Phono stage picking up radio signals?

The strangest thing happened this evening. I just hooked up my Whest phono stage and as I was letting it warm up I turned up the volume slightly to check the noise level and noticed a strange noise coming from the speakers. At first I thought it was a ground loop hum or some feedback, but when I put my ear to the speaker I distinctly heard music. I turned up the volume a bit and to my surprise I could hear and identify the song playing, followed shortly after by DJ banter. It was obvious I was picking up a radio station, but I don't have a tuner or any other radio device in the home. Can anyone give me a clue as to what might be going on.
Zargon, thank you. There are some cable manufacturers who, especially in their speaker cables (which aren't ever "ground shielded",) orient their arrow direction based on "wire draw." Which simply means the direction the wire was pulled through the dies during manufacture. Supposedly, the orientation of the metal crystals as a result of the drawing process makes it easier for the electrons to flow in one direction than the other.

Others who produce spkr. cables and IC's which are symmetrical as far as orientation goes, often include arrow
indications so that (according to them anyway) you'll be able to orient the cables in the same direction, should you have to remove and re-install them after they've been broken in. Personally, I think it's just a "me too" marketing ploy.
I received an email response from James Henriot. It seems there is a modification for the Whest PS .20 for areas with high RF. The modification is now standard on new models of the phono stage sold in the US and Canada. James Henriot from Whest and Bob Leitz at the Analog Shop, where the unit was purchased, have been tremendously helpful and Bob is very much interested in making me a satisfied customer, even though this unit was technically purchased used. I also appreciate all the responses here on this thread, especially Neil who surmised the problem may actually be in the phono stage itself. I've learned a lot here about the various types of noise that can creep into a system.

I'll need to send the unit off, most likely to Mitch Singerman who services these in CA (close to me at least), but I'll post a follow-up when it gets back to me. I'm also going to wait on the cables until it does come back.
There is a lot of necessary missing information in this thread.

A SPG, Single Point Ground is NOT a shield, it is an antenna and DOES put current in the "shield" that is now just a "wire" at this point. How do you think SPG works? CURRENT flows from the infinite open end to ground, thus current flows. A true shield NEVER, EVER has significant current flow. A SHIELD attenuates NOISE from inside to outside, or outside to inside (it works BOTH ways) as a RATIO, in dB, voltage. We should see virtually ZERO current.


If you use SPG, you won't die, but you are trading SIN for antenna coupled noise. BOTH are WRONG to accept as ideal as BOTH add CURRENT to the shield!
A lifted ground system with multiple lifted shields injects noise INTO the poor resistive differential (highest point to lowest point) ground system. As the ground is worse, the POTENTIAL difference from the end of the SPG ground point to the "ground" gets worse, aggravating the problem even more. Where is all that RF going? How is it getting there? What is it that current path parallel to? Maybe one SPG won't be an issue but many SPG added to a compromised ground will push it over the edge.

A SPG is trading off adding capacitive coupled RF noise injection into the core wires under the "shield" for removal of current induced SIN, Shield Induced Noise, from a poorly grounded system. A true shield has zip real current flow as the GROUND is at the same potential everywhere, or should be. By definition a ground at the exact same potential everywhere can't flow ground loop current.

A good shield will shield BOTH ingress RF and egress SIGNAL from a cable. That's  what you want. Yes, our internal signal from digital devices needs to be SHIELDED from getting out of the cable as much as RF needs to be kept out. SPG "leak" RF into the exterior of the cable out as much as let it in.

One point to understand, is that the issues of a bad ground are superposition driven. As you "lift" a bad ground point and increase the resistance it looks more and more like an antenna, and less and less like SIN, Shield Induced Noise. They happen at the same time.

Once you REMOVE a ground point at either cable end for infinite resistance and thus no SIN current, we stop the SIN noise and fully replace it with Antenna coupled noise. A true SHIELD has ZERO current flow through it and is an ATTENUATOR. Making a SPG an antenna to stop SIN shield current isn't what best practice had in mind!
The ideal transfer impedance of the shield "R" times the shield current is the Voltage. Voltage equals current (should be near zero) times the transfer impedance at that frequency. But, when we have a bad ground our "R" goes far higher. Volts is current times resistance so that voltage product goes up as our shield tries to reach neutral state and flows current to the lowest potential spot in the system...where ever it is.

The ideal shield has the SAME resistance (zero) everywhere, same as a good ground and thus NO current potential to flow! It is all the exact same "spot" so current can't flow from HERE to THERE in the same spot. It can when here and there are DIFFERENT resistances relative to ground. This is why shields are rated based on their Transfer Impedance at specific frequencies. How LOW does the resistance look along the shield? Any "wire" will create a ground differential at frequency, so the right shield has to be used.

We can CHANGE the reference voltage from zero to ABOVE ground if we want to, but that EXACT voltage can't "move" or we again create a ground differential. We can have a one volt signal referenced to a million volts with a million and a ONE volt signal. This is still one volt potential difference UNTIL the signal reference point changes up or down. Usually we use something lose to EARTH ground for signal ground, not always. Connecting a SIGNAL ground to EARTH ground can mess this reference up. Make sure the circuit's "lowest potential" spot is understood. It may not be EARTH.

It is hard to remove a shield on an already built cable, true. So lifting a ground may be the better of two BAD situations. That's agreed to, yes. But we have to understand that it is WRONG from a SHIELD standpoint.
Many SPG systems with poor grounds worked better when the SPG were REMOVED and replaced with UNSHIELDED cable! This at least doesn't add noise to the ground bus and, XLR cables of good design can mitigate external noise passively with CMRR built-into the design. Try a UTP balanced cable and see what works. Many XLR have PIN 1 ground issue, too, so be aware of that. No, it isn't "earth" ground but "signal" ground. And yes, PIN 1 can cause SIN noise if they are too far apart in DCR.

NEVER, NEVER, EVER remove a safety ground!!! Now the fault current finds it path to ground through YOU! Touch a faulty unit with a "hot" chassis and guess what? Touch the next GROUNDED device and current goes through YOU. Sometime we learn a lesson ONCE and can repeat it to the angle at the pearly gates. This just tells you you need to FIX your ground, not make it a death trap instead.

Best, Galen Gareis