Kriton Posted July 4, 2005 Share Posted July 4, 2005 Hey ya'll, I just had a very unpleasant surprise...I noticed a faint yellow glow on my TV last night while watching a movie in the lower left hand side of the screen. My TV is an older 36" Toshiba regular-non plasma thing (next to be upgraded - but not right now), and I have my RF-7's placed approximately 1 1/2 to 2 ft. on either side away from the screen. I have a KSP-C6 center sitting on top of the TV, and DVD player, TGIV and 400~7 amp (In that order) sitting closely underneath the screen... So first question, what could be causing this? Are the RF's shielded to prevent magnetically disrupting the screen, or if not how far away is good enough? My Corns will of course light a TV screen up like a "nucular" bomb if placed too close to the tv screen, but I expected the RF's to be shielded for some reason, as they are used often for HT speakers? Here is another strange thing; the KSP-C6 center, which has sat on top of the TV for a while, is to be shielded, as it is designed to sit atop a TV...but when I moved the speaker away from the TV, there was a red streak approx 8 " wide and 2-3"thick in the top right hand corner of the screen? SO follow this, when the speaker is sitting on top of the screen, no color change...blue screen produced when DVD player is off is bright blue with no distortion, but when I the speaker (and I am talking, moving the thing 10' away, completely removing the center), the red streak shows up? WTH? Very confusing, and as I don't want to burn in, can any of you please tell me what you think? K Quote Link to comment Share on other sites More sharing options...
MrMcGoo Posted July 4, 2005 Share Posted July 4, 2005 Kriton, The RF-7s are video shielded. You can see the backs of the drivers with a mirror in the port and a light. I have similar Sunfire amps next to my RPTV. A peak inside the center channel might be in order. It's possible for a bucking magnet to come loose and there goes your shielding. Bill Quote Link to comment Share on other sites More sharing options...
Kriton Posted July 4, 2005 Author Share Posted July 4, 2005 Bill, thanks for the fast reply... OK, what would the "bucking magnet" look like, and would it be loose in the center case? If shaken could I hear it? I thought the RF's were shielded, do you think the Sunfire's could be doing anything like this? If the center is the problem, why would it only indicate that there was interference when the speaker is ? That is what is just befuddling the hell out of me... Also, the yellow cast spot is in the lower right, (not left as stated before) portion of the screen...if the center is what is causing the distortion (just for sake of argument) wouldn't the disortion be at the top near the center, not the lower right hand side of the screen? Is there anything in the TGIV or 400~7 setup that could be causing anything like this? I am afraid that the center may have caused some permanent burnin on the TV with the upper left red mark, but the lower right yellow patch is just making me nuts... Of course this might be a great time to sidle up to the wife and convince her of the need for a new projector... K Quote Link to comment Share on other sites More sharing options...
MrMcGoo Posted July 4, 2005 Share Posted July 4, 2005 Kriton, The shielding looks like a metal dish around the magnet structure on the back of the driver. It should be perfectly centered around the magnet structure. I have a Sunfire 625x2 and a 400x5 within a few inches of my RPTV. I use shielded power cords due to all the low level signals running in the mess of interconnects on the back of the system. My whole system draws about 4 amps. Bill PS: The Sunfire power transformer is heavily shielded. B Quote Link to comment Share on other sites More sharing options...
Malcolm Posted July 4, 2005 Share Posted July 4, 2005 It is possible the faint yellow glow has nothing to do with distortion caused by magnetic fields. CRTs have a glowing filament inside the neck which generates the electrons which ultimately colide with the screen and create the picture. Under some conditions, it is possible to see some of that light leaking through the shadow mask on the front of the screen. Kind of hard to diagnose from here, though. If this is what is happening, there is not much you can do about it, at least without replacing the set. No speaker shielding is perfect. Shielding just cuts down on, or redirects, the stray magnetic field that causes problems. The field is not symmetrical, so changing the orientation of the speaker to the CRT even slightly can observably improve or worsen the symptoms. I would think 2' would not cause a problem, particularly if the woofer is well below the level of the set. If the distortion persists after moving the speaker away, the shadow mask of the CRT has been magnetized. There is a degaussing circuit in the set which is designed to undo moderate magnetization. But if the shadow mask is sufficiently magnetized, you need something more potent. A magnetic tape eraser sometimes does the job. Otherwise, you can get a degaussing coil made for the job. IMHO the distortion you seen really doesn't have anything to do with burn-in. You aren't targeting any part of the CRT screen with an excessive amount of energy. You are just making the electrons from one or more of the guns end up a bit away from where they were meant to go. Quote Link to comment Share on other sites More sharing options...
Kriton Posted July 4, 2005 Author Share Posted July 4, 2005 Interesting, thank both of you for replying... I took McGoo's advice and took apart the center channel...and didn't see anything loose...of course the enclosure is just stupid packed with heavy foam, but no dish shaped things out of wack...I moved the mains back closer to the set, haven't experienced a recurrence of the yellow problem, put the center back on top and haven't seen the red streak either...very strange... Could it be that the tube just gets over worked, over heated, something? The TV had been on for hours (like 6) on a movie marathon this weekend, and we noticed the color problems into the 6th hour...?? What is up with the damn foam batting in these speakers? I just stuck my hand in the RF's port and felt the same damn foam, this time filling up the port enclosure, so no air could have gotten through,...I pushed it back in opening up the port, but good grief, what is up with these things? K Quote Link to comment Share on other sites More sharing options...
MrMcGoo Posted July 4, 2005 Share Posted July 4, 2005 The foam in the speakers is there to reduce cabinet resonances. Shipping seems to disturb it in the RF-7s, so it's best just to push it back into place. Bill Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted July 5, 2005 Share Posted July 5, 2005 If you have your speakers a mere foot or so on each side of a 36" TV you are not getting any stereo separation! You need to get them farther apart! Quote Link to comment Share on other sites More sharing options...
Kriton Posted July 5, 2005 Author Share Posted July 5, 2005 Yes, you are right, I have now separated them substantially. They are probably 8 feet apart or more. I have had no recurrence of the color problem...don't know what it was...perhaps it did just need to degause. It was pretty disturbing though... I still don't get the whole foam thing. Don't I remember a thread where someone said not to put any thick foam into a speaker that would impead the internal volume of the speaker, and thereby change the volume characteristics of the speaker (such as with putting heavy foam in a Cornwall)? Is there no need for these volume calculations in an RF-7, or are these things just not as well thought out? Just curious...thnaks for the replies! K Quote Link to comment Share on other sites More sharing options...
Spkrdctr Posted July 5, 2005 Share Posted July 5, 2005 ---------------- On 7/5/2005 11:04:50 AM Kriton wrote: I still don't get the whole foam thing. Is there no need for these volume calculations in an RF-7, or are these things just not as well thought out? Just curious...thnaks for the replies! K Klipsch Engineers have thought it all out for you. Leave them "as Is" wih the foam inside. Also, your TV was the problem, especially when you said it happened after 6 hours of watching. It is getting old and starting to have problems. Keep nagging the wife for that new 60" model. Good Luck! ---------------- Quote Link to comment Share on other sites More sharing options...
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