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Old 4th September 2003, 02:47 PM   #1
SimontY is offline SimontY  United Kingdom
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Question Should I earth my CD player chassis?

Hi everyone,

I have a CD63ki, and running my finger along the chassis I can feel a buzzing sensation, presumably some current is running through it. (the buzzing is not there when unplugged)

I talked to an owner of a CD63se who had exactly the same thing with his machine. He grounded the chassis to his house earth and the buzzing went, he also felt there was a small increase in SQ.

Is this totally safe to do?

Why do I and others experience this phenomenon?

What else can I do to check and improve the players earthing arrangements?

Should I ground the 'ground' of my home-made clock PSU to the house earth too?

TIA,


-Simon
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Old 5th September 2003, 11:05 AM   #2
alfsch is offline alfsch  Germany
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Hi,
the buzzing feeling comes from some capacitve transferred mains current, together with the cap of our human skin creates this feeling...
try reversing mains plug! (cap of transformers is most times not symm, so there is a different current)
did you test the current to earth?
alf
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Old 5th September 2003, 02:04 PM   #3
SimontY is offline SimontY  United Kingdom
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Hi Alf,

Thanks for the advice!

I have mains polarity correct - tested with an EMI meter for lowest field strength (unless it's different plugged in where it is now compared with where I tested it - never thought of that!!).

When you say "test the current to earth" do you mean one probe on the chassis and one on my house earth? And is that voltage or current setting on my DMM? (my electronics knowledge is basic, sorry!)

So should I be earthing it? You didn't say if I can...


-Simon
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Old 5th September 2003, 02:45 PM   #4
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Default Earthing?

I've always found CDP chassis to sound better under several feet of it.
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Old 5th September 2003, 02:51 PM   #5
SimontY is offline SimontY  United Kingdom
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Quote:
I've always found CDP chassis to sound better under several feet of it.
I don't know if that is a joke referring to how much damping the chassis needs, or an exaggeration of how well it should be earthed electrically. Please clarify...


-Simon
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Old 5th September 2003, 08:22 PM   #6
SimontY is offline SimontY  United Kingdom
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Hi,

I tested for current by putting an electrode to ground and one on a chassis screw. I measured fluctuating current from 0-4uA, mainly staying on 1 or 2 uA.

Interesting thing: when I put the probes across the buzzing went, and took them off it came back again.

I guess I should just earth the thing, I shouldn't get any ground loop hum as my amp has no earth connection...


-Simon
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Old 5th September 2003, 08:56 PM   #7
SimontY is offline SimontY  United Kingdom
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(just in case anyone is following this thread...)

I've temporarily earthed the player now, just using a piece of speaker wire from a screw to a ground terminal I fitted to my power strip.

Buzzing is gone and the sound seems slightly improved. I could be imagining this of course, but I hear a quieter background and better coherance.

Thanks for reading.


-Simon
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Old 5th September 2003, 10:01 PM   #8
Duo is offline Duo  Canada
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I find earthing is extremely important in many audio systems, so I'll post some comments and ideas on what I have done in the past..

First off, I find that by putting an isolation trafo between the power and my amp makes a huge difference in sound, just because it cleanes up the signal a lot. After doing this I grounded the amp to its own exclusive ground rods. This made quite an improvement.

Next thing, I put a saturation isolation transformer on the CDP. To do this, I put the trafo in the line like a normal iso transformer, then ran a ground directly to the CDPs transformer primary winding, this way, the CDP trafo is grounded, but not the whole CDP except for using its connection to the amp, this way there isn't a ground loop.

I did the same things with the other sources, such as turn table, VCR, other transports, reel to reel, whatever I had.

On the VCR I used an iso transformer for the cable input, that way there isn't a ground loop to the cable system, which for some reason has really lousy grounding.

As for the darn computer. There's iso trafos about to go between it and the amp cause it's causing all kinds of problems...
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Old 5th September 2003, 10:21 PM   #9
SimontY is offline SimontY  United Kingdom
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Default Mains tweaking

Good stuff, thanks for the ideas.

I've been thinking about getting a nice big isolation transformer for my cd player, and putting it in a box with some transient suppressors, x and y caps, and maybe some large caps too, but money is a little tight right now, so it will have to wait. I don't see how this solution could be much worse than some rather expensive line filters commonly for sale.

Currently, I use a Russ Andrews Silencer, and a box I put together with some caps including a 10uf lighting cap across L+N, and some transient supressors. (Gives a richer, more mellow sound)

When I have (much) more money I will get a very big transformer just for my amp, but I don't want to choke it with anything smaller or even the same size as it has inside.

I added a .33uf cap to my cd player, as well as a series choke for both L+N. These helped the sound a little.

Also, I totally modified my Belkin power strip by removing the circuitry, cleaning the power rail connectors, and changing the lead for a thick braided beast I made. (these made the sound cleaner and less distorted, and the bass loads better!)

Lots of fun is power! I have no time for people who don't believe power tweaking will make a difference - it does!!


-Simon
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Old 5th September 2003, 11:03 PM   #10
Duo is offline Duo  Canada
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Oh, believe me, power is very important.

For my amp's isolation transformer, I use a 5KVA delta isolation transformer and run it 220 most of the time. This puppy will handle about 25 times the power of my current amp, which is a Harman/Kardon A402. It is 40W per channel. I have however run much much larger amps off this transformer with great performance and improvement over the usual setup.

I find that with good isolation transformers, you don't need much other filtering (inductors and caps). This is because the transformer becomes almost resonant at 60hz it takes a great deal of energy to push transients and high frequency noise through the core. Almost all of this noise ends up being dissipated as heat since the core is very inefficient for transferring it. I find a little tiny bit of noise can get through, but some proper grounding usually finishes that off and maybe putting some small caps to ground from the secondaries.

As for the CDP, it's using a saturation transformer. These use a cap to cause great saturation of the core. This generates much heat, but the result is a very accurately regulated output voltage with very clean power. Noise is even harder to get through these transformers since the cap and transformer creat a resonant circuit that will eat noise up like nothing else. The input voltage can vary a great deal with the output generally staying within 1% of 117V. This makes the CDP sound very detailed and with less stress.

If you can stand the transformers running very hot, this is a good idea to use the saturation type. The only other problem is that they are very expensive. I get mine from retired aircraft ground management equipment and obsolete cable TV distribution systems. This stuff is easy to get your hands on if you're in the local ham radio club of a town that's upgrading stuff. I've recieved all kinds of used equipment in almost perfect condition from the airport, including a sperry RVR computer and a complete ILS system.

For the 5KVA delta, that I took off my uncle's boat when he was re-building it. I got the old radar and a pile of other stuff.
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