Ground Loop?

Work your way back from your amplifier and disconnect all other inputs to your main preamp.

If you just have the JC3 Jr, with no inputs, and your preamp and amp do you get a hum?

Also, if given the chance to use the balanced connections, do so and lift the ground on the destination if possible.

Thanks, I'll give that a try in the AM 9 930 I'll give that a try in the AM tomorrow I got to get some sleep I was up with it all night trying to fix this till around 430 am EST. and iy's 1030 now.

Since you mentioned two dedicated circuits, are you using isolated ground receptacles? If so, check the ground wires. Remember, an isolated ground requires an insulated ground wire. You should not use Romex. The ground wire is not insulated. I’m not an electrician but when I installed a new receptacle for my system. Based on my readings, an isolated ground has different grounding specs. In my case, I could not use an audio grade receptacle like PS Audio or any other brand that required an insulated ground wire for an isolated ground. I ended up using a Hubbell 8300 hospital grade receptacle. Hope this helps.

I tried with only the 2 pieces hooked up, nothing else just the Moon 350P preamp and the JC3 Jr phono preamp plugged directly into the dedicated 20 A line. Using 4 different pair of balanced or unbalanced connectors makes no difference. I hated doing this with full intention of returning it, but I ordered a less expensive MM/MC preamp, and it does the same thing too. It's like I'm cursed on vinyl playback.

I have 2 pr. of Cryo-treated watt gate receptacles wired direct to fuse box. It never had this problem before it just kind of creeped in slowly and it can be heard in segways and quiet portions of the music. 

Do your wattgate receptacles have an isolated ground? If so, check the specs. Call their tech support. Most, if not all, isolated ground receptacles will require an insulated ground wire. If this is the case and you are using standard Romex, your ground is compromised. 

Thanks for the info. When the outlets were installed, I used in wall 20 gage AQ power wires. I've lifted the ground on both and individually with adapters. I even had the 350P or the JC3 Jr hooked up to a regular outlet, 2 completely different lines and lifted the ground on 1 or both in different configurations. 1 using the dedicated line and a standard wall outlet So, it's not the outlets. Still there, but again when I reach back on the JC3 Jr and when I touch the loading pot and only the pot it goes away. When I do touch the pot, the noise slowly fades away. I've been in touch with David and Jason at Parasound via email, and they stopped communicating with me and won't answer any questions or offer any kind of help.

oldrocker52

When the outlets were installed, I used in wall 20 gage AQ power wires.

On a 15A line? Are you in the US? That isn't even close to code where I live.

I've lifted the ground on both and individually with adapters.

That also sounds problematic.

Do you have any other metal to metal contact going on?  Like via your shelf?

One other thing to check is that you have a good neutral.  Use a multimeter to test from Neutral to Ground.  Should see no more than a couple of volts.

Cleeds is correct. At 20 awg, you aren’t even close to a 20 amp code requirement. For a 20 amp circuit, you should have at a minimum, 12 awg wire. Personally, if this was a custom job, I would run 10 awg stranded wire in metal flex conduit. Again, I’m not a certified electrician but you may have much bigger problems than the ground. How long is the run of AQ 20 awg wire? Is the AQ wire rated for 20 amps at the length of your run? For your sake, I hope the electrician verified all the specs before installing the two circuits. Worse case scenario, one or more wires will heat up and possibly cause a short or fire.

I want to thank everyone for their input. It’s not 20 gauge now that I think more about it, it was done 12 years ago and the 10 gage sounds more familiar. The wire was made for this application. I had an electrician install the wire, breakers and receptacles to code. The run is only about 10-15 feet at most. Even so I plugged 1 at a time into a regular receptacle, 1 in the dedicated line and 1 in the regular socket then both with no change. So, I don’t think it’s in the dedicated receptacle and another regular outlet do the same thing. I’ll get my neighbor to check ground and stuff, he knows more about A/C than I do.

I’m so glad! When I read 20 awg, my heart sank. If you used audio receptacles, check the ground requirements. If interconnects are running to a device on a different ground, this may be the source of the ground loop. Hope you figure things out. Have a great weekend!

I was pretty sure the OP meant 20A wiring, so I just skipped right over that. :) 

I had similar problem with a preamp. The solution was purchasing an isolation transformer. 

Perhaps run a temporary drop cord from another outlet to the phono preamp. Costs nothing and maybe the problem goes away? If the problem remains, it’s one more resolution to scratch off the list.

Ground problems are the worst.  Sometimes it can take a while to sort them out.

The original post states "Different TT but still has the issue whether it's connected or not."  So, this means that you get the noise with no turntable connected?  The way to test for sure is to short the phono input.  If the noise persists it's not from the TT, connecting cables, or TT ground.

Here are some other things to try to see if there is any change:

(1) Use the standard AC plug to ground the line preamp and then use "cheaters" to lift the ground for the phono stage and the power amp.

(2) Use a separate single wire to connect the ground lug from the phono stage to the ground lug of the line preamp.

(3) Use a separate single wire to connect the ground lug from the phono stage to the house AC ground (can use the center screw of AC socket plate).

(4) Use a separate single wire to connect the ground lug from the line preamp to the house AC ground.

Maybe you can find the magic combination.  Best of luck.

I once had a ground loop thet crept up when I had my preamplifier on one circuit and my amplifier on the other. These circuits came from different phases in my main breaker box. When I got the amp and preamp on the same phase the issue went away. Don't know if that helps your situation, but I noticed you had two different feeds for components so it may be worth looking at that. Try plugging all components into the same outlet and see what happens.

