Speaker level (70V) to line level

  • Thread starter Thread starter JimL
  • Start date Start date
J

JimL

New member
I have been videotaping school board meetings, for later showing on the
cable community access channel.
I just bought a Behringer MX802A mixer.
I would like to clip onto the terminals on the back of the school's PA system speakers and run that signal into one of the stereo line inputs of my mixer. I don't presently know which of the many output terminals of the school's PA amp (TOA model 912) the speakers are on. It could be 4 ohm, 8 ohm, 25 V, or 70 V. I know that no matter which of the terminals are being used, the signal should be way too powerful to go directly into my mixer. I assume that I will need to use resistors to drop the power of the signal, but am unsure of what values to use. Any suggestions?

Also, the cable that the signal will have to go down will be about 50 feet long. I was planning to use a standard 50 ft. XLR to XLR mic cable, with short adaptor cables at each end - an XLR to alligator clip cable at the PA speaker end, and an XLR to 1/4 stereo phono (with the resistors added on) at the mixer end.

I can solder, have a complete assortment of resistors on hand, so solution to problem need not be an "off the
shelf" item.

JimL
papeles@earthlink.net
 
Hi Jim,
To answer your question. You are playing with fire if you connect the way you propose. I would suggest that you connect the mics to your mixer then feed the PA amp from the mixer. You will end up with a cleaner signal to the tape and to the PA.

Hope this helps.

GRIZ
 
Grizzly suggested plugging school's mics into my board, but I can't - they have many more mics than my board will accommodate. Also, I don't want to be responsible should their sound go out...

JimL
 
There is no line level feed off of the schools PA that you can use? Sends/stereo out/mono out - tape out... anything?
 
I don't have access to the amp - it's in a grammar school, so it's in a locked steel case!

Only source for signal for me, that I can count on being able to get to, is from terminals on back of speakers.

JimL
 
You'd be better off putting up a mic then. You don't want to get that 70V tapped line stuff anywhere near your mixer.
 
Hi Jim,
Well seeing that you can't get to the PA then I would suggest that you place a mic in front of the speaker. But do not connect the speaker to the mixer. If you do you are certain to burn out the mixer..

GRIZ
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by JimL:
Grizzly suggested plugging school's mics into my board, but I can't - they have many more mics than my board will accommodate. <HR></BLOCKQUOTE>

You don't have to plug ALL of them in. One is quite enough...
 
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