transformer in the circuit creates a "false" reading.

 

My only thought is that there is "continuity" between the hot and neutral via the secondary of the transformer which the tester does not expect to be present?

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Dear all,

 

I am also using an isolation transformer and faced the same issue. My tester could not recognize phase from neutral anymore.

 

I have received 3 days ago the new ISO Regen, that I have installed in replacement of a Regen. I am using a Sbooster as power supply.

 

My first listening of the ISO Regen was a bit disappointing. I decided to wait for a while, considering a potential burn in issue... Until this post gave me the idea to reverse the connection of my Sbooster plug...

 

Significant difference now. I start to enjoy the ISO Regen.

 

Am I dreaming?

 

Dominique

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Cornan   
1 hour ago, Dominique-Tanguy said:

Dear all,

 

I am also using an isolation transformer and faced the same issue. My tester could not recognize phase from neutral anymore.

 

I have received 3 days ago the new ISO Regen, that I have installed in replacement of a Regen. I am using a Sbooster as power supply.

 

My first listening of the ISO Regen was a bit disappointing. I decided to wait for a while, considering a potential burn in issue... Until this post gave me the idea to reverse the connection of my Sbooster plug...

 

Significant difference now. I start to enjoy the ISO Regen.

 

Am I dreaming?

 

Dominique

 

A question. Do you prefer ISO Regen with GI off or GI on? That's important for my personal conclution.

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Cornan   
6 hours ago, mourip said:

 

Dunoh! I am very curious also...

 

It is a guess on my part based upon repeatable results but with not enough understanding to be certain. I was hoping someone with more EE knowledge would shed some light on it. All I can say is that using the meter with a transformer in the circuit creates a "false" reading.

 

My only thought is that there is "continuity" between the hot and neutral via the secondary of the transformer which the tester does not expect to be present?

 

What you'll need to know it that a isolation transformer with floating secondary change the 0v reference from ac mains to the transformer. The meter is simply not seeing the safety ground. It is seeing the chassi of the isolation transformer.

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Cornan   
13 hours ago, Ralf11 said:

I attempted to create a Summary of this length thread.  Much of it direct quotes of John Swenson.

 

Interwinding capacitance being low is the key spec, ~~ 0.0001pF

 

Rule of thumb : (Sum all Watts, VA of audio equipment) / 0.6 = VA of isolation transformer

 

 

Plug everything into a Tripp Lite PS series power strip (which has no filtering in it)

 

Lowest interwinding capacitances:

Topaz 91002-32 - 0.0005 pF   1 kVA

 

Topaz 91001-32 - 30 amp

 

To reduce audible hum: The final solution is a larger box over a smaller box with air holes on the top of each with sheets of fiberfill (my wife is a quilter, she has lots of this stuff!) between boxes. On the top where the air needs to go up the sheets are diagonal so air can still go up, but there is not a straight channel for sound. It works very well at reducing the level of the hum and still leaves a fair amount of air flow so the transformer just barely gets warm.

 

Leakage Currents

 

Most leakage current consists primarily of line frequency with some harmonics.

 

 the loop that forms through one PS to its DC output through a device (usually the negative, but it can be the positive) through an interconnect,(again usually the ground or shield) (digital or audio) to another device, through ITS power supply and back through the AC line to the first power supply.   This is a low impedance loop in normally connected systems, usually less than an ohm through everything.

 

Leakage Loops are not the same as what most people call "ground loops". The traditional ground loop is caused by differences in the voltage of the safety ground wire (the third pin in the AC plug). Frequently these are caused by the AC in the hot/neutral wires causing induction into the ground wire that is traveling along with them (in the three wire "romex").

 

Leakage loops are completely different. They are caused by leakage of the AC line (hot/neutral) through capacitances in the power supply to the DC output of the PS. They have nothing to do with the ground wire.  Ground loops usually cause audible hum, but leakage loops do not typically result in any audible hum or buzz noise.  Leakage loops can decrease SQ.  Effects: noise floor, details and clarity in the timbre of voices and instruments, soundstage.  

