How close can you put an RS28A-4 to a TV?

[JonW]

I’m thinking about making 3 Modula MT speakers as my first experience in speaker building. Two for regular listening and one for a center channel. I’m wondering if this will be OK for the center channel. The RS-180 is shielded, so no problem there. How about the RS28A-4 tweeter? How close can you put that to a TV? To keep things simple for this first effort, I was thinking about keeping to the RS-180/RS28A-4 design because there are more photos of crossover, etc. out there. I realize I couldn’t just drop in a shielded RS28 for the center channel without changing the crossover.

Looks like in this Modula MT, the tweeter is 4.5” from the top. If the TV is on a 1/2” thick shelf. And let’s say there is 3” of TV plastic (plugs, buttons, speakers, etc.) on the bottom, between the TV bottom and the tube. So if the speaker is placed immediately below the TV, it’s about 7” from the tweeter center to the TV tube. Will this present a problem? Thanks.

[ThomasW]

The distance is completely dependant on how well shielded the TV is....

[JonW]

TV's have their own shielding? I had no idea. Go figure...

[cjd]

That depends on whether you plan to USE the TV as well.

C

[---k---]

My subs have a single layer of steel on the inside, and it does amazingly well at sheilding them. A lot better than I anticipated. I have scooted my sub all the way up next to my Toshiba tv, and nothing. The raw driver along side the tv would cause distortion. My tv could just be well sheilded, who knows.

With something much smaller like a tweater, one layer of steel should easily fix it, if you have any problems at all.

[JonW]

-k-

What kind of steel did you use and where did you get it? That might be an option. Although I'd think it might rattle around in the cabinet, unless it's really fastened down well (how?). Maybe just put a piece of the steel below the TV, on the shelf.

That depends on whether you plan to USE the TV as well.

Everybody's a comic. :P

[Marzen]

Maybe just put a piece of the steel below the TV, on the shelf.

I tried that with a sheet of mu-metal with some success. I think the magnetic field just wraps around it. For this application, any ferrous material such as steel, mu-metal, radio metal, or molybdenum work best. Hey, if you're a Nascar guy - exposed diamond plate steel might be cool.

[Brian Walter]

I just tested the RS28 with my TV. When placing the tweeter under my TV and about even with the front, it starts to interfere with the picture at about 5" below the bottom of the TV. When I place it along side of the TV it is again about 5", except near the upper corner, where it causes problems at around 7" - 8". I also tried placing it above the TV, and again, it interferes at about 7" - 8". Just for the fun of it, I tried placing a sheet of 18 ga sheet metal between the tweeter and TV and I would say it allowed the tweeter to move about 2" - 3" closer to the TV befor it interfered.

As Thomas said, this can vary, depending on how well the TV is shielded. It would appear that my TV is shielded much better on the bottom than on the top. I know that my testing leaves a lot to be desired, but it might be better than no testing at all.

Brian Walter

[JonW]

Thanks guys.

Brian, your testing makes perfect sense. Gives me some idea. That's just the kind of test I was thinking about. Maybe I should buy parts for 2 speakers, try a similar thing and if it's OK, then buy the third set of parts.

When you it started to make a difference at 5", is that the distance between the edge of the tweeter and the edge of the tube? If so, that's just about the distance I'd have if I put the speaker right under the TV. Good to hear some metal helped.

Marzen, I'm no big NASCAR guy, but shiny diamond plate steel is kind of neat. Are diamond plate, mu-metal, radio metal, and molybdenum easy and cheap to come buy? Never heard of mu-metal or radio metal.

[ThomasW]

http://www.mushield.com/

[---k---]

I just used the galvanized steel that is used for roof flashing. You can find it at Home Depot over in the building materials area. I beleive it was 16gage. It was like $12 for a 10' roll. You have to be carefull though, because the Aluminum gets mixed in with the Steel on the shelf, and Aluminum won't do you any good.

I adheared it to the inside of the box using contact cement. I also tried to put some screws in it to hold it down, but I had problems with it coming loose at the corners when I predrill it. I probably didn't have the surface of the steel clean enough prior to glueing it down. You probably should roughen it with steel wool, and then wipe down with alcohol, then glue.

I'm suprised that Thomas hasn't mentioned the center that him and Tibor built. Iirc, he told me that they used an inner layer of 16gage steel, and then a second layer on the outside of the box. After that, no problems with putting the center directly on the TV.

You may be able to also try bucking magnets. I picked up 8 of them from PE, just in case. The informal testing I did, putting 2 or 4 of the biggest ones PE sells on the back of my sub driver seemed to cut the safe distance in half. They are really cheap (the shipping was more expensive), so add a couple to your basket next time you place an order. If nothing else, fun to play with.

I'm guessing that I must have a really well sheilded tv, because I did a lot of testing with my sub woofer, and it seems like I could get it about the same distance from the tv as you guys with little tweeters are.

Good luck.

[JonW]

Ryan- Thanks for the info. Quite helpful. Maybe I'll try simply having a piece of steel outside of the speaker, if it's needed at all.

By the way, I'm the guy that will be hosting Steve Callas' pre amp test. See you then.

-Jon

[---k---]

Cool.... see you then. really looking forward to hearing your sub.

[Dotay]

Ryan- Thanks for the info. Quite helpful. Maybe I'll try simply having a piece of steel outside of the speaker, if it's needed at all.

By the way, I'm the guy that will be hosting Steve Callas' pre amp test. See you then.

-Jon

When is this going down? Any more details? I could potentially be interested in attending as Lafayette isn't terribly far away...that is if I'm welcome.

[JonW]

When is this going down? Any more details? I could potentially be interested in attending as Lafayette isn't terribly far away...that is if I'm welcome.

I'll drop you a PM now.