I tried to post this yesterday but it didn't make it to the forum, so if it gets posted twice, that is why. I must concur with Carl109 as to the quality and efficacy of a safety ground connection made by the shield of an IC. I completely agree with him that this type of connection is likely not capable of carrying the fault current necessary for protection. Additionally, you run the risk of too high of an impedence to ground to reach the current needed to trip the breaker due to a hot chassis. Since the chassis of the equipment sitting next to the source does have a low impedence path to ground, touching both boxes at the same time could prove unhealthy. These problems don't occur when you ensure electrical safety via the designed method. I strongly recommend against defeating the intended safety ground and do not endorse relying on a ground provided by an IC to protect against fault currents. Besides, there is no good reason to do this. Solving the problem correctly is possible without creating any hazard. |
Newbee, it's true that your source will be grounded via the IC (if it doesn't have it's own) to the amp's ground pin, provided your amp & source use the chassis as a common ground (usually the case), but that's under normal operating conditions.
The big problem is that IC cables are not designed to take mains voltages, and it will be the outer conductor in the IC that cops it - often a very fine copper braid designed for just a few volts. Using Australia's mains as my example, I doubt a typical IC will stand up to 240VAC at 10amps for long, and in a split second you may be back to having a CD player with a live outer casing. At the very least it would likely burn out the IC and start a fire.
As I said earlier, I'd be looking for the source or cause of the hum, not removing a safety aspect. If a component has a 3-pin PC, then the unit is not double insulated and by law has to be properly earthed. If a fire started due to the removal of an earth pin, I know what your insurance company would say..... |
That depends on whether your interconnect is connecting the chassis of the source to the chassis of the preamp. If the interconnect is connecting the chasses then no, you still have all chasses grounded. However, if that is true, that then I would consider leaving your ground intact on the power cord from the source to the power conditioner and lifting the connection of the shield pin on one end of your interconnect. That is likely the connection that is causing the ground loop problem. |
Musicnoise/Carl109, A question..........
I have a source connected to a power conditioner with PC and an IC to the pre-amp. I have the Pre-amp PC going to the same power conditioner and its IC to an amp. I have the Amps connected to a difference power source. The Power conditioner, the pre-amp, and the amps all have their grounds intact.
Are you saying that having the ground prong from the source PC defeated that I have created a potential source for electrocution?
If yes, please explain. I don't understand. I do understand why the power conditioner should have a ground, and the amps have a ground, so just address the issue of the source ground defeat.
Thanks...... |
Carl109: I agree wholeheartedly. What further amazes me is that audiofiles will go to great lengths and expense to add 'tweaks' to their systems (most of which are meaningless) propose theories that audio equipment and music are too complex for even the most modern scientific instruments to measure, attempt to discuss subatomic particles and the philosophical aspects of current flow, but when there is a ground loop hum, what happens - "let's chop off the ground - look ma no more hum, ain't it grand". |
I'm very surprised and bothered by the sheer number of people who disconnect/remove the earth from their PC to solve a hum or noise issue. That earth connection is there for a very good reason - to stop people dying from mains voltage shocks in the event of a component failure.
There are times when the quickest and cheapest solution to a problem is not the smartest, and this is one of them.
Quite frankly, in this day and age of modern high end gear, I'd take an amp/source component straight back to the dealer for a refund if it 'hummed', or have my house wiring checked out, not start stuffing around with mains voltages and risk a live chassis. |
My Wadia 302 has a tendency to cause hum in some set ups - I just cut the ground prong off a PC to cure it. Don't need the add on 'cheater plug' and you get a much more secure connection.
FWIW, it came with a standard 3 prong plug and the manual sez nothing about what to do if you hear a hum. |
My meridian has the same problem and lifting the ground resolved it. I have a fusion audio impulse power cord and Eric lifted the ground at no charge (just shipping). The other option would be power conditioning where an outlet or 2 are on an internal isolation transformer.
I would NOT remove the ground from the outlet. |
I have read somewhere that my Wadia 302 is known for this and is actually suppled with a 2 pronged plug (without ground pin). I can't say for sure since I bought my unit on the 2nd hand market, the cord supplied wasn't the original...perhaps I'll send an email to Wadia. I have had 4 or 5 other CD players on the is receptacle and no problems til now. |
Cheating out the ground may get rid of the hum but the problem isn't that you have a grounded chassis. The way to address the problem is to find the cause and address the cause. As Carl109 pointed out that the 'fix' of cheating out the ground has its drawbacks. |
Well I have some sort of ground loop hum and the solution was lifting the ground on my cdp. I currently use one of those 99 cent adapters. |
I'm sure you already know this, but the presence of a ground connection indicates no double-insulation, so removing the ground does expose you to the small but real risk of electric shock if the casing ever became live.
Is the improvement in sound worth such a risk? |
I don't recommend using one of those 99 cent adapters...they ruin the sound. I would disconnect the ground from the outlet as ozzy suggested, |
Just disconnect the ground in the outlet. |
Simply use a common 99 cent adaptor from the dollar store. You know, the one with the little ground wire hanging off. Why damage your power cords. You'll be able to test polarity as well if you make the wide spade on the adaptor narrower. |
Some PS Audio power cords have a removable ground pin. (http://www.musicdirect.com/product/74108) I'm not certain about any other companies. |
