Re: So..... - jneutron - Propeller Head Plaza

Re: So.....

Posted by jneutron (A) on April 30, 2004 at 11:48:19

In Reply to: So..... posted by Commuteman on April 30, 2004 at 10:35:39:

Peter: ""In a balanced environment, is the effect different given that the ground/chassis connections are not necessarily part of the signal path?""

I would expect that it is the same, it's just that the CMMR is taking care of it. The ground is actually the signal path, (it can always be argued, of course) but we count on both signal lines being afffected the exact same way, then subtracted out.

Peter: ""In some equipment, the chassis and protective ground are connected to the signal ground through a resistor. Presumably, the primary effect on your diagram is to greatly increase Rtot and therefore reduce ILoop. Any other impact?

Can't say w/r to any specific amp. Do you know if the resistor was put there because they already knew what I was talking about? Or was it put there because it somehow reduced hum and interference, placed randomly there because it "sounded better". But yah, I would expect it to lower the Iloop..

Peter : ""Can you explain the mechanism behind the blue "geometric coupling " areas? If the termination point for Zin is at the input connector, (rather than to the chassis some distance away and therefore including some portion of the green loop), does the effect disappear?""

Yes, I would think so..However, if there is a ground current from the input connector, then that blue loop could be some other part of the circuit. If the shield goes from the input connector and is used by the input circuitry, how do you prevent the blue'd area from causing the input shield to develop a voltage as a result of the current between it and the chassis. The input shield at the circuit board will no doubt have a different impedance-of-loop from the center conductor, so the voltage presented to the actual input can still be different than the shield voltage..

The real question is: if there are currents flowing through the IC shield, through the chassis, are those currents capable of coupling to the input of the amp by some ridiculous fashion?

Perhaps a single to differential conversion directly at the input jack, with diff signals running to the amplifier PC..

Or, some really clever method of shielding the input jack to circuit board shield from the currents on the shield..

Cheers, John

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Follow Ups Full Thread

Topic - PC/IC/amp/source interactions - jneutron 09:22:51 04/28/04 (23)

Are we missing the interesting point about this post? - Commuteman 09:19:08 05/03/04 (3)

makes sense - Mau'dib 19:08:20 05/05/04 (0)

Re: Are we missing the interesting point about this post? - Jon Risch 10:39:29 05/03/04 (1)

Re: Are we missing the interesting point about this post? - jneutron 08:09:04 05/04/04 (0)

Re: PC/IC/amp/source interactions - Jon Risch 17:54:35 05/02/04 (14)

You gotta read the posts accurately, and review my diagram. - jneutron 07:24:17 05/03/04 (12)

Re: You gotta read the posts accurately, and review my diagram. - Jon Risch 10:35:14 05/03/04 (11)

Re: You gotta read the posts accurately, and review my diagram. - john curl 20:47:50 05/04/04 (7)

Re: You gotta read the posts accurately, and review my diagram. - Steve Eddy 21:40:52 05/04/04 (6)

Re: You gotta read the posts accurately, and review my diagram. - john curl 21:48:35 05/04/04 (0)

Re: You gotta read the posts accurately, and review my diagram. - john curl 21:47:33 05/04/04 (4)

In addition to the "allegations" from cables... - jneutron 06:14:38 05/05/04 (0)

Re: You gotta read the posts accurately, and review my diagram. - Steve Eddy 22:41:12 05/04/04 (2)

Re: You gotta read the posts accurately, and review my diagram. - john curl 23:50:16 05/04/04 (1)

Re: You gotta read the posts accurately, and review my diagram. - Steve Eddy 11:44:21 05/05/04 (0)

Holy mackeral Jon, READ THE DAMN POSTS ENTIRELY - jneutron 07:55:25 05/04/04 (2)

Re: Holy mackeral Jon, READ THE DAMN POSTS ENTIRELY - Phil Tower 08:30:18 05/04/04 (1)

Thanks Phil. - jneutron 08:52:16 05/04/04 (0)

Re: PC/IC/amp/source interactions - Dan Banquer 06:28:50 05/03/04 (0)

So..... - Commuteman 10:35:39 04/30/04 (3)

Re: So..... - jneutron 11:48:19 04/30/04 (2)

It's like this.... - Commuteman 09:06:19 05/03/04 (1)

Re: It's like this.... - jneutron 08:20:16 05/04/04 (0)

Follow Ups

Re: So..... - jneutron 11:48:19 04/30/04 (2)

It's like this.... - Commuteman 09:06:19 05/03/04 (1)

Re: It's like this.... - jneutron 08:20:16 05/04/04 (0)

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