Shielded Speakers

[Ace H]

Pardon what might be a dumb question but regarding speakers, video shielded and magnetically shielded are the same?

[NickWH]

That is correct.

[Ace H]

I just ordered the Velodyne CHT-12. AFTER ordering I discovered it is NOT video shielded. Would this pose a problem if the sub is placed approx. 3.5 to 4 feet from the TV?

[This Guy]

It may or may not. It has a 55 ounce magnet. My subwoofer with the same magnet size doesn't affect my 32" toshiba and it's 6" away. It's highly dependent on your tv. The magnetic field from a speaker only affects direct view sets (CRT), so if you have a rear projection and I think DLP would also be fine.

[Ace H]

I have a Direct View set. A 36" JVC D Series TV. I would certainly hate to screw up this TV.

[hifimaster]

Ace H,

3.5 to 4 feet will be fine. When you get near 2 feet you have to be careful. Better safe than sorry though. If left too close long enough, the tv will be damaged permanently.

James

[Ace H]

I see where the Velodyne VRP-1200 is video shielded. However the specs show a frequency response of 29 - 140 Hz +/- 3db. (Velodyne CHT-12 has a response of 25-120 Hz +/-3 dB)

My cheap Sony SA-WM40 has a frequency response of 20-200 Hz, 0.8% THD.

Is the Velodyne VRP-1200 rated differently or will I loose significant low level bass with the VRP-1200?

[hifimaster]

"My cheap Sony SA-WM40 has a frequency response of 20-200 Hz, 0.8% THD."

Pay attention to the ratings. They are usually reffered to as "+/- 3 db". Many manufacturers just throw in "20hz - XXXhz" as a standard. That Sony is NOT going to do 20hz at any audible level. I'd be surprised if you could get 30hz out of it.

James

[Ace H]

Thanks "hifimaster" for your input. I really want to get a handle on all my questions by this evening as I still have time to cancel/change my order.

The 29 - 140 Hz +/- 3db frequency response on the VRP-1200 doesn't seem to be that low IMO. Would this range be ok for Movies? I primarily watch TV and Movies and listen to a little bit of music.

In all honesly I have a psychological barrier on those frquency response numbers.

[This Guy]

No it's not that low, but it defiently goes lower than the Sony. This is +/- 3 dB where the sony doesn't even tell you. it's probably +/- 15 dB. They do this to trick people like you into thinking it goes lower than most other subs. And why are you worrying about this, i thought you bought the CHT not the VRP?

[hifimaster]

Remember, those numbers are usually generated from response graphs in an anechoic chamber. In the real world, putting the sub near a wall or corner will reinforce the low frequencies (corner loading). So -3db @ 29 hz is not bad for movies. Besides most sounds in movies are at higher frequencies (40hz-80hz). The critical thing is if it is loud enough for you, without reaching the performance limits of the sub.

James

[Ace H]

I ORDERED the CHT on line last night. I still have time to cance/change the order.

[Geoffcin]

I just ordered the Velodyne CHT-12. AFTER ordering I discovered it is NOT video shielded. Would this pose a problem if the sub is placed approx. 3.5 to 4 feet from the TV?

I use unshielded subs with much larger magnets, and at about 3ft they have no effect on the TV. Most good TV's now have an auto-degauss circuit built in, so if you do magnetize the screen they will be able to de-magnetize it with little problem.