cylinder enclosure- is basket too close to inside baffle? - diyAudio
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Old 26th August 2013, 11:36 PM   #1
osd1 is offline osd1  Canada
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Default cylinder enclosure- is basket too close to inside baffle?

Hey now.

I am about to start building a speaker enclosure. I have a 6" midwoofer and I want to do something a little different. I was thinking of making a cylinder enclosure for the midwoofer, then one for the tweeter.

The basket is about 5.75" so I was going to make the from baffle with a 5.75" cutout inside of a 9" circle. After that I was going to increase the size of the cutout hole of the 9" circle, making it 8."

Is that an ok idea? I am not going to run into any problems with standing waves am I? Also, is it ok if the basket is 1-1/8" away from the inside baffle all the way around?

I have no problems building it as i am a woodworker, its just the sound side of things I have questions on.

Thanks in advance
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Old 27th August 2013, 10:13 AM   #2
AllenB is offline AllenB  Australia
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It's a little hard to say but easy enough to take precautions. Can you chamfer the inside of the inner baffle so that it doesn't restrict the rearward flow? Make sure the space behind the driver doesn't seem small compared to the cone unless you are designing it to be that way, and don't overstuff it for the same reason.

Try not to reflect any sound from nearby walls directly back at the driver. This is not easy with a curved rear panel and, together with room for stuffing, might be one more reason to have just a little more room behind the driver.
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Old 27th August 2013, 03:00 PM   #3
badman is offline badman  United States
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Make sure the basket can "breathe" as stated, and after 5.75", 8" should be plenty, so long as you don't impede airflow with fluffy stuffing around the driver. Lining the walls with felt may be worthwhile depending on the frequencies of concern.
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Old 27th August 2013, 07:06 PM   #4
osd1 is offline osd1  Canada
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Quote:
Originally Posted by AllenB View Post
It's a little hard to say but easy enough to take precautions. Can you chamfer the inside of the inner baffle so that it doesn't restrict the rearward flow? Make sure the space behind the driver doesn't seem small compared to the cone unless you are designing it to be that way, and don't overstuff it for the same reason.

Try not to reflect any sound from nearby walls directly back at the driver. This is not easy with a curved rear panel and, together with room for stuffing, might be one more reason to have just a little more room behind the driver.
I can def chamfer inside the cutout of the woofer. This is for a 6" midrange in a 3 way. I am not gonna be sure what the crossover point is gonna be for the 6". There will be an 8" driver for the bass operations.

So the SB23NRX 8" will be in a regular rectangle enclosure. On top of it, the SB 17NRX 6" will be in its own enclosure, a cylinder one. Above that will be a Morel tweeter, in its own cylinder enclosure.

So far I have a depth of 8.25" interior measurement. That, unstuffed, will give me a volume of .23 ft3 including driver displacement. Madisound recommends .25ft3 for the SB 6" woofer but doesn't say how much stuffng is needed.
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Old 27th August 2013, 07:08 PM   #5
osd1 is offline osd1  Canada
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Originally Posted by badman View Post
Make sure the basket can "breathe" as stated, and after 5.75", 8" should be plenty, so long as you don't impede airflow with fluffy stuffing around the driver. Lining the walls with felt may be worthwhile depending on the frequencies of concern.
I am not quite sure exactly what frequencies in specific are gonna be sent to this driver. I won't know till I get a crossover design from the person who is doing it. I can tell you that its probably going to be an upper midbass and midrange.
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Old 27th August 2013, 10:18 PM   #6
badman is offline badman  United States
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Then probably a 1/2" layer of felt, for a midbass, is a wise idea- won't block the backwave but will soak up some early reflections.
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Old 28th August 2013, 01:22 AM   #7
osd1 is offline osd1  Canada
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Then probably a 1/2" layer of felt, for a midbass, is a wise idea- won't block the backwave but will soak up some early reflections.
do i want to block the back wave?
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Old 28th August 2013, 09:57 AM   #8
AllenB is offline AllenB  Australia
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It looks as if you might end up choosing a crossover as far as 1kHz - 4kHz??

It's not a bad idea to have your stuffing distributed over say, half of the cabinet depth. This ensures that it will work more consistently over a range of frequencies.

You'll then want to adjust the density of the material, which you could do while listening.

Last edited by AllenB; 28th August 2013 at 10:00 AM.
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Old 28th August 2013, 05:08 PM   #9
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Cross the 6" over at around 2.5-2.7kHz for best off axis power response.
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Old 29th August 2013, 02:46 PM   #10
badman is offline badman  United States
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Originally Posted by osd1 View Post
do i want to block the back wave?
No. You definitely don't want to reflect sound back towards the cone- that's why lining the walls around the driver with felt, rather than using stuffing, is a good idea. Stuffing's okay too but takes more care, you'd want it quite loose, and keeping it from interfering with cone motion can be challenging (something like a "sock" will add it's own reflective and absorbtive properties to the mix)
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