I agree that shorting plugs on all of the unused inputs (especially of course the phono input, but I'd suggest the others as well) should be step 1.
I doubt that the speaker cables have anything to do with it, in part because the very low output impedance of the amplifier would tend to "short out" any rfi/emi picked up there. And also because it would seem unlikely that anything picked up there would make it back to a circuit point near the input of the preamp section, where it could be amplified.
I'd suggest one other experiment that I'm curious about. Do you get the same radio signal pickup when NOTHING is connected to the inputs of the 2010S (meaning with the cdp disconnected)? (Obviously, turn power off while you are disconnecting the cable).
Regards,
-- Al |
Hi Marty,
Are they truly shorting plugs, which look like an rca plug and connect the center pin to the outer ground sleeve? Or are they just caps, which simply cover the opening on the jack (which I would expect would not be an effective fix)?
Assuming they are shorting plugs, yes removing the moving coil stage would seem like a logical thing to try. Presumably it comprises a small removable circuit board dedicated to that function, since it is an option with that particular amplifier.
You might ask the manufacturer or dealer how to identify it when the top cover is removed, in which case you could probably remove it yourself (while taking precautions to prevent the possibility of damage being caused by static electricity -- let us know if you'd like further advice in that regard).
Good luck!
-- Al |
No, by "outer ground sleeve" I simply meant the cylindrical outer part of the rca phono jacks themselves, which the shorting plugs would connect to the center pins of the jacks.
-- Al |
Jim, I really doubt that the writeup you referenced is applicable in this case. It is dealing with the situation where a ham radio transmitter, which typically may be outputting several hundred or even 1000 watts of rf energy, is interfering with a neighbor's tv set perhaps 100 feet away.
In that situation, yes, it seems conceivable that speaker cables in or connected to the tv set could pick up some of that energy, from where it would blast its way into the audio or video circuits of the tv and be rectified, and perhaps amplified as well.
With Marty's integrated amp, on the other hand, the speaker cables are likely to be picking up rf measured in microvolts, or millivolts at most, corresponding to nanowatts. That pickup will be loaded down to much less than even that low level, by the amplifier's output impedance (likely a tiny fraction of an ohm), and also by the speaker, which is not capable of reproducing low level rf signals unless they are both rectified and amplified.
The power cord and wiring would seem to me to be an unlikely entry point as well, due to the capacitive filtering, etc., that is in the amplifier between the ac input and the signal path.
Best regards,
-- Al |
Is it possible the amp could sound good and still have a cold solder joint somewhere along a signal ground path? Yes, that certainly is conceivable, Jim, although of course it would be very difficult to troubleshoot. Marty, I realize that this is all probably moot, because you are proceeding to look for a replacement amplifier, but I see in the thread that you started today that you actually did mention nearby radio transmitters. It would be interesting to know how far away they are, whether they are am or fm, how many watts they are (perhaps that is indicated on their website), and if when you hear them through your system you hear actual music and/or voices, or just static-like interference. Regards, -- Al |
Hmm ... It's hard to envision how an FM signal could be detected/decoded by your integrated amplifier into something resembling intelligible voice or music, assuming that is indeed happening. AM would be a different story, and more easily explainable.
A home demo of the next amp certainly seems like a good way to proceed. Good luck!
-- Al |
Hi Marty,
Yes, those things could certainly pick up low level rf energy. But as I explained above it seems very unlikely that pickup on the speaker wires could result in audible sound. And the rca inputs presumably wouldn't have been able to pick up anything significant when you had the shorting plugs on them.
And as I said, it is very difficult to imagine how an fm signal could be decoded into intelligible audio by anything that is not specifically designed for that purpose. Perhaps it is really being caused by a more distant am station.
Regards,
-- Al |
Glad to hear it, Marty. But I'm truly surprised, given all the reasons I cited as to why it was unlikely to be due to speaker cable pickup. So somehow what was being picked up in those cables was making its way back to the front end of the integrated amp, where it could be affected by the volume control and source selection, amplified, and detected/rectified somehow (I still doubt that it was an fm signal, for which no detection mechanism is present).
Jim, I owe you a beer!
Regards,
-- Al |
Hi Marty,
Can you describe the sound of the "rfi." If it is just high frequency hiss, audible only within 6 inches of the speaker, it certainly may be normal and would not be uncommon. It could be low level noise intrinsically generated in the power amplifier, preamplifier, or (if it is volume control sensitive) in the source component. Or it could be due to pickup in interconnects, from power cords or from sources of rfi elsewhere within the house or external to it.
Best regards,
-- Al |
