Mains noise!

[Anton]

After alot of searching and question asking I finally picked up an all in one surge protector and mains filtering power board from Surge Shield, namely the Premium A2 (http://www.surgeshield.com.au/a2.htm) I was so impressed when I first fired up my system and had a long listening session, it opened up my system that little bit more, needless to say I thought it was bliss. After finishing up and switching off the lights in my lounge room, "THUMP", what the? I switched the light back on and off again "THUMP". The noise was coming from my sub. I've had this problem since day one and hoped that the Surge Shield would remedy the problem, but alas no.

The next day I sent an email to the Technical brain at Surge Shield, he was quick to reply stating that the Premium A2 filters out the high frequency noise from the main but not the low frequencies.

Hence the reason for this posting, has anyone have a remedy for this low frequency noise? I'm not using any specialty power cables just the Premium A2 direct from the closest wall socket and then to my gear. Any ideas?

[David Meek]

Anton, just as a baseline, plug the sub into an outlet (try several) that's not in the same area as the one you are currently using. It'll take a decent quality extension cord unless you are willing to haul the sub around from room to room. The idea being to try an outlet on another breaker. This is a fairly quick and easy way to find out if you have something like a fluorescent light/refrigerator/whatever on the specific circuit that is causing the extraneous noise.

[Anton]

No luck

Thanks for the tip David, i tried every other socket in the lounge room and two in adjacent rooms and i have no good news, the whole ground floor of my unit is on the same circuit. I think I'm pretty stuck. Any other suggestions?

[aarsoe]

Have you tried to play with the level settings on your sub? You may be able to turn its volume down to a level, where it wont react. You will have to turn you processor level up instead..

Also - you could try a cheater plug to remove the ground, as the sound it likely created by a current running through the ground wire..

[Anton]

I'll give the level setting a go. The cheater plug idea sounds good too, how do I go about doing that?

[David Meek]

Sorry Anders, but Karl stay away from cheater plugs! A cheater plug, is a two-prong plug on the wall-side with a three-prong (for ground) configuration on the other side. It breaks the ground at the outlet, and that can be VERY dangerous for your equipment. Think dead. If you use it for just a few minutes as a check for grounding issues, that's one thing. But don't use it any longer than that. You are putting your components at risk if you do.

[Anton]

Thanks for the quick save

:T
Well thats is a good bit of advice.

I'm glad I didn't go down that track too swiftly.
The amp level is a good idea I'll tackle that first, It's just so annoying :M .
Being in a rebtal property I can't just put in a dedicated line like I want to, that would be the BEST, no mucking around then.

[chrispy35]

There's been a lot of talk about cheater plugs lately and many statements about equipment damage and/or personal safety issues associated with using a cheater plug.

I can understand the personal safety issue: the chassis of your equipment is no longer tied to the same potential as your feet are so, if the chassis becomes energized somehow, you run the risk of electrical shock if you touch it.

I don't grasp how the equipment is at risk though. I thought the ground pin of the receptacle was strictly for safety purposes. Under normal operation, there should be no current flowing the ground pin at all, right? (Everything coming out of the hot pin should go right back down the neutral pin.)

Can someone explain in detail how the equipment is at risk when not properly grounded?

[aarsoe]

I think it all comes down to how your safety braeker works. The design of theese breakers are very different country to country. In Europe a lot of the countries have plugs without any grounding pin - and there is no issue at all, as the safety breakers are designed so that as soon as there is a current leak, it will trip. But this only applies to personel safety.
I must admit that I have never heard of issues with gear "frying" or something like that.

A footnote - since we are talking about a subwoofer - the box is most likely made from wood, so even if there were a current in the chassis, you would not be electricuted, as wood is not a conductor. BUT BETTER SAFE THAN SORRY.

[chrispy35]

I think it all comes down to how your safety braeker works. The design of theese breakers are very different country to country. In Europe a lot of the countries have plugs without any grounding pin - and there is no issue at all, as the safety breakers are designed so that as soon as there is a current leak, it will trip. But this only applies to personel safety.
I must admit that I have never heard of issues with gear "frying" or something like that.

A footnote - since we are talking about a subwoofer - the box is most likely made from wood, so even if there were a current in the chassis, you would not be electricuted, as wood is not a conductor. BUT BETTER SAFE THAN SORRY.

