Lowering the impedance of P.A. speakers

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Martin Abend
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Lowering the impedance of P.A. speakers

Post by Martin Abend »

Is there a device on the market that can lower the impedance (sp?) of 8-Ohm-P.A.-speakers to 4 ohm so the power amp can deliver more power to them?
Does this make sense anyway?

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LARRY COLE
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Post by LARRY COLE »

You could add resisters but they would eat up the extra power and only make your amp work harder and not get any more power to the speakers and maybe less. You could always add another set of cabinets.

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Bill Crook
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Post by Bill Crook »

If you replace 8 ohm speakers with 4 ohm units, You WILL get more sound(read this as volumne) but,,

1) you can damage the output xmer if you drvin' a "Fender" type of amp.(tube amp)

2) if your useing a Solid-State amp, at low and moderate volumnes, I think you are safe.

At loud volumne levels, distortion is most noted sounds. Also should you blow a speaker or output transistor, MAJOR repairs is the norm.

In NO way should the combined output DC resistance be less than 4 ohms. At 2 ohms, expect a short lived performance from the amp.
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Martin Abend
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Post by Martin Abend »

Thanks guys,

I was talking about the small P.A.system of our band. We bought 300 watt-cabinets and our power amp is able to deliver 250 watts per channel @ 4 ohm, but with these 8-ohm-cabinets only 125 watts are possible. So I thought that maybe there is a way to get more power to the speakers without buying new ones. But I guess it's just not possible...

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johnnyb
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Post by johnnyb »

.<font size="1" color="#8e236b"><p align="center">[This message was edited by johnnyb on 04 June 2005 at 07:36 AM.]</p></FONT>
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Larry Beck
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Post by Larry Beck »

The what is at work here is that the 8 ohms is impedance rather than resistance. The same principals apply, however. As Johnnyb said, running two speakers in parrallel will cut the impedance in half (8 to 4) while running the same two in series will double the impedance (8 to 16 ohms)

Many speakers provide two jacks on the unit which if correctly wired, will let you run from the amp to the first speaker and then from the first speaker to the second. That would get you the 4 ohms. Bridging the amp (mono mode) would get you the full wattage out to the 4 ohm speakers.
It is all moot because the club owner is just going to tell you to turn down anyway ;-)