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Old 5th June 2004, 02:24 PM   #11
Bricolo is offline Bricolo  France
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There's something I don't understand.

If it's just a 1:1 transformer, and that it takes the harsh and noise out, why wouldn't any classibal step down transformer do the same for the noise & harsh?
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Old 5th June 2004, 04:08 PM   #12
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Quote:
if you have DC on your AC wall power you have more to worry about than your stereo!
I have no idea what you mean by that. Most AC outlets contain some amount of DC for well known reasons. IME it's usually in the tens or hundreds of milivolts but apparently can get up to a few volts in some cases.
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Old 5th June 2004, 04:19 PM   #13
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Originally posted by analog_sa


I have no idea what you mean by that. Most AC outlets contain some amount of DC for well known reasons. IME it's usually in the tens or hundreds of milivolts but apparently can get up to a few volts in some cases.
Please tell me how the this alleged DC gets through the step down transformer on the street before it comes into your house? Here's a clue - it can't.
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Old 5th June 2004, 04:36 PM   #14
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Please tell me how the this alleged DC gets through the step down transformer on the street before it comes into your house? Here's a clue - it can't.
It doesn't. It originates on my side of the transformer.
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Old 5th June 2004, 04:37 PM   #15
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Originally posted by analog_sa


It doesn't. It originates on my side of the transformer.

WHAT!!!???? Please tell me why and how.
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Old 5th June 2004, 04:38 PM   #16
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Bricolo - yes all xfrmrs were the same. From your last post, I don't think you have a solid understanding of xfrmr operation (haaa, do any of us really?). It's true an isoxfrmr is 1:1 and removes noise, but they are usually made a bit differently than regular power xfrmrs in that the primaries & secondaries are wound in a "nonconcentric" manner (i.e. they don't overlap or interleave), therefore they have less mutual coupling which in turn doesn't conduct the signal as well (i.e. noise). Anyway, that's just one of the many aspects if isos. As far as your step-down reference goes, that kind will actually "step-down" the voltage to say,..half the value (e.g. 240v to 120v),...a different kind of beast altogether.

The xfrmrs I purchased were of the split-bobbin type, or non-concentrically wound. I purchased them for their isolation characterstics and have come to learn that is really the kind one needs for audio. Toroids are popular but are wider in bandwidth, something that can be argued against in an audio supply. And with that statement - let the rumble begin!!..) (boy oh boy, I love this place!)
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Old 5th June 2004, 04:56 PM   #17
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Thank you for the explanation.


So, split bobbin or non concentrically wound transformers "reject" noise. But isn't it better to use such transformers in out amps power supplies, rather than a split bobbin (or non concentrically wound) isolation transformers and toroids in the PS?
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Old 5th June 2004, 05:08 PM   #18
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Default toroid noise rejection

Quote:
Originally posted by Bricolo
So, split bobbin or non concentrically wound transformers "reject" noise. But isn't it better to use such transformers in out amps power supplies, rather than a split bobbin (or non concentrically wound) isolation transformers and toroids in the PS?
Maybe the best way to reject noise is to cancel it via balancing the AC on a high-bandwidth balanced transformer? The higher the bandwidth, the more high frequency noise generated before or after the transformer is cancelled? See white paper discussions on the Equi=Tech website.

I've tried (still own) lossy EI balanced isolation transformers and opposite-of-lossy high bandwidth toroid balanced isolation transformers and the latter win hands down. I mean, no contest whatever in what I heard.
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Old 5th June 2004, 05:12 PM   #19
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Default split bobbin or non concentrically wound transformers "reject" noise

Yes, they do. A further explanation would be that the interwinding capacitance is cut way down, say from several 100 pf to say 1pf, quite a reduction. It is this capacitance path that allows leakage for high freqs. Remember, caps are "shorts" at high freqs.

As for the rest of your question, I am sorry,..try as I might, I don't understand a word of it... "in out amps power supplies" has me scratching my head.
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Old 5th June 2004, 05:20 PM   #20
Bricolo is offline Bricolo  France
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sorry it was a typo

the correct sentense is


So, split bobbin or non concentrically wound transformers "reject" noise. But isn't it better to use such transformers in our amps power supplies directly, rather than a split bobbin (or non concentrically wound) isolation transformers and toroids in the amps PS?
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