DS7200 Static Crackling Noise

[jafdc]

I just got the DS7200 home theater system (one of the last, I gather). I like the design (especially putting all the power amps in the subwoofer) and the piano-finish speakers a lot. It also sounds great -- except for a static crackling noise that is very noticeable. The noise comes evenly from all five speakers and is not affected by the volume setting. It is audible anywhere in the room when there is no source and close to the speakers when music is playing. All my system components are on the same electrical circuit (and anyway unplugging all connections from the preamp except for the subwoofer / power amp does not affect the noise). It does vanish, though, as soon as I turn off or disconnect the preamp (even without turning off the subwoofer / power amp). I have tried resetting the preamp by pushing the three front panel buttons as indicated in the manual, but that did not affect the noise. Have I got a defective product or is there something else I can try?

If it is defective, now that the DS7200 has been discontinued can I still get a replacement preamp if it can't be repaired? If I have to return it, can I just bring the preamp to the dealer or do I have to box up the subwoofer and cart it down too?

Also, on operation, is there any way to set the surround sound mode for each source, so that it doesn't revert to stereo every time I switch back to a component?

Thanks.

-JAFDC

[Kenneth Swauger]

Hello,
Thanks for contacting us. You mention that the noise stops when you turn the AC power off on the pre-amp processor, correct? If so, are you using the orignal DB25 cable between the processor and the sub-woofer? Did you need to run this cable through walls or did you add extensions to the DB25 cable?
Also, is the noise program dependant? Meaning is it on all sources? Or, only when you watch DVD movies, but not FM listening?
Regards, Ken

[jafdc]

Ken-

Thanks for responding. Yes, the sound stops when I shut off the system power or unplug the preamp (even without turning off the sub/amp unit). The preamp is connected to the sub/amp unit with the original cable; I didn't need any extensions and didn't run it through any walls (it goes out and around the back of a bookshelf/cabinet unit and then along the wall to the preamp). The noise appears to be independent of the source selected, of whether the source is actually playing (or only selected with no input), and of the volume setting. (It seems to be more noticeable at night, but I think that is just because everything else is quieter then.)

Also, I should note that although yesterday I avoided using the word "hum" because the noise had struck me as more like white noise than like a tone, after listening to it again last night I think that maybe "hum" is accurate after all. And another correction: it might be overstatement to say that it is audible anywhere in the room when there is no source playing; it can be distinctly heard next to each speaker, and even in the middle of the room there is that sense of relief after turning the system power off that lets you know there was a background hum before, but the sound is not loud enough to consciously identify a couple yards away from a speaker.

I may be off the internet for most of next week, so if I don't follow up on further questions it's not because I lost interest; I will be back the following week.

Regards.

-Jim Frazer

[Kenneth Swauger]

Hello Jim,
Thanks for the response. It is possible there is a ground loop in the system, causing the humming. A way to check for this is to remove all of the incoming sources to the pre-amp processor. Leave the FM antenna and the DB25 cable connected. If the humming goes away something, in the associated components, is causing a ground loop.
Let me know the results.
Ken

[jafdc]

Ken-

No, I saw that in the manual and already tried removing all inputs to the preamp except the DB25 cable, but it didn't affect the noise. I also made sure that the preamp and the sub/amp unit were plugged into the same outlet (they are usually on different outlets although I think it is the same circuit) but that didn't help either

-Jim