markipowell;207322 Wrote: > Guys been reading this thread with interest I have transporter > wired via the unbalanced ouputs from the Tp to the DIN input > of the Naim NAp 250. Now I would not say I get a hum although > there maybe a slight hum but I can definatly hear what I think is > a radio station when the tranporter is off or indeed in the silence > between tracks even if I unplug the Tp from the mains. > It goes away if I pull out the interconnects. Could this be a similer > problem ? This doesn't sound like a grounding issue. It's more likely that the interconnect cable is acting as an aerial and the circuitry inside the MAP250 is demodulating it. This used to be a common problem with turntable inputs on preamps due to the very high gain. I've never heard of it on a line level input. Have you got a taxi firm or a radio ham nearby?
To eliminate it, there are a number of things you can try: 1. Tie a very loose reef knot in the interconnect. This may sound like a joke, but this was advice given to me by Naim themselves when I had a similar problem on the phono input of a Naim preamp. I think it affects the inductance (or is it the reactance?) of the cable and might prevent it acting as an aerial. 2. Try ferrite cores clamped around the interconnect. Or wrap the interconnect through ferrite rings. 3. Add some capacitance across the input of the NAP250. Just a few hundred picofarads should be enough. This will shunt the high frequencies (where the modulated radio signal is) to ground. You could loose some extreme top end by doing this, so it's a last resort. 4. No, tell a lie: the very last resort is to hunt down the source of the radio tranmissions and bomb the place :-) -- cliveb Transporter -> ATC SCM100A ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=33414 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
