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Old 8th June 2008, 05:43 PM   #1
ixe13 is offline ixe13  Canada
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Join Date: Nov 2006
Default Speakers impedance

Hi.

Is there a way to get a 8 ohms load out of two 8 ohms speakers cabinets.

I do know that connected in parallel I'll get 4 ohms and in series 16 ohms...

Do I need a fancy circuit ? or maybe a simple resistor at the right place?

See, I'm not too strong at theory so I thought of asking here.

thanks in advance for your time.

Yves
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Old 8th June 2008, 06:26 PM   #2
ixe13 is offline ixe13  Canada
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Join Date: Nov 2006
So I kept looking and looking all over the place on the whole forum, and I finally got to a few posts that are basicaly saying the same thing :

A resistor ( 12 watts) in series on the speaker connection would make the amp see the right impedance, but it's gonna heat like hell, and more importantly will affect the sound.

Hmmmm! well that's that I guess!

Sorry for the waste of space and broadband, should have been more patient before posting...

But still, if there's anybody that has any avices or comments to make, I'll appreciated it none the less...


Yves
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Old 8th June 2008, 06:50 PM   #3
opcom is offline opcom  United States
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Join Date: May 2008
Location: Texas
You could find a matching transformer. Since the power level and impedances are known, a wide variety of solutions are available.

You can even use 70V line-to-speaker transformers as autotransformers, providing you will accept close approximations and slight degradations.

Oversizing the transformer will reduce degradations.

For a very good result, you can buy a hi-fi tube type output transformer with 0-4-8-16 windings, and use it as an autotransformer; connect your amp to the 8 ohm tap, and connect your speakers in parallel to the 4 ohm tap. (the high voltage primary windings should be taped up (insulated) and not used) Buy one 1.5x to twice the wattage you need to minimize the effect of using it in the first place. The more iron, the better the low frequency response will be.

That's the most direct solution I can think of.
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Old 8th June 2008, 07:03 PM   #4
ixe13 is offline ixe13  Canada
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Join Date: Nov 2006
Hey opcom, thanks,

so that's what an autotransformer is...

Well I might try that solution, plus I'll upgrade an amp I already have in a not so distant future, and will end up with two extra Tranformers.

Right there I have the hardware.

Thanks again

Yves
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