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#### mcallister

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I have a sono build that uses an Avalanche 18. The sonotube is 30" diameter and from bottom end cap to top endcap measures 54.5". The Length across the endcaps is 32".

Now I had my brother in law build this as I am terrible at DIY and really don'g understand it
So as of now I believe it's tuned to 16Hz. I'm wanting to lower the tuning to around 11Hz. Forgot to mention I am using an 8 inch port not flared (sonotube as well). The port now is 20". Curious what port length would be for 11-13hz tuning (flattest response)?

What lower tune can I go to and still have a good response curve?

The reason I'm wanting to lower the tuning is for Christmas he built me a sealed cabinet that I'm putting an Maelstrom in. I will be using both subs (I know some people frown upon different subs and getting them setup but what the hell)

Thanks for any help!!!

#### mcallister

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"paging mr. herman, mr. herman you have a telephone call" (bump)

#### mjg100

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Lv={ 8466.4R^2/(Vb)Fb^2} - 1.463R

Lv=port length

R= radius of port (half the diameter)

Vb=volume of box in cubic feet

Fb=tuning frequency

#### mcallister

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
Quote:
Originally Posted by mjg100 /forum/post/15573730

Lv={ 8466.4R^2/(Vb)Fb^2} - 1.463R

Lv=port length

R= radius of port (half the diameter)

Vb=volume of box in cubic feet

Fb=tuning frequency

This is what I don't understand?

#### mjg100

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For your sub tuned to 11 Hz.

R=4

Vb=22.2826 CF

Fb=11

Lv=44.39" This is based on using 8" diameter port. (11Hz)

For 12 Hz Lv=36.37"

For 13 Hz Lv=30.12"

As far as flat curve, I do not know which tuning will provide the flattest response.

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