Many sonotube questions in one place

Discussion in 'Archived Threads 2001-2004' started by James Slade, Jan 9, 2002.

  1. James Slade

    James Slade Second Unit

    Nov 20, 2001
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    I have ordered a tempest, like a lot of people seem to be doing lately. And I have purchased an 18" tube. I have built excellent cherry top and base plates to cover the plugs. I also ordered two 3" flared ports from adire.
    Now the questions.
    The adire alignment on their website seems excellent using the two 3" ports. I was originally going to build a tube to these basic specs. I then started to come across other designs by forum members. One such design is from Dustin. He is using 260L as apposed to the Adire 214L and a 6" port verese two 3" with Adire. Dustins port is over 2 feet long and the Adire alignment is under 1 foot. The Adire Alignment is tuned to 15.4Hz and Dustin's to 17Hz. What are some pro's and con's of each design besides physical size. I understand a larger port will slow down the air in the port, but what is it's effect on the sound besides just air in the port???
    Powering the Tempest.
    This seems to never be discussed. I want to wire the tempest in the way which will give the best possible performance. I will supply as much power is required. What do you recommend? A two channel amp, wiring the two Vc's together? Ideas.
    The Amp!!!
    Most people seem to be going with plate amps, this is not my plan. I want the amp in the rack not in the tube. Plate amps typically have a phase, gain, and crossover control.
    I am not too concerned about the cross over but I would like the other controls. Any suggestions?? I also don't like fans, unless it is super quite.
    The legs!!
    This also is never talked about. Adire's legs are 4 inches. Is this a requirement? Hopw much space does a driver need?
    This sub is going to be tall saving a few inches on the legs would be great!!
    Thanks to everyone who takes the time to read this and more thanks if you reply. Seems like maybe a sonotube forum is need, with the amount of questions being asked on the subject. To the experts who keep answering all of the questions thanks a bunch, we appreciate it!
  2. Brian Bowles

    Brian Bowles Second Unit

    Dec 3, 2001
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  3. Dustin B

    Dustin B Producer

    Mar 10, 2001
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    There is some formula that gets applied to figure out how much clearance a driver needs. I never looked into it enough to figure out what it is or why it is that way. However for a Tempest the result of the formula as given to me by Dr. Hyre of Adire is, damnit, can't find the email. Anyways it's either 3.5" or 4", email Adire and they can tell you what the actual minimum length required is.

    Two 3" ports have a combined surface area of 14.1372 in^2. One 6" port has a surface area of 28.2744 in^2. So one 6" port is essentially twice the porting you are considering. The general rule of thumb is that the port's length should be no more than 5x it's width. My port is just uner 25", which is just over 4 times the ports width.

    But what all this means is that if the port air speed is too high you can get audible port noise that people describe as a chuffing sound during high output. The more surface area there is for air to pass through the less likely this is to happen. People also talk about port compression in regaurds to multiple smaller ports vs single larger one, I don't understand this part so hopefully someone else can explain it.

    The wiring of the Tempest will depend on the amp you get. If it's a two channel amp with decent power into 8 ohms I'd go one channel to each voice coil. If you get a single channel amp then it better handle 4 ohms and you should then wire the voice coils in parellel. What amps are you considering. Also keep in mind that in my allignment 250 watts at 4ohms is all it takes to get the driver to Xmax.

    I'd think a QSC RMX 850 would be oodles of power (200 watts x2 at 8 ohms, 830watts bridged at 4ohms) and can be had for $299 new and less used. One of the reasons I went with the AVA250 was the rumble filter. According to LspCAD the AVA250 can get my Tempest to Xmax in my allignment, but that rumble filter also makes it impossible to bottom. You could just build a box for the AVA250 and stick that in your component rack :p)

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