Most SW's still have their amp exposed though...

Anyhow, there still seems to be no evidence for equipment damage. So I guess it's safe (pun intended) to say that a cheater plug in itself only creates the possibility of damaging yourself rather than your gear.

That said, the danger to yoursefl is certainly real unless you're 100% sure that some other connection you've made to the 'cheated' equipment has grounded it instead.

[Wayne A. Pflughaupt]

Yes, the issue is personal safety, not the equipment. Normally a ground is connected to the chassis of the equipment. Thus, if the A/C hot ever gets loose and contacts the chassis, it will trip the breaker.

If there is no ground and that happens, you will become the path to ground when you touch the chassis. Zzzztt!

Regards,
Wayne A. Pflughaupt

[aarsoe]

I agree on the personal safety issue - but in all fairness, the way the breaker is designed over here, that will only happen in case you are insulated from ground. Also if the ac hot gets loose and touches the chassis, that will create a short, so the fuses would blow immidiatly. So in all likelyhood it you should only be at risc if you where standing on a rubber surface, while putting one finger on hot and one on neutral...
But as I said, safety first..

[ekkoville]

Here is a question to you electical gurus......most codes in New Hampshire anyway, require an arc-fault breaker to be used in any bedroom for safety purposes in case of the current arcing. If the breaker used for the amp is an arc-fault breaker, would the high sensitivity of the breaker trip and prevent injury?

Erik

[Glen B]

Here is a question to you electical gurus......most codes in New Hampshire anyway, require an arc-fault breaker to be used in any bedroom for safety purposes in case of the current arcing. If the breaker used for the amp is an arc-fault breaker, would the high sensitivity of the breaker trip and prevent injury?

Erik

Most likely not. It is not a ground fault circuit interrupter, which works differently from an arc-fault circuit interrupter (AFCI). The GFCI works by detecting current imbalance between the hot and neutral (like in the case of a fault from hot to ground). An AFCI works by detecting specific unique signatures of electrical arcing, something completely different.

[chrispy35]

I agree on the personal safety issue - but in all fairness, the way the breaker is designed over here, that will only happen in case you are insulated from ground. Also if the ac hot gets loose and touches the chassis, that will create a short, so the fuses would blow immidiatly. So in all likelyhood it you should only be at risc if you where standing on a rubber surface, while putting one finger on hot and one on neutral...
But as I said, safety first..

Not so sure about this. If AC/hot gets loose and contacts the chassis AND the chassis is no longer grounded due to a cheater plug --> you end up with a chassis that is hot and no fuse being blown. If you're not isolated (wearing rubber boots) and you touch the chassis you become the path from hot to ground.

[aarsoe]

Agree - but that would drop the current and the breaker would step in - but it is again a theoretical exercise, since we all agree on the safety issue.
Never do anything that could be dangerous unless you know what you are doing, and then I would still recommend you to think again.

On the other hand, one of my friends is an electrician, the way he locates the hot wire is by licking his finger and touching it. He says that if the finger is not wet, then he cant really feel it.
What can I say - he is SCARY... and I hate it when he does it..
NEVER EVER EVER EVER EVER DO THIS!!!!

[ekkoville]

He says that if the finger is not wet, then he cant really feel it.

Is that like putting a 9volt battery to your tongue!!??

[whoaru99]

With some equipment I think it might be possible for it to be damaged if connected without a ground. Fairly unlikely, but possible. The case might be if the equipment has surge supression or some other type of line fault protection built in that relies on ground for function.

BTW - A GFCI will not protect you from touching the hot and grounded ("neutral") wire, it will only function as designed by a fault from hot to a grounding path that creates a "leak" out of the circuit.

[Anton]

After asking the question I haven't had much input into the topic but, I invited my most qualified friend on the subject of main supply over to test my supply.
He ran a check on the distribution box all the sockets on the circuit powering my hi-fi. The end result proved that the best way to keep your system clean from outside noise is to seperate the whole kit'n'kaboddle from the rest of the house. Cheater plugs are just asking for meltdown, my buddy who is an electrical engineer and certified electrician agrees.
Being in a rental property I don't have the option to dedicate a circuit to my system. It will be my first course of action in my own place though.

The noise in my system will have to be lumped with until I can have a dedicated line of power. I took the earlier advise and lowered the gain of my sub amp, this helped alittle but not fully.