Help with a grounding problem

[bigpigbig]

I have a grounding issue. I am trying to digitally archive some vinyl. I want to do it once and use as little post processing as necessary. It seems most of the posts about grounding on this forum are much more complex than this and I hope someone here can just tell me, "hey stupid newbie, just do this".

I have been stupidly obsessive about getting the following right:

1) cleaning the records: i have built a cleaning / vacuuming setup and do the following: wet brush with Stanton Brush and solution, Dry brush, wet brush again and vacuum dry. I even bought a pressure pump sprayer (garden variety) for dirtier projects (I'll spare you the description of how that is used)

2) Turntable: I bought a Stanton 681 EEE MKIII cartridge and Pro-Ject Debut III turntable. The counterweight that came with the turntable was good for carts weighing up to 5.5g and the Stanton cart is 6.2g. So...I ordered a heavier counterweight. Balanced the tonearm to specs (floating then +1.25g) and set the anti-skate to match.

I am getting a (very) small buzz from my amp when it is switched to "phono". This is only audible when volume is set close to 0db which for music would be deafening, but still bugs me. I unplugged all other equipment from the amp to isolate the turntable and amp from other sources. I plugged the TT and Amp directly into the mains (normally on a power strip). I think I tracked the culprit down to the wiring in the house! When I turn the light (on a dimmer switch) up and down or off, the buzz sound changes (slightly). When the light is off, it doesn't eliminate it completely, but cuts it in half. The noise floor is sitting at about -52db with the light on and goes to -56db when switched off. Strange thing is that it is stronger in one channel than the other!? In fact, one channel is almost completely silent. And, one more piece of the puzzle, when recording, the channel that has the stronger buzz, has a slightly lower recording level. ???

Any suggestions would be most welcome.

Should I hire an electrician? Or live with it and post process?

[cogsncogs]

Hi bigpigbig!

Grounding can be a complex issue! Do you only get the buzz only when your amp is connected to your sound card? If so you may have a ground loop problem. Is your turntable properly grounded, say at you amp? You could try grounding your turntable to your PC, if it will reach. How long is the interconnect from your amp to your sound card? If your amp has the old 2-prong (not polarized) plug you could try reversing it. If it's not don't try defeating it! Are your outlets grounded? You could get an outlet tester to see, but please leave any electrical wiring stuff to an electrician. RF noise from fluorescent lighting and other devices connected to the mains can travel a good distance along the house wiring. Cable or Sat TV grounding can cause a ground loop especially if they are connected to your sound system. I see you have already thought of that!

Is your amp/turntable/PC plugged into the same power strip? That would usually be ideal, but not in every case! If all else fails you may need a ground loop isolator. Google "rca ground loop isolator". I've never used one so I can't comment on what detrimental effect it would have on the quality of your signal. A good transformer based one would be best but expensive. You could try a separate/different RIAA preamp if you have one or can borrow one.

Some sound cards aren't very good and can be noisy, sometimes more on one channel than the other, some amps fall into that too! I've encountered situations where the arm tube had bad grounding leading to a buzz, the same with a few carts i.e. the grounding strap which connects the cartridge body to one channel's ground pin. BTW the 681 is a good cart! When you set up your cart weight did you take into account the weight of the brush? You have to ADD that to your actual dial up setting otherwise your tracking force will be off (lighter) by 0.5 gram or something like that, I don't remember exactly how much the brush weighs. Try moving your turntable to different location... you see there is no simple, easy answer; like HEY DUMMY do this!

Hope I was of some help!
Good luck and stay safe!

Wayne

[bigpigbig]

Originally Posted by cogsncogs

Hi bigpigbig!

Grounding can be a complex issue! Do you only get the buzz only when your amp is connected to your sound card? If so you may have a ground loop problem.

It is worse when connected to my Macbook Pro (tape out RC to line in jack 1/8") when it is plugged in. As long as it is on battery power is makes no difference.

Originally Posted by cogsncogs

Is your turntable properly grounded, say at your amp? You could try grounding your turntable to your PC, if it will reach. How long is the interconnect from your amp to your sound card? If your amp has the old 2-prong (not polarized) plug you could try reversing it. If it's not don't try defeating it!

The ground plug looks like a small fork (two pronged) and is screwed in tightly to the dedicated ground on my amp (Denon 3805). I have loosened this screw and touched the ground to other bits and had it loose. All are worse than when it is connected.

Originally Posted by cogsncogs

Are your outlets grounded? You could get an outlet tester to see, but please leave any electrical wiring stuff to an electrician. RF noise from fluorescent lighting and other devices connected to the mains can travel a good distance along the house wiring. Cable or Sat TV grounding can cause a ground loop especially if they are connected to your sound system. I see you have already thought of that!

Yes, I have unplugged everything except the TT and AMP to no joy.

Here is another mystery when I unplug the Sky Cable Box from the strip the buzz gets louder even though the cable box is totally isolated from the amp???

Originally Posted by cogsncogs

Is your amp/turntable/PC plugged into the same power strip? That would usually be ideal, but not in every case!

I have tried both the wall outlet and the same power strip. Same results.

Originally Posted by cogsncogs

If all else fails you may need a ground loop isolator. Google "rca ground loop isolator". I've never used one so I can't comment on what detrimental effect it would have on the quality of your signal. A good transformer based one would be best but expensive. You could try a separate/different RIAA preamp if you have one or can borrow one.

Gosh, I hope not. I bought the TT recently from a Hi-Fi shop in town, so I'll take it back and test it on their equipment to see if it is the problem.

When it is disconnected (RCA's) from the amp there is no buzz. When it is connected, even with no power to it, buzz on.

Originally Posted by cogsncogs

Some sound cards aren't very good and can be noisy, sometimes more on one channel than the other, some amps fall into that too! I've encountered situations where the arm tube had bad grounding leading to a buzz, the same with a few carts i.e. the grounding strap which connects the cartridge body to one channel's ground pin.

I see what you mean by "complex issue".

Originally Posted by cogsncogs

BTW the 681 is a good cart! When you set up your cart weight did you take into account the weight of the brush? You have to ADD that to your actual dial up setting otherwise your tracking force will be off (lighter) by 0.5 gram or something like that, I don't remember exactly how much the brush weighs.

I love the cart! It sounds so sweet that I have started really enjoying my vinyl again. I had the Stanton 500 and it was just so dull (in hindsight). As far as the weight goes, I think the brush sucks. He's why. I believe that tonearm counterweighting is hyper-critical to sound quality. The brush lands differently everytime it hits the record. Sometimes it sounds good other times it sounds light. I have just stopped using it because of the inconsistent sound. Great idea, poor execution (IMO). The bristles touch the record in a vertical direction and then are forced into a curved shape by the rotation of the record. It is this curve that pushes back against the tonearm. It is just not consistent.

Originally Posted by cogsncogs

Hope I was of some help!
Good luck and stay safe!

Wayne

Thanks an absolute million. You are too kind to help out in this way.

One more (Important) observation, when I touch the ground along its length, from where it comes out of the amp all the way to the amp the buzz increases quite a bit.

The strange thing (to me) is that the buzz is there whether the TT is plugged in or not. And touching the ground wire still makes it louder even when the TT is not plugged in?

There is no buzz from the amp when any other source is selected.

Cheers,

Basil