 

 

Leakage loops go through AC line, power supply of box, through interconnects to another box, through ITs PS to the AC line and back to the original box. You may have MANY such loops in a complex system.

 

Make a schematic drawing of your system, include all the boxes and both their AC power connections and signal interconnects between boxes. Make a bunch of copies of this and trace out possible leakage loops.

 

Next, assess which loops are going to be most detrimental to sound quality. Loops going through the actual audio equipment are the most likely, so a loop through a DAC, preamp, poweramp etc are the most critical ones to look at. It's important to asses the amplitude of the loops, this is broken up into two primary issues, power supply type and impedance of the connections. Switching supplies (SMPS) usually have significantly [greater] leakage issues than linear supplies. Thus a loop going through two SMPS is going to have the highest amplitude, a loop going through two linears is going to be low amplitude and a loop with one SMPS and one linear is going to medium amplitude.

 

A very common situation is a computer with a USB connection to a DAC. This can be a very bad loop because the computer frequently uses a switching supply, AND is frequently on a different outlet or power strip from the DAC. Thus you have high amplitude from the SMPS and high impedance on the AC side of the loop. You can help this in several ways: put a linear supply in the computer, put the computer PS on the same strip as the DAC, or break the loop with an isolating device such as an intona or the upcoming ISO REGEN on the USB connection.

 

Devices like the LPS-1 and the Intona actually BLOCK leakage loops, the LPS-1 through the device it is powering, and the Intona through the USB line. This is particularly important because the SMPS in most computers is usually the source of the worst leakage loop in the system, which goes through the computer to DAC and back through the line. The leakage loop through the DAC is particularly bad because the noise from the leakage loop can modulate the clock in the DAC.

 

Devices like DACs, preamps, power amps etc that have their own AC power supplies, WILL have leakage loops

 

 

An Isolation Transformer does NOT block leakage currents. 

It prevents high frequency noise from outside your audio system from getting into your audio system, AND provides surge suppression without requiring MOVs which can degrade sound quality.

 

Once the leakage currents are eliminated or reduced via an Intona, LPS-1, etc. an isolation Transformer with a simple (Tripp-Lite) power strip attached is a simple, elegant way to decrease the effect of leakage loops through other devices.

 

I really appreciate your sum-up and really enjoy it. Great work! However, there is more to it than what meets the eye. General suggestions is just things that works in usual or normal circumstances. If you want to step-up in performance there is no other way than to experiment. Who knows if you've got an unusual and uncommon setup? Just saying. Not even John Swenson can keep track on every single varaible in every single setup. His recommendation is general. That's it! 😊

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Cornan   
51 minutes ago, Dominique-Tanguy said:

Hi,

 

I prefer with the switch on the "I" position.

 

Dominique

 

For me I preferred the GI off until I bought the Luckit BluWave USB to Spdif (powered by a battery supply) and used it between the IR/USPCB and Brooklyn DAC. Now I prefer the GI on.

 

IMG_6832.thumb.JPG.47b939c20ee7af832e1956d9fd9de4ce.JPGIMG_6822.thumb.JPG.5b20b8d0215a27c1ccba3122ba57d669.JPG

 

Another thing was that I had the DC- output grounding of my SMPS powering the ISO Regen. The SQ jumped when removing that perticular DC- output grounding and leaving the ones connected to network devices only. 

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6 hours ago, Cornan said:

 

For me I preferred the GI off until I bought the Luckit BluWave USB to Spdif (powered by a battery supply) and used it between the IR/USPCB and Brooklyn DAC. Now I prefer the GI on.

 

IMG_6832.thumb.JPG.47b939c20ee7af832e1956d9fd9de4ce.JPGIMG_6822.thumb.JPG.5b20b8d0215a27c1ccba3122ba57d669.JPG

 

Another thing was that I had the DC- output grounding of my SMPS powering the ISO Regen. The SQ jumped when removing that perticular DC- output grounding and leaving the ones connected to network devices only. 

