[Gzerro]

I could use some help diagnosing a buzzing noise. It doesn't sound like ground loop hum, it is more of a very slow buzz. The buzzing happens without a record playing. I haven't made any changes to my system for a few months, and it just started happening out of the blue a couple of days ago.

My equipment is a VPI Scout -> Parasound JC3 PS -> Parasound P7 Pre. I run a ground cable from the Scout to the JC3.

To diagnose here is what I have done so far:

1) TT motor unplugged, buzzing still happens. Not the motor.
2) Unplugged cable from back of phono stage, buzzing stops. It must be before phono stage.
3) Reconnect cable to back of phono stage, unplug from TT - Buzzing continues. Cable is picking up the buzz.
4) Swap VPI branded interconnect for Blue Jeans LC1 with better shielding. Before plugging into turntable buzzing is almost inaudible but still there.
5) Reconnect turntable and buzzing gets a little louder, enough to be irritating but much better than with the VPI cable.
6) If I touch the turntable, tonearm or twisted tonearm wires the buzzing gets louder.

Is this RFI? What would be the best fix for this? Any idea what would cause this to start happening?

Any help would be appreciated.

Tom

[neobop]

Hi, your description is a little hard to follow.  This sounds like a microphone buzzing?

This ground wire from your table to JC3 - is this the tonearm ground or a separate ground ?   How many in total?

Any new devices plugged in just before this started happening? 

neo

[Wayner]

What cartridge are you using? Have you moved any pieces of equipment lately (power transformers can induce hum into phono circuits). Have you added any electronics to the system recently, even a wall wart can cause problems if too close to the arm/cart.

Wayner

[Gzerro]

Hi, your description is a little hard to follow.  This sounds like a microphone buzzing?

This ground wire from your table to JC3 - is this the tonearm ground or a separate ground ?   How many in total?

Any new devices plugged in just before this started happening? 

neo

Sorry if I didn't describe it very well. It is difficult to put into words. It sounds like a slow buzzing, with the blips of the buzz rapid but seperated, so it is a low frequency oscillating "ba-ba-ba-ba-ba-ba" noise. In the past when I have had grounding issues it has always been a steady humming, so this seems different.

There are two ground wires on the TT. The main ground wire from the ground lug on the tonearm wire/RCA jack junction box to the JC3 and another short wire from the bottom of the tonearm to the same ground lug. I have tried disconnecting the ground wires, but it had no impact on the noise I am describing.

I haven't made any changes to my system or added any new electrical appliances or lighting.

I hope that is clearer.

Tom
Thank you again.

[Gzerro]

What cartridge are you using? Have you moved any pieces of equipment lately (power transformers can induce hum into phono circuits). Have you added any electronics to the system recently, even a wall wart can cause problems if too close to the arm/cart.

Wayner

Cartridge is a Dynavector 20x2L. The PS adds 68db gain. I haven't added or moved anything recently.

I do have a ton of gear going to the same socket to avoid ground loops. My HT and analog systems share the amplifier and speakers. I will try unplugging everything but the bare minimum for the vinyl setup to see if that helps.

Thank you for the suggestion.

Tom

[Wayner]

Because the system was running fine awhile ago and now there is a problem, makes me think that there is some kind of a contact problem, maybe even at the cartridge terminals. I know here, where it gets humid, then dry in just a couple of days, raises hell with the connectors. Perhaps simply unplugging the tonearm connectors and re-plugging them in will help, or better if you have some De-oxit 5 spray (don't spray on the cart, but in a small bowl or the cap of the De-oxit and then brush it on with a small (paint) brush.

I'd also check the outer sleeve of the RCAs, for proper contact, and perhaps spray them too.

It could also be the connector on the Scout, going from the tonearm to the little J-box. I'd unplug/replug that too. So that is at least 4 places for the signal to go to hell.

It certainly is looking like a small, mechanical contact problem.

[Gzerro]

Because the system was running fine awhile ago and now there is a problem, makes me think that there is some kind of a contact problem, maybe even at the cartridge terminals. I know here, where it gets humid, then dry in just a couple of days, raises hell with the connectors. Perhaps simply unplugging the tonearm connectors and re-plugging them in will help, or better if you have some De-oxit 5 spray (don't spray on the cart, but in a small bowl or the cap of the De-oxit and then brush it on with a small (paint) brush.

I'd also check the outer sleeve of the RCAs, for proper contact, and perhaps spray them too.

It could also be the connector on the Scout, going from the tonearm to the little J-box. I'd unplug/replug that too. So that is at least 4 places for the signal to go to hell.

It certainly is looking like a small, mechanical contact problem.

I don't think it is related to anything on the TT itself, because I can hear the noise as soon as I plug a cable into the back of the phono stage, even without connecting to the turntable at all.

The biggest contributor to the noise was the VPI branded phono cable, and it got a bit louder plugging in the turntable, then a little louder if I touch the tonearm or tonearm wire.

Switching to the Blue Jeans cable almost eliminates the cable noise, but the TT picks up some noise. Overall maybe 25% as loud as with the VPI cable.

It seems to be something environmental.

