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In Reply to: Re: a good isolating trannie is FAR better, two could give you balanced AC posted by Brian Walsh on February 20, 2007 at 09:45:16:
"I'm not a proponent of balanced power. For one thing it can raise safety concerns, and for another not all components will work with it, for example EMMlabs gear doesn't. I imagine they and others have valid reasons this is so."Please enlighten us as to how Balanced power is NOT safe!!
I have been using balanced power for over 5 years in 3 seperate systems and all the gear I've owned/used works on Balanced Power and works extremely well!! I am at a loss as to the EMM labs gear. Is the EMM labs gear designed to operate on 120VAC? If so, it will certainly function if fed balanced power.
Curious minds want to know where your getting your information.
Cheers,
Follow Ups:
HowdyBalanced power isn't simply 120V, it's safety ground is at 60V relative to either side instead of 0V relative to neutral and 120V relative to hot. Since this isn't 'standard' it may be violating the assumptions of the designers of various gear. The assumption is that unless their is a failure the ground is within a few volts of the neutral leg. There are a lot of ways of tying the safety ground to the signal ground, thru a resistor, a fuse, a gas discharge tube, a "ground lift" switch, etc. Not all of these react well to a constant 60V difference when just a few volts are expected. One can easily imagine audio degradation if not outright failure with balanced power on some components.
If you insist on balanced power IMO you should contact the manufacturer of every piece of equipment that you are going to plug in to it and ask if their design works with balanced power. If it doesn't don't blame them, it's balanced power that's the oddball.
I also appreciate equipment that checks it's assumptions about the ground and shuts down if the ground is more than a few volts different than the neutral. This indicates to me that they are interested in my safety.
Thanks, Ted. You said it as well as anyone else could have.
Best regards,
"If you insist on balanced power IMO you should contact the manufacturer of every piece of equipment that you are going to plug in to it and ask if their design works with balanced power. If it doesn't don't blame them, it's balanced power that's the oddball."With Balanced power, one still gets the full 120VAC swing that is delivered with unbalanced power. The main difference is that the voltage swings -60VAC and +60VAC at a 60/50hz rate and I don't see how that could in any way effect component functionality.
"Not all of these react well to a constant 60V difference when just a few volts are expected. One can easily imagine audio degradation if not outright failure with balanced power on some components."
Yes, the chassis of said component should be electrically attached to the earth GND of the balanced power supply for optimum performance/safety BUT if the component employs a 2 prong plug in the first place and is UL listed as being safe, how is utilizing Balanced power going to pose a safety/electrical hazard?Cheers,
HowdyI wasn't restricting my post to two pronged equipment. Heck the only two pronged equipment in my system are Tivos and CD jukeboxes :)
"I wasn't restricting my post to two pronged equipment. Heck the only two pronged equipment in my system are Tivos and CD jukeboxes :)"Even still, there R NO safety dangers with Balanced Power. It is perfectly safe and one only needs to do some research to find out it is. I still can't fathom how any piece of equipment designed to operate on 120VAC would not function safely on balanced power!
Please peruse the link provided :-)Cheers,
~kenster
HowdyI can't see how anyone couldn't see the danger. I'm serious.
Did you read my post? What don't you believe that I said in that post?
There are many devices which will obviously work. There are many which obviously won't. Then there are the ones which work for a while and then catch fire :) (Only slightly kidding.) Even if it could theoretically work for some equipment that equipment isn't tested in this configuration so we really shouldn't put too much confidence in that testing...
I'll never take a manufacturer of balanced power's word for it that it's safe. There are people out there that think MultiWave is a good idea too :)
............I certainly did read your post and reply'd in what I felt to be in a competent manner. Did U read the FAQ's about balanced power?"I'll never take a manufacturer of balanced power's word for it that it's safe."
Oh please, it's UL listed as being safe!!
"There are people out there that think MultiWave is a good idea too :)"
What do U have against PS Audio's Multiwave?
HowdyUL doesn't test with a ground at 60V for the life of the equipment so their test isn't necessarily relevant for the long term health of the equipment. It's only a slight exaggeration to say that UL doesn't care if your device self destructs under test, they only care if it hurts someone in doing so.
All of my arguments against MultiWave are the same as my arguments again indiscriminate use of balanced power. I'll try to write them in generic form for both MultiWave and balanced power:
They violates the assumptions of the designer of the equipment. That equipment isn't tested with inputs like that and some equipment which is competently designed will fail when put under that needless stress of unexpected input. The equipment isn't tested with those kinds of input and unforeseen problem could arise later if not when first plugged in... I wouldn't ever use such a feature without consulting the manufacturer (well actually for some of my equipment that I know uses a quality switching power supply I know that it doesn't care about MultiWave, then again why would I use anything but a pure sine for it anyway.)
"UL doesn't test with a ground at 60V for the life of the equipment so their test isn't necessarily relevant for the long term health of the equipment. It's only a slight exaggeration to say that UL doesn't care if your device self destructs under test, they only care if it hurts someone in doing so."The 60VAC is irrelevant. What is it that your missing? Balanced power STILL has the 120VAC swing and the device will still be protected in either situation.
I would refer U to the benefits of Multiwave but it sounds like U have already made up your mind. Either way, I still use the sinewave mode on my PS Audio PP-600 as it does sound better with tube equipment :-)
Cheers and thanx for the banter,
HowdyThe voltage of the safety ground certainly isn't irrelevant. As I mentioned before since standard practice is that it's very close to the same voltage as neutral except when some component has failed there are many ways that a designer could build something that cares when it isn't and in fact some better pro gear specifically shuts down when the safety ground is too far away from the neutral. UL doesn't care if something shuts down under test, but the user might :) Another example is the equipment that has a bleed resistor from the safety ground to the signal ground which may not be designed for the continuous current that 60V implies.
My point is that operating equipment outside of it's design parameters and it's testing domain is asking for trouble.
Good to see that you went to bed :) Have a good night. I'll listen to Rachmaninov another time or two...
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