Can't tell,if my house is properly grounded
GOOD NEWS!!!The cheater plug on the amp did break the ground loop circuit, but that does not prove the amp is at fault. It could still be the preamp causing the problem. So now, hopefully, when my new Decware integrated tube amp comes in it wont exhibit this buzz/hum, if it does at least I know its not the AC line. Time will tell. Good luck, Jim |
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GOOD NEWS!!! So I found a proper cheater plug and tried putting it on the tube amp only - buzz completely gone whether the phono pre was on or off. So it appears the amp was to blame and the phono preamp just amplified the problem. So now, hopefully, when my new Decware integrated tube amp comes in it wont exhibit this buzz/hum, if it does at least I know its not the AC line. I want to thank everyone who spent their time an energy helping me out! I learned a bunch and tracked down my problem. |
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Will do - just so I'm clear: hot = smaller blade neutral = larger blade ground = small round hole below the two blade holes. I know I sound like a simpleton here, but I don't want to shock myself or damage the equipment. Also I'm assuming I will not damage the equipment as long as I follow the above procedure - for instance testing hot and neutral at the same time while equipment is on. |
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OP, I realize you already have a Furman Elite Power conditioner, but to the point of the thread (based on the topic title), there are plenty of electrical testing devices to check for proper grounding. Something simple like an Emotiva CMX-2 which can remove DC (not saying that is the cause of your hi/low buzz) also has line monitor LED indicators that detect "line correct", "open ground", "open neutral hot ground reversed", "open hot" and "hot neutral reversed". |
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@last_lemming ... jea48 was very helpful to me in finding the cause of hum in my system. I just unplugged everything but the amp. I didn't notice before the same buzz/hum is there but bearly audible. This make me think that the noise is in the AC line. The phono preamps amplifies small signals so is it possible this bearly audible sounds becomes easily audible once it's boosted?An easy test would be to use a heavy-duty extension cord and run it to a receptacle on a different breaker, (as mentioned above). Then listen to amp only. |
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Just to add to the general dust cloud that the OP is removing hair over... I had a persistent 60cps 'hmmm' that sent me on a search & destroy mission. Went through the usual 'disconnect this/eliminate that' routine on my system to no avail. Moved on to the ac circuit, unplugging or disconnecting everything, including the GFCI 's that were part of that line... It persisted. Visions of 'Reddy Kilowatt' giving me the middle finger salute. Spouse said "Why don't you try a different circuit?" Since I subscribe to 'the women are smarter' theory (as they've got us pretty much where they want us), I got out the extension cord...3 wire, of course. *Poof* Gone. Beats me as to why. Only operative reason may be a noisy breaker. Since the existence of the new extension cord isn't a tragedy nor an issue I'm in no rush to buy a new breaker, BUT... It could be that simple. Easy enough to try, can't hurt to do so. Good luck. Spouse got thanks, big hug and kiss. ;) She likes my hobby...she likes how it all sounds as well although the complexity of 'the mains' confounds her. So the project at hand is to develop a simple 'work-around' for her to enjoy the solution as well. *S* Marital bliss requires maintenance...;) |
With only the preamp connected to the power amp, TT not connected to the inputs of the preamp, unplug the preamp from the AC power. Turn on power amp and check for the buzz/humDid this and no hum. I'm not clear what that proves or disproves, if the preamp isn't plugged in then the ground isn't plugged in and no ground loop can occure. |
I second Erik's suggestion of having a tech look at it. There is the possibility that a safety cap in the receptacle is leaking ac, especially the one from N to ground. If the fuse blew with that extension cord, it's possible you reversed polarity and ac went to ground through the bad cap, especially if there is an earth line choke between the safety caps. To be clear it made the noise prior to me trying to use the cheater plug that flipped the polarity. |
Ok, I did everything everybody said, and there is no change buzz is still there. to answer a question from above I switched the room the phono pre was in and went from single ended to xlr because the tube amp doesn’t have xlr. I have had the same issue with an old Conrad Johnson amp, where it would buzz as well. Could the tube amp be the culprit? Bad tube? i also noted that the buzz/hum is older on different wall outlets. |