 

[*Scotty*]

It pretty much has to be RFI. Wayner's suggestion is a good one, check your all of your connections. There is also another possibility, a new source of RFI has come online somewhere near you. A large increase in the amount radio frequencies bathing your neighborhood could be the straw the broke the camel's back.
 The give away to the RFI problem is the increase in the noise levels when you touch the tonearm, also the reduction in noise when you went to a better shielded cable. Your body is acting as an additional antenna and increasing the signal strength injected into the phono-stage when you are touching the tonearm.
 I suffered a similar problem when the selector switch in my preamp became intermittent and noisy. A thorough cleaning and then treatment with CAIG ProGold restored blessed silence and freedom from RFI.
Scotty

[Gzerro]

It pretty much has to be RFI. Wayner's suggestion is a good one, check your all of your connections. There is also another possibility, a new source of RFI has come online somewhere near you. A large increase in the amount radio frequencies bathing your neighborhood could be the straw the broke the camel's back.
 The give away to the RFI problem is the increase in the noise levels when you touch the tonearm, also the reduction in noise when you went to a better shielded cable. Your body is acting as an additional antenna and increasing the signal strength injected into the phono-stage when you are touching the tonearm.
 I suffered a similar problem when the selector switch in my preamp became intermittent and noisy. A thorough cleaning and then treatment with CAIG ProGold restored blessed silence and freedom from RFI.
Scotty

Sounds like a little project to clean all my connections is in order. I will give that a try and see if it helps.

Thanks!

[neobop]

Scotty,
I'm wondering how you distinguish RFI from a plain old ground problem.  I'm not saying you're wrong about Wayner's suggestion and a possible solution, it would be the first logical thing to service, but why is this necessarily RFI?  I'm asking you about this because I think you might live in an area plagued by such problems and have dealt with it before.  Seems that many who live in SF bay area mention this and with our increasing use of RF this problem should get worse for more people.

Gzerro described the noise as a low frequency buzz or oscillation.  Wouldn't that suggest AC/ground problem?  Is it typical for RFI to manifest like this?  When you serviced your selector switch and cured the problem, why was that necessarily RFI, type of noise? 
When Gzerro replaced the VPI cable with Blue Jeans and rid 75% of the noise, it might have been due to RFI, but might not.  LS-1 is a co-ax, do you know what VPI cable is?  What if it's twin lead with shield and does double duty also in balanced configuration (I don't know).  Such a cable is usually hooked up single ended with a floating ground using the shield, and one of the twin leads also as ground.

I'm not trying to be argumentative.  If we have an idea of the cause of a problem it should be easier to fix without having to fix everything.  I recently fixed a vintage preamp by cleaning all the controls  and switches.  Intermittent functions and the sound in general got better, but I didn't think RFI had anything to do with it, but maybe it did.  My friend's phono pre once, many years ago faintly picked up a Japanese radio station. At the time I lived 30 miles away and mine (same one) never did, that I'm aware of.  His was in an aluminum box and mine was in plastic.  Think his box acted as an antenna?     What about the aliens, think our RF messes with their communication?  Probably not, they might use if for intelligence, if you can call it that.  Maybe they hack the NSA and get it presorted.   

-----*****<>*****-----

neo 
 

[Wayner]

When I trouble shoot things, I go for the first line of culprits, that being the connections. The problem is that a bad RCA shield connection can mimic the sound of RF and in a way, it is RF because the shield connection was not solid. Like once in awhile motor noise (mechanical vibration) can also sound like RF. So people scramble trying to figure out how to eliminate RF and the problem was something else.

I know my suggestions are "from the crib", but 99% of the cure is the diagnosis, and checking the obvious things first can help eliminate them from the culprit list. They may also expose a clue to the real problem. When we go to the doctor, we can just say "I don't feel good", he wont have a clue, but when you give some more specifics, the cause gets narrowed down quickly.

I had a hum problem not long ago and discovered that a cart connector was not making good contact. It looked good, but that don't mean a thing. I had another hum in the area of my SL1200 and discovered it was a mechanical hum, coming from my Tripp-lite surge outlet. It was vibrating on my counter top. A little pad and the noise was gone.

That damn low frequency stuff is omnidirectional and hard to find.

Wayner

[*Scotty*]

My selector switch only the changes positive signal leg, the ground from all sources is always connected.
Increasing the shunt capacitance at the input of the phono stage made a small improvement as did changing from un-shielded to shielded ICs. The problem manifested itself when the regulators were changed on the phono stage. This allowed the 600volt/micro-second circuit to operate with a much wider bandwidth making it  potentially much more sensative to RFI. I also have around 10 inches of hair sized wire between the RCA jacks and the end of the armtube that is unshielded equaling more antenna.
 The increased resistance and potential diode effects at the switch contacts in the hot signal leg made RFI break through much more likely. The entire system is connected with unshielded rwisted pair ICs. I was'nt surprised to have this problem show up.
Scotty

[Gzerro]

I finally figured this out.

It ended up being my internet connection that uses the home electrical wires. I unplugged it and the buzzing noise stopped. Oddly when I plug it back in, it makes an occasional noise, but not a steady buzzing noise any more.

I have been using this unit for 2-3 years to stream audio files from a computer in another room and have not had any problem until now. It is on a separate outlet from my audio gear but nearby and on the same circuit. I suspect it has a poorly shielded power supply that is causing the issue, there isn't a wallwart or external psu and the unit is just a small plastic box.

Thanks for your help along the way.

[bladesmith]

I had a simulare problem, found the radio transmitter for my home security system was the culprit.

(Sounds like a "di di di didididi diiiiiiiii", its a simple slow speed data transmit. And no I am not crazy)

I have a backup radio transmitter for my home security,  just in case the landline fails.

The radio antenna was situated right under my stereo system in the basement.

Took me a long time to find that little culprit...very aggravating...