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? |
No wall warts and yes I disconnected the computer and cable line going into the modem as well. No change. |
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. |
What TT are you using? Cartridge?
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. |
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. |
I replaced the fuse and it plays fine. |
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. |
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/hum Did 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 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? |
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. |
The house is 15 years old. So new buy code standards. The room is a small bedroom. |
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 I have tried this but I didn't try ALL outlets. I can give it another try. By chance do you own a multimeter? yes, what do you suggest? |
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. |
That clarifies everything. I'm not too scared of it, i've done a little bit of electrical investigation on cars and a little on homes but I just like being very clear when I do stuff with it! |
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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Ok here is the results with power of preamp and amp on:
hot + neutral = 120.5V+/-
hot + ground = 120.5V +/-
neutral + ground = .05V steady |
Jea48,
i did get the hum with the preamp turned completely off - though barely audible, it
was there, just not as loud.
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