AC Filtering, Grounding Boxes, Linear PSU and Balanced Power.

[Jud]

2 hours ago, allhifi said:

literally, ground-breaking discoveries

 

They really just use basic laws of electricity.

[marce]

Had a look around at balanced power, I would be wary of using it in the USA, in the UK its a definite no way... Unless the whole dwelling has be designed for balanced power then to me the risks are not worth it for domestic audio (again we have approx 2X the line voltage here in the UK). Isolation transformers are far better.

Just one of the safety critical views, there are more:

http://www.soundonsound.com/sound-advice/crosstalk-readers-writes

[One and a half]

One aspect of balanced power is why it was introduced in the first place that discussion here is non existent. Standard type EMC filters are symmetrical by design like this:

When the neutral is tied to ground, it messes up the current flows, balanced power fixes that 'imbalance'.  Every audio device worth its salt has an EMC filter to prevent crud leaking back into the network, so it makes sense to provide a voltage that's suitable. 

I'm quite happy with the Equitech Q, it provides a great way to suppress background noise, for years I listen to the silky black provided by this power source. 

For safety, there's a RCD on the output of the Equitech, and balanced power is only used for audio equipment. Plain daft to use it for computers or anything else for technical reasons and code compliance. I did draw a circuit in another thread for reference.

 

@marce 230V is still 230V whether referenced to 115V either side or a TN 230V. 60V is considered 'low voltage' (in my country) and that classification requires regulatory principals the same as if it were < 1000V. Voltages 24V and lower are considered non lethal and non licensed persons can do what they like with that equipment.

Higher voltages generally have lower harmonics, but have twice as much leakage currents as 120V systems. Your choice?

I found the article from Sound on Sound to be uninformative and in some cases misleading and BS. There are ways to protect people and equipment.

[marce]

Yes but most hosues and systems don't have the double fusing set up as the article said. Also refer to the Bill Whitlock links earlier.

[marce]

Anyone actually measured the difference balanced mains makes? would be curious to see if there is any difference in a domestic environment and if so how much... 

[Cornan]

It would be very interesting to know anyones opinion about the Ultra isolation transformers http://www.aelgroup.co.uk/hb/hb019.php as well, since these IT´s have the ground tied to the electrostatic shield? 

 

I have two setups. One with a safety IT connected to a ac mains DC blocker trap filter and one with a Ultra IT connected to a star grounded Naim strip.  Both is very good, but if I would to choose one I would without a doubt choose the safety IT (ie. with floating secondary). It simply sounds better to me with digital music.

 

BTW. I found this "Power Quality Myths and Magic" interesting http://www.aelgroup.co.uk/pdf/wp_powqal.pdf

[zilch0md]

On 5/30/2017 at 6:55 AM, Cornan said:

It would be very interesting to know anyones opinion about the Ultra isolation transformers http://www.aelgroup.co.uk/hb/hb019.php as well, since these IT´s have the ground tied to the electrostatic shield? 

 

I have two setups. One with a safety IT connected to a ac mains DC blocker trap filter and one with a Ultra IT connected to a star grounded Naim strip.  Both is very good, but if I would to choose one I would without a doubt choose the safety IT (ie. with floating secondary). It simply sounds better to me with digital music.

 

BTW. I found this "Power Quality Myths and Magic" interesting http://www.aelgroup.co.uk/pdf/wp_powqal.pdf

 

Most modern ITs have electrostatic (Faraday) shields between the Primary and Secondary coils and, if there, they are always grounded.  I would be very surprised to learn that you IT doesn't also have a grounded shield, as shown in both of the diagrams I recently posted.

 

Floating the secondary's neutral attenuates normal-mode noise and prevents "backwash" to the mains.

Grounded-neutral secondaries attenuate common-mode noise.

 

I am still very satisfied with my conclusion that stacking them serially, gives me the lowest noise floor:

 

Mains > IT with grounded-neutral secondary (a single IT with sufficient rating to power everything in the chain) > Individual ITs with floating-neutral secondary.

 

Affordable and effective:

 

https://www.amazon.com/Tripp-Lite-Isolation-Transformer-Outlet/dp/B00006HPHN/  (grounded-neutral secondary)

 

https://www.amazon.com/Precision-1604A-Single-Isolation-Transformer/dp/B000LDLF3M (floating-neutral secondary)

 

I like @One and a half 's recommendation of using an RCD at the output of an IT (or balanced-power solution) that has a floating-neutral secondary. In the end, I can hear the same thing you're hearing - a lower noise floor with digital audio when using an IT that has a floating-neutral secondary.  Adding an RCD to the output puts to rest any safety concerns (in addition to the safety ground that already runs uninterrupted through the IT from the component all the back to the wall outlet.)

