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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => Pro AV FUD Forum Archive => Topic started by: Brian Beatty on October 18, 2010, 12:19:52 am

Title: Which signal do I boost?
Post by: Brian Beatty on October 18, 2010, 12:19:52 am
I run a karaoke show from a laptop/software combo.  My goal is to be able to hook into the bars TV via coaxial cable with minimal snow.

Laptop VGA out into scan converter.
From the scan converter into a cable RF Modulator via RCA vid. out.
From the RF Modulator into an cable TV signal booster/amplifier. via coaxial cable.

Now, I hooked it up this way to a big screen TV and I got a snow storm!  I adjusted the gain on the cable tv signal booster all the way and it did nothing.  It was working though, because if I turned it down, you could see nothing but snow.

#1
Do I need to be amplifying the VGA signal into the scan converter?

#2  Do I need to buy a stronger cable TV booster?  

#3  Do I need to buy a VGA amplifier AND a stronger cable TV amplifier?

Thanks for your help everybody.  Smile
Title: Re: Which signal do I boost?
Post by: Brad Weber on October 18, 2010, 07:34:43 am
Well, one issue may be whether you are using an analog NTSC modulator while the TVs have ATSC digital tuners that have been required for all TVs sold over the past couple of years.

If both the modulator and tuner are analog or both are digital then are you tuning the TV tuner to the channel associated with the modulator?

Are you running direct into the antenna inputs on the TV or into an existing RF distribution system feeding multiple TVs?  If the latter, then you may need to make sure there is not already something on the channel/frequency you are using and that the system supports whatever channel you are using.

I don't know what modulator you are using or its output nor what you are dealing with as far as cable runs and any RF distribution system but unless you are trying to drive a long cable run or feeding a distribution system after any of its amplification, then you may not need an RF amplifier.

Just so there are no surprises, a VGA output scan converted to composite video, modulated onto RF and then scaled at the TV is probably not going to look that great.
Title: Re: Which signal do I boost?
Post by: Ken Freeman on October 19, 2010, 12:29:31 am
Brad Weber wrote on Mon, 18 October 2010 04:34



Just so there are no surprises, a VGA output scan converted to composite video, modulated onto RF and then scaled at the TV is probably not going to look that great.


Yeah, what Brad said.  Just because you can, does not mean you should.

Ken