Am a bit confused about what has changed. Seems like hum came when you changed room...and the gear change was a switch to single ended rather than balanced cables from phono stage, and new speakers? Speakers and amp seem to check out ok, correct? But the phono cable introduces the noise? Can you go back to balanced cables to see if that matters? If not, can you adjust the gain level on the phono to see if that has any effect? |
I second Erik's suggestion of having a tech look at it. There is the possibility that a safety cap in the receptacle is leaking ac, especially the one from N to ground. If the fuse blew with that extension cord, it's possible you reversed polarity and ac went to ground through the bad cap, especially if there is an earth line choke between the safety caps. It's a long shot but it could explain why you're getting a groundloop even when plugged into the same outlet as the amplifier. |
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I will try removing the cables tonite. However the TT has no power and is not directly plugged into anything (VPI prime TT). The problem arose when I moved my TT setup to another room and switched to single ended output from the phono pre instead of my XLR cable I used previously. The speakers in this new system are super sensitive (101 db) and these noise noticeable. |
last_lemming OP 265 posts 02-20-2017 10:46am
I have a Dynavector 20x2L, and the cables are Cardas Clear Light. They have never given me trouble before. I don’ t know if this matters but the noise is coming from both speakers, but I assume if one cable was bad then that noise would affect both, but I really don’t know. I will try swapping out cables tonight to see if that helps. //Did you try what I suggested, disconnect the TT phono cables from the phono preamp? You said the hum/buzz was independent of the volume control setting, so just turn down the volume control and listen if the hum/buzz is still there with the TT disconnected from the phono preamp. If the hum/buzz is gone then there something between the TT and the phono preamp going on. IF the hum/buzz is gone then I would say the problem, issue, is not between the preamp and power amp. If the Hum/buzz is still there then the next thing I would ask is how close is the Parasound JC3+ Phono preamp to the power amp? Try moving the preamp as far away as possible from the power amp. Especially the power transformer of the power amp. Try turning off and unplugging the power cords of any other equipment near the preamp. Only have the preamp, power amp and TT plugged into the AC power. |
I have a Dynavector 20x2L, and the cables are Cardas Clear Light. They have never given me trouble before. I don' t know if this matters but the noise is coming from both speakers, but I assume if one cable was bad then that noise would affect both, but I really don't know. I will try swapping out cables tonight to see if that helps. |
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i did try and the polarity reverse to no avail. I also tried a cheater plug, but since I didn't have one designed for that purpose on hand I used an old extension cord for 2 prong components. It had a little bump out on the end to block the ground prong so a person couldn't "cheat". I cut this prong off and plugged the phono pre into it and promptly blew the fuse. I'm not sure why, maybe when I plugged it in I had the plug reversed? Not sure. |
@last_lemming Did you try the polarity reverse switch? If not you should give that a shot! |
I have cable tv and I turned off all lights when I was checking. Nothing seemed to work. I also disconnected the cable tv. HOWEVER - I diconnected everything but the amp (and speakers) no noise. I plugged in in the phono pre into the same wall outlet as the amp - no noise. i connected the RCA connects to the amp from the phono preamp- NOISE! so I guess there's a ground loop between these two pieces, what I don't get is why, both are going to the same electrical outlet. Only when the interconnects are connected do I get the sound. If I connect a ground wire from chassis to chassis nothing happens. Any thoughts? |
Do you have satellite tv? If so is there a phone line connected. I had trouble years ago and was able to acquire a isolater for the phone line and the buzz was gone. Another common contributor to this type of issue is the ground to the component. Have you tried lifting the ground to the Parasound? I have 5channel amp, that I have the ground lifted to eliminate a light buzz in the rear speakers. |
This is unlikely to be a house grounding issue, however make sure your ground and neutral are properly bonded at the service panel. Are you sure you don't have a wall wart like Wifi supply or PC going on? Good that you tried your TV cables! Most problems are coming from them. I'd try to minimize your problems. Start with the amp, with nothing connected, then work your way towards your source. When you have the absolute minimum that causes hum, come back. :) Best, E |