 

https://www.amazon.com/TRC-90265-6-012-Shockshield-Portable-Protection/dp/B000XU5MEG

 

 

[zilch0md]

By the way, I really like this paragraph.  

 

Qutoing:  http://www.aelgroup.co.uk/hb/hb019.php

 

Quote

If a shielded transformer feeds another shielded transformer, there is an effect of the attenuation ratio multiplying as shown in Figure 3. If the attenuation ratio is 100:1 in each of the transformers, the total attenuation will be 100x100=10,000:1. Obviously, cascading inherently multiplies the attenuation effectiveness of shielded transformers. The term cascading means that two or more transformers are connected in series on the same system.

 

[Cornan]

Thanks Mike! Detailed as always! ?

 

10 minutes ago, zilch0md said:

 

Most modern ITs have electrostatic (Faraday) shields between the Primary and Secondary coils and, if there, they are always grounded.  I would be very surprised to learn that you IT doesn't also have a grounded shield, as shown in both of the diagrams I recently posted.

 

AFAIK the Ultra IT have the electrostatic shield connected to ground. But, do you mean that a IT with grounded secondary is in fact exactly the same as a Ultra IT?

 

13 minutes ago, zilch0md said:

 

I am still very satisfied with my conclusion that stacking them serially, gives me the lowest noise floor:

 

I am equally sure that stacking them is the way to go to deal with both common-mode  and differential-mode noise. However, there is more than one way to do that. AFAIK using for example balanced power supply, a AC mains DC blocker or a UPS pre a floating IT can do the trick as well.

 

18 minutes ago, zilch0md said:

Adding an RCD to the output puts to rest any safety concerns (in addition to the safety ground that already runs uninterrupted through the IT from the component all the back to the wall outlet.)

 

I use mine without a RCD/GFCI without being scared. Too many catastrophic failures that'll have to go wrong for it to be leathal. But I would never recommend not to use it anyway! ?

[Cornan]

15 minutes ago, zilch0md said:

By the way, I really like this paragraph.  

 

Qutoing:  http://www.aelgroup.co.uk/hb/hb019.php

 

 

 

I can imagine you liked it! Mee too! ?

[EuroChamp]

I have a diy IT in use, together with a DC blocker. I compared it to other commercially available solutions and I am satisfied.

This is my transformer:

http://www.amplimo.nl/images/downloads/ds audio/ZN1902S.pdf

 

The DC filter consists of four diodes and two Mundorf elkos.

[zilch0md]

4 hours ago, Cornan said:

Thanks Mike! Detailed as always! ?

 

 

AFAIK the Ultra IT have the electrostatic shield connected to ground. But, do you mean that a IT with grounded secondary is in fact exactly the same as a Ultra IT?

 

 

I am equally sure that stacking them is the way to go to deal with both common-mode  and differential-mode noise. However, there is more than one way to do that. AFAIK using for example balanced power supply, a AC mains DC blocker or a UPS pre a floating IT can do the trick as well.

 

 

I use mine without a RCD/GFCI without being scared. Too many catastrophic failures that'll have to go wrong for it to be leathal. But I would never recommend not to use it anyway! ?

 

Hey Micael,

 

In answer to your first question, have another look at this diagram:

 

 

You can have a grounded Faraday shield with or without a grounded-neutral secondary.

 

And this diagram, where the text reveals that both types of ITs have grounded Faraday shields:

 

 

So, I wasn't saying that an IT with a grounded-neutral secondary is exactly the same as the Ultra IT, because there's probably an IT made by somebody that has a grounded-neutral secondary without also having a grounded Faraday Shield.  

 

----

 

I, too, have been using my floating-neutral secondary IT without an RCD, but agree that it can't hurt to have one. (Ordered.)

 

[zilch0md]

I wish I had your skills @EuroChamp  

[theophile]

On 26/05/2017 at 5:16 AM, marce said:

No but I have bags and bags of my German Sheppard's hair... 

Free.

Great hangover cure.

[Cornan]

11 hours ago, EuroChamp said:

I have a diy IT in use, together with a DC blocker. I compared it to other commercially available solutions and I am satisfied.

This is my transformer:

http://www.amplimo.nl/images/downloads/ds audio/ZN1902S.pdf

 

The DC filter consists of four diodes and two Mundorf elkos.

