# Looking for help with desing on tempest

Discussion in 'Home Theater Projects' started by andrewPerc, Jan 7, 2005.

1. ### andrewPerc Auditioning

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I am looking for some info on some possible issues I'm having with design of a 4th order bandpass box and a tempest 15" driver.

Note: I have built tons of boxes in the past but nothing within the last 8 years, so it is an understatement that I'm rusty with design let alone with the math. After say that here goes.

I want to use a 1 tempest driver in a 4th order bandpass design and then move to 2 in a isobaric design depending on the output I can achieve from a single driver.

I have been using the equations that I found off the “DIY subwoofer page: by Brain Steele” and I have some concerns/questions about the results obtained. With the use of the white paper for the tempest driver I calculated the box volumes for both the ported and seal side of the design. I received the following values:

Vented chamber 94.503 liters
Sealed chamber 79.847 liters
This was with a lower 3dB cutoff frequency of 28 Hz and a gain of 3.4.

When I calculate for gain of zero I get the following values at the same lower cutoff frequency:

Vented chamber 94.503 liters
Sealed chamber 134.641 liters

Neither of these volumes seems to be appropriate for a driver of this nature. A sealed chamber for a high power 15” with the T/S numbers of such I would suspect would run a lot more efficient in a much larger enclosure. I triple checked my math and the techniques to obtain these values and all seem to be correct.

I would like to know if anyone has tried this. What type of volumes are you guys getting with sealed boxed with a similar cutoff frequency?

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3. ### Patrick Sun Moderator Moderator

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In the past, people have had good experiences with the Tempest placed in a polyfill-stuffed 5 ft^3 enclosure, and rely on room gain to get that last bit of low end bass.

4. ### andrewPerc Auditioning

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So I can go with a sealed design of approx 5 cuft to obtain the same gain to freq cuttoff ratio?

5. ### ThomasW Cinematographer

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IMO bandpass are the worst sounding subs on the planet, one note bass, poor definition, poor transient response. (Bose designs are bandpass)

Since you have a Tempest and since Adire's already done a bunch of designs, just use one of their applications

6. ### andrewPerc Auditioning

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I'll look into it. It seems that every program I find or make for that matter changes the amount of volume needed anyway.

7. ### ThomasW Cinematographer

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The results from LspCAD and Unibox will be consistant.

8. ### andrewPerc Auditioning

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It seems to me, with my not to up-to-date knowledge of these subs, that they will not be able to product the output that I need in the space that I have.

Can anyone recommend a driver for my application?

I want to be able to have a driver or a set of drivers that will be able to take up to 800 watts each and fill 2700 sqft+. But will also have a good responce to lower power apps in smaller space, depending on the box design. From what I have been reading the tempest is the way to go, but will this driver be ablt to handle such a big room?

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