[Vintage-Audio] Re Impedence and RMS Power

Tue Apr 20 22:56:01 2004

They are using the amp and a mixing board, but I do not know if the board is
powered or not. This is in a small church, oddly enough! Supposedly
professionally installed, but obviously somebody did not know what he was doing.
They have already blown the ten inch speakers out of a pair of two-way systems,
and it was not turned up loud. No instruments, just mikes or cassette tape. 	

I guess I am going to have to go take a 'look' for myself and see exactly what
is connected to what. A friend of mine goes there and has asked me for my help
in straightening out the mess. He knows nothing about electronics, but knows
this is wrong intuitively. 	

Another case of an amplifier that is way too big for the room and way too many
speakers and cabinets for such a small area. A 100 watt amp with small mixing
board and a good pair of two-way would be plenty for this particular
application. They really do not even need monitors.	

----------
From: Philip Atchley <[email protected]>
To: [email protected]
Subject: Re: [Vintage-Audio] Re Impedence and RMS Power
Date: Tuesday, April 20, 2004 10:26 PM

Use the 70 Volt output on the amplifier and a matching transformer for each
speaker set if it has a 70 Volt output.  That's the correct way.

OR, go with a really "BIG BIG" professional amplifier like the ones we had
at my last church.  Rack mounted, fan cooled units that put out about 800
Watts each and could easily drive impedance's of less than 1 Ohm! We ran
three of them, one for house sound and two for the two separate monitor
feeds.  They kept adding monitors on and I was afraid they'd blow.  One
finally did, it'd shut down under load.   I took it home to check it out,
but couldn't reproduce the failure in my house.   If I recall correctly, I
think it had 12 output transistors mounted to the back panel.  I told them
to send it to the factory in Washington.

Where I go now we have one little hundred Watt board and the people complain
if it gets turned up very far <grin>.

73 from the "Beaconeers Lair".
Phil, KO6BB

> Agreed.
>
> What is the best, or most safe way, to operate such a system without
damage to
> the amplifier?

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