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Author Topic: 16ohm horns vs 8ohm  (Read 3199 times)

tkroeker

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16ohm horns vs 8ohm
« on: June 06, 2015, 02:36:15 pm »

I building new cabinets but cant ever seem to understand how to decide on 8 vs 16 ohm horns. Lets say I want to build a cabinet with a 12 and a horn to put with an 18 cabinet. internal custom built crossover. I am looking at an 8 and a 16 version of the same driver thats 1300 hz and up. whats my determining factors?

Thanks
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Tim Weaver

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Re: 16ohm horns vs 8ohm
« Reply #1 on: June 06, 2015, 02:59:49 pm »

If you are building a passive crossover, just use whichever one is cheaper to buy crossover parts for. Its probably a wash either way.

If you will Biamp this cabinet I usually choose a 16 ohm driver because you could biamp it with a dsp amp by using one channel for the mid and the other channel for the horn. The 16 ohm horn will draw half the power from the amp meaning your amp power will line up better with the cabinet.
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Tim McCulloch

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Re: 16ohm horns vs 8ohm
« Reply #2 on: June 06, 2015, 03:02:53 pm »

The impedance used will dictate crossover component values to achieve a particular corner frequency.
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Ivan Beaver

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Re: 16ohm horns vs 8ohm
« Reply #3 on: June 06, 2015, 03:08:41 pm »

I building new cabinets but cant ever seem to understand how to decide on 8 vs 16 ohm horns. Lets say I want to build a cabinet with a 12 and a horn to put with an 18 cabinet. internal custom built crossover. I am looking at an 8 and a 16 version of the same driver thats 1300 hz and up. whats my determining factors?

Thanks
Consider the following.

You are going to have to "throw away" a bunch of the lower end of the response of the horn to keep up with the woofer.  This is not a bad thing.

But the TOP END-is where it starts to make a difference.  A 8 ohm driver will have more above 10Khz with a given input than a 16 ohms driver will.

So you will be able to have greater extension with the 8 ohm driver.

Granted you will have to "throw away" more with the 8 ohm than the 16 to stay with the woofer.

HOWEVER-16 ohms coils have lighter wire-so there is less moving mass.

So the high freq is a little better for the 16 ohm version.

But the 8 ohm should overall give you more output in the top octave where it is naturally falling off.
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Keith Broughton

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Re: 16ohm horns vs 8ohm
« Reply #4 on: June 07, 2015, 06:32:55 am »

Consider the following.


So the high freq is a little better for the 16 ohm version.

But the 8 ohm should overall give you more output in the top octave where it is naturally falling off.
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Frank Koenig

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Re: 16ohm horns vs 8ohm
« Reply #5 on: June 11, 2015, 02:19:19 pm »

HOWEVER-16 ohms coils have lighter wire-so there is less moving mass.

Hi Ivan, I'm having trouble with this. By my reckoning for constant input power, loss due to DC resistance, and motor force (B*l*i), the voice coil volume (and mass) is independent of impedance.

i (current) scales as the inverse square root of Z (impedance) for constant power

l (wire length in gap) scales as the square root of Z for constant motor force F = B * l * i

Re (DC resistance) scales as Z for constant loss = i^2 * Re

A (wire cross-sectional area) scales as the inverse square root of Z

v (wire volume) v = l * A remains constant

This neglects insulation volume and sphere-packing edge effects for round wire.

--Frank
« Last Edit: June 11, 2015, 02:22:55 pm by Frank Koenig »
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Ivan Beaver

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Re: 16ohm horns vs 8ohm
« Reply #6 on: June 11, 2015, 04:00:26 pm »

Hi Ivan, I'm having trouble with this. By my reckoning for constant input power, loss due to DC resistance, and motor force (B*l*i), the voice coil volume (and mass) is independent of impedance.

i (current) scales as the inverse square root of Z (impedance) for constant power

l (wire length in gap) scales as the square root of Z for constant motor force F = B * l * i

Re (DC resistance) scales as Z for constant loss = i^2 * Re

A (wire cross-sectional area) scales as the inverse square root of Z

v (wire volume) v = l * A remains constant

This neglects insulation volume and sphere-packing edge effects for round wire.

--Frank
Of course 8 or 16 ohms is not always 8 or 16 ohms, those are just the nearest standard numbers-so as not confuse people with the real facts.

To be honest-I have not actually measured 8 and 16 ohm versions of the same drivers to see the differences.  Our choices are based more on the final impedance desired and output SPL vs sensitivity.

I have been told by a couple of driver manufacturers that this is "the case".  So cannot confirm nor deny
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ProSoundWeb Community

Re: 16ohm horns vs 8ohm
« Reply #6 on: June 11, 2015, 04:00:26 pm »


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