 

Great work! You would´nt have any pictures to show? I would be very interested to see both the IT and the DC blocker. I am using ATL DC blocker trap filter pre my floating IT (Peaktech2240) myself http://www.atlhifi.com/shop/fully-assembled-devices/dc-blocker-trap-filter-assembled-in-case/, but hard-wired and looking like this in the end.

 

 

[EuroChamp]

1 hour ago, Cornan said:

 

Great work! You would´nt have any pictures to show? I would be very interested to see both the IT and the DC blocker. I am using ATL DC blocker trap filter pre my floating IT (Peaktech2240) myself http://www.atlhifi.com/shop/fully-assembled-devices/dc-blocker-trap-filter-assembled-in-case/, but hard-wired and looking like this in the end.

 

 

 

Maybe not the best pictures. I should open the case and make a foto of the finished product

 

 

 

And these are the Mundorfs:

http://www.mundorf.com/en/?category=hifi&menu=caps_power&content=mlytic_ag_2pin

I have the MLGO25-47000

About the diodes, if it where of any interest, I would have to check it.

[Cornan]

33 minutes ago, EuroChamp said:

 

Maybe not the best pictures. I should open the case and make a foto of the finished product

 

 

 

I can see that you are using a ATL PCB built in. Nice one EuroChamp!

 

I am trying to collect enough confidence to build a IT with this DIN-version isolation transformer transformer https://www.conrad.se/?websale8=conrad-swe&pi=1390804.

 

 

It should be easy in theory, but I´ll just need to come across my worst fears (safety) to get this project going. I am looking for a suitable case right now. It will be used post a Ultra IT without a DC blocker.

[EuroChamp]

Just now, Cornan said:

 

I can see that you are using a ATL PCB built in. Nice one EuroChamp!

 

I am trying to collect enough confidence to built a IT with this DIN-version isolation transformer transformer https://www.conrad.se/?websale8=conrad-swe&pi=1390804.

 

 

It should be easy in theory, but I´ll just need to come across my worst fears (safety) to get this project going. I am looking for a suitable case right now. It will be used post a Ultra IT without a DC blocker.

 

I bought the ATL and the case on ebay. Case is from China. I could write down the schematics of my wiring, but not before the evening. I could send you a picture of the sheet. Maybe it helps.

[Cornan]

8 minutes ago, EuroChamp said:

 

I bought the ATL and the case on ebay. Case is from China. I could write down the schematics of my wiring, but not before the evening. I could send you a picture of the sheet. Maybe it helps.

 

Thanks, it would be very helpful indeed. Appreciate it! I am not in a hurry, so no rush!  

 

BTW. Here is the the information about it in germain if anyone else is interested http://www.produktinfo.conrad.com/datenblaetter/1300000-1399999/001390804-da-01-de-FAIL_SAFE_TRANS__100_VA_FST_100_23.pdf

[EuroChamp]

1 hour ago, Cornan said:

BTW. Here is the the information about it in germain if anyone else is interested http://www.produktinfo.conrad.com/datenblaetter/1300000-1399999/001390804-da-01-de-FAIL_SAFE_TRANS__100_VA_FST_100_23.pdf

 

I would prefer a transformer with 2x115V on the secondary site. In the middle of the two 115V coils we could groud it. So we build a new pseudo virtual groud for your stereo. In my tests this was a SQ improvement.

Check and see the transformer I linked some posts ago.

 

=> yellow and blue is shortened and connected to ground.

[Speedskater]

A filter in a box (like pictured above) should have as short an output cord as practicable. A zero length cord would be best, but that would be hard to do.

[Cornan]

1 hour ago, EuroChamp said:

 

I would prefer a transformer with 2x115V on the secondary site. In the middle of the two 115V coils we could groud it. So we build a new pseudo virtual groud for your stereo. In my tests this was a SQ improvement.

Check and see the transformer I linked some posts ago.

 

=> yellow and blue is shortened and connected to ground.

 

But that would make your IT a balanced power supply/balanced IT, right?

What I want to build is a IT with a floating secondary since I already have a Ultra IT (IT with electrostatic shield and grounded secondary) in front of it.

[Cornan]

38 minutes ago, Speedskater said:

A filter in a box (like pictured above) should have as short an output cord as practicable. A zero length cord would be best, but that would be hard to do.

 

Are you referring to this picture?

 

 

It was unfortunately the best option I could do of purly practical reasons (room space/obstacles). I am aware that a shorter input cable would be optimal, but it still improved upon SQ as is, so I am happy!

[Speedskater]

Well yours are almost 6 feet shorter than what most audiophiles use to connect components to power conditioners.

[EuroChamp]

For a simple DC filter, I see no huge disadvantage, when the cable is not the very shortest.

Different story with a HF filter.