 

The reason the SQ drops, is because in your totally floating system, there's no reference to ground only the one that you've connected on the 0V line. So all the digital signal and AC crud (created by the equipment) ends up on the single connection to ground. What's missing are more ground connections. 

 

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Cornan   
7 hours ago, One and a half said:

 

The reason the SQ drops, is because in your totally floating system, there's no reference to ground only the one that you've connected on the 0V line. So all the digital signal and AC crud (created by the equipment) ends up on the single connection to ground. What's missing are more ground connections. 

 

 

My intire system is connected to a star-earth wired PSD into a balanced isolation transformer. All my DC powered devices except the Brooklyn DAC is powered by floating SMPSs. The Aqvox switch and the DC- output powering the switch is grounded to a Entreq Minimus. All the DC cables have dual inline LT3045 voltage regulator a close to the powered device (not the Brooklyn DAC since it is powered by it's internal SMPS). The balanced IT have a toggle switch at the outside of the case where I can choose to ground the center tap or float it.

 

IT_Cornan.thumb.png.892a14ac0c306b0bcb6f68bc125fb5c3.png

There is a major difference in SQ having the center-tap floating. Grounding it clearly decrease SQ. 

Where do you mean that I should add ground connections? I have grounded a lot and if I ground it to anything but the Entreq Minimus it usually turns worse with a edgier sound. I have a star-earth receptacle on the PSD. Not even that one beats Minimus in my setup.

 

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30 minutes ago, Cornan said:

 

My intire system is connected to a star-earth wired PSD into a balanced isolation transformer. All my DC powered devices except the Brooklyn DAC is powered by floating SMPSs. The Aqvox switch and the DC- output powering the switch is grounded to a Entreq Minimus. All the DC cables have dual inline LT3045 voltage regulator a close to the powered device (not the Brooklyn DAC since it is powered by it's internal SMPS). The balanced IT have a toggle switch at the outside of the case where I can choose to ground the center tap or float it.

 

IT_Cornan.thumb.png.892a14ac0c306b0bcb6f68bc125fb5c3.png

There is a major difference in SQ having the center-tap floating. Grounding it clearly decrease SQ. 

Where do you mean that I should add ground connections? I have grounded a lot and if I ground it to anything but the Entreq Minimus it usually turns worse with a edgier sound. I have a star-earth receptacle on the PSD. Not even that one beats Minimus in my setup.

 

I just had a look at the system of power supplies from the profile page, each device in the chain from the Aries has its own power supply.

First question, do you need that many? Can't they be consolidated to just one? Or are the devices different voltages, like the ISOregen and the Aries, USB- S/PDIF converter? 

Second question is the IT, do you know what capacitance it has between the primary and secondary windings? I can work out for you the leakage quickly. The leakage from that transformer couples to everything.

Third question is that switch in the centre point of the transformer. It is illegal to have any switching device in a protective earth. The short circuits on the load travel to the source, and they can't if the connection is open. 

Fourth question is the arrangement of the grounds on the DC supplies, are they star arranged or looped from one to the other? 

Fifth question, the Minimus box, does that have a connection to the protective earth?

 

Very, very complex system. 

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Cornan   
9 hours ago, One and a half said:

I just had a look at the system of power supplies from the profile page, each device in the chain from the Aries has its own power supply.

First question, do you need that many? Can't they be consolidated to just one? Or are the devices different voltages, like the ISOregen and the Aries, USB- S/PDIF converter? 

Second question is the IT, do you know what capacitance it has between the primary and secondary windings? I can work out for you the leakage quickly. The leakage from that transformer couples to everything.

Third question is that switch in the centre point of the transformer. It is illegal to have any switching device in a protective earth. The short circuits on the load travel to the source, and they can't if the connection is open. 

Fourth question is the arrangement of the grounds on the DC supplies, are they star arranged or looped from one to the other? 

