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Old 14th June 2004, 09:31 AM   #11
ABO is offline ABO  Netherlands
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Join Date: Dec 2003

I just tried a loop breaker (after RODE's recipe) with on one side both signal ground (L/R) and on the other side chassis and safety ground.

It made quite some improvement. I still prefer the sound without the safety ground attached. Although the breaker takes away 90% of the problem.

I guess that's the solution then: no loop and hence no loop-breaker. If you don't hear from me again, assume I electrocuted myself for the good of superior audio
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Old 14th June 2004, 10:16 AM   #12
ABO is offline ABO  Netherlands
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Default Question for Mr. Hansen

I sometimes hear that a connection between the case and signal ground helps for amp stability. OTOH, some say that chassis earthing helps prevent EMI. So, what's better?

Connect all grounds to chassis and no earthing


Earth case and no electrical connections between case and circuitry whatsoever?
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Old 14th June 2004, 01:09 PM   #13
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You're best off without earth ground but with the chassis firmly attached to the circuit ground. Usually bolting the rca connectors straight onto the chassis works best for this purpose. The only disadvantage is that the floating circuit ground is now externalised as the chassis ground.

The ideal concept for combining a floating circuit ground and an earth ground is by putting all the circuitry inside a sub-chassis (ie to provide something similar to the above situation) and mounting that -fully insulated- inside the actual equipment box. The latter can then be connected to earth ground.

Personally I stick to balanced connections wherever I can, because it's the only way of preventing rubbish from the mains coming in whenever more than two pieces of equipment are interconnected. Most equipment has capacitors (called Y capacitors) somewhere from the mains going to the chassis as part of a mains filter, in a mistaken attempt to get a cleaner power supply.
The power supply may be cleaner but the ground surely is clean no more!

One such device in an audio system subtly degrades sound quality. Two such devices wreck it. Cables start sounding different depending on the resistance of the shield (rca ground contact). Correctly conceived balanced connections avoid these problems but are badly understood - so badly in effect that many people add unnecessary circuitry but fail to make them work.
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Old 15th June 2004, 10:00 PM   #14
K-amps is offline K-amps  United States
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Default Re: How to earth my amplifier

Originally posted by ABO
In my new amp I have connected the safety earth directly to signal ground at the RCA inputs. Although there is no hum whatsoever, I can still here a difference in sound.

With the connection in place single instruments seem to have a 'aura' around them. At first it sounds like ambient detail, but when the connection is removed, everything sounds more pure and more quiet.

I don't worry much over safety ground, but it's always nice to have it. Further, I can't really decide what sounds best. My speaker do not have enough resolution to know if the aura is part of the signal or some sort of distortion. However, I feel that no connection between safety and signal ground must be better for sound. I can't see any benefits from this other than meeting safety regulations.

Does anyone have similar experiences?

A lot of current can be riding on those "yellow" wires you have from the gnd of the RCA's to the Earth/gnd connection of your AC socket.

I'd suggest using a 100 ohm resistance to isolate heavy current leaks. It will still be enough to form a non-floating ground for the amp's input stages albeit avoid the high current passing through it. This should cause reduction in audible hum.

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