near field c-c spacing question for small FR

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beat

near field c-c spacing question for small FR
« on: 12 Feb 2008, 12:58 am »
Hey guys,

Let me see if I understand the spacing premise correctly. From what I have read here and there, and the way my brain put it all together, the idea is to get your speakers as close together as possible to avoid any distortion. If we shoot for spacing them within one wavelength of the next speaker at their highest operating frequency, and we are running them full range we cant really get them close enough to be optimum so just get them as close as you can right?

I know I am skipping a bunch of science with this basic speech. I just want to make sure I am getting the proper grip on this.

thanks! Beat

OH yeah, for the record. These are 3 inch round and by near field I mean within just a few feet...like the dashboard of a car to be exact.

Rick Craig

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Re: near field c-c spacing question for small FR
« Reply #1 on: 12 Feb 2008, 02:25 am »
Hey guys,

Let me see if I understand the spacing premise correctly. From what I have read here and there, and the way my brain put it all together, the idea is to get your speakers as close together as possible to avoid any distortion. If we shoot for spacing them within one wavelength of the next speaker at their highest operating frequency, and we are running them full range we cant really get them close enough to be optimum so just get them as close as you can right?

I know I am skipping a bunch of science with this basic speech. I just want to make sure I am getting the proper grip on this.

thanks! Beat

OH yeah, for the record. These are 3 inch round and by near field I mean within just a few feet...like the dashboard of a car to be exact.

With one than one driver you don't want to run them full-range because of the comb filtering in the higher frequencies. This becomes even more audible when you are in close proximity to the drivers.

beat

Re: near field c-c spacing question for small FR
« Reply #2 on: 12 Feb 2008, 03:13 am »
With one than one driver you don't want to run them full-range because of the comb filtering in the higher frequencies. This becomes even more audible when you are in close proximity to the drivers.

Ahh,
that is why there is always talk of crossovers. So I should not let them run full range eh? I can manage that. If I let them run all the way up to 6-7000 ( I know that is high for a two way) will I run into the same problems with a 3" round? How do you measure wavelength?

Rick Craig

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Re: near field c-c spacing question for small FR
« Reply #3 on: 12 Feb 2008, 02:31 pm »
With one than one driver you don't want to run them full-range because of the comb filtering in the higher frequencies. This becomes even more audible when you are in close proximity to the drivers.

Ahh,
that is why there is always talk of crossovers. So I should not let them run full range eh? I can manage that. If I let them run all the way up to 6-7000 ( I know that is high for a two way) will I run into the same problems with a 3" round? How do you measure wavelength?

13,560 divided by the driver diameter will give you the one wavelength frequency (4,520 in your case). Because of off-axis driver behavior and cone profiles a cutoff of 1/2 wavelength or lower will be needed.

pheesama

Re: near field c-c spacing question for small FR
« Reply #4 on: 27 Feb 2008, 03:18 am »
Hey guys,

Let me see if I understand the spacing premise correctly. From what I have read here and there, and the way my brain put it all together, the idea is to get your speakers as close together as possible to avoid any distortion. If we shoot for spacing them within one wavelength of the next speaker at their highest operating frequency, and we are running them full range we cant really get them close enough to be optimum so just get them as close as you can right?

I know I am skipping a bunch of science with this basic speech. I just want to make sure I am getting the proper grip on this.

thanks! Beat

OH yeah, for the record. These are 3 inch round and by near field I mean within just a few feet...like the dashboard of a car to be exact.

greeting from Far East

What would happen if I line Full-Range drivers on a concarve baffle? Will this eliminate the comb behavior?

My goal is to archiev line array speakers on open baffle and run them with dozen of 6" Full-rangers.


Rick Craig

  • Industry Participant
  • Posts: 3680
  • Selah Audio
    • http://www.selahaudio.com
Re: near field c-c spacing question for small FR
« Reply #5 on: 28 Feb 2008, 02:43 pm »
Hey guys,

Let me see if I understand the spacing premise correctly. From what I have read here and there, and the way my brain put it all together, the idea is to get your speakers as close together as possible to avoid any distortion. If we shoot for spacing them within one wavelength of the next speaker at their highest operating frequency, and we are running them full range we cant really get them close enough to be optimum so just get them as close as you can right?

I know I am skipping a bunch of science with this basic speech. I just want to make sure I am getting the proper grip on this.

thanks! Beat

OH yeah, for the record. These are 3 inch round and by near field I mean within just a few feet...like the dashboard of a car to be exact.

greeting from Far East

What would happen if I line Full-Range drivers on a concarve baffle? Will this eliminate the comb behavior?

My goal is to archiev line array speakers on open baffle and run them with dozen of 6" Full-rangers.



This is a recipe for disaster because of the interference effects between the drivers. Making the baffle concave won't help.