Star grounding saved my life

[matta]

Okay so the title is a little melodramatic

I just wanted to stress the importance grounding to newbies, like myself.

I had wrapped up my Channel Strip a couple days back (2 Green Pres and a
Calrec EQ) and I thought all was well, a little noisy but by enlarge it
worked great. I did find some anomalies but what came as a shock is that the
grounding was being done through my 002R!!!! The pres would not function if
the Calrec was not plugged into the 002R, all I got was a LOUD hum that went
away if the Calrec was inserted into the 002R.

After I discovered this I went about researching ?star grounding? here on
the board and came up with various posts and guidelines.

In my case I joined all the Pin 1?s on the XLR Ins and Outs to my AC/Chassis
ground and also attached the ground from my PSU to the same point.

After powering up with my new grounding config everything worked flawlessly,
not a single hum, no mater how you config the pres and EQ. The Calrec no
longer distorts or buzzes, which it occasionally did in the past and it is
as quiet as a mouse!

So the moral of the story is evaluate your grounding scheme, and even though
it might work, it might work better. I have def noticed a considerable drop
in noise as well, I?m not sure technically why this happens, but it is def.
noticeable.

Cheers

Matt

 

[nacho459]

I (almost) always ground everything to one of the lugs on the power transformer. Proper grounding becomes an art when you work on guitar stuff that doesn't use transformers on the inputs and outputs, especially if it's high gain.

98% of the time go with a star ground.

 

[Rob Flinn]

I (almost) always ground everything to one of the lugs on the power transformer.

I always make the star ground point as close to the input sockets as possible because I have read several times (don`t remember where) that this is best for least noise/hum

 

[Hulk]

I also had hum/Bzzz (around -40dB on both channels) on my newly build G9 but yesterday I connected proper earth to the 230V power inlets in the studio and all hum/Bzzz problems are history now

 

[CJ]

well duh!

:razz:

 

[daArry]

Isnt it normal to just ground the pin1's on the inputs but leave the output pin1's floating? (to avoid ground loops)?

 

[pucho812]

When I first started was taught to star grould everything. I have been and never had a problem. But a funny ground story I was told about a famous studio here in LA.

Had a chemical ground as their earth ground. My understanding, a chemical ground is where the earth ground is in a vat of chemicals in the earth as opposed to the ground spike just in the earth(ground). This cost more $$ and is better or so I have been told. Anyway one summer this studio started to get ground noise everywhere and it just started happening one day.
They had it in the multitracks,board,speakers,outboard everywhere was ground hum. Well after a week of searching they found that the chemical ground had dried up due to summer heat. So the solution was to water the ground and get the chemicals wet again. After the running staff soaked the ground the hum went away. So if you ever have major ground problems just soak it in water. :green:

 

[amorris]

I had a similar situation as pucho here in FLA. but thev ground spike was in a gravelish dirt and it dried out after a dry summer. i didnt get continuity from the building ground and our special star ground (which of course had all the audio on it) I ran a garden house over the weekend and contiuity returned and the ground noises cleared up.

 

[Butterylicious]

Proper grounding makes all the difference between something that works and something that works properly. Being an electrical contractor by trade, I'm all about grounding.

Now if you want to DIY improve your permises grounding, don't go out and buy a ground rod. You're wasting your time and you'll prolly bust a gut swinging a sledge hammer. They don't make enough contact with the earth to be even remotely effective. NEC states that a grounding system must be within 25 ohms. At 120 volts that's almost 5 amps. I've never measured a ground rod lower than 40 ohms. Completely useless. If your house sits on a slab, it is ideal to unearth a bit of rebar and ground to that. If your plumbing is all metallic, a jumper to a cold water pipe is usually a good ground too. Technically, it's a cold water "bond" and is required to allow stray currents loose in the water system a path back to the grounded electrical system, but voltage knows no code and it will always seek the shortest path to ground. If all else fails, a 30" pit ground with a good 30' of 2/0 wire will always out perform a ground rod. You should always use at least #4 for grounding, unless your service is over 200 amps, then you need to consult the code book.

 

[pucho812]

Grounding humor Story #2.


O.k. so here is another story now I don't have it in front of me so I will type it as well as I remembered reading it. Plus I dunno if it is true but if it is it's funny IMO except for the harm to the dog.

In england, they use a 2 wire circuit for their phone systems. Accross the ground wire they will send 90 volts of electricity to ring the phone you are calling. When the person then picks up it switches over so there can be a 2 way conversation.
Well this elderly lady called the phone company one day saying that she has intermittant ringing of her phone when people call her house. Her dog will usually bark before the phone rings at her place. The phone company sent out a repair tech. He climbed the telephone poll and patched in a test set and proceeded to ring her house. First time no ring, Second time dog is barking loudly, Third time ring ring. The tech climbed down only to find that the dog had been tied to the telephone ground with a metal collar and metal chain. When people would call the lady, 90 volts would shock the dog. THe dog would start to bark and after a few times swould loose muscle control. Loss of muscle control would cause the dog to go to the bathroom on himself and basicly all over. After going to the bathroom the dog would be standing in it's own urine and complete the circuit thus causing the phone to ring.

 

[chrissugar]

:green: :green: :green:

chrissugar

 

[CJ]

Darn, I peed the floor and I still get no calls. :sad: