embarrassed to ask...

[Shpoop]

Well, all my college friends and roommates know I like DIY speaker building and all, so they often come to me for advice. I am quite embarrassed to say that I had no answer for a recent, easy question.

Someone approached me saying that their logitech sub (one of those pretty nice sized ones) says to not place it near electronics. He asked me two questions.

1) Can he place it right next to a refrigerator without any concerns? I can't image there would be any problems...

2) How close clan he place it to a big, 35'' sony trinitron TV (a tube TV) without any screen interference or damage to the tv? For this I guess it's more of a guess-and-check solution, but can you guys give me a ballpark estimate? Let me know if you guys want the exact model number, but I assume all of the "big logitech subs" are pretty much identical.

Thanks a million!
Matt

[theAnonymous1]

1) I wouldn't place it right next to the fridge, the vibrations might rattle the beer and cause excess foamage.

2) "guess-and-check" is about right. Turn the TV on and start moving the sub toward where he wants to put it. If at anytime while it's being moved closer the screen color starts to distort, then it's too close. I would guess you can get within 2-3 feet with no problems.

[myhrrhleine]

Near a TV won't break the TV.
It can mess up the colour, but it isn't broken.
Most TVs automatically fix themselve.
The Bzzzz heard at turn on is the demagnitizing process.

If it's too close, the colours get wrong.
Just move it farther away until the problem goes away.

[planet10]

Re the fridge, you'd be more worried about noise from the fridge getting into the Logitech via the power connection.

With the TV, just move the sub towards the TV until it starts to rainbow. Then back it off quickly. If you set the woofer near to that close, keep an eye on the corner of the TV near the woofer -- if it starts getting "colourful" move the woofer a bit further away.

dave

[Netlist]

Since TV’s usually don’t come with an auto-demagnetizing function, he will need to turn it off (mains switch) for 15 minutes if his colors accidentally get mixed up.

/Hugo

[myhrrhleine]

Originally posted by Netlist
Since TV’s usually don’t come with an auto-demagnetizing function, he will need to turn it off (mains switch) for 15 minutes if his colors accidentally get mixed up.

/Hugo

Is my age showing?
have they discontinued degaussing coils around the tube?

[Netlist]

There is degaussing and auto-degaussing.
TV's need to be switched off for the degaussing circuit to work. (PTC)
An example of auto-degaussing is the Philips Brilliance 201CS monitor. A clever circuit detects changes in close proximity magnetic fields.
When I rotate the mid and tweeter part of my speakers, the effect on the colors is immediately corrected by the auto degauss system.

/Hugo

[AKN]

Hi,

Originally posted by myhrrhleine


Is my age showing?
have they discontinued degaussing coils around the tube?

No and no

Hi,

CRT TV's usually have demagnetising coils in series with a PTC resistor connected to mains switch. This means that every time the TV is turned on with the mains switch, CRT gets demagnetized for a moment with mains frequency magnetic field.

If however CRT gets severely magnetised the built in coil may not be effective enough. Using a large external demagnetising coil can help in such cases.

Edit: I was away for a moment, did not see your post Hugo.

[Shpoop]

Hey guys. Thanks for the plethora of valuable information. This place never disappoints.

Matt

[y8s]

my panasonic has a "geomagnetic correction" feature to fine tune the TV for large magnetic fields. I guess geologically large.