Apologies in advance for my almost complete ignorance of electrical issues!
As part of a whole-house rewire, I had the electrician add two #10 independent ground runs to two brand new Power Ports for the hi fi.
I hear buzz from appliances on other circuits in the speakers, and switching box fans on and off creates pops (these are also on other circuits). I can also hear a buzz from the power supply for the turntable when this is switched on.
All the audio gear is running into one receptacle through an older Chang power conditioner (saving up for a Power Plant).
I’m assuming this means that the new circuits have been wired incorrectly, as I thought these new (apparently) IG runs would eliminate noise from the other circuits.
In advance of talking to the electrician about it, are there any obvious ways this could have been mis-wired to create the above problems?
What kind of electrical service do you have? Are you in the US? In the US most household uses 240v single phase. That means you have two hot wires on opposite phases and a neutral wire which is also the ground wire coming into your main service. To really isolate your stereo circuit from the annoying appliances, it’s best to have the stereo circuit on the phase that’s opposite the appliances, but also have a dedicated neutral and ground so they’re not sharing the same power as the appliances to their circuit breakers. Sometimes noise still leaks through the since both phases have the same neutral, but it helps also to have dedicated grounds to your new circuits.
I don’t know if your two stereo circuits are on opposite phases also. It’s best if they are on the same phase if possible and run two separate neutrals regardless, one for each circuit.
The buzz from your turntable power supply is a ground issue. Make sure your TT motor is properly grounded.
Hope that helps.
We are in the US. I’ll convey this info to the electrician, and hopefully he can fix it.
The turntable is grounded to the phono preamp, which is plugged into the power conditioner, and the TT power supply is also connected to the power conditioner. Not sure how to better ground it?
The motor has to be grounded. Run a wire from a metal part of the motor to the ground of your power supply outlet with a continuity tester and see if you have continuity. I once had to attach a wire from a metal part of my motor to a ground terminal to solve my hum problem.
The wall outlet. If you have continuity to ground there, that means your motor is grounded, so the hum could be something else, possibly your phono pre is picking up the hum. I had noise problem with a lot of phono preamp before, but a good one is pretty quiet. The one I have now is dead quiet. You might want to look there next if it’s not the motor.
Checked this, and we have continuity. Then, I grabbed the phono pre and moved it 10" from where it was- motor hum gone. So that part is solved at least! Thanks for help!
So… today we had the electrician run the two dedicated A/V circuits past the subpanel, wiring them directly to the main panel and their own breakers and ground to service ground. Still the noise from other appliances persists. The TV, plugged either into a separate 3rd circuit, or to one of the new dedicated ones, makes a loud buzz through the speakers, and changing the speed on cheap box fans plugged into other circuits causes loud pops. The electrician seems to be stumped. Does this make any sense at all? Could this be not a electrical wiring problem, but some kind other kind of interference?
At the risk of too many posts in too short a time frame, I’ve narrowed down the problem slightly. I plugged a cd player into the amp to test, and no interference, very quiet. SO, that means interference some other way. I turned up the volume all the way back on the turntable input, and it’s actually picking up radio signals somewhere in addition to all the other noise. Does anyone know if interconnects might be the most likely culprit? Does this kind of thing happen ever? At least I know the electricians did it right. Thanks for any thoughts…
Yes, I had a radio station come into my speakers also. It’s the phono cable acting like antennas because of bad shielding. Find a interconnect with better shielding and make sure you have a very tight solid connection. Loose connections also make noise. The phono cable is very sensitive because of the huge amount of gain from the phono preamp.
Ground hum in A/V systems often is related to the video connection to the audio system. You need to find out which sources have hum and which ones are quiet.
If you have cable tv you can lift the ground on your preamp, and PSAudio now sells a ground lift for the cable coax line.
The turntable hum is a whole different issue, and I do not know enough about that subject other than lots of variables can cause problems.
If you want a more thought out answer you will need to tell the forum what components are in your system and which sources cause you hear the hum.
It can also be a problem with a loose connection somewhere in your electrical wiring or a bad ground connection.
I’m running a Lehmann Black Cube SE II phono preamp, and a Leben 300XS integrated amp. New turntable is Pro-Ject Extension 9 (same noise issues w/ old and new TTs) with a Hana SL cartridge. Using the phono cable that came with the TT. I was using a Budgie step up transformer with the old cart, but removed it for new one. The interconnects from phono pre to amp are approx. 20 year-old Transparent “The Link 200” 1 meter long. These are the basic ones they used to make w/o the “network” pods attached to them.
I am wondering if the old Transparent cables are what’s attracting all the RFI etc., and have ordered a set of Blue Jeans interconnects that are meant to be super well shielded to test this.
There is an optical audio cable connecting the TV to an external DAC, which is then connected to the amp, but the DAC is not powered on when listening to the analog setup.
There’s no cable tv coming into the house.
Right now we are painting the house, and everything’s packed up; when I’m able to set the gear up again w/ new cables I’ll report back. Thanks again!
In case of interest, I’m posting an update now that I’ve discovered what the main issue was. Turns out the source of all the hum and interference was the phono preamp itself. It’s behaving as if it’s ungrounded, and acting as an antenna for at least a few kinds of interference. I’m going to send it in. I swapped it out for another phono pre, with all the same cables (except the preamp power cables), and no problems. I found one thread online from a while ago where someone had very similar problems with a Lehmann phono stage and a low-output cartridge: hum, radio stations being picked up, etc. So perhaps it’s simply an incompatibility issue with the Black Cube SE II and the Hana SL- when the preamp is set at the higher gain for a LOMC, it becomes really sensitive to interference for some reason. In my case, all the higher gain settings for LOMCs created problems. I’m surprised at this, but the fact that I couldn’t find much about it online makes me suspect that something’s wrong with the preamp.