2. analog
  3. 1023683103

Tonearm-Preamp Grounding Problems-HELP

I have this thread posted in "Techincal" but want to put it in Analog to see if someone here can help. I apologise for its LENGTH!
Can someone HELP?
I am having two problems with my phono section and wonder if someone might be able to help.

The Problems are as follows.

1. No matter what type of tonearm cables I use the tonearm itself is "hot" (touching any bare metal to it pops like crazy) and gives off static discharges that cause pops and cracks either during idle or LP playback. Grasping the underside of the arm on a metal surface stops most of the discharges but not all. In fact I can feel a slight current sometimes when I do this.

2. In tracking down a ground loop as the cause for #1, I found that if I disconnect the tuner either from the preamp or the in-wall antenna connection, dependiing upon which tonearm cables I use I get a "flutter" noise through the phono section either by holding/grounding the tonearm or not.

As far as #1 is concerned, I realize I am acting as a new "ground" by touching bare metal to the tonearm or by grasping the underide of the arm, which stops most of the discharges. I was assuming a ground loop effect from within the system but the only thing I can determine is that unplugging all other cables from the preamp and removing all other AC power cords from the wall does not help.
As far as #2 is concerned, I am not sure if this is related to #1 but I disconnected the outside ground wire of the antenna from its ground post, which is not at the mains ground post, and there is no change in either #1 or #2.
It has been a major source of frustration since tracking it down has taken a long time and considerable inconvience. I have been trying to determine the cause since, 11/99, when I upgraded my TT/arm/cart all at once. Since I did not have the exact problem with my old set up
I automatically assumed it was in the cart. or arm.
I remember checking the new arm in the past for the same issues showing now and do not remember it being the problem. The fact that the dealer I am using is in, San Jose, CA., and I am in, Seattle, WA. does not help, as well as my scant electronics background.

What would cause the arm to be "hot" like it is? It seems like it is a preamp grounding issue now. I have the ability to use phono cards within the preamp, or separate phono cards in a separate case outside the preamp which is powered by the preamp's own separate power supply and utilizes a dedicated inputs in the preamp, or a third party phono stage which utilizes a line stage input and all the same problems take place.

I swapped out my preamp with another one of the same and had the same problem. My amp/preamp are NAIM gear and use "star" grounding, which I do not totally understand, could this be part of the problem? Someone mentioned measuring ground potentials before, do you think this may be the problem? My Ac panel uses a grounding rod as its "ground". I went around and un-hooked all other ground wires on the cold water pipes but no change. I have three separate outlets to use, two are separate 20 amp dedicated lines and the other is the original house circuit. I had the two dedicated lines installed to minimise EMI problems in the phono stage, but it only helped a bit. Plugging the amp/preamp into either the original outlet or one of the dedicated outlets, while unplugging all other items does not alter #1 or #2.
What now? I would really appreciate any advice! This has really ot me frustrated since I can hardly enjoy LP's since 11/99.

What I can say at this point is that when the arm is on the Orbe and I touch (with a wire) either the springs, the arm board, spindle, I get the pops. So at this point I am assuming that there is continuity between the arm and the Orbe. If I remove the Graham from the Orbe it still has the problems. The arm cable has no ground wire at the DIN to attach to the Orbe's sub chassis ground screw like a Linn arm cable. If I run a wire from the Orbe's grounding screw to the preamp ground post nothing changes.
Not having another arm to try, Saturday, I borrowed a Linn Basik arm from a local Dlr. and hooked it up to the preamp, and have the same problem! I have it mounted on a wood block cause I cannot mount it on the Orbe. The same problem, touching metal to metal causes pops. I think it rules the Graham out as the source. I hooked the Linns extra ground wire located at the DIN plug to the 52's ground post and nothing changed. I even ran a wire from a cold water pipe in my crawl space and attached it to the above mentioned Linn ground wire and it did not help. I have run an extra wire to the preamp ground to the base of the Graham and it does not help. Only grounding it to myself helps!
The fact that a second Naim preamp of the same model I brought in a while back and tried did similair things says its not my individual preamp.
I have tried cheater plugs on all items mentioned, using in different conmbinations, removed all sources but the preamp and amp and nothing helps.
I know that Naim uses a star grounding approach, is there something going on between the Naim gear and my house AC that may be causing this? The only thing left will be to bring home some non-Naim gear to see if the same problem takes place.

