Dedicated line questions

Forgive me if I'm wrong, but aren't most ground loop problems the result of a difference in potential between grounds, giving rise to "ground loops"? If this is so, then having separate grounds for each outlet would not be wise, right? I can see how having all audio grounded together and separated from other household circuits would be better. Albertporter, this is why you tie the 3 copper bars together, right?

I have 2 20 amp lines run from a submain box that was attached to the main breaker box via conduit. I had an independent ground rod driven for these 2 lines. I think the ground was still tied to the main ground since the two boxes were bonded with the conduit. It was suggested to me in an audio asylum discussion that this arrangement, had created a secondary ground which could endanger my system from lightening strike damage due to the possibility of setting up a loop between the two grounds. If the resistance in the dedicated ground was less the current could feed back through the system. One of the guys provided a technical document supporting the idea. Since i live in an area that has some great thunderstorms (when not suffering from drought as we are now) I moved the ground to the water pipes where the main ground for the house resides and the sound of the system seemed to improve some. The guys in the asylum thought the improvement could have been the result or removing a ground loop that hadn't been at the hum level.

Hi Greysquirrel; "I wish I understood all I know about this"-- an old, but appropriate saying. I just let the electrician ground as they would for a "set" of dedicated outlets for safety purposes. I can tell you two things: (1) my system is sounding excellent, (2) When I plug my amp into the ded. outlet I get fairly loud "ground loop" hum unless I use a two prong adaptor plug (which I do, but wish I didn't have to). I hope Albert P. addresses your question as I'm interested in it too. Cheers. Craig

Greysquirrel, the reason for three ground rods, is that they are spread over approximately a ten foot area of earth in a large triangle configuration. If the ground potential is higher or lower due to the wetness/dryness of the earth in one particular ground rod's area, the stereo ground still gets the benefit of whatever is the least resistant ground plain. In addition, should anything fail among the three rods, or they begin to corrode after a period of time, you still have a safe margin for your electrical. It is dangerous to have no grounds at all, particularly if you had a component failure. The other good thing about this type of grounding is that the stereo has "priority," in that it does not compete for "space" to discharge or find ground. This is critically important if there is a storm and your house takes a lightning strike (or even a near by strike, such as a power pole). Postings have also spoken about the merit of having more than one dedicated outlet for the stereo. I had not mentioned this before, because it really sounds crazy, but, I have fourteen dedicated outlets just for the stereo alone. EACH one has its own 20 amp breaker, and each has its own star grounding as I described. I added outlets until I could not hear any further changes. For instance, each of my mono amps (main stereo speakers) has its own run, as do every other component, (including all four power supplies at the front end, two are for phono, and two for line stage). Even the surround sound has its own breakers. In addition, the digital (home theater) is on one side of the 220 and the analog is on the other side. I made sure that the house's noisy legs were on the digital side, as it is not as critical to me. (The house has to hook to one or the other or there is no power for it!). The analog side shares the AC drop mostly with circuits in the house that are relatively free of noise (i.e.: incandescent light fixtures.) This may all sound really complicated, but I spent less than six thousand dollars on everything I did to my electrical, and understand, the whole house benefited as well as the target, the stereo. If you put it in perspective, the power supply in an amp or preamp is always discussed as being important. Imagine how important the power supply is for the entire system. And, although it was a large outlay, it is permanent, in that changing components does not diminish my investment. Many of us invest this amount of money in power treatment devices, or high end components, and then loose most of our investment when we sell or trade. This investment in power is a huge benefit for your whole system, and lasts for as long as you live in the house. If you must sell the house later, the amount invested is low compared to the value of a home, and much of the investment may be returned if you sell to anyone who finds the enhanced electrical an inviting addition.

In response to the comments from Garfish, the ground hum problem is not necessarily related to whole house ground versus the stereo's dedicated ground. Hum as Garfish describes, is often the result of ground planes within the system "talking" to each other, resulting in hum, pickup of radio, etc. This is usually (but not exclusive to) the interconnect shield/ground and/or the speaker wire. The dedicated wiring and grounding system I suggested may or may not resolve this particluar problem. However, it will provide a guaranteed performance increase for the whole system, whether it solves this particular problem or not. If a ground on a individual component must later be "lifted" to remove hum, so be it. Along this line of thought, another really interesting thing to consider about hum and noise, is the ground plane of the floor of your room, and (metal) stands the equipment may be sitting on. I have some of my metal stands (but not all) grounded to the same dedicated star ground plane as the stereo's electrical. This greatly reduces noise and can even completely eliminate CB radio transmissions or the occasional interference from HAM or AM radio. Remember the components in your stereo are designed to amplify very low level signals, so that you may enjoy them through your speakers. Unfortunately, the components do not know which signals are music and which ones are a nusiance. You must remove the ones you don't want, as the system cannot. An additional benefit of addressing this issue, not previously discussed in this posting, is the "gain" in power, dynamics and headroom by doing all this. If noise is being amplified by any or all of your components, they are using up much their energy and headroom to deliver what could be "spent" on the music. Even worse, it is being used up for negative results in with the music.