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Old 4th May 2012, 01:23 PM   #21
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Quote:
Originally Posted by DF96 View Post
Andrew never asked you to insert 10 ohm resistors in random places. Neither did I. Why not try thinking, instead of poking fun at people trying to help you?
I've gone through the thread. Could you please point out where he is poking fun at people? I can't find it.

j
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Old 4th May 2012, 01:34 PM   #22
AndrewT is offline AndrewT  Scotland
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Originally Posted by Tekko View Post
..............As in having smaller storage caps on each channel which center point is each channels speaker ground with a 10 ohm resistor between it and signal ground and then three leads per channel to the main psu, is this what your trying to say ?

If yes, then that for sure hum loudly as signal and speaker ground shares the same wires.
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................-- but this just seems plain wrong, but it sounds on AndrewT like that is the right way.

But to me is just seems plain wrong.
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....................and i'll continue to recommend it to beginners that come to me for help no matter what ppl say.
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Originally Posted by jneutron View Post
...........point out where he is poking fun at people?.......................
The implication is that his description is one being proposed by Andrew T. And that Andrew T. as well as other ppl (people/Members) are not worth listening to.
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Old 4th May 2012, 01:55 PM   #23
DF96 is offline DF96  England
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Inserting a 10ohm resistor and then questioning whether the resultant circuit is correct, with the clear implication that it was not, despite the fact that the resistor was his idea. Intead of addressing the points raised, he chose instead to put up a clearly ridiculous circuit while implying that was what Andrew had suggested. I call that poking fun. Perhaps I have misunderstood his motives - maybe he is just hopelessly confused?
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Old 4th May 2012, 02:01 PM   #24
SY is offline SY  United States
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Well, if you gentlemen will stop beating Tekko and let him look at my suggested sim, perhaps we can move on?
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Old 4th May 2012, 02:03 PM   #25
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Quote:
Originally Posted by AndrewT View Post
The implication is that his description is one being proposed by Andrew T. And that Andrew T. as well as other ppl (people/Members) are not worth listening to.
Ah, so it's not actually that he is poking fun at others but rather..

Any discussion of those differing opinions has been transformed into IMPLIED poking fun.

And that disagreement has now suddenly been transformed into "your not worth listening to".

Curious.

BTW, star grounds are only useful for IR drop issues. Reliance on the star ground topology for low impedance high gain circuits is wrought with problems, both internally and externally.

I've used a star at cap setup just as he has, I've also done it other ways. I've had both success and failure in both. My percentage success has risen dramatically in the last 2 decades, which I attribute to knowledge..(course, my ex would disagree with that..)

j
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Old 4th May 2012, 02:07 PM   #26
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Quote:
Originally Posted by DF96 View Post
Inserting a 10ohm resistor and then questioning whether the resultant circuit is correct, with the clear implication that it was not, despite the fact that the resistor was his idea. Intead of addressing the points raised, he chose instead to put up a clearly ridiculous circuit while implying that was what Andrew had suggested. I call that poking fun. Perhaps I have misunderstood his motives - maybe he is just hopelessly confused?
He is attempting to attack grounding issues internally and externally. This is by no means an easy exercise. Indeed, most star ground solutions fail to solve both, I haven't seen any universal solution yet.

I guess my tolerance of questions and disagreements is somewhat higher than yours or andrews, so I've not resorted to attributing either motives or confusion to him.

j
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Old 4th May 2012, 02:26 PM   #27
DF96 is offline DF96  England
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Trying SY's idea would help, whether he uses a few ohms or his chosen 10.

The whole idea of this thread seems to be "here is a grounding scheme which works; use it". That is why I suggested thinking instead.
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Old 4th May 2012, 02:48 PM   #28
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Quote:
Originally Posted by DF96 View Post
Trying SY's idea would help, whether he uses a few ohms or his chosen 10.

The whole idea of this thread seems to be "here is a grounding scheme which works; use it". That is why I suggested thinking instead.
Thinking is always a good thing. (I think)

edit: He did indeed present an idea which has worked for him. There is nothing wrong with that. Nor the ensuing discussion of the good or bad aspects of it. That discussion does indeed help everyone think. Derailing by statements of implication or attribution of motives is counterproductive.

SY's idea is a vacuum tube idea.. It is a DC solution to a low impedance high current AC problem. In the days of tubes only, it was good enough. Not now. edit: especially with low z circuits running power gains of 10 power 6 to 10 power 7.

The results of the sim will have limited use. Guidance perhaps, but it does not simulate actual hardware fully.

j

Last edited by jneutron; 4th May 2012 at 03:05 PM.
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Old 4th May 2012, 03:32 PM   #29
Bonsai is offline Bonsai  Taiwan
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Here is how I do it.

1. charging currents to the filter caps flow through a separate ground connection.
2. a 'T' off the filter cap junction ensure no charging current contamination.
3. The ORDER OF THE GROUNDING IS CRITICAL
4. First the chassis ground (either direct or via a GND lifter), Zobel, then the speaker return, then decoupling, and finally signal.
5. The input signal GND and the decoupling GND are separated on the PCB by a 3-10 Ohm resistor.
6. The input connector is isolated from the chassis
7. The speaker GND connector is isolated from the chassis
8. Importantly, there is one, and only one connection to the chassis as shown

-110dB ref 1W out acheivable. And, its not a classic star ground arrangement, but if you look at it carefully, you can see it acheives what a star geound is supposed to acheive, but in a more structured way.

Like jneutron, I struggled to get hum free audio when I was young. My first breakthrough came when I culled the rectifier and filrter cap assembly from my blown up Marantz 240, and realized at the same time that the input signal connector ground has to be isolated from the chassis. My first completely hum/buzz free amp circa 1984.
My Ovation 250 amp uses the same approach shown in the picture and it is hum free - ear against the speaker cones and on a scope.

Note: the line shown between the primary and secondary below is the screen - it it not the transformer core.

Happy wiring!

:-)
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Last edited by Bonsai; 4th May 2012 at 03:48 PM.
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Old 4th May 2012, 04:34 PM   #30
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Quote:
Originally Posted by Bonsai View Post
Here is how I do it.
I note with more than casual interest, how you drew the capacitor connections..It's not often I see four lead capacitors drawn....it is becoming a lost practice.

RF and/or EMC experience, eh?

For others: a four lead capacitor is used to reduce the mutual inductance between the circuits before and after the cap...

j
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