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ABO 13th June 2004 10:35 AM

How to earth my amplifier
 
2 Attachment(s)
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?

jaycee 13th June 2004 11:41 AM

Keep chassis earth (mains safety earth) and power supply + signal earth seperated via a loop breaker, as Rod Elliot shows on his websites - basically this means connecting the two togethr via 2 inverse parallel diodes, a 10R 5W, and a 100nF capacitor (all in parallel)

ABO 13th June 2004 06:15 PM

OK, I've listened some more and now its clear. The sound is better when there is no connection between earth and signal ground.

Once you put your finger on it, the difference becomes very clear and is suddenly not so subtle anymore: all instruments seem more real, alive and better placed within the soundstage.

So, grounding is not only important for hum problems. I wonder how many people don't realise that they have a problem.

Well, perhaps its not really a problem then, is it?

Charles Hansen 14th June 2004 02:11 AM

You are right, the system sounds better when everything is "floating" with no ground connection.

The other thing to check is to make sure that the AC mains power is correctly oriented to each component. Do this one component at time, with *nothing* else connected to it. Try the AC mains in both orientations and measure the AC voltage between the chassis and the safety ground in the wall receptacle. The orientation with the lower voltage is the correct orientiation. This is actually a leakage current on the chassis due to the capacitance between the primary winding of the power transformer and the chassis. The transformer is never perfectly symmetric, so one orientation is better.

If you do both of these things, the sound is significantly better.

Next you will find that if a "cheater" plug is required to float the ground (true in most cases) that this also degrades the sound slightly. Presumably this is due to the extra contacts in the AC power path. Removing the ground pin from the AC power cord is the easiest way to avoid using a cheater plug.

Paradise_Ice 14th June 2004 02:25 AM

I know this may sound silly but do you think that the voltage in each country makes an amplifers sound different?
Some people say the voltage in London is very bad for hi-fi and there hi-fi sound better in other parts of the country?
Is this just wishful thinking or is there something to this?

Charles Hansen 14th June 2004 02:43 AM

Everything makes a difference.

I know in the UK that many places have very high voltage. The EC normalized at 230 VAC, *except* for the UK. They stubbornly stuck with 240 VAC, which they call 230 VAC +/- 6% (the EC limit). However, in many areas the voltage will rise as high as 255 - 260 VAC at times. It's not hard to imagine this causing sonic problems with at least some equipment.

On a separate yet related topic, large industrial cities (London, NYC, Los Angeles, etc.) tend to have "noisier" power than other areas. This will also have a deleterious effect on sound quality. Usually the sound quality will be better late at night, presumably because there is less noise on the AC mains.

fdegrove 14th June 2004 02:47 AM

Hi,

Quote:

So, grounding is not only important for hum problems. I wonder how many people don't realise that they have a problem.
Actually, I'm rather surprised you have this problem at all....
Unless you have the amp(s) plugged into a wall outlet that sports an earthed mains connection, that is.

In Europe, I assume you do live in the Netherlands, these earthed mains outlets are often only found in areas such as the kitchen and other dedicated places where washing machines, deepfreezers and such are in installed.

In short, you won't easily find three pronged outlets in an ordinary living room in Western European houses.

Your description of the effect is pretty accurate, it often sounds better without the Earth link connected to ground.

Oh, in case you follow Charles H's excellent advise on checking mains polarity: mark your plugs for correct polarity once you're sure you have found the correct way around.
It does pay of and it only takes a little of your time...once.

Quote:

Some people say the voltage in London is very bad for hi-fi and there hi-fi sound better in other parts of the country?
Yeah...I heard that before and witnessed it myself...I used to live in a big city (Brussels and Munich) and often found myself enjoying the music only way past midnight when there's alot less pollution on the grid going on.
There's ofcourse alot less background noise which also helps...

Much to my dismay, mains filters (the ones I tried anyway) didn't even improve things for me, quite to the contrary really.
I live in a small city now with hardly any industrial activity to speak of and my system sounds good most of the time, most of the day.
Not always but it's much, much better than before.

Start saving up....:)

Cheers, ;)

millwood 14th June 2004 03:18 AM

Quote:

Originally posted by Paradise_Ice
Some people say the voltage in London is very bad for hi-fi and there hi-fi sound better in other parts of the country?
I have heard that it sounded "foggy" or "rainy" in London.

Quote:

Originally posted by Charles Hansen
large industrial cities (London, NYC, Los Angeles, etc.)
I have never thought of NYC as an "industrial city". there just aren't so many factories here anymore.

sam9 14th June 2004 03:33 AM

I've used the Self method of a star ground. Power gnd, signal common and PS common all meet at one off PCB point. Then the signal input shield is tied to the chasis earth point. The chsis earth point goes to the power entry. I found this conceptually worrisome at first, but it works - no hum, no hiss, no aura, no nothing just dark, cold silence. The only caveat is with regard to saftey - be sure the shield can take the worst case current.

ABO 14th June 2004 07:12 AM

Quote:

Originally posted by fdegrove
Hi,



Actually, I'm rather surprised you have this problem at all....
Unless you have the amp(s) plugged into a wall outlet that sports an earthed mains connection, that is.

In Europe, I assume you do live in the Netherlands, these earthed mains outlets are often only found in areas such as the kitchen and other dedicated places where washing machines, deepfreezers and such are in installed.

In short, you won't easily find three pronged outlets in an ordinary living room in Western European houses.


Well,

The power outlet does indeed not have a earth connection, but the mains extension does. So there can be groundconnections between other gear.
I think that my tuner may be earthed through its cable antenna (you get that?). That may cause the problem.

Charles,

About your advice: I tried that once but it didn't work. Say that I measure my power amp first. I put in the right orientation. Then I proceed with other equipment. When, after all equipment is in the right orientation, I measure the power amp again. To my surprise it must now be connected in the other orientation..

OOps, I just saw that one has to disconnect all other connections, I suppose it will work, sorry!


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