Paging amp and speakers

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I am wondering about speakers connected to a paging amp.  How do I go about
figuring out how many speakers can be connected to a paging amp?  Basic math
and common sense tells me that a 35 watt amp will be able to drive 5 seven
watt speakers.
Is this correct?
Is this one of those circumstances where they say the Amp is 35 watts, but
really it is only 20 watts.
Then again, I know that sometimes the speakers wattage is measured in RMS or
something and what seems like a maximum of 5 speakers is really 10.

So, how do I figure out how many speakers I can connect to my Bogen TPU35B?

Thanks in advance,


Re: Paging amp and speakers

John wrote:
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That has a 70 volt output.  That type of output exists so you can feed
speakers very far away - 1000+ feet.  Also so you can feed many - maybe
60 to 80 or more if you were just playing quiet soothing background
music without paging.  In a warehouse, you might feed 10 to 15 horns
that would be loud enough for paging

The speakers must have a "70volt transformer" - 70v amp would fry the
speaker or at least load the thing down real far.  That transformer
will have 3 to 5 "taps" or wires, each one being louder and a greater
load.  The taps will be identified as "quarter watt, half watt, up to 2
watts probably.  Those WATT numbers cannot exceed 35 when added.

Of course, there is a normal speaker output - 16 ohms is what I see on
the spec I found online.  In that case, I think you just wire in series
parallel as to not end up lower than 8 ohms (my guess the amp is quite
durable) and if you can hear, that's good.

Go 70 volts...that is the standard.

Re: Paging amp and speakers

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Yes and no.  You don't want to be the one closest to a trumpet tapped
at 7 watts.   In general practice, 3-5 amps feeds a trumpet and 1-2
amps feed ceiling speakers very well.

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Three methods, Math, trial and error, and an Impedance bridge or a
combination of the 3.  I hear the new impedance bridges are digital
and pretty slick and TPU 60's aren't very expensive either.

Carl Navarro

Re: Paging amp and speakers
That tells me what I needed to know.  I found out that the speck I was
looking at for the speaker was adding all of the possible taps on the
speaker tranformer to arrive at the 7 watts they were reporting.  I would
not have figured that out if you hadn't pointed me in the right direction.

Thanks for the information.  I don't know what I'd do without you guys
helping me out.


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