Fifth question, the Minimus box, does that have a connection to the protective earth?

 

Very, very complex system. 

 

Sure, it is a very complex system. It sounds great though! 😁

 

You had some questions:

 

1. All devices require different voltages. The only two with same voltages is the Aqvox switch and the BluWave. I am planning to power those two from the same Gophert but will have to order a couple of LT3045s in order to get that project going. Since I am moving to another place in a couple of months it will have to wait.

I can quite easily consolidate ISO Regen, BluWave & Aqvox switch into one plus Aries Mini and Brooklyn into one. I will need to buy additional voltage regulators though.

 

2. I have no idea about the inter-winding capacitance of my ATL balanced IT, but I did ask him to use the transformer with lowest possible inter-winding capacitance. Since it sounds great and better than my other two ITs I am happy.

 

3. I am using a 2-pole RCD/GFCI at the output of the IT and it has a fuse at the input (exept a central circuit breaker panel with RCD/GFCI). Is'nt that safe enough you mean? The toggle switch have a safety cover. I am not touching it while powered on.

 

4. All my Gopherts are connected to the same starquad wired and star-earthed PSD, so they are star arranged (as well as all the other gears connected to the PSD) AFAIK.

 

5. No, the Entreq Minimus do not have a connection to protective earth.

 

 

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1 hour ago, tboooe said:

Hi guys...quick question that I am hoping someone can explain to me.  Does adding an isolation transformer in front of a PS Audio P3/P5/P10 AC regenerator make sense or is it overkill?

 

Here is more info on the PS Audio product:

http://www.psaudio.com/products/p5-power-plant/

On the front end, the isolation transformer will only damp the current pulses from the regenerator.

Far more effective would be to fit it on the output, or as a replacement for the P5. 

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On 11/20/2017 at 4:20 AM, Cornan said:

 

Sure, it is a very complex system. It sounds great though! 😁

 

You had some questions:

 

1. All devices require different voltages. The only two with same voltages is the Aqvox switch and the BluWave. I am planning to power those two from the same Gophert but will have to order a couple of LT3045s in order to get that project going. Since I am moving to another place in a couple of months it will have to wait.

I can quite easily consolidate ISO Regen, BluWave & Aqvox switch into one plus Aries Mini and Brooklyn into one. I will need to buy additional voltage regulators though.

 

2. I have no idea about the inter-winding capacitance of my ATL balanced IT, but I did ask him to use the transformer with lowest possible inter-winding capacitance. Since it sounds great and better than my other two ITs I am happy.

 

3. I am using a 2-pole RCD/GFCI at the output of the IT and it has a fuse at the input (exept a central circuit breaker panel with RCD/GFCI). Is'nt that safe enough you mean? The toggle switch have a safety cover. I am not touching it while powered on.

 

4. All my Gopherts are connected to the same starquad wired and star-earthed PSD, so they are star arranged (as well as all the other gears connected to the PSD) AFAIK.

 

5. No, the Entreq Minimus do not have a connection to protective earth.

 

 

There was some study needed on the LT3045 and understanding of how it works. It's a low noise LM317T in principle, OK.

 

You may have to invest in a higher voltage DC PSU, as the LT3045 needs a little more volts to output 12V, I haven't studied piece by piece. 500mA is the limit for the LT3045, there are no hard drives, so please check this.

 

From the one large Linear PSU, connect all LT3045 in parallel and each one to the load (Isoregen....). For each 0V output connection on the LT3045 output at the source, bring back a separate 1mm or larger green/yellow wire to the 0V of the larger supply.

 

From the 0V of the larger supply, run a 2.5mm or larger single green yellow wire to the centre point of the IT. Remove the earth switch and connect the earth wires of the AC loads to the centre point of the IT.

Ensure the incoming earth cable is connected to the centre tap of the secondary of the transformer.

 

This will give you star grounding and provided the AC distribution is from the one distribution power strip, your earthing is good to go.

 

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