Currently the mains in my house does not have a safety earth (Until not so long ago Dutch houses only had them in bathrooms and kitchens.)
So will something like a balanced power supply actually have advantages? I can imagine that having my dac, phono preamp and linestage etc. all attached to the same psuedo earth will prevent possible ground loop problems.
In my case I could just omit the center tap to safety earth connection?
So will something like a balanced power supply actually have advantages? I can imagine that having my dac, phono preamp and linestage etc. all attached to the same psuedo earth will prevent possible ground loop problems.
In my case I could just omit the center tap to safety earth connection?
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Something like this was tried a year or 2 ago by Ray on the humungous CD 63 / 67 thread.
It's now on his website.
Balanced Power Source
Andy
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It's now on his website.
Balanced Power Source
Andy
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Surprising a ground was not required just a few years back. I assume the utility has grounded the supply at the transformer, but just not required bonds at your panel? I can't imagine the enclosure of your panel is actually floating. Is it tied to neutral (if one is provided)?
A shielded isolation transformer is really all you should need, but I would definitely try to find a way to give yourself a grounded secondary. Maybe grab a tap off your water service or something. I'm not convinced on the need for balanced power when the transformers you connect it to are not balanced. I prefer the grounded neutral / hot method and finding the high capacitance lead on each downstream power transformer I use. That lead connects to the neutral.
I have an AC drive feeding my well pump. It spits out copious amounts of noise. Until I used a C-core power transformer for my D/A, I never had any noise issues. Split bobbin or shielded were sufficient. Once I installed the shielded transformer (1500 VA for the entire system), all was silent as could be. Maybe someday I'll swap out the C-core.
Technically, balanced power is not permitted in a US residence. Next comes many posts with 'hang the code' and 'I've been doing it for years'
A shielded isolation transformer is really all you should need, but I would definitely try to find a way to give yourself a grounded secondary. Maybe grab a tap off your water service or something. I'm not convinced on the need for balanced power when the transformers you connect it to are not balanced. I prefer the grounded neutral / hot method and finding the high capacitance lead on each downstream power transformer I use. That lead connects to the neutral.
I have an AC drive feeding my well pump. It spits out copious amounts of noise. Until I used a C-core power transformer for my D/A, I never had any noise issues. Split bobbin or shielded were sufficient. Once I installed the shielded transformer (1500 VA for the entire system), all was silent as could be. Maybe someday I'll swap out the C-core.
Technically, balanced power is not permitted in a US residence. Next comes many posts with 'hang the code' and 'I've been doing it for years'
It is, but split 240V is not the subject here. Bas has generated 120V single phase with the midtap grounded (60-0-60). The desire is to plug either DIY or commercial products into this supply. These products are designed for 120V operation and have either 2 or 3 wire plugs, typically polarized.
NEC Section 647 specifically addresses this application. Requirement #1:
"The system is installed only in commercial or industrial occupancies."
There are many other requirements that I suspect no DIY'er has bothered to follow. Just ground the center tap and away you go.
NEC Section 647 specifically addresses this application. Requirement #1:
"The system is installed only in commercial or industrial occupancies."
There are many other requirements that I suspect no DIY'er has bothered to follow. Just ground the center tap and away you go.
I have a PS Audio P600 Powerplant & the output of that is a balanced 120V 0V 120V output. I believe that the same is true of the american version which would be similar to what you are planning, the only difference being a 1 to 2 ratio step up transformer just before the output.
I couldn't actually say if this has advantages over the standard system as there is the Powerplant already doing it's own clean up of the mains 🙂
Hi
I'm not sure about in the US but in the UK having an isolation transformer in this manner gets around the "Code" as its an isolated supply.
I think the same would be true in the US as if it were'nt
the code would apply to high voltage supplies in tube amps etc these can be up to 1500Vdc.
Ben Duncan has a compendium of articles entitled "high quality mains audio supplies" which extols the virtues of the balanced supply.
Dam
I'm not sure about in the US but in the UK having an isolation transformer in this manner gets around the "Code" as its an isolated supply.
I think the same would be true in the US as if it were'nt
the code would apply to high voltage supplies in tube amps etc these can be up to 1500Vdc.
Ben Duncan has a compendium of articles entitled "high quality mains audio supplies" which extols the virtues of the balanced supply.
Dam
Bas.... I think your situation is quite similar to what most people in Norway have - grounded outlets in "wet" rooms only , - and the kitchen cooker.
You most certainly have ground in your fuse cab, so either a new circuit for your stuff, or a single ground lead back to the use cab.
An isolation transformer will also do the trick, and maybe get rid of some noise, if there are any heavy industrial subscribers in your area.
If that grounded center tap is the secondary of an amp, I'd use a low ohm fuse resistor , or an NTC ground resistor ala Pass Labs....
EDIT: Just realized that you prob'ly have a hot/neutral circuit? In that case neutral should be connected to earth in the fuse cab - as pr.standard EU reg's...the extra circuit or the new ground lead still holds, though....
You most certainly have ground in your fuse cab, so either a new circuit for your stuff, or a single ground lead back to the use cab.
An isolation transformer will also do the trick, and maybe get rid of some noise, if there are any heavy industrial subscribers in your area.
If that grounded center tap is the secondary of an amp, I'd use a low ohm fuse resistor , or an NTC ground resistor ala Pass Labs....
EDIT: Just realized that you prob'ly have a hot/neutral circuit? In that case neutral should be connected to earth in the fuse cab - as pr.standard EU reg's...the extra circuit or the new ground lead still holds, though....
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Have actually used that one I posted in a recording studio and a scientific lab. One used an off the shelf 240 to 120 transformer and the other was a custom one for the lab. The lab one also got a series LC circuit to force the wave into a sine.
Sumaudioguy,
Question about post#6 – why did you mark secondary windings 60V?
I have actually made one with technical ground etc. I modified Jon Rish’ schematic for my needs. I remember Jon had a long reliability disclaimer on his site, therefore I am showing only a picture.
I also tried the Power Plant 300 - it was running hot even when switched off – a total waste of energy. If I were younger I would take my dedicated room off the grid.
Marek
Question about post#6 – why did you mark secondary windings 60V?
I have actually made one with technical ground etc. I modified Jon Rish’ schematic for my needs. I remember Jon had a long reliability disclaimer on his site, therefore I am showing only a picture.
I also tried the Power Plant 300 - it was running hot even when switched off – a total waste of energy. If I were younger I would take my dedicated room off the grid.
Marek
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That is some sloppy drawing there ehy? Wrong is wrong- it should be 0 and 120 volts.
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