I have found that dirty or ungrounded power will make some strange hard to track down problems.
1. Try separating your amps power from the rest of your gear on its own power source.
2. If that doesnt work, change the amps polarity.
3. Next, switch each piece of gears polarity one at a time to see if it isnt another component's polarity (cable boxes and VCR's are notorious for this.) Use a ground lifter plug if needed.
4. Make sure there is'nt any phone lines running next to your speaker wires or gear. (Phone line and audio gear dont mix)
5. use a multi meter and check the current of your power. Some amps do weird things with weak power.
6. Dimmer switches for lights can cause noise.
7. Last (Defective gear?) I hope this list helps, I have tracked down alot of noises in and out of the studio and these were the source of unwanted noise.
Try changing the polarity of your equipment one at a time to narrow down which piece of gear is causing the problem. A ground lifter plug is a AC plug that changes a (2 slot, one pin) and changes it to a 2 slot. Can be bought at a hardware store,WalMart for about a dollar. Try it on your sub or any piece of electrical gear that plugs into the wall. You know, the "holes in the wall." (On Seinfeld, Frogger/Russian electricial episode) ;)
TPE
Unregistered guest
Posted on
Not to be rude, but dont suggest that. It is the worst recomendation I have seen on this site. You do not by pass the ground, besides if you do this you lose the surge protection abilities. Take some time to learn how a ground system works and why it is there, the last time I saw a AV company do this they got a fine that they are still paying off.
Let me clarify on the ground lifter. Alot of Media rooms have special AV lighting and other gear. Groundlifting is somtimes the only solution for ridding unwanted noise. Groundlifting is a reasonable way of diagnosing and singling out a piece of equipment that is causeing unwanted noise. Once you find the which piece of AV gear is causing the noise, its up to the you to decide if you want to find another power source. If you use a Power Surge Strip like the ones found for under $30 dollars at any Walmart or Computer Store,(And you should anyways), You can use a ground lifter on ANY piece of gear you plug into the power surge strip. Any power surge is eliminated before it reaches your AV gear.
TPE
Unregistered guest
Posted on
I am not just making this stuff up, let me explain. Our company is a electrical contracting firm that has a division in AV. As a electrical contractor we were (and still do) always bump into projects were another AV company tried to alter the ground system. The AV company I mentioned is still trying to work through bankrupcy because of the fine...not that I care, but it was asked. Any ways, the ground is there for a purpose, not to be lifted or 'cheated'. If you truely understand grounding you would know why some equipment does not have a ground (2 prong) and why some do. When you remove the ground at any point this leaves the item with out protection. What is a ground intended for...lightning protection and personal protection (secondary to the first). Lighting hits your cable line, routes through equipment and destroys everything you have, but a ground is hooked up theory being it gives the lightning a low resistance path back to the source, thus bypassing your av equipment. Or wire inside unit is loose, pops off and energizes the shell shocking your little girl when she turns it on, so ground is used to route current back to neutral thus providing personal protection. What to do about interference!?? Isolation transformer, look into it. Remove the ground from a system and good luck getting your insurance co to pay for a fire or damages, fact. Removing the ground in anyway has always been a DIY method of amature status....look into it.
We have used groundlifters in my audio/video production studio to to quickly track down equipment problems for years without an issue. I am talking about serious $$money equipment. Its a fast and effective procedure and it keeps down time to a minimum. Isolation transformer/Farady Shield is the way to go but I am assuming not everyone here has the budget for it. IE..DIY amature method of getting the job done. There are so many variables when it comes to a lighting strike, almost anything is possible. Bottom line is..From my experience, Using a groundlifter to find the source of your problem is a quick,cheap and effective way to diagnose a grounding problem. When you find it, fix it correctly.
TPE
Unregistered guest
Posted on
I have no problem trying to use a 'ground lifter' to help find the problem. But what does one do when he/she finds the problem? You cant leave the ground lifter on. Doesnt matter if you are using 'serious money' equipment or cheap product. What do you do when you find the problem with the 'ground lifter'?
The best and most expensive solution is to install a "Isolation Transformer". Do a search and you will see they are abour $1K and up. If you have seriouse long term plans with your media room or you have alot of money tied up in your gear, then $1k shouldnt scare you away. In the long run its cheap insurance.
The second and cheapest solution is to leave the groud lifter on the unit that is causing the problem. At least make sure you have it pluged into a surge protector strip. Some people feel uncomfortable with this idea. Its a personal call. IMO.
The third solution is to replace the piece of gear with a new one. This is no big deal if its a VCR or cheaper piece of av gear. You could always move the problem unit to another location in your house. If I were on a budget, I would go with solution 3 first. Its not a bad idea working the lo-end gear out of your system anyway. Its also a great excuse to tell the wife you need to spend some money for "safety sake". I could live with the 2nd solution if 3 and 1 were too expensive or if your wife owns a gun.
TPE
Unregistered guest
Posted on
Understand on the cost of a isolation transformer. But what good is the surge protector strip going to be w/out the ground. I am not as concerned with someones equipment as I am with their safety...what happens when the shell of a amp becomes energized via a short, no ground, it sits waiting for someone to touch it. What I would do, find the noise problem, in 99% of the cases it is a specific cable, not the units power supply. IE, a dig coaxial cable may be carring the noise, you can buy isolators for ind. wires that run about $200-$300. Seems pricy but, what costs less...a isolator or deductable on a hospital visit. Dont leave the ground lift on.
I love a good argument, but the only good one here is on Mystro's side. Broadly speaking, TPE has a point on removing ALL your grounds. We've all been taught SAFETY FIRST.
However, having been in AV probably longer than I want to admit, you just can't avoid it when connecting some equipment together. Listening to his opinion, we would have to throw away all those new components we're buying with two-prong plugs.
Fact is, not all equipment require safety grounding. Some acquire grounds through shields of other equipment and thus can be a source of noise (ground loops) if too many grounding points are used.
Lightning... what can I say. See the effects of a lightning strike, just once, and you learn ALL BETS ARE OFF! Grounding, does provide an extra path for normal stray currents, but high frequency currents (lightning) don't flow IN the wire, they flow AROUND it and will follow any path of least resistance. Wire or no wire.
Proper grounding is a science (FM!) in the AV world, sometimes us DIYers have to do a little experimenting to find that magical solution.
just my 2¢
TPE
Unregistered guest
Posted on
You first have to understand it. Too many problems are blamed on the ground using flase terms such as 'dirty power'!? That one always makes me smile. I am not saying that all equipment should have a ground otherwise throw it away. Again understand what you are talking about....why does some equipment have 2 prongs and some have 3 prongs?? Not because one is more safe than others or cheaper...for a manufacturer to issue a piece of equipment with 2 prongs that equipment must be atleast 'double insulated'. Meaning in a nutshell that any electrical wires, components must have atleast two methods of insulation to keep from energizing the shell of equipment. They do not have to be grounded and dont need to 'aquire a ground' from other AV wires. Why do this...to help reduce noise. If for some reason (usually heat) they cannot double insulate they must provide a grounded plug. like you said lighting will take the path of least resistance (thats what a ground is there to do!), when I say lighting protection I mean a distant strike there is no product on the market to protect against a direct hit. Again I am not saying that 2 prong is bad ( I use it when possible), nor am I saying that the ground isnt creating problems, rather that removing the ground is wrong and will not fix the problem, in fact could cause more! Right diagnosis, wrong fix! Hit the books and you will see.
