atcomsystems.ca/forum Forums Telephone Services Security, Alarms and Paging 2 wire Bogen with 4 Wire Valcom

Did you zero/calibrate the meter before connecting to the speaker leads? To calculate power, divide 4900 by the impedance reading. If you measured 10 ohms, that 490 watts, which would explain why you may not hear the tone. You won't hear the tone if there is a shorted wire, a ground fault, an overload, or a combination of all of these, and other things...

Yes on Zero out each time


The Amplifier on site is a 240 watt

Paging works I am just trying to see how much room I have left


I have a Bogen AT6 speaker which has 8,16,32 watt

I used the meter to test

Set on 10X

8w-100 ohm
16w-50 ohm
32w-25 ohm


Something doesn’t seem right

Any thoughts?


JD

No this doesn't seem right, are you sure you're calibrating the meter correctly each and every-time you use it? You must calibrate it each time you change scales. When you measure the impedance of the speaker lines, you have them disconnected from the amplifier, correct?
In 10 years of working on paging systems, I can't say I ever used anything other than 1X...not sure why you're using the 10X mode...
Are you sure this is a 70V system? Where are the speaker terminals landed on the amplifier? Have you checked the system for ground faults? Just because paging works does not mean the amplifier is not overloaded.

To answer the original question, you could probably just feed the TOA amp and the Valcom paging adapter from the same Algo output, as the TOA amp has a high impedance input (provided of course it is connected and configured properly as a line level output). It really sounds like you are in over your head though. My suggestion is to use only 70V speakers and forget the Valcom. No sense in having two systems to accomplish the same thing...

My apologies for being offline so long. Medical issues got in the way.

Are you still having the problem? Have you gotten anywhere with the trouble shooting?

The formula is P=V(squared)/Z

P is the power of the Amp in Watts

V(sq) on a 70.7 Volt system is 70.7 x 70.7, or almost exactly 5000 (

Z is the Minimum impedance of the circuit

So with a 240Watt amp you should see:

240 = 5000/ 21

So you should be reading NO MORE THAN 20 or 21 ohms. If you're reading 0 then maybe you've got a dead short out there - or more likely a speaker hooked up without a transformer.

Try breaking one of the speaker runs in the middle and testing both ways. See what you can find.

Sam