My equipment list is as follows;
Michell Orbe/Graham 2/Ruby 2 attached to a Naim 52 (K) and a Naim 250 amp. Digital sources are a Arcam transport and DAC as well as a Magnum tuner attached to a roof antenna. Phono Cables consist of either Harmonic Technology or Graham and non phono are Naim or some Kimber.

Thanks for your suggestions I look forward to more.
I'm dying here! This is a bugger!
Thanks!
gerardff
gerardff OP
78 posts
 
Richard-
Thanks for the help offer.
I did have two dediacted lines for my audio system added and a couple of extra outdoor and a 220v coverted to 2-110v outlets prior to my ,11/99, system upgrade. After the electrical work my prior TT set-up did not seem any different, in fact some of the things, like the EM/RF, I was trying to alter did not really change. I know he added some minor grounding add on's such as the gas pipe-to-cold water pipe ground wire and he rearranged my antenna wire to enter my house near my tuner instead of the poor way I had it. Other than that I had cable TV installed last year but all the problems I have now were prior to that.
I have some med-high tension lines just outside my house but they were there prior to 11/99, and did not seem to cause me that much of a problem. The street light gives me problems now and then but it's easy to distinguish.
I will await any help you can give me.
Thanks!!
If I could ground whatever is coming in to the tonearm/preamp I could deal with this but outside of works.
extremephono
123 posts
 
1) Get a multimeter, digital from Radio Shack is inexpensive (DMM)

2) Measure the level of ground leakage, by connecting the DMM from tonearm betal to the ground on your wall socket. Repeat this for the Naim, tuner etc. Try to do them in isolation (disconnect interconnects).

3) One suspect is the ground loop from your tuner. Have you tried to remove the tuner totally from your equation ? The roof antenna, if professional installed, probably have a ground to prevent lightning, and you added another ground, plus you have audio dedicated ground, and regular househole circuit ground.

Anyway, by using (2), you should find the component that has highest ground leakage, this is the culprit.

(4) While you're at it, make sure that all your audio equipments plug into outlets with same ground. Verify by measuring the voltage between each outlet where you plug in your audio equipment. It may be a chance that one of the ground outlet (in wall) has a loose connection on the ground. If you can fabricate a real ground plug by cutting off the other 2 prongs for measurement, you should then use the 'measurement plug', and shake vigorously in your outlets during measurement to make sure the connection is not loose, which will definitely cause problem.

5) Measure the quality of your AC. Set DMM to AC, measure the voltage difference between your 'neutral' and 'ground', and measure between your 'hot' and 'neutral'. The value between 'neutral' and 'ground' ideally should be low, but if you have AC quality issue, you get a high voltage reading here.

Give us the above info, and we continue.....

(*BTW, I really wanted to help, but I just could not send e-mail to you, if you can setup an Yahoo mail or something, then reply back to me).

Extremphono
gerardff OP
78 posts
 
Casey,
Thanks for the advice. It will take me a few days to get this done. I will try and e-mail you through a differnt account.

The latest is, my tuner is putting some BIG 500-600kHz RF into my AC line. And if it's plugged in (not on) into the old circuit that I use to use and the dimmer switch which uses the same circuit is on as well, WOW! I was up on my roof trying to figure out what was beaming a big RF signal through my wall and roof line. The dimmer off is not an issue but just having the tuner plugged in and the dimmer on was a gigantic RF signal being pushed through the circuit which looked like it made it back to the AC mains from the street. I was up there timing the cycling of these big events when my wife told me some of the things that she'd been doing. I almost missed it. But man, this thing was amazing.

Unfortunately, it has not solved my problem. The biggest solution so far has been switching to Naim "S" boards. This really makes no sense since they are only differnet by their cartridge loading values, nothing else.

As far as the TV antenna is concerned, it is grouned with a small 12 ga. wire at the AC mains roof post from the street and under the house where it's linked to a 3-way splitter, and the splitter is grounded to the incomming street cold water pipe. I disconnected that ground but nothing improved. I have disconnected the antenna's ground from the AC roof post and nothing improved. Both disconnected did not change anything.

The house has a ground rod from the mains box. I do not have a separate ground for the audio system. I only tried to ground the TT/arm using different grounding sources, but they are not in use at this time.

I have tried removing the tuner totally from the system and a couple things take place, a couple of things puzzle me though. Unplugging the tuner from outlet removes its RF contamination from the circuits but I cannot say for sre if this helps. Unplugging the antenna and or removing its
inputs from the preamp seem to make the popping worse.

I will be working on it tonight and will try a couple of new ideas.
Thanks!!
More to discover