I am new to the forum and hope someone can help me diagnose a problem that is giving me fits.
I do some rent-a-nerd work for a sole practitioner psychiatrist. His wife is the receptionist and he sees patients--there is usually no one else in the office. The office is located in a concrete block building adjacent to a small general aviation airport.
The office has in-ceiling speakers installed in every room, connected to a consumer-grade Teac receiver (about two years old) in a large garage in the back of the building (same building--not an outbuilding). They have been getting ambient music from a five-CD changer attached to the receiver, but they get tired of hearing the same songs cycle through all day. The doctor has an extensive (12,000+ songs, about 100 GB) music collection, originally on CD and now transferred into iTunes. When they asked me for an alternative music solution to the CD changer, I suggested they acquire an iPod. With their blessing, I bought a 160GB seventh-generation iPod Classic, an Apple dock for it, and a 3.5mm to twin RCA plug cable to connect it to the receiver. When I tested the iPod with headphones, it worked as expected.
When I attached the iPod and dock to the receiver, trying several different input connections (phono, aux, tape in), intermittent static started coming through the wall speakers. The static is there even when the CD changer is playing. This is kind of a pop-crackle burst, maybe one second or less in duration (but inconsistent) that occurs irregularly, maybe 2-3 times each minute. Music plays from the iPod through the system as expected, but the static is always there. The static is heard even when no devices are playing through the receiver, so long as the receiver is powered on. If I disconnect the iPod from the receiver, the static goes away. The static is not present when the cable is left plugged in to the receiver, but disconnected from the iPod dock.
The original cable I tried was a conventional Belkin, like the type supplied with most consumer stereo components. I thought I might have a low-quality or defective cable, so I substituted a better-quality Mediabridge cable (http://www.amazon.com/gp/product/B004YEBK66/ref=oh_details_o00_s00_i00). It made no difference.
The receiver is located in an awkward wall-mounted wooden box that was built for that purpose. There's not a lot of room inside the box. I originally ran the cable underneath the receiver and propped the dock and iPod on the edge of the floor of the box, in front of the receiver. I've tried re-routing the cable to run out the back of the box and through onto the top where the CD changer sits, and also alongside the receiver. I've also tried relocating the iPod and dock about two feet from the receiver, which is about as far as the cable allows.
It has occurred to me that the iPod, dock or cable may somehow be picking up RFI from a transmitter at the airport, but the intermittent and brief duration nature of the static bursts make me think this is not the cause. I have no idea why or how an iPod can introduce the static when other components work fine when it is not connected.
I'm out of ideas, and still trying to make this system work. The doctor, who is something of a geek but tends to be clueless about technology (my first job was upgrading his office computer, which was running Windows 95 and saving files to 3.5-inch floppy disks) has been busying himself creating playlists on iTunes in preparation for the new music system. I'd really liek to try and make this work. Internet radio is not an option for them, as they are at the extreme end of their ISP's circuit and their "broadband" connection maxes out at 1 Mbps when the wind is blowing right. Can anyone suggest a solution?