# Raising the amount of power going to one resistor?

Discussion in 'Electronic Basics' started by Jason, Apr 22, 2004.

1. ### JasonGuest

I have a doctor's office and I ran audio to all the room by having one
speaker in every room, connected to the amplifier via a simple
Parallel circuit. However, I had two new rooms built and the speakers
i bought for the new ones are higher powered (??) and require more
electricity (?) and are much lower in volume than the rest of the
speakers throughout my office. Is there a way I can raise the amount
of power that these new speakers receive so that the volume will be
somewhat equal to the other speakers? I imagine there must be a
simple component that forces more electricity to go through a part of
a parallel circuit. If you can, please write me at my email address:

Or you can post it to this group and I will try to check every day.

2. ### John PopelishGuest

The problem with just connecting a bunch of speakers in parallel
(besides the loudness adjustments you mention) is that the amplifier
sees way to low a load impedance, compared to what it was designed to
handle. It will overheat. The solution to this problem has been to
add a small transformer to each speaker to raise its impedance high
enough that many units in parallel do not draw so much current, and to
adjust the amount of transformation to set the power to each speaker
as desired. The two common forms of this transformer are ones
designed to operate with up to 25 volts AC on their inputs, ones
designed to operate with up to 70 volts and ones designed to operate
on amplifier voltages up to 100 volts. At your power levels, probably
any would work but I am guessing that your amplifier does not put out
much more than 25 volts RMS. They can be mounted at the amplifier,
but it is more efficient (from a wiring loss standpoint) to mount each
near its speaker. This also makes selecting the appropriate tap to
set the volume more convenient. You can also add a selector switch
for the taps and mount that on the outside of the speaker enclosure
(including a no tap selection to turn the speaker off) as a local
volume control.

For example:
http://www.edcorusa.com/transformers/audio/audio_speaker.htm
http://www.samsontech.com/products/relatedDocs/ds70_spec.pdf
http://www.hammondmfg.com/117.htm
http://www.rane.com/pdf/note136.pdf
http://www.proacousticsusa.com/products.php?cId=37

4. ### Dan FraserGuest

The new speakers are less efficient. I'm sorry but you need professional
help. Call someone who knows what they are doing and pay them the \$250.00 or
so it will take to do it correctly with transformers on every speaker.

The way you have it wires now will eventually destroy your amplifier.