Odd modem question

[daveleau]

Hi guys.

Whenever I log online, my roommate can hear the tones and static through his speakers very clearly. It is at about half the volume as when his modem connects. What could cause this? I cannot hear when I log on but have the speaker feature turned off in my modem setup. Is there a cross somewhere? I know if we turn off the volume in his config for the modem it will probably get rid of it but was curious as to what could cause this.
Thanks
Dave

[welsh wizard]

Your generating a field some how,is your box earthed properly, you could also try getting an Alloy plate and running an earth to it then put this between your system and his if the interferance persists then you may be getting a leak via the power supply.
WW

PS how close are his speeker to your system.

[This message has been edited by welsh wizard (edited 03-13-2000).]

[daveleau]

The sub is about 6 inches but through about 3/4 inch of pressed wood and one sattelite speaker is about 6 inches also with only air between. Teh cables are intertwined. This would send the modem freq through the phone line? Thanks
Dave

[wyvrn]

If the two lines are close enough, you can get bleed over. I am not sure of the physical explanation, but I do believe that is the reason for twisted pair phone wire-- to eliminate bleed over.

[tonym]

Dave,

You have an EMC engineer's worst nightmare there! You are getting a combination of induced and conducted emissions from the modem into you speaker leads. Remember, the amplitude of the signal that the modem puts on the POTs line is of the order of a few hundred millivolts or so (could be larger or smaller depending upon the actual line characteristics), and the frequency of the modulation is right smack dab in the middle of the audio band (1KHz~3kHz), so you've got the perfect interference situation.

What you need to do is move the speaker wires away from the modem telephone line. Six feet of spacing should give more than adequate attenuation. If this can't be done, then twist the speaker wires (2-3 turns per inch) and this should also provide the required attenuation. Twisting is a pin-in-the-****, but if you have patience, it's worth it. You can use a variable speed electic drill and anchor one side of the wire to a board and slowly put in the twists. And if they (speaker and telephone wires) must cross, make sure they cross at right angles (intercept area small as possible).

Your last resort si shielded speaker wire, but that's a pain-in-the-*****!


Your best bet is to move the wires away form one-another and be done with it!!!


Tony

[tonym]

Now that was funny. The console went haywire all by itself and poof, I give three replies.

Boy, I hate when that happens...

[Dave_H]

Dave,
Just curious, is this the same system your having the Modem, PS, Start-up problems with?
Dave

[daveleau]

Thanks TonyM
Thanks TonyM
Thanks TonyM
Thanks TonyM http://www.sysopt.com/forum/smile.gif
I will try to move them away from each other. Actually I'll unhook them and test that.

Dave_H-
No it's the other system. The one with the power problem is a Cel 366. This one is a P3 500 Katmai