Hi,
this is my second thread.
Some years ago I bought an isolation transformer from Amplimo, which probably are also sold by Plitron. It has 2x115v in and 2x115v out. And a thermo protection circuit. My intention is to put mains in, isolate and have 6 outlets for HiFi only.
The trafo XZ229, comes from their medical product line, and googling shows that balanced mains are used extensively in hospitals, and sometimes in recording studios.
Further googling gives lot of warnings to take precautions when using it, but not much about which precautions.
Two things that repeate is: Dont connect ground with CT, because it will take your ground to 115v. Is that true ? Could be helped upon by using a separate ground for HiFi.
The other thing is: When a fuse blows in a standard device, it still has half potentiel, which can cause chok and/or fire. I think that could be cured by using dual fuses in the power conditioning box.
I would like to make it real balanced like pic. 1. And include some common spike protection also.
Any input will be highly appriciated.
Best regards
Arthur.
this is my second thread.
Some years ago I bought an isolation transformer from Amplimo, which probably are also sold by Plitron. It has 2x115v in and 2x115v out. And a thermo protection circuit. My intention is to put mains in, isolate and have 6 outlets for HiFi only.
The trafo XZ229, comes from their medical product line, and googling shows that balanced mains are used extensively in hospitals, and sometimes in recording studios.
Further googling gives lot of warnings to take precautions when using it, but not much about which precautions.
Two things that repeate is: Dont connect ground with CT, because it will take your ground to 115v. Is that true ? Could be helped upon by using a separate ground for HiFi.
The other thing is: When a fuse blows in a standard device, it still has half potentiel, which can cause chok and/or fire. I think that could be cured by using dual fuses in the power conditioning box.
I would like to make it real balanced like pic. 1. And include some common spike protection also.
Any input will be highly appriciated.
Best regards
Arthur.
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the object of isolation transformer is to eliminate any galvanic contact of the secondary windings with the primary, so no need to earth any part of the secondary circuit...
you must earth(ground) the metallic casings of your gears as well as the metallic casing of your isolation transformer if used....
signal grounding is not to be connected to the power grounding....
you must earth(ground) the metallic casings of your gears as well as the metallic casing of your isolation transformer if used....
signal grounding is not to be connected to the power grounding....
you can still connect the ground at the convenience outlets to the power ground...
but as far as power is concerned, the secondary has no connection by way of center tap....this is how i do it....but the local codes in your locality can have it differently better to consult your local electrical fire safety code...
You can connect protective earth, it won't take it to 115V because the secondary is floating. This is exactly how yellow box power transformers for power tools work.
I can't see how it's going to give you any improvements though, usually it's done simply to reduce the potential for electric shock to 115V.
I can't see how it's going to give you any improvements though, usually it's done simply to reduce the potential for electric shock to 115V.
Thank you
And you think the fusing is safe enough ?
Because the main concern seems to be the missing safety.
fire safety mandates that all metallic chassis be connected to earth to prevent electrical shock to the end user...
fusing is supposed to prevent fires in case of catastrophic overloads within your equipment...
The transformer may help isolate your system from incoming mains noise. On the other hand, it may increase noise coupling between your equipment as a noise generator in one of your PSUs no longer sees the nearly zero mains impedance but the much higher transformer impedance. The net result could be better or worse.
Medical systems use this sort of transformer in order to enhance patient safety. It is unlikely to do much for audio.
Medical systems use this sort of transformer in order to enhance patient safety. It is unlikely to do much for audio.
Actually I dont have noticable noise in my system, just wanted to do everything I can to make it as good as possible. Sometimes people talk about dark background. I think that could partly be reducing noise that you dont explicitly hear.
I will also screen the power cables from the conditioning unit to my HiFi devices, and take care of right connections of phase a null, which I think are arbitrary now.
Balanced mains a reported to be used in recording studios, and the idea came from a book by a Canadian ´guru´ from a company called London Power, by the name of Kevin O´Connor. He is very knowledgable in guitar tube and FET amps.
I will also screen the power cables from the conditioning unit to my HiFi devices, and take care of right connections of phase a null, which I think are arbitrary now.
Balanced mains a reported to be used in recording studios, and the idea came from a book by a Canadian ´guru´ from a company called London Power, by the name of Kevin O´Connor. He is very knowledgable in guitar tube and FET amps.
Note that if any of your units are sensitive to mains polarity (i.e. which is live and which is neutral) and you have them connected the right way for low noise then a balanced supply will probably remove this advantage, as both sides are now live.
I suspect that balanced power is like an athlete's lucky socks: he once won a race wearing them and now attributes his success to them.
I suspect that balanced power is like an athlete's lucky socks: he once won a race wearing them and now attributes his success to them.
DF96 point in post#13 is valid, but mainly for switching powersupplies.
If you use classic or linear powersupplies it will work fine.
Although the mentioned transformer has a shield, it still is a toroid which has a high capacitance between primary and secondary, which means noise from your power line still couples into the secondary, the only improvement will be that this noise is balanced which can be canceled easily.
The shield must be connected to earth for safety and noise, but how clean is your earth ? If your mains earth is polluted, which most are, there will be still noise coupled into the secondary.
I would prefer an E I transformer for this purpose, as these have a limited bandwith.
If you use classic or linear powersupplies it will work fine.
Although the mentioned transformer has a shield, it still is a toroid which has a high capacitance between primary and secondary, which means noise from your power line still couples into the secondary, the only improvement will be that this noise is balanced which can be canceled easily.
The shield must be connected to earth for safety and noise, but how clean is your earth ? If your mains earth is polluted, which most are, there will be still noise coupled into the secondary.
I would prefer an E I transformer for this purpose, as these have a limited bandwith.
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You could be right 
My hopes for the project is to:
- Kill high voltage spikes, via a common filter on the input
- To reduce noise by making it come out +/- 180 degr. I am not sure that works
- Maybe to block DC on the input, if the trafo hums
- To block RF on each output
- Maybe to get rid of some noise by isolation.
Didnt think about the impedance thing. Will that matter if you have good PSU´s with high capacity reserve ?
My hopes for the project is to:
- Kill high voltage spikes, via a common filter on the input
- To reduce noise by making it come out +/- 180 degr. I am not sure that works
- Maybe to block DC on the input, if the trafo hums
- To block RF on each output
- Maybe to get rid of some noise by isolation.
Didnt think about the impedance thing. Will that matter if you have good PSU´s with high capacity reserve ?
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