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Length of sonosub legs? (1 Viewer)

Brian Steeves

Second Unit
Joined
Dec 25, 2000
Messages
320
I am building another sonosub. This one is a dual Shiva in 24" tube. One driver on top and one on the bottom along with the port.
What I need to know is what should the distance be between the base plate and the bottom end cap? 4"? 6"?
Maybe Tom V will chime in here?
 

Brian Steeves

Second Unit
Joined
Dec 25, 2000
Messages
320
Hey Julian.
Yeah it really doesn't matter, I just thought Tom had done some tests on that dimension and came up with some more output at a certain height. It may or may not be the same for a sub like this but I just thought I'd ask. My last one, the single Tempest, had a distance of 6".
 

Rick P.

Stunt Coordinator
Joined
Mar 2, 1999
Messages
63
My legs are 2.25" and they're a bit too short, as Tom said they would be. As I recall, his 'magic number' was just under 3". You could probably go a bit lower if you use wide flared ports, but my ports (2x4") just use a 3/4" rounded routered edge.
I have played with my height a bit and found that low-end output improves by 3 or 4 dB until my subs are about 4" off the floor. Above that there is no change in the output.
BTW, how big of a port are you planning on using with dual drivers?
Rick
------------------
 

Dustin B

Senior HTF Member
Joined
Mar 10, 2001
Messages
3,126
Found what Dr. Hyre wrote to me in my email archive. This is in regards to a Tempest.
-----
For max performance, we recommend at least 3x cone area
in clearance under the sub driver (~4"), and at least one
vent diameter clearance from the wall, more on both if
possible.
-----
-----
(PI*D*H) = 3 * (PI*R*R) gives H=3.75" between floor &
driver.
-----
So the height for a Shiva would be around 3". But if you are using a 4" port than it should be at least 4" is how I interpret it.
 

Brian Steeves

Second Unit
Joined
Dec 25, 2000
Messages
320
Hey Guys, thanks for the responses.
This sub is more or less a Mike Knapp "Water Heater" clone. Although mine has beefier end caps and internal bracing.
So the port being used is 8" PVC (down firing).
 

Kyle Richardson

Screenwriter
Joined
Jan 1, 1998
Messages
1,073
I believe my Shiva sonosub had 4" legs while my Tempest has 6" legs. I don't know if they are the correct lengths but they seem to work well. :)
------------------AOL Instant Messenger Name: kyler70
 

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