One of my friends is a retired electrician and I'm going to get him to give the A/C line a go over. I also ordered a ground loop eliminator from Amazon a Btuty Buzz, if it doesn't work, I'll send it back.

I’d never had a problem with Ground Loop until my wife turned on an infrared space heater in the basement.  I had no idea what was happening and it drove me nuts until I figured it out.  What’s funny is we switched to a regular space heater and haven’t had any issues since.

I have had a similar issue. Finally resolved with isolation transformer. You may consider using a cheezy inexpensive audio xformer ($12 on Amazon) for troubleshooting before purchasing something like the iso-max that uses Jenson transformers.

Thanks everyone for the input. I have a friend that used to be licensed but now retired to give it a go over. I'll post this Sunday if that device worked and if my friend has time to take a look at it.

@erik_squires 

your luxman is up to NEC standards I assure you, it is internally grounded. You don't have to have an equipment ground to be NEC approved.

@invalid AFAIK, the equipment ground is not an NEC thing but a UL thing.

AFAIK, you do not have to ground a metal chassis IF the power supply is double shielded from the chassis. The Luxman is not double shielded.

What does internally grounded even mean?

@erik_squires the luxman amps i have seen pictures of all have the the class2 insignia.

@invalid I'm not an expert in all things that need to be tested and approved, but based on my amateur reading of the requirement for a class 2 insignia, the device needs to be double insulated, and, again, from my eyeballs, it's no better insulated than any other power amplifier.

Please see the middle picture where I show the bare fuse holders, with the AC cables to the right of them.  That is what you would see immediately upon removing the bottom panel.

To my poor unqualified eyes that is not a class 2 cabinet.  Maybe some one else can help me understand how it is.

Luxman 507uX.

I don’t see any indication the amp is Class II Listed. Can some one point it out...

Funny thing is, I didn’t remember seeing that either. I own exactly that model. :) I’m not breaking my back to find out. :-) AFAIK, double insulated gear has a dual square logo and I haven’t seen that. I’d have questioned if it was even legitimate based on how the unit is constructed.

Forgot to post the blog with the images I referenced, my bad:

https://inatinear.blogspot.com/2023/04/luxman-507ux-empower-project.html

There is a separate blog about how it seems the Luxman has the wrong leg fused here:

https://inatinear.blogspot.com/2023/04/luxman-507ux-ac-inlet-mistake.html

I kind of fixed it, no help from Parasound, but if I take a small piece of wire with a spade lug and slide it under the pot and connect it to the ground it goes away. I've never heard of such a thing it's not a hum but a chattering noise with static. Parasound has had it twice with no problems found. I've never spent so much money on something that's under warranty and the total lack of help is ridicules. Buyers beware.

Grounding Boxes

This may sound really dumb, and I don't have even a smidgen of the electrical chops that the old hands on the forum have; but I was having a similar problem awhile back with some new equipment and decided to make my own DIY "ground boxes" that use the RCA connections as a "signal ground." I found that in my system signal grounding only the CD transport and the DAC plus the REL subwoofers worked best and that every component need its own dedicated box. My boxes contained mostly sand and powdered graphite - the kind that hardware stores sell for lubricating door locks and such. Nestled in this mixture was a copper mesh conductor linked through the box to conductive wire leads soldered to RCA male connectors which interface with the female RCA connectors on the back of the components.

The upshot was that any little hums vanished and that the music became more relaxed sounding.

I don’t understand why that works either, but I took a 4" piece of wire attached 2 spade lugs, 1 slid tight behind the loading potentiometer located on the back of the unit and connected the other end to the phono ground lug and the noise slowly dissipates. It’s screwy too that the noise cancelation points seem to move too. It was only when I touched the gain toggle now it moved to the pot. Totally unbelievable I have no explanation for any of this it just crept in and now prevents me from listening to any vinyl. 5 different A/C cords, dedicated lines, Audience Forte V-8 power conditioner, plugged into other outlets not connected to dedicated lines, lifted grounds, Ground Hum eliminator and even cocked my head to the left. EVERYTHING in front and behind has been replaced, swapped, moved and tested. This has been going on for almost 8 months with all the shipping times and at least $700 in various shipping and services of TT and this preamp numerous times with no results other than a lighter wallet and an extreme migraine. Trying to download a picture but I’ve never done this here but the lay out is pretty simple. You have 2 toggles with the pot in between the 2 switches and ran it to its own ground lug, not a wall ground that does nothing I’ve tried that too. I’ve unplugged just about everything in the house other than the refrigerator and the house A/C, no new nothing installed. I did notice that when using a multi meter, both toggle switches and the pot don’t show ground continuity that all the other connections have at their bolts on their basses, I didn’t know if that’s normal or should be? And again, it’s not a hum, it’s a tapping staticky popping noise similar to the sound of a motor, thud, thud thud, with a slight popping sizzle sound in the background and so on. I’ve never heard of this type of noise before. STRESSED!!!

The potentiometer knob is plastic but with the spade or actually a U clip lug tucked up between and under it, and it kind of wraps around the metal post of the knob. So, what I’m doing is grounding the potentiometers metal post. It’s been to service twice and shipping isn’t free. Closest Parasound service center is over 200 miles away. The last I heard from Parasound was over 9 days ago and just said fill out the form again for an RMA said ship it to us. Both times they said they replaced the power supply and found no other problem. Shipping isn’t free and with today’s economy it’s twice what it cost before. I already could have bought the JC3+ instead. I can't sell something I have suspicions about or just take a total dump on it. It least that worked for now and so maybe my ulcer will settle down. 

Simplify life a bit in the future and use a li'l isolator like this perhaps...