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Old 29th September 2012, 01:15 PM   #1
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Default center channel crossover woofers were 16ohm going to 8ohm

i got some older Cerwin vega speakers the other day one of them is a center channel it came with 2 16ohm mid/woofers and one 8 ohm tweeter. I would like to switch the 16ohm speakers to 8 ohm speakers, but with the crossover that is being used they would come out to be a 4 ohm load not the 8 ohm load is there a way to wire them for a 8 ohm load or would it be simpler to get a new crossover.
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Old 29th September 2012, 01:34 PM   #2
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You will not end up with four ohm load. If the woofers are connected in parallel they will be 8 ohms the 8 ohm tweeter is not really in parallel with the woofers so doesn't drop the load to four ohms...

The crossover rolls off the tweeter (and the effective impedance below the crossover frequency gets much higher) similarly the crossover rolls off the woofer and the effective impedance abover the crossover frequency gets much higher. This means that the impedance in parallel with the 8 ohm woofer is much higher than 8 ohms so doesn't have much effect, similarly for the tweeter so if you have an 8 ohm woofer and an 8 ohm tweeter, you will have a nominally 8 ohm load

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Old 29th September 2012, 01:48 PM   #3
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Thanks for the reply then i'm missing something then when i tested the load on the speaker when i put in the two 8 ohm speakers in place of the 16 ohm speakers i'm getting a load of 4.2 ohm.
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Old 29th September 2012, 01:59 PM   #4
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No actually I was missing something!! sorry I thought you were paralleling two 16 ohm speakers to get 8 ohms, but I see now that was what was there before and now you are replacing the 16's with 8's, I didn't read it properly

You are correct it will be 4 ohms load, it will also mess up the crossover point. You would be best doing measurements with the new drivers and doing a new crossover from scratch.

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Old 29th September 2012, 02:41 PM   #5
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never tried making a crossover but the old one seems to run the woofers in parallel which is why i get the 4 ohms in stead of the 8 ohms i want. i'm guessing takeing the woofers and running neg to neg and running the pos side to each from the crossover won't work? I haven't dealt much with crossovers wired up many a guitar cab but no home audio cabs with crossovers.
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Old 29th September 2012, 03:04 PM   #6
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Basically , you need to unwind the coil to a certain point , as the cutoff frequency is related to the load, and a 4Ω speaker needs less 'copper', a smaller inductor,than a 8Ω speaker to let the sound decay at a certain frequency. Check also some 'online calculator' like the two-way crossoverStrassacker: Speaker - kits - do it yourself .
If the crossover is second order , 12 dB per octave, also the capacitor needs to be changed. But that's academical, as a new pair of speakers would-may be
totally different, like their sensibility; you would need to align also the tweeter
to the new configuration.
So it may be fairly easy, like unwinding a meter or so of wire from the lowpass coil, or a total re-build
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