DIY balanced power conditioner

traf said:
I also made plug-in boxes with some higher value caps and even MOVs (though I definately do not recommend MOVs soldered anywhere permanently as they degrade and must be replaced at some point + sometimes fail in a fireworks mode, beware).
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I have had no problems using MOVs. You just need to carefully select ones of suitable ratings. I bought a bunch of them from Digi-key and just replace periodically.
 
I agee on the grounding the center tap. Another Q: Is it necessary (and why) to connect the power grownd of the loads (e.g. the center 0 Volt reference in the cap rails of the amp) to the ground comming from the balanced transformer? I intend to disconnect those (have ground loops that were not resolved by the balanced power as I hoped).
 
You lost me on the part about "the cap rails of the amp." Have you gone though a process of elimination to learn what is causing your ground loop(s) ? Try removing interconnects and reinstalling them one pair at a time. ICs with the shield attached at only one end may help.
 
I did lots of tests and found that one of the 2 amps had a ground loop which was solved only after I separated the power/audio ground (they cannot be separated) from the earth/shassi. My concern here is if the balanced power must have a connection between the centar tap of the balanced transformer (the earth) and the power grond of the unit (this I called the 0 Volt rail, or the star ground point, where the audio ground also goes).

Now, the other amp develops a hum after I attach any sort of cable to its input (same with /w/o the xo at the other end of that cable). This is not a loop, looks like magnetic/RF coupling. Here I am lost (tried various cables, one end shields and alike...)

I wish to aplogise for the off-topic part of my post, but I made it as I still find a relationship with the balanced power issue as it is widely beleived to cure noise/humming problems. If you have more suggestions on the loops/humming, rfi, please post them on my thread about hum/buzz.

To summarise the key relevant point, the main issue here is if the balanced power must feed only gronded loads (grounded to its cenetr tap) or this is not a must (stabiliy?)
 
Balanced power can feed grounded and ungrounded loads. My CD player and turntable are two-wire and fed from balanced power with no problems.
 
Glen B said:
Balanced power can feed grounded and ungrounded loads. My CD player and turntable are two-wire and fed from balanced power with no problems.
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Something that concerns me: if you have a typical grounded unit plugged in, when that unit is switched off, only one 60vac leg is disconnected, and the other leg is still on at 60vac to ground. It seems to me that you would nearly ALWAYS want to switch off the balanced power, and not just the plugged-in unit.

I once posted some obscure Australian and Canadian and other info on having a dedicated ground sub-system, which apparently is used in recording studios and elsewhere. In such a system you would have the 0 in this 60-0-60 system NOT connected to mains ground, but instead to a dedicated/isolated ground, maybe another copper rod via 10ga wire. I understand there are safety issues, but the point is that there are specialized applications where this is done, and legitimately. I can't recall the term for such a system, though. Obviously it is done to avoid any shared noise on the ground from appliances, groundwiring-as-antenna, etc.
 
I am happy to hear that grounding is not essential for the proper (stable) operation of BP, as this is my last hope to kill these invading hums.

As to the one leg still live issue, this is a toy compared to loop nighmare. You could install new two leg power switches (some equipment have those already) or, like me, power-on the entire group from a master switch at the BP primary.

As for safety, grounding of the case is a must, in my view.
 
traf said:
I am happy to hear that grounding is not essential for the proper (stable) operation of BP, as this is my last hope to kill these invading hums.
[snip]
As for safety, grounding of the case is a must, in my view.
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Nitpick: grounding IS essential, but there is a legit way to use a secondary ground system.

I do the master switch thing too.

Definitely ground the case.
 
tubino said:
Something that concerns me: if you have a typical grounded unit plugged in, when that unit is switched off, only one 60vac leg is disconnected, and the other leg is still on at 60vac to ground. It seems to me that you would nearly ALWAYS want to switch off the balanced power, and not just the plugged-in unit.
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Er, why ? :confused: In both grounded and ungrounded equipment the "neutral" leg will still be live when the power switch is off (unless it is of the double throw type, in which case both legs will be off). There is no reason to shut off balanced power unless the chassis of the equipment connected to it is being opened, and one would want to first unplug that equipment before opening it anyway, regardless whether it is being operated on balanced or standard power.
 
traf said:
a similar project: http://www.audiocircle.com/circles/index.php?topic=18441.0;wap2
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My comments on the cautions in the Felicia thread:

2. All output lines should be fused on both legs, as they are both now 'hot'. If the intended component is has both lines fused and switched internally, you may forgoe this, but frankly, you never know what you'll plug into what, so I'd include it regardless. Sort of a belt and suspenders approach. The fuses used should be exactly those in the component you intend to power.
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I never could quite get this idea of fusing both hot lines. If the main fuse in the connected component blows, there is no more current going to its power transformer so its "off." Yes, the "neutral" side is still hot but when was the last time you saw a problem develop in the short distance between where the neutral side wiring enters a component to the point where it goes to the power transformer that would cause an overcurrent situation ? I don't see any of the manufactured balanced power units having fused outputs -- GFCIs yes, an important safety device which I don't see recommended in the Felicia thread.

Then there's the argument that you never know what may be plugged into the balanced power unit. Oh really ? C'mon, who goes around thinking let's see, I think I will reach around in back of my equipment rack, plug that toaster into my DIY balanced power unit and make myself some toast. Or, I think I will run the vacuum cleaner on balanced power.

3. When working on components with the cover off, NEVER have it plugged into a balancing transformer. Do your mods or troubleshooting with the component pluged into a conventional single phase line for safety reasons, if the unit has to be powered.
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This is common sense.

4. A component plugged into any balancing transformer, whether Felicia or commercial unit, when not powered, should be unplugged or taken out of the circuit via a dpst switch on both output lines. The reason is that unless the components switch is a dual pole, ie switching both lines, the formerly neutral line will have leakage to ground which is not balanced by leakage from 'hot' to ground. You'd be unbalancing you balanced leakage and significantly defeating its purpose..
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This is something I had not considered but may have some merit. Not an issue for me anyway since I use separate trannys for analog and digital anyway -- amp and preamp on one tranny and always on together, CD player on the other.
 
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