Can't edit, unfortunately. In my current "Nirvana" project I use +6.3V, -120V, +240V, and +420V. All outputs of all supplies are connected together in one point that is the ground. The same approach I use in all my designs, so I do not care what waveform of currents flow to rectifier, from rectifier, through any of it's wires, since they anyway float in respect to the ground.
Didn't the competition end in '85 with the Carver Challenge ?
"Is it possible to make a $700 'mainstream-audio' power amplifier sound exactly like a high-priced perfectionist amplifier? Bob Carver, of Carver Corporation, seemed to think he could, so we challenged him to prove it. "
"The Final Achievement . . . This time, the listening went on through the whole afternoon and much of the evening, until all of us were listened out. More leisurely listening, refreshed by a good night's sleep, failed to turn up anything. As far as we could determine, through careful comparisons and nit-picking criticisms, the two amplifiers were, in fact, sonically identical. It is a gross understatement to say that we were flabbergasted! "
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The issue being addressed by this extra complication is of current flow into an imperfect "ground". If grounds were perfect, that is, if no impedances common to dirty sources and clean signal existed, then there would be no issue. Not knowing your circuit, but trusting your abilities, I can only comment that a star ground with no ground loops is "perfect" in this respect.
If a power supply has a "power supply ground" and a single ground wire running over to meet signal ground imbalance currents flow through it. This is then *not* a star ground. If OTOH a power supply of however many parts each completely floats, then no current except that drawn by the loading amplifier flows into "ground".
Thanks,
Chris
Chris, once more: The Ground is where Outputs of voltage stabilizers are connected together. Al wires from transformers to that final point are FLOATING. No ground loops. Except through capacitances between secondaries to the shield between them and primaries. But this loops are closed through themselves, and voltage drops on them are not applied anywhere.
What about currents flowing into your reservoir caps? Is everything that comes after the transformer secondary going to be perfectly symmetrical?
se
Careful. Those wallwarts will give you frogs.
se
........... I've been swamped before ........
I think we're getting at *why* this complication is used pretty well considering no drawing is in use. Well, there was a good drawing earlier.
The reason John Curl suggested thinking of batteries is that they float, and it's the floating that matters. Imagine a really messy noisy rectifier and cap followed by an appropriate filter. If this messy noisy power supply is truly floating no current will flow through its output terminals except that drawn by its load.
And what else floats? "A duck!" "Very small rocks?" "A witch!"
If power supplies are arranged so that *only* load current flows from its output terminals and she weighs the same as a duck, then she must be a witch.
Thanks,
Chris
In John's case it is a little bit more complicated. I usually have transformer, rectifiers, and stabilizers, in the same box that they power, even when they are in different compartments shielded from each other. John had relatively long wires from power supply to the preamp. According to US regulations safety ground has to be connected to chassis directly near power socket, so such simple star ground approach that I use is impossible.
However, there are always many ways to skin the cat, so John used his own one.
However, there are always many ways to skin the cat, so John used his own one.
You don't think he switched to performance art ?
Bob Carver's 900 watt monoblock amps on Ebay
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You can create a "center tap" with batteries just as you can with transformer windings. So telling someone to think about batteries doesn't inform them as regards "floating" any more than telling someone to think about transformers does.
Only if everything is perfectly symmetrical.
So as I asked previously, is everything after the transformer secondary perfectly symmetrical?
se
Thats why you need to rectify, smooth and regulate the split secondaries first and combine them after that. Only signal return currents will then flow in the non-power ground, and if you bias everything up into class A (we are talking pre-amps here) only DC will flow in the supply rails - no signal related harmonics and wide band hash. Localized decoupling and filtering (no shunt regs please!) will further improve the overall noise performance.
Single secondary 'flipper' designs that generate a split rail suffer from more ripple and higher charging currents. And single rail, FWB rectified, smoothed and then split using a buffer to create a ground also have major compromises - especially so since the splitter is effectively in series with the signal.
You get nothing without paying for it somewhere along the line.
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