Phono stage picking up radio signals?

Nsgarch,

As for the Nordost cables they are not shielded according to what I found on their website. They have also provided a reason as follows:

"The use of flat cable geometry coupled with very precise conductor spacing alleviates the need for conventional shielding. In addition, the use of extruded Teflon provides better shielding than conventional insulation techniques. Nordost cables are not shielded because shielding increases the capitance of the cable by a factor of 55% or more when applied in the conventional manner. If the capacitance of the cable is increased high frequency information is rolled of and you don't hear all of the musical information."

Not sure if this is a proper explanation or if it is contributing to the problem as you indicate, but the P300 didn't solve anything and now I'm going back to the Cary to compare.

I'll post an update and in the meantime post a thread for suggestions of shielded ICs.

Hooked up the Cary PH-301 which has 3 x 12AU7 and 2 x 12AX7 for tube compliment and while its noisy (hiss and some static) there is no FM or other radio interference that I can tell.

I'm at a loss at this point. More suggestions are welcome if any one can think of anything. Thanks

Clio:

1.) Re the Nordost claims: Bullpucky! (especially for phono use)

2.) A tube phono preamp is less susceptible to RFI because the signal is not physically coupled all the way through as with a SS unit.

3.) I wouldn't use both power conditioners on the same electrical (house) circuit. They could produce their own ground loop.

4.) I would ground the TT. There are several alternate ways to do this. The main thing is not to connect the phono preamp ground lug to the preamp ground lug. The best way would be to connect both the phono cable ground wire and a wire from the TT lug to the preamp lug. Alternately, you could connect the phono cable ground wire to the TT lug, and another wire from the TT lug to the preamp lug.

5.) As for shielded cable choices, a number of manufacturers make cables specifically for use as phono IC's, including Cardas, Hovland, XLO, Straightwire, and others. I'd just get some cheap Monster or old MIT 330's for a try.

Nsgarch,

Thanks for the comments. I have one question. Can I connect a wire from the TT lugnut to the phono preamp lugnut, then connect the tonearm cable ground wire to the phono preamp lugnut as well?

Here is one question I asked the constructor of the Whest PS.20, James Henriot, before I bought the unit:

I have heard some rumours that the PS.20 is sensible to RFI signals.
Since I sometimes have problems with radio signals, I just wonder if this is correct.

Henriot's answer:
The rumours are right but we rectified the problem about 4 months ago and it was found that our loading supplier made the plugs incorrectly.

This was one month ago, and I have had no RFI problems with this unit.